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TECHNICAL NOTES on Brick Construction

Index

1850 Centennial Park Drive, Reston, Virginia 20191 | www.gobrick.com | 703-620-0010

June 2009

Subject Index Technical Notes on Brick Construction

SUBJECT

is a series of bulletins that contain design, detailing and construction information based on the latest technical developments in brick masonry. Drawings, photographs, tables and charts illustrate appropriate topics. They are available individually or as a set. Registered purchasers of a complete set will receive notification of new or revised editions via email.

Materials 21A Passive Solar Heating 43 Properties 21 Chimneys 19-19C Classification of Brick 9A Cleaning 20 Efflorescence 20 Coatings for Brick 6, 6A Cold Weather Construction 1 Guide Specifications 11A Color - Brick 9 Mortar 8 Columns and Pilasters 3B Compressive Strength Brick Masonry 3A, 39A, 42 Brick Units 9A, 39 Mortar 8 Series Walls 39A, 42 Condensation 28B, 47 Control Joints (see Expansion Joints) Copings 36 Corbels and Racking 36A Corrosion Metal Ties 7A, 44B Shelf Angles 7A Steel Lintels 7A, 31B Coursing Tables for Brick 10 Cracking 18 Curtain and Panel Walls 17L

Individual copies are available to view and download free of charge from BIA’s website at www.gobrick.com. To view, download or order Technical Notes, go to the BIA website at www. gobrick.com and select Technical Notes.

SUBJECT

NUMBER

A ACI 530/ASCE 5/TMS 402 Building Code 3 Admixtures in Mortar 1,8 Anchor Bolts 44 Arches 31-31C Construction 31 Flashing 31 Semi-circular 31C Structural Design 31A ASTM International Standards Anchors and Ties 7A, 28B, 44B Brick 9A Mortar 8 Pavers 9A, 14 Testing 39 Series

B Barrier Walls Beams Bearing Walls (see Engineered Brick Masonry) Bonds and Patterns in Brickwork Paving Patterns Bond Breaks Bond - Mortar Reinforced Brick Masonry Brick Sizes

7 17B

30 14, 29 18A, 21B 8 Series 17, 17A 9B, 10

C Calculated Fire Resistance Caps Cavity Walls Construction Detailing Glazed Brick

16 36A 21-21C 21C 21B 13

NUMBER

D Dampproofing Differential Movement Bond Breaks Expansion Joints in Paving Expansion Joints in Walls Flexible Anchorage Material Properties Structures without Shelf Angles Volume Changes and Effects Dimensioning Direct Gain, Passive Solar Heating Drainage Walls

46 18, 18A 18A 14 Series 18A 18A 18 18A 18 10 43 7

E Efflorescence Identification and Prevention Causes and Prevention Removal Empirical Design of Brick Masonry Energy Codes Embodied Heat Transmission Coefficients Engineered Brick Masonry Allowable Design Stresses Bearing Wall

© 2009 Brick Industry Association, Reston, Virginia

23 23A 20 42 4B 48 4

SUBJECT

NUMBER

Building Code Requirements Construction Detailing Guide Specifications Material Properties Quality Control Section Properties Shear Wall Design Testing Wall Types and Properties Equivalent Thickness Estimating Material Quantities Expansion Joints Paving

3, 16 24F 24G 11 Series 3A 39B 3B 24C 39 Series 3B 16 10 18A 14 Series

F Fasteners for Brick Masonry 44A Fences 29A Field Panels 9B Fireplaces, Residential 19-19E Contemporary, Projected Corner, Rumford, Multi-faced 19C Details and Construction 19B Finnish Style Masonry Heater 19E Russian Style Masonry Heater 19D Fire Resistance 16 Flashing, Types and Selection 7A Arches 31 Details 7 Replacement 46 Flexible Paving Systems 14 Floor-Wall Connections, Bearing Wall 26 Freeze Thaw Durability 7A, 9A, 9B Freezing, Protection from 1

G Garden Walls Girders, Reinforced Brick Masonry Glazed Brick Specifications Walls Glossary Green Building Grout Properties Testing Guide Specifications

29A 17M 9A 13 2 48 17, 17A 3A 39 11 Series

H Heat Transmission Coefficients High-Lift Grouting Hollow Brick Masonry Reinforced Hot Weather Construction

4 17A 41 17 Series 1

3A, 39A 24

Page 1 of 4

SUBJECT

NUMBER

I Inspection Reinforced Brick Masonry Initial Rate of Absorption

46 17A 7A, 8B, 9A 9B, 39

L Landscape Architecture Garden Walls Miscellaneous Applications Paving Pedestrian Applications Lateral Forces, Shear Wall Design LEED Lintels Reinforced Brick Structural Steel Loadbearing Brick Homes

29-29B 29A 29B 14 Series 29 24C 48 17B 31B 26

M Maintenance 46 Cleaning 20 Manufacturing Brick 9 Material Properties 3A Masonry Heaters 19D, 19E Modular Brick Masonry 10 Moisture Control Barrier Walls 7 Caps and Copings 7, 36A Condensation 47 Corrosion 7A, 31B, 44B Drainage Walls 7 Flashing 7A Glazed Brick Walls 13 Maintenance 46 Mortar 8 Rain Screen Wall 27 Repointing 46 Water Repellent Coatings 6A Weeps 7 Moisture Expansion 18 Mortars for Brickwork 8 Series Cold Weather Construction 1 Efflorescence 8, 23 Series Estimating Quantities 10 Guide Specifications 11E Joints 7B, 21C Materials 8 Mixing 8B Paving Systems 14 Quality Assurance 8B Reinforced Masonry 17A Repointing 46 Selection 8B Movement (see Differential Movement)

N Noise Barrier Walls Structural Design

45 45A

P Painting Brick Masonry Parapets Passive Solar Cooling Details

6 7, 18 Series, 36A 43C 43G

SUBJECT

NUMBER

Heating 43 Materials 43D Patterns 30 Paving Systems 14 Series Accessibility 14 Bases 14 Clay Pavers 9A, 14 Cleaning 20 Coatings 6A Details 14 Series Drainage 14 Series Edge Restraint 14 Series Expansion Joints 14 Series Ice and Snow Removal 14 Installation 14 Series Interlock 14A Maintenance 14 Series Patterns 14, 29 Permeable Pavements 14 Sand Setting Bed 14A Traffic 14 Piers and Pilasters 3B Portland Cement/Lime Mortar 8 Series Prefabricated Brick Masonry Introduction 40 Thin Brick 28C Pressure-Equalized Rain Screen Wall 27

R Rain Penetration (see Moisture Control) Rain Screen Wall 27 Recycled Content 48 Reinforced Brick Masonry Beams 17B Curtain and Panel Walls 17L Flexural Design 17B Girders 17M High-Lift Grouted 17A History 17 Hollow Brick Masonry 26, 41 Inspection 17A Lintel Design 17B Materials 17A Mortar and Grout 17A Specifications 11 Series Workmanship 17A Repointing 46 Retrofit 28A Rigid Paving Systems 14 Rumford Fireplaces 19C R-Values 4, 4B

SUBJECT

NUMBER

Slip/Skid Resistance 14 Soffits 36 Solar Energy (see Passive Solar Systems) Sound Barriers (see Noise Barrier Walls) Sound Insulation 5A Spalling 46 Specifications, General 11 Series ACI 530.1/ASCE 6/TMS 602 3 Brick 9A Cold and Hot Weather Construction 1 Mortars 8, 11E Pavers 9A Stains Identification and Prevention 23 Removal 20 Steel Studs 28B Steps and Ramps 29 Sustainability 48 Sustainable Development 29

T Terminology 2 Terraces 29 Testing of Brick and Mortar 39 Series Allowable Design Stresses 3A, 39A Quality Control 39B Thermal Expansion of Walls 18 Series Thermal Storage Walls, Passive Solar Heating 43 Thermal Transmission Coefficients 4 Thin Brick 28C Ties and Reinforcement Adjustable 44B Corrosion Resistance 7A, 44B Joint Reinforcement 44B Specifications 11A Tolerances 9A, 11C Tooling 7B Tuckpointing (see Repointing)

U Used Brick U-Values

15 4, 4B

V Veneer Construction Existing Construction Hollow Brick Steel Studs Thin Brick Veneer Wood Studs

28 Series 28A 41 28B 28C 28

W

S Salvaged Brick Sealers (see Water Repellents) Sealants Section Properties Selection of Brick Serpentine Walls Shelf Angles Typical Details Corrosion Resistance Single-Wythe Bearing Walls Sills Sizes of Brick

15 18A, 28 3B 9B 29A 7, 28B 7A 26 36 9B, 10

Wall Ties 44B Water Penetration (see Moisture Control) Water Repellent Coatings 6A Weeps 7, 46 Winter Construction (See Cold Weather Construction) Workmanship 7B, 21C Reinforced Brick Masonry 17A Specifications 11 Series

www.gobrick.com | Brick Industry Association | TN INDEX | Subject Index | Page 2 of 4

Numerical Index Technical Notes are rewritten to include new technical information. The issue date of a current Technical Note is shown between brackets [ ]. Current editions supersede earlier editions. The designation Reissued indicates that the edition of the Technical Note shown in brackets [ ] has been thoroughly reviewed and found to be technically accurate. Other editions dated on or after the bracketed [ ] date are still valid; only minor editorial changes have been made. The reissued date appears in parentheses ( ). Missing numbers have been discontinued.

1 [June 2006] Cold and Hot Weather Construction 2 Rev [Jan./Feb. 1975] (Reissued March 1999) Glossary of Terms Relating to Brick Masonry 3 Rev [July 2002] Overview of Building Code Requirements for Masonry Structures ACI 530-02/ASCE 5-02/TMS 402-02 and Specifications for Masonry Structures ACI 530.1-02/ASCE 6-02/TMS 602-02 3A [Dec. 1992] Brick Masonry Material Properties 3B [May 1993] Brick Masonry Section Properties 4 Rev [Jan. 1982] (Reissued Sept. 1997) Heat Transmission Coefficients of Brick Masonry Walls 4B Rev [Feb. 2002] Energy Code Compliance of Brick Masonry Walls 5A [June 1970] (Reissued Aug. 2000) Sound Insulation – Clay Masonry Walls 6 Rev [May 1972] (Reissued Dec. 1985) Painting Brick Masonry 6A [Aug. 2008] Colorless Coatings for Brick Masonry 7 [Dec. 2005] Water Penetration Resistance – Design and Detailing 7A [Dec. 2005] Water Penetration Resistance – Materials 7B [Dec. 2005] Water Penetration Resistance – Construction and Workmanship 8 [Jan. 2008] Mortars for Brickwork 8B [Oct. 2006] Mortars for Brickwork – Selection and Quality Assurance 9 [Dec. 2006] Manufacturing of Brick 9A [Oct. 2007] Specifications for and Classification of Brick 9B Rev [Dec. 2003] Manufacturing, Classification and Selection of Brick – Selection, Part III 10 [Feb. 2009] Dimensioning and Estimating Brick Masonry 11 Rev [Dec. 1971] (Reissued Aug. 2001) Guide Specifications for Brick Masonry, Part I

11A Rev [June 1978] (Reissued Sept. 1988) Guide Specifications for Brick Masonry, Part II 11B Rev [Feb. 1972] (Reissued Sept. 1988) Guide Specifications for Brick Masonry, Part III 11C Rev [July 1972] (Reissued May 1998) Guide Specifications for Brick Masonry, Part IV 11D [Aug. 1972] (Reissued Sept. 1988) Guide Specifications for Brick Masonry, Part IV Continued 11E Rev [Sept. 1991] Guide Specifications for Brick Masonry, Part V, Mortar and Grout 13 [Dec. 2005] Ceramic Glazed Brick Exterior Walls 14 [Mar. 2007] Paving Systems Using Clay Pavers 14A [Oct. 2007] Paving Systems Using Clay Pavers on a Sand Setting Bed 15 Rev [May 1988] Salvaged Brick 16 [Mar. 2008] Fire Resistance of Brick Masonry 17 Rev [Oct. 1996] Reinforced Brick Masonry, Introduction 17A Rev [Aug. 1997] Reinforced Brick Masonry – Materials and Construction 17B Rev [Mar. 1999] Reinforced Brick Masonry Beams 17L Rev [Feb./Mar. 1973] (Reissued Sept. 1988) Four-inch RBM Curtain and Panel Walls 17M [July 1968] (Reissued Sept. 1988) Reinforced Brick Masonry Girders – Examples 18 [Oct. 2006] Volume Changes – Analysis and Effects of Movement 18A [Nov. 2006] Accommodating Expansion of Brickwork 19 Rev [Jan. 1993] Residential Fireplace Design 19A Rev [May 1980] (Reissued Aug. 2000) Residential Fireplaces, Details and Construction 19B Rev [June 1980] (Reissued Apr. 1998) Residential Chimneys – Design and Construction 19C Rev [Oct. 2001] Contemporary Brick Masonry Fireplaces 19D [Jan. 1983] (Reissued June 1987) Brick Masonry Fireplaces, Part I, Russian-Style Heaters 19E [1983] (Reissued Feb. 1998) Brick Masonry Fireplaces, Part II Fountain and Contemporary Style Heaters 20 [June 2006] Cleaning Brickwork 21 Rev [Aug. 1998] Brick Masonry Cavity Walls – Introduction 21A Rev [Feb. 1999] Brick Masonry Cavity Walls – Selection of Materials 21B [Apr. 2002] Brick Masonry Cavity Walls – Detailing

21C Rev [Oct. 1989] Brick Masonry Cavity Walls – Construction 23 [June 2006] Stains – Identification and Prevention 23A [June 2006] Efflorescence – Causes and Prevention 24 Rev [June 2002] Brick Masonry Bearing Walls – Introduction 24C Rev [Sept./Oct. 1970] (Reissued May 1988) The Contemporary Bearing Wall – Introduction to Shear Wall Design 24F Rev [Nov./Dec. 1974] (Reissued Sept. 1988) The Contemporary Bearing Wall – Construction 24G [Dec. 1968] (Reissued Feb. 1987) The Contemporary Bearing Wall – Detailing 26 Rev [Sept. 1994] Single Wythe Bearing Walls 27 Rev [Aug. 1994] Brick Masonry Rain Screen Walls 28 Rev [Aug. 2002] Anchored Brick Veneer, Wood Frame Construction 28A [Apr. 2008] Adding Brick Veneer to Existing Construction 28B [Dec. 2005] Brick Veneer / Steel Stud Walls 28C [Jan. 1986] (Reissued Jan. 2001) Thin Brick Veneer – Introduction 29 Rev [July 1994] Brick in Landscape Architecture – Pedestrian Applications 29A Rev [Nov. 1968] (Reissued Jan. 1999) Brick in Landscape Architecture – Garden Walls 29B [Apr. 1967] (Reissued May 1988) Brick in Landscape Architecture – Miscellaneous Applications 30 Rev [Mar. 1999] Bonds and Patterns in Brickwork 31 Rev [Jan. 1995] Brick Masonry Arches 31A [Oct. 1967] (Reissued July 1986) Structural Design of Brick Masonry Arches 31B Rev [Nov./Dec. 1981] (Reissued May 1987) Structural Steel Lintels 31C Rev [Feb. 1971] (Reissued Aug. 1986) Structural Design of Semicircular Brick Masonry Arches 36 Rev [July/Aug. 1981] (Reissued Jan. 1998) Brick Masonry Details, Sills and Soffit 36A Rev [Sept./Oct. 1981] (Reissued Feb. 2001) Brick Masonry Details, Caps and Copings, Corbels and Racking 39 Rev [Nov. 2001] Testing for Engineered Brick Masonry – Brick and Mortar 39A [July/Aug. 1975] (Reissued Dec. 1987) Testing for Engineered Brick Masonry – Determination of Allowable Design Stresses 39B Rev [Mar. 1988] Testing for Engineered Brick Masonry – Quality Control 40 Rev [Aug. 2001] Prefabricated Brick Masonry – Introduction 41 [Jan. 2008] Hollow Brick Masonry 42 Rev [Nov. 1991] Empirical Design of Brick Masonry

www.gobrick.com | Brick Industry Association | TN INDEX | Numerical Index | Page 3 of 4

43 Rev [May/June 1981] Passive Solar Heating with Brick Masonry – Part I Introduction 43C [Mar. 1980] (Reissued Feb. 2001) Passive Solar Cooling with Brick Masonry, Part I – Introduction 43D [Sept./Oct. 1980] (Reissued Sept. 1988) Brick Passive Solar Heating Systems, Part IV – Material Properties 43G [Mar./Apr. 1981] (Reissued Sept. 1986) Brick Passive Solar Heating Systems, Part VII – Details and Construction 44 [Apr. 1986] Anchor Bolts for Brick Masonry 44A [May 1986] (Reissued Aug. 1997) Fasteners for Brick Masonry 44B Rev [May 2003] Wall Ties for Brick Masonry 45 [Feb. 1991] (Reissued July 2001) Brick Masonry Noise Barrier Walls – Introduction 45A [Apr. 1992] Brick Masonry Noise Barrier Walls – Structural Design 46 [Dec. 2005] Maintenance of Brick Masonry 47 [June 2006] Condensation – Prevention and Control 48 [June 2009] Sustainability and Brick

Changes to Technical Notes (since December 2005)

New and Revised 1 June 2006 6A August 2008 7 December 2005 7A December 2005 7B December 2005 8 January 2008 8B October 2006 9 December 2006 9A October 2007 10 (replaces 10, 10A & 10B) February 2009 13 December 2005 14 March 2007 14A October 2007 16 (replaces 16 & 16B) March 2008 18 October 2006 18A November 2006 20 June 2006 23 June 2006 23A June 2006 28A April 2008 28B December 2005 41 January 2008 46 (replaces 7F) December 2005 47 (replaces 7C & 7D) June 2006 48 June 2009

Retired 7C (replaced by 47) 7D (replaced by 47) 7F (replaced by 46) 8A 10A (replaced by 10) 10B (replaced by 10) 16B (replaced by 16)

June 2006 June 2006 December 2005 January 2008 February 2009 February 2009 March 2008

www.gobrick.com | Brick Industry Association | TN INDEX | Numerical Index | Page 4 of 4

TECHNICAL NOTES on Brick Construction

1

1850 Centennial Park Drive, Reston, Virginia 20191 | www.gobrick.com | 703-620-0010

June 2006

Cold and Hot Weather Construction Abstract: This Technical Note defines cold and hot weather conditions related to brick masonry construction and describes the unfavorable effects of these conditions on masonry materials and their performance. It provides information on weather prediction necessary for construction planning and recommends practices to achieve optimum performance of masonry constructed during periods of extreme temperatures. Key Words: absorption, ambient temperature, climatology, cold weather, evaporation, freezing, grout, hot weather, meteorology.

SUMMARY OF RECOMMENDATIONS: • Comply with cold and hot weather requirements of applicable building codes

• Follow requirements given in Table 1

INTRODUCTION Adequate planning and preparation can make brick construction possible in virtually all weather conditions. Cold and hot weather can negatively affect masonry materials and the quality of constructed masonry. However, implementing recommended changes to construction practices can usually ensure quality construction. Although “normal,” “cold,” and “hot” are relative terms, normal, used in this Technical Note, is any temperature between 40 ºF and 100 ºF (4.4 ºC and 37.8 ºC). Cold is defined as temperature below 40 ºF (4.4 ºC); and hot, any temperature above 100 ºF (37.8 ºC).

BUILDING CODE REQUIREMENTS In many instances, building codes include mandatory measures intended to ensure the quality of masonry constructed during cold or hot weather. The International Building Code (IBC) [Ref. 1] includes a list of required cold and hot weather construction provisions for masonry that are essentially identical to those found in Specification for Masonry Structures (ACI 530.1/ASCE 6/TMS 602) [Ref. 11] and required by Building Code Requirements for Masonry Structures (ACI 530/ASCE 5/TMS 402) [Ref. 6], both of which are referenced by the IBC. The Specification for Masonry Structures provisions differ from those of the IBC in that they also require the submittal and acceptance of a description of the hot and cold weather construction program prior to its use. The mandatory cold and hot weather construction practices required by the IBC and Building Code Requirements for Masonry Structures are summarized in Table 1. Specific cold and hot weather provisions are not included within the International Residential Code (IRC) [Ref. 2]. However, the IRC states that mortar for use in masonry construction shall comply with ASTM C 270, which requires mortar for other than masonry veneer to be prepared in accordance with the Masonry Industry Council's "Hot and Cold Weather Masonry Construction Manual" [Ref. 8]. Hot and cold weather provisions apply to brick veneer when the provisions of Building Code Requirements for Masonry Structures are used in lieu of the IRC masonry provisions.

PLANNING FOR EXTREME WEATHER To successfully build during periods of extreme weather conditions, designers and contractors utilize knowledge of local meteorological conditions, as well as historic climatological information for a given area. During project planning, designers are concerned with climatological data such as the average and extreme daytime and nighttime temperatures or average wind velocity for use in designing mechanical or structural systems. Contractors, however, are more concerned with meteorological conditions during construction, such as hourly temperatures and mean daily temperature, as well as the predicted temperatures and wind velocities for the next few days. Mean daily temperature is determined by adding together the maximum temperature for each day (24 hours, midnight to midnight) and the minimum temperature for the same day and dividing by two. Ambient temperature as used in this Technical Note is the outdoor temperature at the time considered. Page 1 of 9

TABLE 1 Requirements for Masonry Construction in Hot and Cold Weather Temperature1

Hot Weather

Above 115 ºF or 105 ºF with a wind velocity over 8 mph (46.1 ºC or 40.6 ºC with a 12.9 km/hr wind)

Preparation Requirements

Construction Requirements

Protection Requirements

(Prior to Work)

(Work in Progress)

(After Masonry Is Placed)

Use cool mixing water for mortar and grout. Ice must be melted or removed before water is added to other mortar or grout materials.

Comply with hot weather requirements below.

Shade materials and mixing equipment from direct sunlight. Comply with hot weather requirements below.

Comply with hot weather requirements below. Maintain mortar and grout at a temperature below 120 ºF (48.9 ºC).

Above 100 °F or 90 °F with 8 mph wind (above 37.8 °C or 32.2 °C with a 12.9 km/hr wind)

Provide necessary conditions and equipment to produce mortar having a temperature below 120 ºF (48.9 ºC).

Flush mixer, mortar transport container, and mortar boards with cool water before they come into contact with mortar ingredients or mortar.

Maintain sand piles in a damp, loose condition.

Maintain mortar consistency by retempering with cool water.

Fog spray newly constructed masonry until damp, at least three times a day until the masonry is three days old.

Normal Weather

Use mortar within 2 hr of initial mixing. 100 °F to 40 °F (37.8 °C to 4.4 °C)

40 °F to 32 °F (4.4 °C to 0 °C)

Normal Procedures.

Normal Procedures.

Do not lay masonry units having either a temperature below 20°F (-6.7°C) or containing frozen moisture, visible ice, or snow on their surface.

Heat mixing water or sand to produce mortar between 40 °F (4.4 ºC) and 120 °F (48.9 ºC).

Remove visible ice and snow from the top surface of existing foundations and masonry to receive new construction. Heat these surfaces above freezing, using methods that do not result in damage.

Do not heat water or aggregates used in mortar or grout above 140 ºF (60 ºC). Heat grout materials when their temperature is below 32 ºF (0 ºC).

Normal Procedures.

Completely cover newly constructed masonry with a weather-resistive membrane for 24 hr after construction.

Comply with cold weather requirements above.

Cold Weather

Maintain mortar temperature above freezing until used in masonry. 32 °F to 25 °F (0 °C to -3.9 °C)

Comply with cold weather requirements above.

Heat grout materials so grout is at a temperature between 70 ºF (21.1 ºC) and 120 ºF (48.9 ºC) during mixing and placed at a temperature above 70 ºF (21.1 ºC). Comply with cold weather requirements above.

25 °F to 20 °F (-3.9 °C to -6.7 °C)

Comply with cold weather requirements above.

Heat masonry surfaces under construction to 40°F (4.4°C) and use wind breaks or enclosures when the wind velocity exceeds 15 mph (24 km/h).

Comply with cold weather requirements above.

Completely cover newly constructed masonry with weatherresistive insulating blankets or equal protection for 24 hr after completion of work. Extend time period to 48 hr for grouted masonry, unless the only cement in the grout is Type III portland cement.

Heat masonry to a minimum of 40°F (4.4°C) prior to grouting.

Comply with cold weather requirements above. 20 °F and Below (-6.7 °C and Below)

Comply with cold weather requirements above.

Provide enclosure and heat to maintain air temperatures above 32 ºF (0 ºC) within the enclosure.

Maintain newly constructed masonry temperature above 32°F (0°C) for at least 24 hr after being completed by using heated enclosures, electric heating blankets, infrared lamps, or other acceptable methods. Extend time period to 48 hr for grouted masonry, unless the only cement in the grout is Type III portland cement.

1. Preparation and Construction requirements are based on ambient temperatures. Protection requirements, after masonry is placed, are based on mean daily temperatures .

www.gobrick.com | Brick Industry Association | TN 1 | Cold and Hot Weather Construction | Page 2 of 9

Meteorological information can be obtained from the National Weather Service, a branch of the National Oceanographic and Atmospheric Administration (NOAA). The National Weather Service has information centers located at major airports in cities throughout the country. These centers provide current weather information and regularly scheduled weather forecasts for the surrounding region. Climatological information can be obtained from the National Climatic Data Center, also a branch of NOAA. The National Climatic Data Center usually provides climatic information in the form of maps as shown in Figure 1. These maps contain daily, monthly and annual data for a region and may be obtained free online or by contacting the Center [Ref. 7].

LEGEND

January Mean Daily Minimum Temperature

January Mean Daily Maximum Temperature

Figure 1 Examples of Climatic Data Available

NEGATING THE EFFECTS OF COLD WEATHER Successful construction considers the effects of cold weather on masonry materials in the planning, scheduling and set up of the masonry work and protection of the completed work. This section describes the properties of masonry and masonry materials that are changed by low temperatures and code prescribed construction procedures that overcome these effects. In addition to anticipating specific weather conditions, these provisions, presented in Table 1, assist the contractor in determining how to protect building materials, unfinished and newly constructed masonry. In regard to the quality of masonry constructed during cold weather, perhaps the most critical factor is ensuring that mortar and grout maintain adequate heat for normal cement hydration. Without sufficient heat, cement hydration slows and may stop completely, arresting the development of the masonry’s compressive and bond strengths.

Heating Materials Masonry Units. Masonry units are the components of a masonry assembly least affected by below-normal temperatures. The physical properties of masonry units are essentially unchanged by cold weather, however, the temperature of brick and their absorption characteristics influence the rate of freezing of masonry. A cold masonry unit will have a slightly smaller volume than one at normal temperatures. Cold units draw heat from mortar and more rapidly reduce the temperature of mortar to points at which normal cement hydration is retarded and freezing occurs. Preheating masonry units prior to laying helps to maintain heat within the mortar and minimize the effect of cold temperatures on mortar hydration. When ambient temperatures are below 20 ºF (-6.7 ºC), masonry units must be heated to a temperature of at least 40 ºF (4.4 ºC) prior to laying. Masonry units having either a temperature below 20 °F (-6.7 °C) or containing frozen moisture, visible ice or snow on their surface must not be laid. Frozen masonry units must be thawed and should by dried before use. Unit temperature can be measured using a metallic surface contact thermometer or flat, instant-read thermometer. It may be advantageous to heat brick even when ambient temperatures are above 20 ºF (-6.7 ºC). Preheated brick will exhibit the same absorption characteristics as those laid at normal temperatures. Brick with higher Initial Rates of Absorption (IRAs) more rapidly absorb water from mortar or grout, thereby reducing the risk of damage from the expansive forces of freezing water in the mortar. Mortar. Mortar mixed using cold materials has different properties from mortar mixed with materials at normal temperatures. Low temperatures retard the hydration of the cement in mortar. Mortar mixed during cold weather often www.gobrick.com | Brick Industry Association | TN 1 | Cold and Hot Weather Construction | Page 3 of 9

has lower water content, increased air content, and reduced early strength compared with mortar mixed at normal temperatures. In freezing weather, ice may be present in mixing water and moisture in the sand may turn to ice. Ice in the mixing water must be melted or removed before the water can be added to the mixer. Do not use sand containing frozen particles or frost. At a minimum, any ice must be melted and additional heating may further improve mortar performance. Avoid freezing of mortar during construction in all cases. In cold weather, mix mortar in smaller amounts so it can be used before it cools. In any case, use mortar within 21/2 hours from the time of initial mixing. Mortar that freezes may experience significant reductions in compressive strength. Further, bond strength, extent of bond and water penetration resistance of masonry may be reduced. Mortar having a water content exceeding six percent of the total volume may be damaged due to the increase in volume as freezing water is converted to ice. Mortar mixed with heated materials can approximate the performance characteristics of mortar mixed at normal temperatures. For these reasons, the codes include requirements for heating mortar materials. When ambient temperatures fall below 40 ºF (4.4 ºC) sand or mixing water must be heated to produce mortar that is between 40 ºF (4.4 ºC) and 120 ºF (48.9 ºC) at the time of mixing. Ideal temperatures for mortar are between 60 ºF (15.6 ºC) and 80 ºF (26.7 ºC). Mortar temperatures over 120 ºF (48.9 ºC) may lead to flash set, resulting in lower compressive strength and reduced bond strength. Thus, do not heat sand or water above 140 ºF (60.0 ºC). Water is the easiest and best material to heat because it does not lose heat readily. Heating prepackaged materials such as portland, mortar and masonry cements and hydrated lime can be difficult. If the air temperature is below 32 ºF (0 ºC), maintain the temperature of mortar above freezing until used. Consider altering mortar constituents or proportions within permissible ranges to reduce the impacts of cold weather. Increasing sand content provides a stiffer mortar that better supports the weight of subsequently laid masonry. Using masonry or mortar cements, or reducing lime content allows mortars to lose water more rapidly, thus reducing the potential for freezing. High-early-strength (Type III) portland cement may also be used to increase the rate of early strength gain. If a brick with a low IRA is used, the water content of the mortar should be the minimum necessary for workability. Set accelerating admixtures, as discussed later in Other Cold Weather Considerations may also be used, however heating and protection measures are still required. Avoid freezing of mortar during construction in all cases, and protect mortar in newly completed masonry from freezing. Specific requirements for protection of mortar are found in Table 1. Grout. High water content is necessary in grout for ease of flow, but it greatly increases the amount of volumetric expansion which can occur upon freezing. Thus grout, like mortar, must be mixed with heated materials if the temperature of the materials is below 32 ºF (0 ºC), to prevent the damaging effects of freezing. If the ambient temperature is below 32 ºF (0 ºC), grout aggregates and mixing water must be heated to produce a grout temperature between 70 ºF (21.1 ºC) and 120 ºF (48.9 ºC) at the time of mixing. Do not heat grout aggregates and mixing water above 140 ºF (60.0 ºC) and keep the grout temperature above 70 ºF (21.1 ºC) when it is placed. High-earlystrength (Type III) portland cement may be used to increase the rate of early strength gain of grout. Admixtures may also be used, but heating and protection of the grouted masonry is still required. All grout must be placed within 11/2 hours of mixing. Newly Constructed and Completed Masonry. Because the hydration of cement is a process that continues for an extended period, it is necessary to ensure that masonry surfaces under construction do not extract excessive heat from mortar and grout. Code provisions address this by requiring masonry under construction, or that is to receive grout, to be heated to a minimum temperature of 40 ºF (4.4 ºC) when the ambient temperature reaches 25 ºF (-3.9 ºC) or below. If wind velocities exceed 15 mph, wind breaks or enclosures must be used during construction. In addition to these measures, if the ambient temperature falls to 20 ºF (-6.7 ºC) or below, the masonry under construction must be enclosed and the air within the enclosure maintained at a temperature above 32 ºF (0 ºC). Newly constructed masonry that is frozen may be moistened after thawing to reactivate the hydration process and continue to develop strength. If snow or ice is visible on existing foundations or masonry, the codes prohibit building new masonry on them. There is danger of movement when the base thaws, and bond cannot be developed between the mortar bed and frozen supporting surfaces. Ice and snow must be removed and the top surface must be heated to above freezing, in a manner that does not damage the masonry. www.gobrick.com | Brick Industry Association | TN 1 | Cold and Hot Weather Construction | Page 4 of 9

Protecting Materials and Masonry In addition to heating materials to adjust for cold weather, the IBC and Building Code Requirements for Masonry Structures require protection of masonry constructed in cold weather. Protection is one of the most effective adjustments that can be made to construction practices. Material Storage. Careless material storage can increase the cost of laying masonry if removal of ice and snow from materials and thawing of masonry units is necessary before construction begins. Measures to consider include covering masonry materials with tarpaulins or polyethylene sheets to keep them dry and free of ice and snow, locating sand so that water does not drain into it and storing masonry units on raised platforms to avoid contact with the ground. Newly Constructed Masonry. As mentioned, the development of strength and bond in masonry continues for some time after the masonry is completed, and may be compromised if freezing occurs. Therefore, newly constructed masonry must be protected so that it maintains enough heat for cement hydration. When the mean daily temperature falls to 40 ºF (4.4 ºC) or below, a series of protective measures are required, beginning with covering newly constructed masonry with a weather-resistive membrane for 24 hr after completion. As temperatures decrease, more stringent protection is required. Specific provisions for the progressively colder temperatures are presented in Table 1.

Photo 1 Cover Protecting Newly Constructed Masonry

Materials used to cover brickwork should be weighted or otherwise fixed in place and extend a minimum of 2 ft (0.6 m) down each side of the wall, as shown in Photo 1, to prevent contamination by water, ice or snow.

HEATING METHODS AND EQUIPMENT Individual Materials

Photo 2 Heating of a Sand Pile with an Electric Blanket

There are many types of equipment are available as sources of heat for cold weather construction. The type selected will depend upon availability of equipment, fuel source, economics, size of project and severity of exposure. A few common methods for heating individual materials are described below. Materials may also be heated by placing them within heated enclosures prior to use. Both water and sand used in mortar and grout may be heated to provide proper temperatures for construction. Sand may be heated by placing an electric heating pad on top of the sand pile and covering with a weather-resistant tarpaulin, as shown in Photo 2. The electric pad can safely heat the sand overnight without exceeding a temperature of 100 ºF (37.8 ºC). A more labor intensive method of heating the sand is to place over a heated pipe or to pile the sand around a horizontal metal culvert or smoke stack section in which a slow fire is built, as shown in Photo 3.

Photo 3 Sand Pile Warmed by Heated Pipe

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Other methods for heating sand involve the use of a steam lance or other steam heaters. Pay careful attention to the fire or other heat source and the sand as it should be heated slowly to avoid scorching. Alternatively, an electric rod can be used to heat mixing water and sand simultaneously. The electric heating rod is placed in a drum of water in the center of a sand pile. The rod heats the water over several hours. The sand surrounding the drum slowly absorbs heat from the drum and insulates the drum from further heat losses. Mortar may also be placed on electrically heated mortar boards to help maintain proper temperature. Be careful to avoid excessive drying of the mortar.

Newly Constructed Masonry (Enclosures) Contractors have used several different methods to provide heat and protection for newly constructed masonry, including complete and partial enclosures. Large tents, temporary wood structures covered with clear plastic, and shelters built of prefabricated panels covered with clear plastic sheets are examples of complete enclosures. Partial enclosures often consist of enclosed scaffolds which may be moved from floor to floor when necessary, as shown in Photo 4. Commercial electric blankets may also be used to cover walls and provide heat during the curing period. Forced air heaters (sometimes called torpedo heaters or salamanders) are widely used as a source of heat within enclosures. When complete enclosure of the work area is provided, space heaters are recommended, as shown in Photo 5. Cold weather provisions require circulation of warm air on both sides of the masonry wall within the enclosure.

Photo 4 Scaffold Enclosures

Photo 5 Space Heater in Enclosure

OTHER COLD WEATHER CONSIDERATIONS Admixtures Accelerators. Accelerators are admixtures used to speed the setting time of mortar and grout. By increasing the rate of cement hydration, accelerators increase the rate of early strength gain. The most common accelerators are inorganic salts such as calcium chloride, calcium nitrate, soluble carbonates and some organic compounds. Evaluate any accelerator for deleterious effects on masonry strength and materials. Admixtures that contribute to staining or efflorescence or cause corrosion of metal accessories are not desirable for use in masonry construction. Indiscriminate use of accelerators can adversely affect the performance of the completed masonry. Using accelerators alone does not address all concerns related to cold weather construction and is not recommended. Masonry constructed using accelerators in mortar or grout must still be protected from freezing as cement hydration essentially stops at temperatures below 40 ºF (4.4 ºC). Calcium chloride, while highly effective as an accelerator and widely used in the past, is not recommended as it causes corrosion of metals used in masonry such as ties, anchors and reinforcement. For this reason, admixtures with more than 0.2 percent chloride ions are prohibited for use in mortar when masonry is constructed under the provisions of Building Code Requirements for Masonry Structures. The incidence of efflorescence may also increase if the accelerator contains excessive salts.

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Calcium nitrite and calcium nitrate are inorganic non-chloride compounds also used as accelerators. These compounds require higher dosages by weight and are more costly than calcium chloride, but will not corrode metals or contribute to efflorescence. Antifreeze. Do not use antifreeze compounds. These admixtures are alcohols or combinations of salts. If used in the quantities required to be effective, significant reductions in mortar compressive and bond strengths usually result. Most commercial mortar “antifreeze” admixtures do not lower the freezing point of mortar or grout, but are actually accelerators. However, some true antifreeze admixtures are available.

NON-MANDATORY COLD WEATHER RECOMMENDATIONS In addition to the mandatory requirements for cold weather masonry construction found in Table 1, the following items can be incorporated in the specifications of the project manual where applicable: -

Protect masonry units, cementitious materials and sand so that they are not contaminated by rain, snow or ground water.

-

Units with higher initial rates of absorption (up to 40 g/min/30 in.2 (40 g/min/194 cm2)) may be used to resist mortar freezing. However, units with suctions in excess of 30 g/min/30 in.2 (30 g/min/194 cm2) should be wetted, but not saturated, with heated water just prior to laying. Water used for wetting should be above 70 ºF (21.1 ºC) when units are above 32 ºF (0 ºC). If units are 32 ºF (0 ºC) or below, water temperature should be above 120 ºF (48.9 ºC).

If walls are properly covered when work is halted, ice or snow removal from walls should not be necessary. However, in the event that the covering is displaced, the top course may be thawed with steam or a carefully applied portable blowtorch. The heat should be sustained long enough to thoroughly dry the masonry. If portions of the masonry are frozen or damaged, replace defective parts before progressing with new work.

NEGATING THE EFFECTS OF HOT WEATHER This section describes the properties of masonry and masonry materials that are changed by high temperatures and the code prescribed procedures that overcome these effects. Periods of hot weather may also adversely affect the construction of masonry. The contractor must ensure that the quality of masonry construction does not suffer from the effect of high temperatures. The IBC and Building Code Requirements for Masonry Structures define hot weather as temperatures above 100 ºF (37.8 ºC); however, wind speed, relative humidity and solar radiation also influence the absorption of masonry units, the rate of set, and the drying rate of mortar. High temperatures and high humidity are not as damaging to the performance of the masonry as are low temperatures and low humidity. The increased rate of cement hydration and favorable curing conditions in hot, humid weather will help develop masonry strength if sufficient water is present at the time of construction. The primary concern during hot weather is rapid evaporation and absorption of water from the mortar. Without sufficient water, cement hydration slows or stops and the bond strength and extent of bond between brick and mortar is reduced. The integrity of the masonry may also be compromised if mortar that is too hot flash sets before it completes hydration. The adjustments to construction practices required by the IBC and Building Code Requirements for Masonry Structures further improve the quality of masonry constructed in hot weather. These mandatory provisions, triggered when the ambient air temperature reaches 100 ºF (37.8 ºC), or 90 ºF (32.3 ºC) with a wind velocity greater than 8 mph (12.9 km/hr), are presented in Table 1 and are discussed below along with additional non-mandatory recommendations for successful hot weather construction. Keeping materials cool during periods of hot weather provides the best results.

Cooling Materials Lowering the temperature of materials may be the easiest approach to achieving performance characteristics associated with masonry constructed at normal temperatures. Masonry Units. Masonry units are not significantly affected by hot weather. However, the interaction between the masonry units and the mortar or grout is critical. Masonry units that are hot absorb more water from mortar and www.gobrick.com | Brick Industry Association | TN 1 | Cold and Hot Weather Construction | Page 7 of 9

increase the temperature of the masonry. Lower bond strength and extent of bond result if not enough water is present in the mortar when the units are laid. Keep masonry units cool by storing them in a shaded area. Shading of masonry units from direct sunlight is required when ambient temperatures exceed 115 ºF (46.1 ºC) or 105 ºF (40.6 ºC) with a wind velocity over 8 mph (12.9 km/hr). Brick with field IRAs over 30 g/min/30 in.2 (30 g/min/194 cm2) may be required to be wetted prior to laying to reduce their rate of absorption. Otherwise, they can draw too much water from the mortar too quickly. Brick may be required to be surface dry at the time of laying and have an IRA less than 30 g/min/30 in.2 (30 g/min/194 cm2). Brick may be wetted immediately before laying, but the preferred method is to wet them 3 to 24 hours before use. Mortar. Mortar mixed at high temperatures often has a higher water content, lower air content, and a shorter board life than mortar mixed at normal temperatures. It also tends to lose plasticity rapidly due to evaporation of water and the increased rate of cement hydration. Consider using mortar with a high lime content and high water retention. Rapid stiffening of hot mortar, or flash set, occurs if mortar plasticity is lost before the cement hydrates sufficiently. To avoid this, be sure mortar used during hot weather maintains a temperature less than 120 ºF (48.9 ºC). Retempering of mortar with cool water should always be permitted, and is required for maintaining consistency during hot weather. Use mortar within 2 hr of initial mixing. Hot weather provisions require that all mortar materials be shaded from direct sunlight when the ambient temperature exceeds 115 ºF (46.1 ºC) or 105 ºF (40.6 ºC) with a wind velocity over 8 mph (12.9 km/hr). Sand. When ambient temperatures exceed 100 ºF (37.8 ºC) or 90 ºF (32.2 ºC) with winds exceeding 8 mph (12.9 km/hr), keep sand in a damp, loose condition. This can be achieved by sprinkling sand piles with water, and leaving them uncovered, which also reduces the temperature of the sand through evaporative cooling. Damp sand takes longer to heat up. Water. Cool water may be used to help control the temperature of mortar and grout. Cool mixing water for mortar and grout are required by hot weather provisions when the ambient temperature exceeds 115 ºF (46.1 ºC) or 105 ºF (40.6 ºC) with a wind velocity of 8 mph (12.9 km/hr). Ice is highly effective in reducing the temperature of the mix water. Ice must be completely melted or removed before combining the water with any other ingredients. Grout. Grout reacts to hot weather in a manner similar to mortar. Water evaporates more rapidly and thereby reduces the water-cement ratio. Because grout requires a slump of at least 8 in. (203 mm) for use in masonry, maintain a high water-cement ratio by initially mixing grout with adequate water to offset evaporation. Building Code Requirements for Masonry Structures requires grout to be used within 11/2 hours of mixing. As with mortar, ice may be used to lower the mix water temperature. Admixtures. The use of admixtures to increase plasticity is not recommended unless their full effect on the mortar is known. Admixtures for grout that increase the flow rate or reduce the water content are not recommended. Shrinkage compensating admixtures are recommended. Equipment. A significant amount of heat can be absorbed by equipment that is exposed to sunlight for extended periods during hot weather. Mixers, wheelbarrows and mortar pans can impart this heat to mortar, raising its temperature. Mortar boards made of wood may also absorb more water from mortar. To prevent this from compromising the quality of masonry, the IBC and Building Code Requirements for Masonry Structures require mixers, containers and mortar boards to be flushed with cool water before they come in contact with mortar or mortar materials. As with mortar materials, equipment is also required to be shaded from direct sunlight when the ambient temperature exceeds 115 ºF (46.1 ºC) or 105 ºF (40.6 ºC) with an 8 mph (12.9 km/hr) wind velocity.

Protecting Materials and Masonry Wet curing or fog spraying may further improve masonry strength development during periods of high temperatures and low relative humidity. Hot weather provisions require fog spraying of newly constructed masonry until damp, at least three times a day for three days when the mean daily temperature exceeds 100 ºF (37.8 ºC) or 90 ºF (32.2 ºC) with a wind velocity over 8 mph (12.9 km/hr.) Use wind breaks to prevent rapid drying of mortar during and after placement, and cover walls with a weatherresistant membrane at the end of the work day to prevent rapid loss of moisture from the masonry assemblage.

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SUMMARY Construction and protection requirements in both cold and hot weather help ensure uninterrupted, quality masonry construction. Performance characteristics associated with materials mixed and constructed during normal temperatures can be achieved by following recommendations in this Technical Note. Table 1 summarizes practices required by building codes for cold and hot weather construction. The information and suggestions contained in this Technical Note are based on the available data and the combined experience of engineering staff and members of the Brick Industry Association. The information contained herein must be used in conjunction with good technical judgment and a basic understanding of the properties of brick masonry. Final decisions on the use of the information contained in this Technical Note are not within the purview of the Brick Industry Association and must rest with the project architect, engineer and owner.

REFERENCES 1. 2003 International Building Code, International Code Council, Inc., Falls Church, VA, 2003. 2. 2003 International Residential Code for One- and Two-Family Dwellings, International Code Council, Inc., Falls Church, VA, 2003. 3. ASTM C 270, Standard Specification for Mortar for Unit Masonry, Annual Book of ASTM Standards, Vol. 04.05, ASTM International, West Conshohocken, PA, 2006. 4. Brown, M.L., “Speeding Mortar Setting in Cold Weather,” The Magazine of Masonry Construction, Vol. 2, No. 10, Addison, IL, October 1989. 5. Bigelow, O., “Cold Weather Masonry Construction,” Masonry Magazine, Schaumburg, IL, October 2005. 6. Building Code Requirements for Masonry Structures (ACI 530/ASCE 5/TMS 402), The Masonry Society, Boulder, CO, 2005. 7. Color Climate Atlas Maps, National Climatic Data Center, retrieved March 20, 2006 from http://gis.ncdc.noaa.gov/website/ims-climatls/index.html. 8. "Hot and Cold Weather Masonry Construction Manual," Masonry Industry Council, Schaumburg, IL, 1999. 9. Randall, Jr., F.A., and W.C. Panarese, Concrete Masonry Handbook, Portland Cement Association, Skokie, IL, 1991. 10. Schierhorn, C., “Preventing Hot-Weather Construction Problems,” The Magazine of Masonry Construction, Vol. 7, Addison, IL, June 1994. 11. Specification for Masonry Structures (ACI 530.1/ASCE 6/TMS 602), The Masonry Society, Boulder, CO, 2005. 12. Suprenant, B.A., “Laying Masonry in Cold Weather,” The Magazine of Masonry Construction, Vol. 1, No. 9, Addison, IL, December 1988. 13. Van der Klugt, L.J.A.R., “Frost Damage to the Pointing and Laying Mortar of Clay Brick Masonry,” TNO Building Construction and Research, 9th International Brick/Block Masonry Conference, Rijswijk, The Netherlands, October 1991.

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Technical Notes 2 - Glossary of Terms Relating to Brick Masonry Jan/Feb 1975 (Reissued Mar. 1999)

ABSORPTION: The weight of water a brick unit absorbs, when immersed in either cold or boiling water for a stated length of time. Expressed as a percentage of the weight of the dry unit. See ASTM Specification C 67. ADMIXTURES: Materials added to mortar to impart special properties to the mortar. ANCHOR: A piece or assemblage, usually metal, used to attach building parts (e.g., plates, joists, trusses, etc.) to masonry or masonry materials. ANSI: American National Standards Institute. ARCH: A curved compressive structural member, spanning openings or recesses; also built flat. Back Arch: A concealed arch carrying the backing of a wall where the exterior facing is carried by a lintel. Jack Arch: One having horizontal or nearly horizontal upper and lower surfaces. Also called flat or straight arch. Major Arch: Arch with spans greater than 6 ft and equivalent to uniform loads greater than 1000 lb. per ft. Typically known as Tudor arch, semicircular arch, Gothic arch or parabolic arch. Has rise to span ratio greater than 0.15. Minor Arch: Arch with maximum span of 6 ft and loads not exceeding 1000 lb. per ft. Typically known as jack arch, segmental arch or multicentered arch. Has rise to span ratio less than or equal to 0.15. Relieving Arch: One built over a lintel, flat arch, or smaller arch to divert loads, thus relieving the lower member from excessive loading. Also known as discharging or safety arch. Trimmer Arch: An arch, usually a low rise arch of brick, used for supporting a fireplace hearth. ASHLAR MASONRY: Masonry composed of rectangular units of burned clay or shale, or stone, generally larger in size than brick and properly bonded, having sawed, dressed or squared beds, and joints laid in mortar. Often the unit size varies to provide a random pattern, random ashlar. ASHRAE: American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. ASTM: American Society for Testing and Materials. BACK FILLING: 1. Rough masonry built behind a facing or between two faces. 2. Filling over the extrados of an arch. 3. Brickwork in spaces between structural timbers, sometimes called brick nogging. BACKUP: That part of a masonry wall behind the exterior facing. BAT: A piece of brick. BATTER: Recessing or sloping masonry back in successive courses; the opposite of corbel. BED JOINT: The horizontal layer of mortar on which a masonry unit is laid.

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BELT COURSE: A narrow horizontal course of masonry, sometimes slightly projected such as window sills which are made continuous. Sometimes called string course or sill course. BLOCKING: A method of bonding two adjoining or intersecting walls, not built at the same time, by means of offsets whose vertical dimensions are not less than 8 in. BOND: 1. Tying various parts of a masonry wall by lapping units one over another or by connecting with metal ties. 2. Patterns formed by exposed faces of units. 3. Adhesion between mortar or grout and masonry units or reinforcement. BOND BEAM: Course or courses of a masonry wall grouted and usually reinforced in the horizontal direction. Serves as horizontal tie of wall, bearing course for structural members or as a flexural member itself. BOND COURSE: The course consisting of units which overlap more than one wythe of masonry. BONDER: A bonding unit. See Header. BREAKING JOINTS: Any arrangement of masonry units which prevents continuous vertical joints from occurring in adjacent courses. BRICK: A solid masonry unit of clay or shale, formed into a rectangular prism while plastic and burned or fired in a kiln. Acid-Resistant Brick: Brick suitable for use in contact with chemicals, usually in conjunction with acid-resistant mortars. Adobe Brick: Large roughly-molded, sun-dried clay brick of varying size. Angle Brick: Any brick shaped to an oblique angle to fit a salient corner. Arch Brick: 1. Wedge-shaped brick for special use in an arch. 2. Extremely hard-burned brick from an arch of a scove kiln. Building Brick: Brick for building purposes not especially treated for texture or color. Formerly called common brick. See ASTM Specification C 62. Clinker Brick: A very hard-burned brick whose shape is distorted or bloated due to nearly complete vitrification. Common Brick: See Building Brick. Dry-Press Brick: Brick formed in molds under high pressures from relatively dry clay (5 to 7 percent moisture content). Economy Brick: Brick whose nominal dimensions are 4 by 4 by 8 in. Engineered Brick: Brick whose nominal dimensions are 4 by 3.2 by 8 in. Facing Brick: Brick made especially for facing purposes, often treated to produce surface texture. They are made of selected clays, or treated, to produce desired color. See ASTM Specification C 216. Fire Brick: Brick made of refractory ceramic material which will resist high temperatures. Floor Brick: Smooth dense brick, highly resistant to abrasion, used as finished floor surfaces. See ASTM Specification C 410. Gauged Brick: 1. Brick which have been ground or otherwise produced to accurate dimensions. 2. A tapered arch brick.

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Hollow Brick: A masonry unit of clay or shale whose net cross-sectional area in any plane parallel to the bearing surface is not less than 60 percent of its gross cross-sectional area measured in the same plane. See ASTM Specification C 652. Jumbo Brick: A generic term indicating a brick larger in size than the standard. Some producers use this term to describe oversize brick of specific dimensions manufactured by them. Norman Brick: A brick whose nominal dimensions are 4 by 2 2/3 by 12 in. Paving Brick: Vitrified brick especially suitable for use in pavements where resistance to abrasion is important. See ASTM Specification C 7. Roman Brick: Brick whose nominal dimensions are 4 by 2 by 12 in. Salmon Brick: Generic term for under-burned brick which are more porous, slightly larger, and lighter colored than hard-burned brick. Usually pinkish-orange color. "SCR Brick" (Reg U.S. Pat Off., SCPI (BIA)): See SCR (Reg U.S. Pat. Off., SCPI (BIA)). Sewer Brick: Low absorption, abrasive-resistant brick intended for use in drainage structures. See ASTM Specification C 32. Soft-Mud Brick: Brick produced by molding relatively wet clay (20 to 30 percent moisture). Often a hand process. When insides of molds are sanded to prevent sticking of clay, the product is sand-struck brick. When molds are wetted to prevent sticking, the product is water-struck brick. Stiff-Mud Brick: Brick produced by extruding a stiff but plastic clay (12 to 15 percent moisture) through a die. BRICK AND BRICK: A method of laying brick so that units touch each other with only enough mortar to fill surface irregularities. BRICK GRADE: Designation for durability of the unit expressed as SW for severe weathering, MW for moderate weathering, or NW for negligible weathering. See ASTM Specifications C 216, C 62 and C 652. BRICK TYPE: Designation for facing brick which controls tolerance, chippage and distortion. Expressed as FBS, FBX and FBA for solid brick, and HBS, HBX, HBA and HBB for hollow brick. See ASTM Specifications C 216 and C 652. BUTTERING: Placing mortar on a masonry unit with a trowel. CAPACITY INSULATION: The ability of masonry to store heat as a result of its mass, density and specific heat. C/B RATIO: The ratio of the weight of water absorbed by a masonry unit during immersion in cold water to weight absorbed during immersion in boiling water. An indication of the probable resistance of brick to freezing and thawing. Also called saturation coefficient. See ASTM Specification C 67. CENTERING: Temporary formwork for the support of masonry arches or lintels during construction. Also called center(s). CERAMIC COLOR GLAZE: An opaque colored glaze of satin or gloss finish obtained by spraying the clay body with a compound of metallic oxides, chemicals and clays. It is burned at high temperatures, fusing glaze to body making them inseparable. See ASTM Specification C 126. CHASE: A continuous recess built into a wall to receive pipes, ducts, etc. CLAY: A natural, mineral aggregate consisting essentially of hydrous aluminum silicate; it is plastic when sufficiently wetted, rigid when dried and vitrified when fired to a sufficiently high temperature.

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CLAY MORTAR-MIX: Finely ground clay used as a plasticizer for masonry mortars. CLEAR CERAMIC GLAZE: Same as Ceramic Color Glaze except that it is translucent or slightly tinted, with a gloss finish. CLIP: A portion of a brick cut to length. CLOSER: The last masonry unit laid in a course. It may be whole or a portion of a unit. CLOSURE: Supplementary or short length units used at corners or jambs to maintain bond patterns. COLLAR JOINT: The vertical, longitudinal joint between wythes of masonry. COLUMN: A vertical member whose horizontal dimension measured at right angles to the thickness does not exceed three times its thickness. COPING: The material or masonry units forming a cap or finish on top of a wall, pier, pilaster, chimney, etc. It protects masonry below from penetration of water from above. CORBEL: A shelf or ledge formed by projecting successive courses of masonry out from the face of the wall. COURSE: One of the continuous horizontal layers of units, bonded with mortar in masonry. CULLS: Masonry units which do not meet the standards or specifications and have been rejected. DAMP COURSE: A course or layer of impervious material which prevents capillary entrance of moisture from the ground or a lower course. Often called damp check. DAMPPROOFING: Prevention of moisture penetration by capillary action. DOG'S TOOTH: Brick laid with their corners projecting from the wall face. DRIP: A projecting piece of material, shaped to throw off water and prevent its running down the face of wall or other surface. EBM: See Engineered Brick Masonry. ECCENTRICITY: The normal distance between the centroidal axis of a member and the parallel resultant load. e1/e2: Ratio of virtual eccentricities occurring at the ends of a column or wall under design. The absolute value is always less than or equal to 1.0. EFFECTIVE HEIGHT: The height of a member to be assumed for calculating the slenderness ratio. EFFECTIVE THICKNESS: The thickness of a member to be assumed for calculating the slenderness ratio. EFFLORESCENCE: A powder or stain sometimes found on the surface of masonry, resulting from deposition of water-soluble salts. ENGINEERED BRICK MASONRY: Masonry in which design is based on a rational structural analysis. FACE: 1. The exposed surface of a wall or masonry unit. 2. The surface of a unit designed to be exposed in the finished masonry. FACING: Any material, forming a part of a wall, used as a finished surface. FIELD: The expanse of wall between openings, corners, etc., principally composed of stretchers.

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FILTER BLOCK: A hollow, vitrified clay masonry unit, sometimes salt-glazed, designed for trickling filter floors in sewage disposal plants. See ASTM Specification C 159. FIRE CLAY: A clay which is highly resistant to heat without deforming and used for making brick. FIRE RESISTIVE MATERIAL: See Non-combustible Material. FIREPROOFING: Any material or combination protecting structural members to increase their fire resistance. FLASHING: 1. A thin impervious material placed in mortar joints and through air spaces in masonry to prevent water penetration and/or provide water drainage. 2. Manufacturing method to produce specific color tones. FROG: A depression in the bed surface of a brick. Sometimes called a panel. FURRING: A method of finishing the interior face of a masonry wall to provide space for insulation, prevent moisture transmittance, or to provide a level surface for finishing. GROUNDS: Nailing strips placed in masonry walls as a means of attaching trim or furring. GROUT: Mixture of cementitious material and aggregate to which sufficient water is added to produce pouring consistency without segregation of the constituents. High-Lift Grouting: The technique of grouting masonry in lifts up to 12 ft. Low-Lift Grouting: The technique of grouting as the wall is constructed. HACKING: 1. The procedure of stacking brick in a kiln or on a kiln car. 2. Laying brick with the bottom edge set in from the plane surface of the wall. HARD-BURNED: Nearly vitrified clay products which have been fired at high temperatures. They have relatively low absorptions and high compressive strengths. HEAD JOINT: The vertical mortar joint between ends of masonry units. Often called cross joint. HEADER: A masonry unit which overlaps two or more adjacent wythes of masonry to tie them together. Often called bonder. Blind Header: A concealed brick header in the interior of a wall, not showing on the faces. Clipped Header: A bat placed to look like a header for purposes of establishing a pattern. Also called a false header. Flare Header: A header of darker color than the field of the wall. HEADING COURSE: A continuous bonding course of header brick. Also called header course. INITIAL RATE OF ABSORPTlON: The weight of water absorbed expressed in grams per 30 sq. in. of contact surface when a brick is partially immersed for one minute. Also called suction. See ASTM Specification C 67. IRA: See Initial Rate of Absorption. KILN: A furnace oven or heated enclosure used for burning or firing brick or other clay material. Kiln Run: Brick from one kiln which have not been sorted or graded for size or color variation. KING CLOSER: A brick cut diagonally to have one 2 in. end and one full width end. LATERAL SUPPORT: Means whereby walls are braced either vertically or horizontally by columns, pilasters, cross

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walls, beams, floors, roofs, etc. LEAD: The section of a wall built up and racked back on successive courses. A line is attached to leads as a guide for constructing a wall between them. LIME, HYDRATED: Quicklime to which sufficient water has been added to convert the oxides to hydroxides. LIME PUTTY: Hydrated lime in plastic form ready for addition to mortar. LINTEL: A beam placed over an opening in a wall. MASONRY: Brick, stone, concrete, etc., or masonry combinations thereof, bonded with mortar. MASONRY CEMENT: A mill-mixed cementitious material to which sand and water must be added. See ASTM C 91. MASONRY UNIT: Natural or manufactured building units of burned clay, concrete, stone, glass, gypsum, etc. Hollow Masonry Unit: One whose net cross-sectional area in any plane parallel to the bearing surface is less than 75 percent of the gross. Modular Masonry Unit: One whose nominal dimensions are based on the 4 in. module. Solid Masonry Unit: One whose net cross-sectional area in every plane parallel to the bearing surface is 75 percent or more of the gross. MORTAR: A plastic mixture of cementitious materials, fine aggregate and water. See ASTM Specifications C 270, C 476 or BIA M1-72. Fat Mortar: Mortar containing a high percentage of cementitious components. It is a sticky mortar which adheres to a trowel. High-Bond Mortar: Mortar which develops higher bond strengths with masonry units than normally developed with conventional mortar. Lean Mortar: Mortar which is deficient in cementitious components, it is usually harsh and difficult to spread. NOMINAL DIMENSION: A dimension greater than a specified masonry dimension by the thickness of a mortar joint, but not more than 1/2 in. NON-COMBUSTIBLE MATERIAL: Any material which will neither ignite nor actively support combustion in air at a temperature of 1200 F when exposed to fire. OVERHAND WORK: Laying brick from inside a wall by men standing on a floor or on a scaffold. PARGETING: The process of applying a coat of cement mortar to masonry. Often spelled and/or pronounced parging. PARTITION: An interior wall, one story or less in height. PICK AND DIP: A method of laying brick whereby the bricklayer simultaneously picks up a brick with one hand and, with the other hand, enough mortar on a trowel to lay the brick. Sometimes called the Eastern or New England method. PIER: An isolated column of masonry. PILASTER: A wall portion projecting from either or both wall faces and serving as a vertical column and/or beam. PLUMB RULE: This is a combination plumb rule and level. It is used in a horizontal position as a level and in a

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vertical position as a plumb rule. They are made in lengths of 42 and 48 in., and short lengths from 12 to 24 in. POINTING: Troweling mortar into a joint after masonry units are laid. PREFABRICATED BRICK MASONRY: Masonry construction fabricated in a location other than its final inservice location in the structure. Also known as preassembled, panelized and sectionalized brick masonry. PRISM: A small masonry assemblage made with masonry units and mortar. Primarily used to predict the strength of full scale masonry members. QUEEN CLOSER: A cut brick having a nominal 2 in. horizontal face dimension. QUOIN: A projecting right angle masonry corner. RACKING: A method entailing stepping back successive courses of masonry. RAGGLE: A groove in a joint or special unit to receive roofing or flashing. RBM: Reinforced brick masonry REINFORCED MASONRY: Masonry units, reinforcing steel, grout and/or mortar combined to act together in resisting forces. RETURN: Any surface turned back from the face of a principal surface. REVEAL: That portion of a jamb or recess which is visible from the face of a wall. ROWLOCK: A brick laid on its face edge so that the normal bedding area is visible in the wall face. Frequently spelled rolok. SALT GLAZE: A gloss finish obtained by thermochemical reaction between silicates of clay and vapors of salt or chemicals. SATURATION COEFFICIENT: See C/B Ratio. SCR (Reg U.S. Pat Off., SCPI (BIA)): Structural Clay Research (trademark Of the Structural Clay Products Institute, BIA). "SCR acoustile" (Reg U.S. Pat Off., SCPI (BIA) Pat. No 3,001,6O2): A side-construction two-celled facing tile, having a perforated face backed with glass wool for acoustical purposes. "SCR brick" (Reg U.S. Pat Off., SCPI (BIA)): Brick whose nominal dimensions are 6 by 2 2/3 by 12 in. (Reg U.S. Pat Off., SCPI (BIA)): "SCR building panel" (Reg U S. Pat Off., SCPI (BIA) Pat. No. 3,248,836): Prefabricated, structural ceramic panels, approximately 2 1/2 in. thick. "SCR insulated cavity wall" (Reg U.S. Pat Off., SCPI (BIA)): Any cavity wall containing insulation which meets rigid criteria established by the Structural Clay Products Institute (BIA). "SCR masonry process" (Reg. U.S. Pat Off., SCPI (BIA)): A construction aid providing greater efficiency, better workmanship and increased production in masonry construction. It utilizes story poles, marked lines and adjustable scaffolding. SHALE: Clay which has been subjected to high pressures until it has hardened. SHOVED JOINTS: Vertical joints filled by shoving a brick against the next brick when it is being laid in a bed of mortar.

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SLENDERNESS RATIO: Ratio of the effective height of a member to its effective thickness. SLUSHED JOINTS: Vertical joints filled, after units are laid, by "throwing" mortar in with the edge of a trowel. (Generally, not recommended.) SOAP: A masonry unit of normal face dimensions, having a nominal 2 in. thickness. SOFFIT: The underside of a beam, lintel or arch. SOFT-BURNED: Clay products which have been fired at low temperature ranges, producing relatively high absorptions and low compressive strengths. SOLAR SCREEN: A perforated wall used as a sunshade. SOLDIER: A stretcher set on end with face showing on the wall surface. SPALL: A small fragment removed from the face of a masonry unit by a blow or by action of the elements. STACK: Any structure or part thereof which contains a flue or flues for the discharge of gases. STORY POLE: A marked pole for measuring masonry coursing during construction. STRETCHER: A masonry unit laid with its greatest dimension horizontal and its face parallel to the wall face. STRINGING MORTAR: The procedure of spreading enough mortar on a bed to lay several masonry units. STRUCK JOINT: Any mortar joint which has been finished with a trowel. SUCTION: See Initial Rate of Absorption. TEMPER: To moisten and mix clay, plaster or mortar to a proper consistency. TIE: Any unit of material which connects masonry to masonry or other materials. See Wall Tie. TOOLING: Compressing and shaping the face of a mortar joint with a special tool other than a trowel. TOOTHING: Constructing the temporary end of a wall with the end stretcher of every alternate course projecting. Projecting units are toothers. TRADITIONAL MASONRY: Masonry in which design is based on empirical rules which control minimum thickness, lateral support requirements and height without a structural analysis. TUCK POINTING: The filling in with fresh mortar of cut-out or defective mortar joints in masonry. VENEER: A single wythe of masonry for facing purposes, not structurally bonded. VIRTUAL ECCENTRICITY: The eccentricity of a resultant axial load required to produce axial and bending stresses equivalent to those produced by applied axial loads and moments. It is normally found by dividing the moment at a section by the summation of axial loads occurring at that section. VITRIFICATION: The condition resulting when kiln temperatures are sufficient to fuse grains and close pores of a clay product, making the mass impervious. WALL: A vertical member of a structure whose horizontal dimension measured at right angles to the thickness exceeds three times its thickness. Apron Wall: That part of a panel wall between window sill and wall support.

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Area Wall: 1. The masonry surrounding or partly surrounding an area. 2. The retaining wall around basement windows below grade. Bearing Wall: One which supports a vertical load in addition to its own weight. Cavity Wall: A wall built of masonry units so arranged as to provide a continuous air space within the wall (with or without insulating material), and in which the inner and outer wythes of the wall are tied together with metal ties. Composite Wall: A multiple-wythe wall in which at least one of the wythes is dissimilar to the other wythe or wythes with respect to type or grade of masonry unit or mortar Curtain Wall: An exterior non-loadbearing wall not wholly supported at each story. Such walls may be anchored to columns, spandrel beams, floors or bearing walls, but not necessarily built between structural elements. Dwarf Wall: A wall or partition which does not extend to the ceiling. Enclosure Wall: An exterior non-bearing wall in skeleton frame construction. It is anchored to columns, piers or floors, but not necessarily built between columns or piers nor wholly supported at each story. Exterior Wall: Any outside wall or vertical enclosure of a building other than a party wall. Faced Wall: A composite wall in which the masonry facing and backings are so bonded as to exert a common reaction under load. Fire Division Wall: Any wall which subdivides a building so as to resist the spread of fire. It is not necessarily continuous through all stories to and above the roof. Fire Wall: Any wall which subdivides a building to resist the spread of fire and which extends continuously from the foundation through the roof. Foundation Wall: That portion of a loadbearing wall below the level of the adjacent grade, or below first floor beams or joists. Hollow Wall: A wall built of masonry units arranged to provide an air space within the wall. The separated facing and backing are bonded together with masonry units. Insulated Cavity Wall: See "SCR insulated cavity wall". Loadbearing Wall: A wall which supports any vertical load in addition to its own weight. Non-Loadbearing Wall: A wall which supports no vertical load other than its own weight. Panel Wall: An exterior, non-loadbearing wall wholly supported at each story. Parapet Wall: That part of any wall entirely above the roof line. Party Wall: A wall used for joint service by adjoining buildings. Perforated Wall: One which contains a considerable number of relatively small openings. Often called pierced wall or screen wall. Shear Wall: A wall which resists horizontal forces applied in the plane of the wall. Single Wythe Wall: A wall containing only one masonry unit in wall thickness. Solid Masonry Wall: A wall built of solid masonry units, laid contiguously, with joints between units completely filled with mortar or grout.

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Spandrel Wall: That part of a curtain wall above the top of a window in one story and below the sill of the window in the story above. Veneered Wall: A wall having a facing of masonry units or other weather-resisting non-combustible materials securely attached to the backing, but not so bonded as to intentionally exert common action under load. WALL PLATE: A horizontal member anchored to a masonry wall to which other structural elements may be attached. Also called head plate. WALL TIE: A bonder or metal piece which connects wythes of masonry to each other or in other materials. WALL TIE, CAVITY: A rigid, corrosion-resistant metal tie which bonds two wythes of a cavity wall. It is usually steel, 3/16 in. in diameter and formed in a "Z" shape or a rectangle. WALL TIE, VENEER: A strip or piece of metal used to tie a facing veneer to the backing. WATER RETENTIVITY: That property of a mortar which prevents the rapid loss of water to masonry units of high suction. It prevents bleeding or water gain when mortar is in contact with relatively impervious units. WATER TABLE: A projection of lower masonry on the outside of the wall slightly above the ground. Often a damp course is placed at the level of the water table to prevent upward penetration of ground water WATERPROOFING: Prevention of moisture flow through masonry due to water pressure. WEEP HOLES: Openings placed in mortar joints of facing material at the level of flashing, to permit the escape of moisture. WITH INSPECTION: Masonry designed with the higher stresses allowed under EBM. Requires the establishing of procedures on the job to control mortar mix, workmanship and protection of masonry materials. WITHOUT INSPECTION: Masonry designed with the reduced stresses allowed under EBM. WYTHE: 1. Each continuous vertical section of masonry one unit in thickness. 2. The thickness of masonry separating flues in a chimney. Also called withe or tier.

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Technical Notes 3 - Overview of Building Code Requirements for Masonry Structures (ACI 530-02/ASCE 5-02/TMS 402-02) and Specification for Masonry Structures (ACI 530.1-02/ASCE 6-02/TMS 602-02) July 2002 Abstract: This Technical Notes provides a review of the national masonry design standard, ACI 530/ASCE 5/TMS 402, and its accompanying masonry specification, ACI 530.1/ASCE 6/TMS 602. New provisions and revisions of existing standards for masonry design are emphasized. Subjects discussed pertaining to the design standard are: allowable stress and strength design of unreinforced and reinforced masonry, prestressed masonry, empirical design, glass block masonry, masonry veneer, quality assurance, and seismic provisions. Items addressed for the masonry specification are: requirements checklist and submittals, masonry quality assurance and inspection requirements, reinforcement and metal accessories, erection tolerances, construction procedures and grouting requirements. Key Words: adhered veneer, allowable stress design, anchored veneer, building code, design standard, empirical design, inspection, prestressed masonry, specification, strength design.

INTRODUCTION The American Concrete Institute (ACI), American Society of Civil Engineers (ASCE), and The Masonry Society (TMS) promulgate a national consensus standard for the structural design of masonry elements and a standard specification for masonry construction. These standards are titled the Building Code Requirements for Masonry Structures (ACI 530/ASCE 5/TMS 402) and the Specification for Masonry Structures (ACI 530.1/ASCE 6/TMS 602). They were developed to consolidate and advance existing standards for the design and construction of masonry. This Technical Notes, the first in a series, discusses various sections of the Building Code Requirements for Masonry Structures and the Specification for Masonry Structures in brief detail. Emphasis is placed on the new requirements in the 2002 edition of the standards. Changes from prior masonry standards dealing with the design of brick masonry structures are also presented. Other Technical Notes in this series provide material and section properties of brick masonry members and more extensive discussion of the requirements of these standards. For more information about the requirements of these standards and examples of their application, the reader is referred to the Masonry Designer's Guide (MDG). The MDG is published by The Masonry Society and contains an extensive number of design examples that illustrate the proper application of the MSJC Code and Specification requirements. In this Technical Notes, the Building Code Requirements for Masonry Structures and the Specification for Masonry Structures are referred to as the Masonry Standards Joint Committee (MSJC) Code and Specification, respectively. The pertinent section and article numbers from the MSJC Code and Specification, are stated in parentheses following the discussion of particular topics for quick reference.

HISTORY AND DEVELOPMENT

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The development of this single masonry standard for the design and construction industry began in 1977. At that time, there were several design standards for masonry. These standards did not have consistent requirements. It was difficult for engineers and architects to select the appropriate design criteria for masonry elements. Concerned individuals representing masonry materials and the design profession saw the need for a single, national consensus standard for the design and construction of all types of masonry. In 1977, ACI and ASCE agreed to jointly develop a consensus standard for masonry design with the support of the masonry industry. The MSJC was formed with a balanced membership of building officials, contractors, university professors, consultants, material producers and designers who are members of ACI or ASCE. The Masonry Society joined as a sponsoring organization in 1991. Currently, the MSJC is comprised of over eighty regular (voting) and forty associate members. The MSJC Code and Specification are available from each of the sponsoring organizations or from the Brick Industry Association. Changes to the MSJC Code and Specification are written, balloted and approved within the MSJC. A review by the sponsoring organizations' technical activity committees follows. In order to obtain a national consensus, the approved draft undergoes a public review. Approval by the MSJC of the first edition of the MSJC Code and Specification occurred in June 1986. Public review began in 1988 with the final approval of the 1988 MSJC Code and Specification in August 1989. Commentaries for the MSJC Code and Specification were also developed. These documents provide background information on the design and specification provisions. Considerations of the MSJC members in determining requirements and references to research papers and articles are included in the commentaries for further information. The MSJC Code, Specification and Commentaries are revised on a three- or four-year cycle. The first revision was issued in 1992. Most of the changes were editorial in nature or clarified intent or omissions. In 1995 new chapters on glass unit masonry and anchored masonry veneers were added, and the MSJC Specification was reformatted. Metric conversions were added throughout the standards in accordance with the metrication policy of ASCE in addition to an index of key words. The 1999 edition includes a number of significant changes. The MSJC Code and its Commentary were reformatted. A chapter on prestressed masonry, a section on adhered veneer and a quality assurance program were added. Other changes in the MSJC Code and Specification include new design values for elastic moduli and masonry compressive strength and the inclusion of mortar cement. In the 2002 edition there were significant changes to the seismic design provisions, with prescriptive requirements for specific shear wall types. A chapter on strength design was added. Other minor changes are documented in this Technical Notes.

Building Code Acceptance The MSJC Code is to be adopted by a model building code and, subsequently, by a local jurisdiction. State and local building code committees are encouraged to adopt the model building codes which include the MSJC Code for the design of masonry. With adoption of the MSJC Code, the Specification is automatically adopted because the MSJC Code requires that materials and construction comply with the MSJC Specification. The local jurisdiction has the responsibility for enforcement and compliance of masonry construction to the MSJC Specification once it is adopted. Two of the previous model building code organizations, the Standard Building Code Congress International (SBCCI) and the Building Officials and Code Administrators (BOCA), chose to include the MSJC Code in their documents. This adoption by reference began in 1988 and1989, respectively. The International Council of Building Officials (ICBO) chose to maintain masonry design criteria within the Uniform Building Code itself, rather than adopting the MSJC standards by reference. However, many of the masonry design and construction requirements of the

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Uniform Building Code have been changed over the last several years to be consistent with the requirements of the MSJC Code and Specification. The International Code Council (ICC) was formed by the three existing code organizations (SBCCI), (BOCA) and (ICBO) with the charge to produce a single set of codes, referred to as the I-codes. Two I-codes that are important to the brick industry are the International Building Code (IBC) and International Residential Code (IRC). The National Fire Protection Association (NFPA) is also developing another building code called NFPA 5000. The I-codes and NFPA 5000 reference the 2002 MSJC Code.

Benefits The MSJC Code and Specification have had positive results; the design and construction community has become more confident with their use. Designers have one national standard that covers nearly all types of masonry construction. Architects are able to prepare and submit complete, concise specifications more easily. Contractors have more consistent and better quality specifications for projects. Owners obtain more uniform quality of masonry. Other benefits presented by the MSJC Code and Specification are:

1. Nearly all forms of masonry are covered, including unreinforced, reinforced and prestressed masonry, glass unit masonry, and adhered and anchored veneer masonry.

2. Requirements for all masonry materials are covered, including clay and shale brick, concrete block, stone, glass unit, mortar, grout and metal accessories.

3. Differences in material properties are recognized and quantified. 4. The same rational design procedures are utilized for clay and concrete masonry. 5. Responsibilities and duties of the owner, designer, testing agency, and contractor are clearly established.

6. Quality assurance and inspection requirements are included. 7. Design, materials and testing are the decision of the architect or engineer. 8. Contract administration is easier. Since the introduction of the MSJC standards in 1988, there has been a shift in the masonry design and construction communities. Designers and contractors use the MSJC Code and Specification with more frequency. Indicative of this growth, the MSJC Code is now a required reference for the Professional Engineer's Principles and Practice examination. The MSJC Specification has placed greater demands on the masonry contractor with the use of masonry as a structural material. Many requirements are performance related, which may require more site inspection for verification of compliance. These demands are advantageous and vital to the development of confidence that the masonry strengths assumed by the designer are met by the constructed masonry.

THE MSJC CODE (ACI 530/ASCE 5/TMS 402) The MSJC Code is the basis for masonry design by the architect or engineer. The provisions of the MSJC Code will dictate the size and shape of masonry walls, beams, pilasters and columns. Further, it influences the masonry materials the designer will require in the project specification. It consists of seven chapters, which are listed below.

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Chapter 1 - General Design Requirements for Masonry Chapter 2 - Allowable Stress Design Chapter 3 - Strength Design of Masonry (New Chapter) Chapter 4 - Prestressed Masonry Chapter 5 - Empirical Design of Masonry Chapter 6 - Veneer Chapter 7 - Glass Unit Masonry Some relevant sections of the codes are discussed in this Technical Notes and are indicated in parentheses for each of the chapters.

Chapter 1 - General Design Requirements for Masonry Chapter 1 contains the scope of the minimum requirements for the design of any masonry element. In this chapter, it states that the MSJC Code supplements the model building code enforced in a jurisdiction. When the MSJC Code conflicts with the local building code, the local building code governs. (1.1) Project drawings and specifications must identify the individual responsible for their preparation. Items required by the MSJC Code must be clearly marked such as: loads used in design, specified compressive strength of masonry, reinforcement, anchors and ties with size and spacing, size and location of all structural elements, provisions for differential movement, and size and location of conduit, pipes and sleeves. Contract documents must include a quality assurance program. (1.2) The MSJC Code permits alternative design methods from those stated in the MSJC Code. This is to recognize new applications of masonry and different structural analysis techniques. (1.3) Chapter 1 also includes the notation and definitions contained within the MSJC Code. Capital letters are used for permitted stresses and lower case letters are used for calculated or applied stresses. (1.5) For example, Fa is the notation for the allowable compressive stress due to axial load, while fa denotes the calculated compressive stress due to axial load. The definitions are specifically related to their meaning as used in the MSJC Code. Definitions in the MSJC Code are coordinated with those in the MSJC Specification. Definitions of terms relating to strength design of masonry and for prestressed masonry have been added. (1.6) The following are brief summaries, highlights, of several sections within Chapter 1. Section 1.7 - Loading. Service loads are used as the basis of design and are governed by the building code that adopts the MSJC Code. If a building code is not enforced in the area under consideration, then the MSJC Code requires that the load provisions of the 1993 edition of ASCE 7 Design Loads for Buildings and Other Structures apply to masonry structures. Allowable stresses given in the MSJC Code are based on failure stresses with a factor of safety in the range of 2 to 5. The structural system must resist wind and earthquake loads and accommodate the resulting deformations. (1.7.3) The effects of restraint of movement due to prestressing, vibrations, impact, shrinkage, expansion, temperature changes, creep, unequal settlement of supports and differential movement must also be considered in design. (1.7.4) Section 1.8 - Material Properties. Material properties are included for both clay and concrete masonry. The MSJC Code and Specification was the first national masonry standard to state design coefficients for thermal expansion, moisture expansion, shrinkage and creep. For design

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computations, the amount of shrinkage of brick masonry is taken as zero. The moduli of elasticity, Em, of clay and concrete masonry is no longer based on the net area compressive strength of the brick and the type of mortar used in construction. Em is now directly related to the specified compressive strength of masonry, f'm. For clay masonry, Em is equal to 700 times f'm. Alternately, Em may be determined by the chord modulus of elasticity taken between 0.05 and 0.33 of the maximum compressive strength of each prism determined by test in accordance with Article 1.4 B.3 of the MSJC Specification. Refer to Technical Notes 18 Series for an extensive discussion of differential movement of brick masonry elements. (1.8.2.2) Section 1.9 - Section Properties. Section properties are used to determine stress computations. Computations for stiffness, radius of gyration and flange design for intersecting walls are based on the minimum net area of the section. This is normally the mortar-bedded area. When different materials are combined in a single element, the transformed area must be used to account for differences in elastic moduli of the dissimilar materials. Radius of gyration of the section, rather than the minimum thickness, is used to determine the slenderness reduction for members in compression. (1.9) Section 1.10 - Deflection. Deflection limits are imposed for beams and lintels that support unreinforced masonry. The deflection should not exceed the span length divided by 600 or 0.3 in. (7.6 mm). Deflection of the masonry member should be calculated based upon uncracked section properties. (1.10, 1.9.2) Section 1.11 - Stack Bond Masonry. The MSJC Code requires that stack bond masonry be reinforced with a prescriptive amount of horizontal reinforcement. This may be placed as joint reinforcement or in bond beams spaced not more than 48 in. (1.2 m) on center vertically. (1.11) Section 1.12 - Details of Reinforcement. The reinforcement detailing requirements given in this chapter are similar to those for reinforced concrete under ACI 318, Building Code Requirements for Reinforced Concrete. The maximum size of reinforcing bar permitted in masonry members, designed by the allowable stress or empirical design methods, is a No. 11 (M #36) bar. Horizontal joint reinforcement is permitted as structural reinforcement for the same design methods. Placement limits for reinforcement include minimum grout spaces between the bars and masonry units of 1/4 in. (6.4 mm) and 1/2 in. (12.7 mm) for fine and coarse grout, respectively. (1.12.2 1.12.3) This section contains protection requirements for reinforcing steel. A minimum amount of masonry cover is required, depending upon the exposure conditions. Corrosion protection is required for joint reinforcement, wall ties, anchors and inserts in exterior walls. (1.12.4) Minimum development lengths are stated for reinforcement. A 50 percent increase is recommended for epoxy coated bars. (2.1.10.2) Standard hooks, minimum bend diameters, and splice requirements are consistent with those for reinforced concrete members. (1.12.5, 1.12.6) Chapter 3 contains variations in some of these requirements when strength design is used. Section 1.13 - Seismic Design Requirements. These requirements apply to the design and construction of all masonry, except glass unit masonry and masonry veneers, for all Seismic Design Categories (SDC) as defined in ASCE 7-98. Early editions of the MSJC included seismic design information as optional information in the Appendix and based the requirements on Seismic Zones. Since 1995, the seismic requirements are mandatory parts of the Code. Seismic provisions for masonry veneers are found in Chapter 6, Veneers. Special seismic requirements in Section 1.13 are invoked by SDC. The requirements are additive for each higher SDC. For example, buildings in category D must meet all the requirements for buildings in categories A, B and C, plus the additional requirements stated in Section 1.13 for buildings in category D. Five types of shear walls that serve as the lateral force-resisting system are described. Each has a required design method and prescriptive reinforcement requirements, see Table 1. Their use is permitted by the seismic design category applicable to the structure under design.

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TABLE 1 Requirement for Masonry Shear Walls Based on Shear Wall Designation Shear Wall Designation Empirically Designed Ordinary Plain (unreinforced) Detailed Plain (unreinforced) Ordinary Reinforced Intermediate Reinforced Special Reinforced

Reinforcement Requirements None None

Permitted SDC SDC A SDC A and B

Section 1.13.2.2.2.1 and 1.13.2.2.2.2 Section 1.13.2.2.2.1 and 1.13.2.2.2.2 Section 1.13.2.2.4 Section 1.13.2.2.5

SDC A and B SDC A, B, and C SDC A. B, and C SDC A, B, C, D, E and F

In category A, the provisions of Chapters 2, 3, 4, or 5 of the MSJC Code apply. There is a calculated story drift limit of 0.007 times the story height. Anchorage of masonry walls must meet a minimum design force of 1000 times the effective peak velocity-related acceleration. (1.13.3) For buildings in category B, the lateral force-resisting system must comply with the requirements of Chapter 2, 3, or 4 of the MSJC Code. It cannot be designed in accordance with the empirical requirements of Chapter 5. The lateral force-resisting system includes structural masonry members such as columns, beams and shear walls. It does not include non-loadbearing elements, such as partition walls. (1.13.4) Masonry buildings in category C must meet more stringent requirements. Members that are not part of the main lateral force-resisting system must be isolated so that they do not adversely affect the response of the lateral force-resisting system. Connections are strengthened and minimum amounts of reinforcement are required for shear walls and non-loadbearing masonry members in order to provide more ductility to the structure. (1.13.5) Partition walls, screen walls and other elements that are not designed to resist vertical or lateral loads other than their own weight must be isolated from receiving these loads and designed to accommodate drift. The special seismic provisions for categories D and E are still more restrictive. Minimum reinforcement requirements are increased for all members. Type N mortar and masonry cement mortars are not permitted for the lateral force-resisting system. (1.13.6, 1.13.7) Section 1.14 - Quality Assurance. This section defines a quality assurance program with different requirements based on the type of facility and method of design. Minimum tests, submittals and inspection requirements are defined for three levels of quality assurance. (1.14.1) The quality assurance program must include procedures for reporting, review and resolution of noncompliances. (1.14.5) Qualifications for testing laboratories and for inspection agencies must also be defined. (1.14.6) The quality assurance program requires that each wythe of masonry and the grout, if present, must meet or exceed the specified compressive strength of masonry, f'm. Compressive strength of masonry must be verified in accordance with the provisions of the MSJC Specification. (1.14.2) Section 1.15 - Construction. Construction of masonry must comply with the MSJC Specification. Requirements for grouting are introduced in Section 1.15. The type of grout, either

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fine or coarse, determines the minimum grout space dimensions and maximum grout pour height permitted. New in the 2002 edition is the inclusion of a grout demonstration panel. The limits can be exceeded if the panel indicates that the spaces are filled and adequately consolidated. Grout must attain a minimum compressive strength of 2000 psi (13.8 MPa) at 28 days. (Table 1.15.1) In addition, Section 1.15 contains provisions for pipes and conduits embedded in masonry elements. The effect on structural performance of the opening caused by the embedded item must be considered. Limitations on location, size, relative area and materials contained within pipes and conduit are included. (1.15.2) Chapter 2 - Allowable Stress Design Allowable stress design (ASD) methodology has been used in masonry design for many years. The ASD provisions of the MSJC Code are the most advanced to date for masonry members and are reflective of the extensive amount of research and experience gained over the last century. Chapter 2 of the MSJC Code states general provisions and establishes the scope of the rational design requirements. The rational design provisions are based upon a few assumptions inherent in the ASD approach, which are as follows:

1. Masonry materials are linearly elastic under service loads (materials rebound to original position when unloaded, rather than deforming permanently).

2. Stress is directly proportional to strain (applied load is directly proportional to displacement).

3. Masonry materials behave homogeneously (brick, mortar and grout behave as one element rather than separately).

4. Sections plane before bending remain plane after bending (flexural members do not warp). Service loads are used as the basis of allowable stress design. Allowable stresses given in the MSJC Code are based on failure stresses with a factor of safety in the range of 2 to 5. Section 2.1.2 contains the loading combinations to be used for allowable stress design. For moment strength design under Section 4.5.3.3.2, factored loads shall be combined as required by the general building code. When the general building code does not provide load combinations, structures or members shall use the most restrictive combinations of loads. (2.1.2) The specified compressive strength of masonry, f'm, must be determined by the designer and clearly stated in the contract documents. The specified compressive strength must be verified by the contractor as required by the methods stipulated in the MSJC Specification. (2.1.3) Anchor bolts consist of plate, headed and bent bar assemblies. Allowable loads for tension, shear and combined tension and shear are given. Provisions for minimum embedment length are provided to ensure proper transfer of load between the masonry and the anchor bolt. (2.1.4) Refer to Technical Notes 44 for further discussion of the design of anchor bolts. The MSJC Code requirements differentiate between multiwythe walls with respect to composite or non-composite action. Composite action requires a rigid transfer of stress between wythes so that the wythes act as a single element in resisting loads. The wythes must be bonded with a filled collar joint and metal ties or with masonry headers. Prescriptive size and spacing limitations for metal wall ties are taken from previous masonry standards. For multiwythe, composite walls, criteria for allowable shear stresses at the interface between a wythe and a collar joint have been introduced that were not included in previous masonry standards. These allowable shear stresses are: a) 5 psi (34.5 kPa) for mortared collar joints, b) 10 psi (69.0 kPa) for grouted collar joints, and c) the square root of the unit compressive strength of the header. (2.1.5.2.2) When non-composite action occurs, each wythe is designed to individually resist the effects of imposed loads. Loads are apportioned to wythes based upon their relative stiffnesses. As with

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composite walls, prescriptive requirements for metal wall ties are based on past experience. (2.1.5.3 ) Wall ties with drips are now prohibited. Columns are isolated vertical members whose horizontal dimension at right angles to the thickness does not exceed 3 times its thickness. Also, the member's height must be at least 3 times its thickness. The minimum dimension of a column is 8 in. (203 mm) and the maximum ratio of effective height to least nominal dimension (slenderness ratio) of a column is 25. Columns must contain a minimum of four vertical reinforcing bars and a minimum amount of lateral ties. (2.1.6) Pilasters are thickened elements of a wall which provide resistance to lateral loads or a combination of axial and lateral loads. Design procedures consider the pilaster and wall to act integrally, provided the two are properly bonded. Vertical reinforcement that is intended to resist axial loads must be laterally tied in the same manner that is required for columns. (2.1.7) Concentrated loads must be distributed over a prescribed length of wall. Requirements depend on bond pattern, presence of bond beams and the width of the wall. The allowable bearing stress is one-fourth of the specified compressive strength of masonry, but may be increased for smaller bearing areas. (2.1.9) Provisions for development of reinforcement are included. (2.1.10) Bars, hooks, welded wire fabric, and splices are covered. Section 2.2 - Unreinforced Masonry. Section 2.2 covers requirements for the design of masonry structures in which tensile stresses in masonry are taken into consideration. This is known as unreinforced (plain) masonry. Such members may, in fact, contain reinforcement for shrinkage or other reasons, but this reinforcement is neglected in the structural design process. The allowable axial compressive stress equation uses a different slenderness reduction factor from that used in earlier masonry standards. The factor is a function of the radius of gyration of the member's cross section, rather than its thickness. Additionally, the factor of safety changed from 5 in previous masonry standards to 4 in the MSJC Code. Unlike previous masonry design standards, the MSJC Code does not place an arbitrary limit on the slenderness ratio of walls. Rather, the slenderness reduction factor becomes very small for more slender walls. An equation limiting the applied axial load to one-quarter of a modified Euler buckling load is included. The classic Euler buckling load has been modified to reflect a member with negligible tensile strength. The unity equation has been used to limit the combination of bending and axial load in masonry design for many years. (2.2.3, 2.3.3) Variables affecting flexural tension of masonry include the plane on which the stress acts, mortar materials, unit cross-section, and presence of grout. The allowable flexural tension stresses for grouted masonry normal to bed joints were modified in the 2002 edition. (2.2.3.2) Allowable shear stresses are based upon a parabolic shear stress distribution rather than an average shear stress distribution, as used in previous masonry standards. Consequently, allowable shear stresses are approximately 1.5 times those in previous masonry standards. Four allowable shear stresses for in-plane shear must be evaluated. No allowable shear stress values are given for out-of-plane shear, but typically these same values for in-place shear are applied. (2.2.5) Section 2.3 - Reinforced Masonry. Section 2.3 contains requirements for the allowable stress design of masonry elements neglecting the tensile strength of masonry. This is commonly termed reinforced masonry. In this procedure, steel reinforcement is used to resist all tensile forces. Reinforcement may also be required to resist shear forces. The MSJC Code does not prescribe a minimum amount of reinforcement, except for masonry columns and for buildings in Seismic Design Categories as given in Chapter 1. The size and placement of compressive, flexural and shear reinforcement is determined by design requirements. (2.3.1) Allowable steel stresses are taken from previous masonry standards. Reinforcement used to resist compressive stresses must be laterally tied. (2.3.2.2) When the applied shear stress exceeds the given allowable shear stress for reinforced masonry

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without shear reinforcement, shear reinforcement is required. For reinforced masonry containing shear reinforcement, allowable shear stresses are increased by a factor of 3.0 for flexural members and 1.5 for shear walls. To use the increased allowable shear stresses, shear reinforcement must be provided to resist 100 percent of the shear force. (2.3.5) Chapter 3 - Strength Design of Masonry This chapter is new in the 2002 edition of the MSJC Code. This chapter was developed from research funded by the National Science Foundation and the masonry industry. Strength design identifies the possible failure modes that the masonry element can exhibit. By performing this type of analysis the engineer can preclude an undesirable failure. Strength design provides for design of inelastic performance of masonry. The loads and stresses considered are similar to those used in allowable stress design, but service level loads are replaced with strength design loads and allowable stresses are replaced with nominal values based on research. The required strength of the masonry must be greater than its nominal strength multiplied by a strength reduction factor, Ø. The strength reduction factors selected are similar to those used in concrete. Strength design of masonry shall comply with the minimum requirements of this chapter. In addition, the requirements of Chapter 1, Section 3.1, and either Section 3.2 or 3.3 also apply. (3.1.1) The strength requirements are in accordance with the legally adopted building code. When this information is not defined in the building code then the requirements of ASCE 7-98 govern. (3.1.2) Notations and definitions used in strength design are found in Sections 1.5 and 1.6, respectively. The remainder of Chapter 3 covers design strength (3.1.3), strength reduction factors (3.1.4), deformation requirements (3.1.5), headed and bent-bar anchor bolts (3.1.6), material properties (3.1.7), reinforced masonry (3.2), and unreinforced (plain) masonry (3.3). Design equations are similar to those for allowable stress design when possible. Perhaps the most significant difference is in the development length. The strength design formula includes cover, bar size, and masonry specified compressive strength as variables. This formula also applies to splices. This chapter includes maximum reinforcement ratios chosen to prevent brittle failure of shear walls. These are applied with specific limits on strain in the masonry and steel. There are also dimensional limits for beams, piers, and columns. It must be pointed out that Strength Design of Masonry may not be practical in many situations and may in fact not provide the results a designer may seek. Chapter 4 - Prestressed Masonry Prestressed masonry is used to eliminate tensile stresses in masonry due to externally applied loads. A controlled amount of precompression is applied to the masonry to offset the tensile forces created under service loads. The use of prestressing is well documented in concrete design and construction; however its use in masonry construction in the United States is limited. The United Kingdom has a history of successful prestressed masonry construction for over two decades. The equipment for prestressed masonry is similar to that used in concrete construction. Some proprietary systems have been developed specifically for use in prestressed masonry. Types of structures that have utilized prestressed masonry in the United States include freestanding walls, such as fences, bearing walls and masonry veneers designed to span between columns, rather than span floor-to-floor. Prestressing tendons placed in openings in the masonry may be grouted or ungrouted. The tendons may be pre-tensioned or post-tensioned. Pre-tensioned tendons are stressed against external abutments prior to placing the masonry. Post-tensioned tendons are stressed against the masonry after it has been placed. Most construction applications to date have been post-tensioned, ungrouted masonry because of the ease of construction and overall economy. As

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a result, the MSJC Code focuses primarily on post-tensioned masonry. Chapter 4 provides minimum requirements for the design of structures that are prestressed with bonded or unbonded prestressing tendons. The general design requirements found in Chapter 1, including seismic provisions, apply to prestressed masonry with a few modifications. (4.1) Prestressed members are designed using elastic analysis and allowable stress design. A new term, f'mi, is defined as the specified compressive strength of masonry at the time of transfer of the prestress force. (4.2) The remainder of Chapter 4 covers permissible stresses in the prestressing tendons, effective prestress, axial compression and flexure, axial tension, shear, deflection, prestressing tendon anchorages, couplers, end blocks, protection of prestressing tendons and accessories, and development of bonded tendons. Chapter 5 - Empirical Design of Masonry Chapter 5 presents empirical requirements for masonry structures. These requirements are based on past proven performance. Configuration of masonry structures for compliance with empirical limits is a technique that predates rational design methods. The empirical provisions of previous masonry standards have been modified and advanced in Chapter 5 to reflect contemporary construction materials and methods. The requirements are essentially unchanged from the 1999 edition. The empirical requirements in Chapter 5 may be applied to the following masonry elements:

1. The lateral force-resisting system for buildings in Seismic Design Categories (SDC) A, and for other building elements in SDC A through C, as defined in ASCE 7-98. (5.1.2)

2. Buildings subject to basic wind speed of 110 mph (145 km/hr) or less as defined by the ASCE 7-98 standard. (5.1.2.2)

3. Buildings not exceeding 35 ft (10.67 m) when the masonry walls are part of the main lateral force-resisting system. (5.2) The empirical requirements may not be applied to structures resisting horizontal loads other than those due to wind or seismic events, except that foundation walls may be as permitted in Section 5.6.3. The empirical requirements for foundation walls include limits on the height of backfill. There are a number of restrictions on the backfill soil and the configuration of cross walls. (5.6.3.1) The 2002 Code also requires foundation piers to be a minimum of 8 in. (203 mm) in thickness. (5.6.4) The empirical requirements of the MSJC Code are discussed in Technical Notes 42 Revised. Chapter 6 - Veneers. The requirements of Chapter 6 apply to masonry veneers. In the 2002 MSJC Code, provisions address anchored masonry veneer and adhered masonry veneer. The requirements of this chapter are especially important to the brick industry as the majority of brick produced in the United States is used as veneer. Section 6.2 - Anchored veneer. The majority of this chapter contains prescriptive requirements for masonry veneer, but alternative design methods are permitted. (6.2.1) The prescriptive requirements cannot be used in areas where the wind speed exceeds 110 mph (145 km/hr) as given in ASCE 7-98. (6.2.2.1) Many of the requirements are based upon those found in Technical Notes 28 Series on brick veneer walls and Technical Notes 44B on wall ties. (6.2.2.3-6.2.2.9) Seismic requirements are included for buildings in SDC C, D, and E. (6.2.2.10) Section 6.3 - Adhered veneer. Adhered veneer can be designed by the prescriptive requirements contained in this section or by alternative design methods. (6.3.1) Prescriptive requirements found in the 2002 MSJC Code are based on similar requirements that have been used in the Uniform Building Code for over 30 years. These requirements limit unit size to no more than 2 5/8 in. (66.7

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mm) in specified thickness, 36 in. (914 mm) in any face dimension and 5 ft2 (0.46 m2) in total face area. The weight of adhered veneer units is limited to15 lbs/ft2 (718 Pa). (6.3.2) Adhesion between the veneer units and the backing must have a shear strength of 50 psi (345 kPa) or greater based on gross unit surface area when tested in accordance with ASTM C 482. Alternatively, adhered units may be applied using the procedure found in MSJC Specification Article 3.3C. (6.3.2.4) Chapter 7 - Glass Unit Masonry Chapter 7 applies to glass unit masonry. The 2002 edition contains few changes from the 1999 version. The provisions are largely based upon those in the three previous model building codes. Requirements are primarily prescriptive and empirical. Maximum wall areas are imposed by a design wind pressure graph for standard units, 3 7/8 in. (98.4 mm) thick. When 3 in. (76.2 mm) thick units are used, a maximum wind pressure of 20 psf (958 Pa) is imposed and the maximum wall area is reduced. The size of interior wall panels is limited to 250 ft2 (23.22 m2) and 150 ft2 (13.94 m2) for standard and thin units, respectively. (7.1, 7.2) Provisions regarding lateral support for panels limited to one unit wide or one unit high are included. (7.3) The MSJC Code also imposes requirements for expansion joints. (7.4) Base surface treatment requires the surface on which glass unit masonry panels are placed to be coated with an elastic waterproofing material. (7.5) Glass unit masonry shall be built with Type S or N mortar. (7.6) Glass unit masonry panels must contain a minimum amount of horizontal joint reinforcement. The MSJC Code requires a minimum of two parallel W1.7 (MW11) wires spaced at 16 in. (406 mm) o.c. vertically. Joint reinforcement is very important because the limitations on wall panel size are based upon the failure of the reinforced section, rather than the first cracking strength of panels. (7.7)

THE MSJC SPECIFICATION (ACI 530.1/ASCE 6/TMS 602) The MSJC Specification is a reference standard that an architect or engineer may cite in the contract documents for any project. The MSJC Specification contains requirements for the contractor regarding materials, construction and quality assurance. The MSJC Code requires compliance of construction of the masonry with the MSJC Specification, so it is an integral part of the MSJC Code. The language is in imperative voice for ease of interpretation and enforcement. The MSJC Specification should be referenced in the contract documents and may be modified as required for the particular project. The 2002 edition of the MSJC Specification consists of three components: a) Part 1 - General, b) Part 2 - Products and c) Part 3 - Execution. The format was changed to the present one in 1995 to be more consistent with the Construction Specifications Institute's MASTERFORMAT. Major changes in the 2002 edition relate to quality assurance and ease of use. Quality assurance is established in conjunction with the MSJC Code and the MSJC Specification contains specific instructions for the parties involved. The phrase “When required” was eliminated. Inclusion of this phrase in earlier editions made it necessary for the user to extensively edit the MSJC Specification for application to a particular project. Requirements Checklists and Submittals The requirements checklists help the designer to choose and specify the necessary products and

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procedures found in the contract documents. Building codes set minimum requirements to protect property and life safety. However, written contract documents may have more restrictive requirements than provided in the building code. Adjustments for the particular project should be made by the designer by reviewing the requirements checklists. There are two checklists, mandatory and optional, that alert the designer to issues that must be addressed. The mandatory list requires a choice on inspection, testing, material selection and items not provided on the drawings or details of the project. The most significant change from the 1999 MSJC Specification in the mandatory checklist is exclusion of determining specified compressive strength compliance. In addition, the 1999 MSJC Specification required that the level of quality assurance be specified. Part 1 - General In Part 1 it is stated that the MSJC Specification covers requirements for materials and construction of masonry elements. The provisions govern any project unless other requirements are specifically stated in the contract documents. (1.1) Definitions are provided and are coordinated with those found in the MSJC Code. (1.2) All standards referenced in the MSJC Specification are listed. These standards include material specifications, sampling procedures, test methods, detailing requirements, construction procedures and classifications. The references are updated to the most current edition at the time of the MSJC Code and Specification approval. (1.3) The compressive strength of each wythe of masonry must equal or exceed that specified by the engineer or architect. The compressive strength must be verified by the contractor by one of two methods: unit strength or prism test. The unit strength method is a means to evaluate the strength of masonry based upon the tested compressive strength of individual units and the mortar type specified. The prism test method requires the sampling and testing of masonry prisms built with the same types of materials that are used in the masonry construction. The MSJC Specification specifies prism testing to be done in accordance with ASTM C 1314, Standard Test Method for Compressive Strength of Masonry Prisms. (1.4B) Adhesion of adhered veneer units to their backing is to be determined in accordance with ASTM C 482, Test Method for Bond Strength of Ceramic Tile to Portland Cement. (1.4C) Part 1 provides a list of items to be included in project submittals. Submittals should include mortar and grout mix designs and test results, masonry unit samples and certificates, samples of metal items such as reinforcement and wall ties. This also includes construction procedures for cold- and hot-weather construction. (1.5) Quality assurance is required by the MSJC Specification. The duties and services of the testing agency, inspection agency and contractor are specified and are dependent upon the level of quality assurance required. Article 1.6A outlines the responsibilities of the testing agencies. Article 1.6B specifies the responsibilities of the inspection agency. Article 1.6C contains the contractor's services and duties. The contractor must employ an independent testing laboratory to perform required tests, to document submittals, certify product compliance, establish mortar and grout mix designs, provide supporting data for changes requested by the contractor, or appeal rejection of material found to be defective. The contractor must include in the submittals the results of all testing performed to qualify the materials and to establish mix designs. Quality assurances are actions taken by the owner or the owner's representative. They provide assurance that actions of the contractor and supplier are in accordance with applicable standards of good practice. Quality assurances are administrative policies and responsibilities related to quality control measures that meet the owner's quality objectives. Quality control is the action taken by the producer or contractor. This is simply systematic performance of construction, testing and inspection to verify that proper materials and methods are used. Quality assurance involves inspection and testing, preparation and erection of the masonry structure. Inspection is assumed for every masonry project under the MSJC Code, a change from previous masonry standards. The level of inspection and the amount of testing depend upon the

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level of quality assurance specified. The level of quality assurance is determined according to facility function, as defined by the general building code, and the method of design. The MSJC Specification contains the same Quality Assurance tables that are found in the MSJC Code. (1.6) Sample panels for masonry walls are required for Level 2 or 3 quality assurance. The construction of a grout demonstration panel, used to depart from the requirements of Articles 3.5 C-E is also a part of quality assurance. (1.6D) Requirements for delivery, storage and handling of masonry materials are stated in order to avoid contamination that might reduce the quality of the constructed masonry. (1.7) Project-specific conditions such as support of construction loads by the masonry and shoring and weather exposure during construction must be addressed. Cold- and hot-weather construction requirements are included and are mandatory when they apply. The provisions for cold-weather construction have been revised in the 2002 MSJC Specification. Provisions for both cold-and hot-weather construction are separated into preparation, and construction protection. In most cases the methods to achieve the requirements are left to the discretion of the contractor. (1.8) Part 2 - Products This section lists the available American Society for Testing and Materials (ASTM) standards for masonry materials, including masonry units, mortar, grout, reinforcement and metal accessories. Specific requirements are given if an appropriate ASTM standard does not exist. Referenced ASTM standards for brick and tile are C 34, C 56, C 62, C 126, C 212, C 216, C 652, and C 1088. There are provisions for spacing of cross wires in joint reinforcement that are not included in standard for this material. Minimum corrosion protection requirements for metal items are stated including galvanized and epoxy coatings. Requirements for corrosion protection of bonded and unbonded prestressing tendons are also included. Criteria are specified for prestressing anchorages, couplers and end blocks. An accessories section provides requirements on contraction joint material, expansion joint material, asphalt emulsions, masonry cleaners and joint fillers. (2.1-2.5) The MSJC Specification contains requirements for the mixing of mortar and grout. Time of mixing and additives to mortar are limited. The grout must meet ASTM C 476 and be furnished and placed with a slump between 8 in. (200 mm) and 11 in. (275 mm). (2.6) Standard fabrication limits are stated for reinforcement and for prefabricated masonry panels. These include bend and hook requirements for reinforcing bars. Prefabricated masonry panels must conform to the provisions of ASTM C 901. (2.7) Part 3 - Execution The execution of the work includes initial inspection; preparation; masonry erection; reinforcement, tie and anchor installation; grout placement; prestressing tendon installation and stressing procedure; field quality control; and cleaning. Dimensional tolerances for foundations on which masonry is placed are provided and should be measured prior to the start of masonry work. (3.1) As part of the preparation requirements, clay or shale masonry units having initial absorption rates 2

in excess of one gram per minute per in , as measured with ASTM C 67 must be pre-wetted, so 2

the initial rate of absorption will not exceed one gram per minute per in when the units are used. Cleanouts are required at the base of masonry to be grouted whenever pour heights exceed 5 ft (1.5 m). (3.2) Standard requirements for good workmanship are required by the MSJC Specification. These include the requirement for completely filled mortar joints and grouted spaces. Proper support of masonry and bracing during construction is required but is not prescribed. Dimensional tolerances for the masonry are listed to ensure structural performance. The tolerances should not be used to establish appearance criteria, unless specifically noted as such by the project specifications. (3.3) Inspection of reinforcement and metal accessories is required to ensure that they have been properly placed and are free of materials that hinder bond. Tolerances for locating and placing

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reinforcing steel, wall ties, and veneer anchors are prescribed. Criteria for adjustable wall ties, which are repeated from the MSJC Code, are included. Placement requirements for veneer anchors have been added (3.4) Prior to grout placement, debris must be removed from grout spaces. The grouting requirements found in the MSJC Code are repeated in the MSJC Specification. Maximum grout pour heights are determined by the type of grout used and the dimensions of the grout space. Consolidation of grout is required to fill voids created by the loss of water from grout by absorption into the masonry. Alternate grout placement requirements, established through the use of a grout demonstration panel, are permitted. (3.5) Prestressing tendon installation and stressing requirements include: tolerances; application and measurement of the prestressing force; grouting bonded tendons; and burning and welding operations. (3.6) As part of field quality control, the specified compressive of masonry f'm is verified in accordance with Article 1.6, Quality Assurance; grout is sampled and tested in accordance with Articles 1.4B and 1.6. Provisions for cleaning exposed masonry surfaces complete the MSJC Specification. (3.8)

SUMMARY This Technical Notes provides an overview to the criteria contained in the MSJC Code and Specification. The discussion centers on the design requirements to be followed by architects and engineers and the masonry specifications to be implemented by the contractor during construction. Changes to the Code and Specification in the 2002 editions are emphasized. The MSJC Code and Specification provide the designer with coordination between the design and construction phases of all masonry buildings. The information and suggestions contained in this Technical Notes are based on the available data and the experience of the engineering staff of the Brick Industry Association. The information contained herein must be used in conjunction with good technical judgment and a basic understanding of the properties of brick masonry. Final decisions on the use of the information contained in this Technical Notes are not within the purview of the Brick Industry Association and must rest with the project architect, engineer and owner.

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Technical Notes 3A - Brick Masonry Material Properties December 1992 Abstract: Brick masonry has a long history of reliable structural performance. Standards for the structural design of masonry which are periodically updated such as the Building Code Requirements for Masonry Structures (ACI 530/ASCE 5/TMS 402) and the Specifications for Masonry Structures (ACI 530.1/ASCE 6/TMS 602) advance the efficiency of masonry elements with rational design criteria. However, design of masonry structural members begins with a thorough understanding of material properties. This Technical Notes is an aid for the design of brick and structural clay tile masonry structural members. Clay and shale units, mortar, grout, steel reinforcement and assemblage material properties are presented to simplify the design process. Key Words: brick, grout, material properties, mortar, reinforcement, structural clay tile. INTRODUCTION The Masonry Standards Joint Committee (MSJC) has developed the Building Code Requirements for Masonry Structures (ACI 530/ASCE 5/TMS 402) and the Specifications for Masonry Structures (ACI 530.1/ASCE 6/TMS 602). In this Technical Notes, these documents will be referred to as the MSJC Code and the MSJC Specifications, respectively. Their contents are reviewed in Technical Notes 3. The MSJC Code and Specifications are periodically revised by the MSJC and together provide design and construction requirements for masonry. The MSJC Code and Specifications apply to structural masonry assemblages of clay, concrete or stone units. This Technical Notes is a design aid for the MSJC Code and Specifications. It contains information on clay and shale units, mortar, grout, steel reinforcement and assemblage material properties. These are used in the initial stages of a structural design or analysis to determine applied stresses and allowable stresses. Material properties are explained to aid the designer in selection of materials and to provide a better understanding of the structural properties of the masonry assemblage based on the materials selected. CONSTITUENT MATERIAL PROPERTIES Because brick masonry is bonded into an integral mass by mortar and grout, it is considered to be a homogeneous construction. It is the behavior of the combination of materials that determines the performance of the masonry as a structural element. However, the performance of a structural masonry element is dependent upon the properties of the constituent materials and the interaction of the materials as an assemblage. Therefore, it is important to first consider the properties of the constituent materials: clay and shale units, mortar, grout and steel reinforcement. This will be followed by a discussion of the behavior of their combination as an assemblage. Clay and Shale Masonry Units There are many variables in the manufacturing of clay and shale masonry units. Primary raw materials include surface clays, fire clays, shales or combinations of these. Units are formed by extrusion, molding or dry-pressing and are fired in a kiln at temperatures between 1800oF and 2100o (980oC and 1150oC). These variables in manufacturing produce units with a wide range of colors, textures, sizes and physical properties. Clay and shale masonry units are most frequently selected as a construction material for their aesthetics and long-term performance. Consequently, material standards for clay and shale masonry units contain requirements to ensure that units meet a level of durability and visual and dimensional consistency. Clay and shale masonry units used in structural elements of building constructions are brick and structural clay tile. Material standards for brick and structural clay tile include: ASTM C 216 (facing brick), ASTM C 62 (building brick), ASTM C 652 (hollow brick), ASTM C 212 (structural clay facing tile) and ASTM C 34 (structural clay load-bearing tile).

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While brick and structural clay tile are both visually appealing and durable, they are also well-suited for many structural applications. This is primarily due to their variety of sizes and very high compressive strength. The material properties of brick and structural clay tile which have the most significant effect upon structural performance of the masonry are compressive strength and those properties affecting bond between the unit and mortar, such as rate of water absorption and surface texture. Unit Compressive Strength. The compressive strength of brick or structural clay tile is an important material property for structural applications. In general, increasing the compressive strength of the unit will increase the masonry assemblage compressive strength and elastic modulus. However, brick and structural clay tile are frequently specified by material standard rather than by a particular minimum unit compressive strength. ASTM material standards for brick and structural clay tile require minimum compressive strengths to ensure durability, which may be as little as one-fifth the actual unit compressive strength. A recent Brick Institute of America survey of United States brick manufacturers resulted in a data base of unit properties [6]. A subsequent survey of structural clay tile manufacturers was conducted. The compressive strengths of brick and structural clay tile evaluated in these surveys are presented in Table 1. As is apparent, all types of brick and structural clay tile typically exhibit compressive strengths considerably greater than the ASTM minimum requirements. Compressive strength of brick and structural clay tile is determined in accordance with ASTM C 67 Method of Sampling and Testing Brick and Structural Clay Tile.

1Extruded only. 2

Made from other materials or a combination of materials.

3Based on gross area.

Unit Texture and Absorption. Unit texture and absorption are properties which affect the bond strength of the masonry assemblage. In general, mortar bonds better to roughened surfaces, such as wire cut surfaces, than to smooth surfaces, such as die skin surfaces. Cores or frogs provide a means of mechanical interlock. The bond strength of sanded surfaces is dependent upon the amount of sand on the surface, the sand's adherence to the unit and the absorption rate of the unit at the time of laying. 2

In practically all cases, mortar bonds best to a unit whose suction at the time of laying is less than 30 g/min/30 in 2 (1.55 kg/min/m ). Generally, molded units will exhibit a higher initial rate of absorption than extruded or dry-pressed units. Unit absorption at the time of laying is an alterable property of brick and structural clay tile. In accordance with 2 2 the MSJC Specifications, units with initial rate of absorption in excess of 30 g/min/30 in. (1.55 kg/min/m ) should be wetted to reduce the rate of water absorption of the unit prior to laying. In addition, suction of very absorptive units may be accommodated by using highly water-retentive mortars. Mortar

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The material properties of mortar which influence the structural performance of masonry are compressive strength, bond strength and elasticity. Because the compressive strength of masonry mortar is less important than bond strength, workability and water retentivity, the latter properties should be given principal consideration in mortar selection. Mortar materials, properties and selection of masonry mortars are discussed in Technical Notes 8 Series. Mortar should be selected based on the design requirements and with due consideration of the MSJC Code and Specifications provisions affected by the mortar selected. Laboratory testing indicates that masonry constructed with portland cement-lime mortar exhibit greater flexural bond strength than masonry constructed with masonry cement mortar or air-entrained portland cement-lime mortar of the same Type. This behavior is reflected in the MSJC Code allowable flexural tensile stresses for unreinforced masonry, which are based on the mortar Type and mortar materials selected. In addition, masonry cement mortars may not be used in Seismic Zones 3 and 4. Other MSJC Code and Specifications provisions are the same for portland cement-lime mortars, masonry cement mortars and air-entrained portland cement-lime mortars of the same Type. These include the modulus of elasticity of the masonry, allowable compressive stresses for empirical design and the unit strength method of verifying that the specified compressive strength of masonry is supplied. Following is a general description of the structural properties of each Type of mortar permitted by the MSJC Code and Specifications. Type N Mortar. Type N mortar is specifically recommended for chimneys, parapet walls and exterior walls subject to severe exposure. It is a medium bond and compressive strength mortar suitable for general use in exposed masonry above grade. Type N mortar may not be used in Seismic Zones 3 and 4. Type S Mortar. Type S mortar is recommended for use in reinforced masonry and unreinforced masonry where maximum flexural strength is required. It has a high compressive strength and has a high tensile bond strength with most brick units. Type M Mortar. Type M mortar is specifically recommended for masonry below grade and in contact with earth, such as foundation walls, retaining walls, sewers and manholes. It has high compressive strength and better durability in these environments than Type N or S mortars. For compliance with the MSJC Specifications, mortars should conform to the requirements of ASTM C 270 Specification for Mortar for Unit Masonry. Field sampling of mortar for quality control should follow the procedures given in ASTM C 780 Test Method for Preconstruction and Construction Evaluation of Mortars for Plain and Reinforced Unit Masonry. Test procedures for masonry mortars are covered in Technical Notes 39 Series. Grout Grout is used in brick masonry to fill cells of hollow units or spaces between wythes of solid unit masonry. Grout increases the compressive, shear and flexural strength of the masonry element and bonds steel reinforcement and masonry together. For compliance with the MSJC Specifications, grout which is used in brick or structural clay tile masonry should conform to the requirements of ASTM C 476 Specification for Grout for Masonry. Grout proportions of portland cement or blended cement, hydrated lime or lime putty, and coarse or fine aggregate are given in Table 2.

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1

Aggregate measured by volume in a damp, loose condition.

The amount of mixing water and its migration from the grout to the brick or structural clay tile will determine the compressive strength of the grout and the amount of grout shrinkage. Tests indicate that the total amount of water absorbed from grout by hollow clay units appears to be more dependent on the initial water content of the grout than the absorption properties of the unit [3]. Grouts with high initial water content exhibit more shrinkage than grouts with low initial water contents. Consequently, use of a non-shrink grout admixture is recommended to minimize the number of flaws and shrinkage cracks in the grout while still producing a grout slump of 8 to 11 in. (200 to 280 mm), unless otherwise specified. The MSJC Specifications require grout compressive strength to be at least equal to the specified compressive strength of masonry, f'm, but not less than 2,000 psi (13.8 MPa) as determined by ASTM C 1019 Method of Sampling and Testing Grout. Test procedures for grout are explained in more detail in Technical Notes 39 Series. In general, the compressive strength of ASTM C 476 grout by proportions will be greater than 2,000 psi (13.8 MPa). Prediction of the compressive strength of grout which is proportioned in accordance with ASTM C 476 is difficult because of the many possible combinations of materials, types of materials and construction conditions. However, ASTM C 476 grout proportions produce a rich mix which is recommended to complement the high compressive strength of brick and structural clay tile. Steel Reinforcement Steel reinforcement for masonry construction consists of bars and wires. Reinforcing bars are used in masonry elements such as walls, columns, pilasters and beams. Wires are used in masonry bed joints to reinforce individual masonry wythes or to tie multiple wythes together. Bars and wires have approximately the same modulus of elasticity, which is stated in the MSJC Code as 29,000 ksi (200,000 MPa). In general, wires tend to achieve greater ultimate strength and behave in a more brittle manner than reinforcing bars. Common bar and wire sizes and their material properties are given in Table 3. As stated in the MSJC Specifications, steel reinforcement for masonry structural members should comply with one of the material standards given in Table 4.

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1

From reference [5].

ASSEMBLAGE MATERIAL PROPERTIES The properties of the constituent materials discussed previously combine to produce the brick or structural clay tile masonry assemblage properties. Following is a discussion of the material properties of the masonry assemblage. Compressive Strength Perhaps the single most important material property in the structural design of masonry is the compressive strength of the masonry assemblage. The specified compressive strength of the masonry assemblage, f'm, is used to determine the allowable axial and flexural compressive stresses, shear stresses and anchor bolt loads given in the MSJC Code. The compressive strength of the masonry assemblage can be evaluated by the properties of each constituent material, termed in the MSJC Specifications the "Unit Strength Method," or by testing the properties of the entire masonry assemblage, termed the "Prism Testing Method." These methods are not to be used to establish design values; rather, they are used by the contractor to verify that the masonry achieves the specified compressive strength, f'm . Unit Strength Method. A benefit of verifying compliance of the compressive strength of masonry by unit, mortar and grout properties is the elimination of prism testing. Each of the materials in the masonry assemblage must conform to ASTM material standards mentioned in previous sections of this Technical Notes. For compliance with

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these material standards, the compressive strength of the unit and the proportions or properties of the mortar and grout must be evaluated. Not surprisingly, there have been attempts by numerous researchers to accurately correlate the assemblage compressive strength with unit, mortar and grout compressive strengths. Testing an assemblage of three materials produces a large scatter of compressive strengths covering all possible combinations of materials. Therefore, estimates of the masonry assemblage compressive strength based on unit, mortar and grout properties are necessarily conservative. The correlations provided in the MSJC Specifications, shown in Table 5, between unit compressive strength, mortar type and the masonry assemblage compressive strength represent a lower-bound to experimental data. In addition, the MSJC Specifications unit strength method does not directly address variable grout strength, multi-wythe construction or the influence of joint reinforcement on the compressive strength of the masonry assemblage. Consequently, compliance with the specified compressive strength of masonry by prism testing will always produce a more accurate and optimum use of brick or structural clay tile masonry's compressive strength than the unit strength method. The conservative nature of Table 5 should not be overlooked by the designer. A comparison of the predicted assemblage compressive strength by the unit strength method in the MSJC Specifications and a data base of actual brick masonry prism test results [1] reveals this conservatism. The average compressive strength of prisms of solid brick units was found to be about 1.7 times the masonry compressive strength predicted by Table 5. The average compressive strength of prisms of hollow units ungrouted and grouted was found to be 1.9 and 1.4 times the compressive strengths predicted by Table 5, respectively.

1Linear Interpolation is permitted.

Prism Test Method. Prism testing of brick or structural clay tile masonry provides a number of advantages over constituent material testing alone. The primary benefit of prism testing is a more accurate estimation of the compressive strength of the masonry assemblage. Another benefit of prism testing is that it provides a method of measuring the quality of workmanship throughout the course of a project. Low prism strengths may indicate mortar mixing error or poor quality grout. The MSJC Specifications permit testing of masonry prisms to show conformance with the specified compressive strength of masonry, f'm. In addition, the material components must meet the appropriate standards of quality. Masonry prisms are tested in accordance with ASTM E 447 Test Methods for Compressive Strength of Masonry Prisms, Method B as modified by the MSJC Specifications. At least three prisms are required by the MSJC Specifications for each combination of materials. The average of the three tests must exceed f'm. Further explanation of prism testing procedures is provided in Technical Notes 39B. Shear Strength The shear strength of a masonry assemblage may be separated into four parts: 1) the shear strength of the unit,

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mortar and grout assemblage, 2) the effect of the shear span-to-depth ratio, M/Vd, 3) the enhancement of shear strength due to compressive stress, and 4) the contribution of shear reinforcement in the masonry assemblage. All four phenomenon are represented in the allowable shear stresses provided in the MSJC Code. However, only the first and fourth items are controlled by material properties. Items two and three vary with member size and applied loads. The shear strength of the masonry assemblage is directly related to the properties of the unit, mortar and grout. Shear failure of a unit-mortar assemblage is by splitting of units, step-cracking in mortar joints, or a combination of the two. Unit splitting strength is increased by increasing the compressive strength of the unit. In general, unit splitting is not a common shear failure mode of brick or structural clay tile masonry. Unit splitting occurs in masonry assemblages of weak units and strong mortar and may also occur in shear walls which are heavily axially loaded. Cracking in mortar joints is the more common shear failure mode for brick and structural clay tile masonry assemblages. Mortar joint failure occurs by sliding along bed joints and separation of head joints. Mortar joint shear failure is affected by bond strength and the frictional characteristics between the mortar and the unit. In general, a unit-mortar combination which provides greater bond strength will also provide greater shear strength. Grouting the masonry assemblage will also increase shear strength by providing a shear key between courses. The shear strength of a masonry assemblage may be evaluated in accordance with ASTM E 519 Test Method for Diagonal Tension (Shear) in Masonry Assemblages. The contribution of unit, mortar and grout to the allowable shear stresses stated in the MSJC Code are based on ASTM E 519 tests of masonry assemblages. Steel reinforcement may be added to the masonry assemblage to increase shear strength. Shear reinforcement should be provided parallel to the direction of applied shear force. The MSJC Code also requires a minimum amount of reinforcement perpendicular to the shear reinforcement of one-third the area of shear reinforcement. When shear reinforcement is provided in accordance with the MSJC Code, allowable shear stresses given in the MSJC Code for reinforced masonry are increased three times for flexural members and one and one-half times for shear walls. Flexural Tensile Strength Reinforced brick and structural clay tile masonry is considered cracked under service loads and the flexural tensile strength of the masonry is neglected in design. However, cracking of an unreinforced brick or structural clay tile masonry member constitutes failure and must be avoided. Thus, flexural tensile strength is an important design consideration for unreinforced masonry. Flexural tensile strength is the bond strength of masonry in flexure. It is a function of the type of unit, type of mortar, mortar materials, percentage of grouting of hollow units and the direction of loading. Workmanship is also very important for flexural tensile strength, as unfilled mortar joints or dislodged units have no mortar-to-unit bond strength. Allowable flexural tensile stresses stipulated in the MSJC Code for unreinforced masonry are given in Table 6. The allowable flexural tensile stresses for portland cement-lime mortars are based on full-size wall tests in accordance with ASTM E 72 Method of Conducting Strength Tests of Panels for Building Construction. Values for masonry cement and air-entrained portland cement-lime mortars are based on reductions obtained with comparative testing. Flexural tensile strength may be evaluated by testing small-scale prisms in accordance with ASTM E 518 Test Method for Flexural Bond Strength of Masonry or ASTM C 1072 Test Method for Measurement of Masonry Flexural Bond Strength, but these results may not directly correlate to the allowable flexural tensile stresses in the MSJC Code.

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1For partially grouted masonry allowable stresses shall be determined on the basis of linear interpolation between hollow units which are fully grouted or

ungrouted and hollow units based on amount of grouting.

Elastic Modulus The elastic modulus of the masonry assemblage, in combination with the moment of inertia of the section, determines the stiffness of a brick or structural clay tile masonry structural element. Elastic modulus is the ratio of applied load (stress) to corresponding deformation (strain). The elastic modulus is roughly proportional to the compressive strength of the masonry assemblage. Testing of brick masonry prisms indicates that the elastic modulus of brick masonry falls between 700 and 1200 times the masonry prism compressive strength [4]. If the Unit Strength Method is used to show compliance with the specified compressive strength of masonry, f'm, an accurate estimation of the actual compressive strength of the masonry assemblage may not be known. Consequently, the elastic modulus of the masonry assemblage is determined by the mortar type and the unit compressive strength. See Table 7. The data in Table 1 can be used to estimate the modulus of elasticity of the masonry assemblage for the type of unit selected. The elastic modulus of grout is computed as 500 times the compressive strength of the grout in accordance with the MSJC Code. In general, the elastic modulus of grout and the elastic moduli of brick or structural clay tile and mortar masonry assemblages are comparable and are often considered equal for design calculations. However, the MSJC Code recommends that the method of transformation of areas based on relative elastic moduli be used for computation of stresses in grouted masonry elements.

1 MSJC Code Table 5.5.1.2.

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Dimensional Stability Dimensional stability is also an important property of the masonry assemblage. Expansion and contraction of the brick or structural clay tile masonry may exert restraining stresses on the masonry and surrounding elements. Material properties which affect dimensional stability of clay and shale unit masonry are moisture expansion, creep and thermal movements. Effects of these phenomenon may be evaluated by the coefficients provided in the MSJC Code, which are listed in Table 8. The coefficients in Table 8 represent average quantities for moisture expansion and thermal movements and an upper-bound value for creep. Moisture expansion and thermal expansion and contraction are independent and may be added directly. The magnitude of creep of clay or shale unit masonry will depend upon the amount of load applied to the masonry element.

1

Conversion based on equivalent deformation at 100 oF (38 oC).

SUMMARY This Technical Notes contains information about the material properties of brick and structural clay tile masonry. This information may be used in conjunction with the MSJC Code and Specifications to design and analyze structural masonry elements. Typical material properties of clay and shale masonry units, mortar, grout, reinforcing steel and combinations of these are presented. The information and suggestions contained in this Technical Notes are based on the available data and the experience of the engineering staff of the Brick Institute of America. The information contained herein must be used in conjunction with good technical judgment and a basic understanding of the properties of brick masonry. Final decisions on the use of the information contained in this Technical Notes are not within the purview of the Brick Institute of America and must rest with the project architect, engineer and owner. REFERENCES 1. Atkinson, R.H., "Evaluation of Strength and Modulus Tables for Grouted and Ungrouted Hollow Unit Masonry," Atkinson-Noland and Associates, Inc., Boulder, CO, November 1990, 47 pp. 2. Building Code Requirements for Masonry Structures and Commentary (ACI 530/ASCE 5/TMS 402-92) and Specifications for Masonry Structures and Commentary (ACI 530.1/ASCE 6/TMS 602-92), American Concrete Institute, Detroit, MI, 1992. 3. Kingsley, G.R., et al., "The Influence of Water Content and Unit Absorption Properties on Grout Compressive Strength and Bond Strength in Hollow Clay Unit Masonry," Proceedings 3rd North American Masonry Conference, The Masonry Society, Boulder, CO, June 1985, pp. 7:1-12. 4. Plummer, H.C., Brick and Tile Engineering, Brick Institute of America, Reston, VA, 1977, 466 pp.

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5. "Steel Reinforcement Properties and Availability," Report of ACI Committee 439, Journal of the American Concrete Institute, Vol. 74, Detroit, MI, 1977, p. 481. 6. Subasic, C.A., Borchelt, J.G., "Clay and Shale Brick Material Properties - A Statistical Report," submitted for inclusion, Proceedings 6th North American Masonry Conference, The Masonry Society, Boulder, CO, June 1993, 12 pp.

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Technical Notes 3B - Brick Masonry Section Properties May 1993 Abstract: This Technical Notes is a design aid for the Building Code Requirements for Masonry Structures (ACI 530/ASCE 5/TMS 402-92) and Specifications for Masonry Structures (ACI 530.1/ASCE 6/TMS 602-92). Section properties of brick masonry units, steel reinforcement and brick masonry assemblages are given to simplify the design process. Section properties are used to calculate stresses and to determine the allowable stresses given in the ACI 530/ASCE 5/TMS 402-92 Code. Key Words: brick, dimensions, section properties, steel reinforcement. INTRODUCTION An assemblage's geometry determines its ability to resist loads. Section properties are properties of a masonry assemblage which are based solely on its geometry. Section properties are used in design and analysis of brick masonry structural elements. Section properties are used to determine allowable stresses which may be applied to brick masonry elements, as well as to calculate an element's stress under applied loads. Because brick is a small building unit, it may be used to construct assemblages of nearly any configuration. While this is a benefit of construction with brick masonry, it can make design tedious because each masonry assemblage will have unique section properties. To simplify the design process, this Technical Notes presents the section properties of brick units, steel reinforcement and typical brick masonry assemblages. The section properties are based on specified dimensions of the units and assemblages. This Technical Notes is a design aid for the Building Code Requirements for Masonry Structures (ACI 530/ASCE 5/TMS 402-92) and the Specifications for Masonry Structures (ACI 530.1/ASCE 6/TMS 602-92). These documents, which are promulgated by the Masonry Standards Joint Committee (MSJC), will be referred to as the MSJC Code and the MSJC Specifications, respectively. References are made to the MSJC Code and Specifications to indicate where each section property applies. Other Technical Notes in this series provide an overview of the MSJC Code and Specifications and material properties of brick masonry. NOTATION Following are notations used in the text, figure and tables in this Technical Notes. Where applicable, notations are the same as used in the MSJC Code and Specifications. 2

2

An Net cross-sectional area of masonry, in. (mm ) 2

2

As Area of steel, in. (mm ) b Width of section, in. (mm) bflange Width of flange, in. (mm) bweb Width of web, in. (mm) d Distance from extreme compression fiber ot the centroid of tension reinforcement, in. (mm) Em Elastic modulus of masonry, psi (MPa) Es Elastic modulus of steel, psi (MPa)

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4

4

I Moment of inertia, in. (m ) j Ratio of distance between centroid of flexural compressive forces and centroid of tensile forces to depth k Ratio of distance between compression face and neutral axis to distance between compression face and centroid of tensile forces s

m

n Elastic moduli ratio, E /E

Q First moment about the neutral axis of a section of that portion of the cross section lying between the neutral axis and extreme fiber, in.3 (m3) r Radius of gyration, in. (mm) S Section modulus, in.3 (m3) SECTION PROPERTIES OF CONSTITUENT MATERIALS The constituent materials of units, mortar, grout and reinforcement combine to form brick masonry assemblages. The section properties of each constituent material may be required in the design process. The section properties of clay and shale masonry units are the basis for the section properties of the total brick masonry assemblage. The section properties of steel reinforcement are used to determine the size and spacing of reinforcement within a brick masonry assemblage.

Clay and Shale Masonry Units Clay and shale masonry units are manufactured in a number of sizes and shapes. Clay and shale masonry units are classified as either solid units or hollow units. Solid units may contain up to 25 percent void area as a percentage of the gross cross-sectional area of the unit. Hollow units are classified as H40V for units with a total void area greater than 25 percent and less than 40 percent of the gross cross-sectional area, or H60V for units with a total void area greater than 40 percent and less than 60 percent of the gross cross-sectional area. The number and size of voids

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vary with unit size and manufacturing equipment. The range of sizes of clay and shale masonry units is given in Table 1. The names given for unit sizes in Table 1 were established by consensus of United States brick manufacturers and are standard terminology for the brick industry. Further information on masonry unit sizes and coursing of brickwork can be found in the Technical Notes 10 series on estimating brickwork.

One criteria for unit selection may be accommodation of reinforcement within the unit itself. Placement of steel reinforcement within the cores or cells of hollow units or solid cored units is permitted by the MSJC Code and Specifications. A core is a void area less than or equal to 1 1/2 in.2 (970 mm2). A cell is a void area which is larger than 1 1/2 in.2 (970 mm2). When placing reinforcement within a unit, adequate space for grouting must be provided. Specifically, MSJC Code Section 8.3.5 requires that the minimum distance between the steel reinforcement and the surrounding masonry unit be 1/4 in. (6 mm) when fine grout is used and 1/2 in. (13 mm) when coarse grout is used. In certain instances, the cross-sectional area of masonry units may need to be determined. For example, the compressive strength of a masonry prism is determined based on the unit's gross cross-sectional area when the prism is constructed of solid units or fully grouted hollow units, and on the unit's net cross-sectional area when the prism is constructed of hollow units. For solid units which contain cores, the gross cross-sectional area is used as the net cross-sectional area. Unit cross-sectional area may be determined in accordance with ASTM C 67 Methods of Sampling and Testing Brick and Structural Clay Tile. The shell and web thickness of hollow units may need to be determined because hollow unit brick masonry walls are typically face-shell bedded, while columns, pilasters and the first course of walls must be fully bedded. Minimum thickness requirements for shells and webs of hollow units are established by ASTM C 652 Specification for Hollow Brick (Hollow Masonry Units Made From Clay or Shale). These limits are given in Table 2. Many manufacturers exceed the minimum thickness requirements given in Table 2, so it is advisable to request actual unit dimensions for design purposes. TABLE 2 Hollow Unit Section Properties

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1

Cores greater than 1 in.2 (650 mm2) in cored shells shall be not less than 1/2 in. (13 mm) from any edge. Cores not greater than 1 in.2 (650 mm2) in shells cored not more than 35% shall be not less than 3/8 in. (10 mm) from any edge. 2The thickness of webs shall not be less than 1/2 in. (13 mm) between cells, 3/8 in. (10 mm) between cells and cores or 1/4 in. (6 mm)

between cores.

Steel Reinforcement Steel reinforcement for brick masonry assemblages consists of bars and wires. Reinforcing bars are placed in grouted cavities, pockets, cores, cells or bond beams of brick masonry walls, columns, pilasters and beams. Steel wire reinforcement is placed in brick masonry mortar joints to reinforce individual assemblages or to tie structural elements together, such as the wythes of a multi-wythe wall. Common bar and wire section properties are given in Table 3. The sizes of reinforcement listed in Table 3 are those permitted by the MSJC Code. The cross-sectional area of reinforcement is used in MSJC Code Eq. 7-10 to determine the spacing of shear reinforcement. The diameter of reinforcement is used to establish placement limits and minimum reinforcement development length requirements given in Chapter 8 of the MSJC Code.

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SECTION PROPERTIES OF BRICK MASONRY ASSEMBLAGES The section properties of the assemblage of the constituent materials, along with the strength of the materials, will determine the magnitude of loads the assemblage can resist. Consider the section properties required in the design of brick masonry assemblages following the MSJC Code. The width of the brick masonry assemblage, b, is used in MSJC Code Eqs. 6-7 and 7-3 and the effective depth of reinforcement, d, is used in MSJC Code Eqs. 7-3, 7-5, 7-8 and 7-10. Moment of inertia, I, is used in MSJC Code Eqs. 6-6 and 6-7. Radius of gyration, r, is used in MSJC Code Eqs. 6-3, 6-4, 6-6, 7-1 and 7-2 to determine allowable compressive stresses and axial load. The first moment of area, Q, is used in MSJC Code Eq. 6-7 to determine the shear stress in an unreinforced masonry element. The dimensionless quantities k and j are used to determine a cracked, reinforced masonry element's compressive stress and the allowable shear stress given in MSJC Code Eq. 7-3. The quantities k and j are functions of the area of reinforcement, As, and the moduli ratio, n. The moduli ratio, n, is the ratio of the modulus of elasticity of steel, Es, to the modulus of elasticity of masonry, Em . Following is a discussion of the section properties of typical brick masonry assemblages. Tables 4 through 7 provide section properties of these assemblages based on the dimensions indicated, which are based on the least specified brick unit dimensions given in Tables 1 and 2. The MSJC Code requires that the computation of stresses be based on the minimum net cross-sectional area of the element under consideration, An. For ungrouted, hollow brick units laid with face-shell bedding, the minimum net cross-sectional area is the mortar bedded area. The computation of stiffness of a brick masonry element may be based on the average net cross-sectional area of the element. The average cross-sectional area is permitted for stiffness computations, because the distribution of material within an element may be non-uniform. Examples of structural elements which have a non-uniform distribution of materials include partially grouted or ungrouted hollow unit masonry walls. Walls Brick masonry walls may be constructed of a single wythe (one unit in thickness) or multiple wythes and can be reinforced or unreinforced. Brick masonry walls may be loaded perpendicular to the plane of the wall or in the plane of the wall. Out-of-plane loads may be caused by wind or earth pressures or by earthquake induced ground motions. In-plane loads may be the dead weight of the structure, live loads or the result of the transfer of out-of-plane loads through wall connections.

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Section properties used in the MSJC Code's design equations for unreinforced masonry walls are I, r and Q. Section properties used in the MSJC Code's design equations for reinforced masonry walls are j, b and d. Additional section properties used to compute applied stresses are An, S and k. Effective areas for partially grouted, hollow unit masonry walls are illustrated in Figure 1. Shading indicates net uncracked area, net cracked area and shear area for a cracked cross section. For all illustrations in this Technical Notes, cross-hatching indicates mortar bedded areas. In Figure 1(b), the effective width, b, is taken as the least of s, 6t and 72 in. (1.8 m). In Figure 1(c), the effective width, b, is taken as the width of the grout space plus the thicknesses of the adjacent web and end web.

Effective Areas for Partially Grouted, Hollow Unit Masonry Walls FIG. 1 Section properties for typical ungrouted and grouted brick masonry walls are given in Tables 4 and 5, respectively. The quantities k and j are not provided in this Technical Notes because they are dependent upon the quantity of reinforcement provided, the elastic moduli of the masonry and the steel and the loading conditions. The elastic moduli of the masonry and the steel will determine the moduli ratio, n. The moduli ratio is used to determine the state of stress in the steel and the masonry under loads. The loading conditions may be a combination of out-of-plane and in-plane loads. Walls which are subject to flexural and axial loads must be designed considering the interaction of axial load and bending moment, which may be accomplished by the use of a moment-load interaction diagram. The method of development of a moment-load interaction diagram is beyond the scope of this Technical Notes. TABLE 4 Ungrouted Wall Section Properties1

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1Per foot (305 mm) of wall. 2Section properties are based on minimum solid face shell thickness (see Table 2) and face shell bedding.

TABLE 5 Grouted Wall Section Properties1

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1Per foot (305 mm) of wall. Section properties are based on minimum solid face shell thickness (see Table2) and face shell

bedding of hollow unit masonry.

Columns Columns, as defined by the MSJC Code, are isolated elements whose horizontal dimension measured at a right angle from the thickness dimension does not exceed three times the thickness dimension and whose height is at least three times its thickness. Brick masonry columns are used to support large axial loads. Axial loads are typically due to the permanent weight of the structure and the transient floor or roof load which is tributary to the column. According to the MSJC Code, columns must be reinforced with a minimum of four reinforcing bars, and the area of reinforcement, As, must be at least 0.0025 but not more than 0.04 times the column's net cross-sectional area, An. The minimum nominal dimension of a column is 8 in. (200 mm) and the ratio of height to least lateral dimension must not exceed 25. These requirements will influence the brick masonry column cross section selected. Typical brick masonry column configurations and section properties are given in Table 6. Section properties are based on uncracked cross sections. Typically, a brick masonry column will be in compression and will not crack under loads. However, columns which are loaded by a eccentric axial load or a large lateral load may crack in flexure. A moment-load interaction diagram should be used to design and analyze such columns, considering the section properties of the cracked cross section. The method of development of a moment-load interaction diagram is

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beyond the scope of this Technical Notes. TABLE 6 Column Section Properties

Pilasters A pilaster is simply an increase in the effective thickness of a wall at a specific location. To work together, the wall and the thickened section must be integrally constructed. MSJC Code Section 5.10 permits three methods of bonding a pilaster to create integral construction: 1) interlocking fifty percent of the masonry units, 2) toothing at 8 in. (200 mm) maximum offset and attachment with metal ties and 3) providing reinforced bond beams at a maximum spacing of 4 ft (1.2 m) on centers vertically. The length of the wall or flange that is considered to act integrally with the pilaster from each edge of the pilaster or web is the lesser of six times the thickness of the wall or the actual length of the wall. Typical brick masonry pilaster configurations and uncracked section properties are given in Table 7. As noted previously, cracked section properties such as k and j must be determined based on the amount of reinforcement, the moduli ratio and the loading conditions. Pilasters which are loaded both out-of-plane and in-plane must be designed considering the interaction of axial load and bending moment, which may be accomplished by the use of a moment-load interaction diagram. The method of development of a moment-load interaction diagram is beyond the scope of this Technical Notes. TABLE 7

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Pilaster Section Properties

1Section properties are based on minimum solid face shell thickness (see Table 2) face shell bedding of the flange and full bedding of the

web.

Beams Reinforced brick masonry beams may be used to span over wall openings such as windows and doors. Brick masonry beams provide a number of advantages over precast concrete or steel lintels. For example, brick masonry beams are a more efficient use of materials and produce a visually appealing brick masonry soffit. Some typical brick masonry beam configurations and their section properties are given in Technical Notes 17H and 17J. SUMMARY Section properties of brick masonry materials and assemblages are required whenever a rational design of brick masonry structural elements is developed following the criteria of the MSJC Code and Specifications. This Technical Notes provides a summary of section properties of brick masonry. Section properties of clay and shale masonry units, steel reinforcement and typical brick masonry assemblages are given. The information and suggestions contained in this Technical Notes are based on the available data and the experience of the engineering staff of the Brick Institute of America. The information contained herein must be used in conjunction with good technical judgment and a basic understanding of the properties of brick masonry. Final decisions on the use of the information contained in this Technical Notes are not within the purview of the Brick Institute of America and must rest with the project architect, engineer and owner. REFERENCES 1. Building Code Requirements for Masonry Structures and Commentary (ACI 530/ASCE 5/TMS 402-92) and Specifications for Masonry Structures and Commentary (ACI 530.1/ASCE 6/TMS 602-92), American Concrete Institute, Detroit, MI, 1992.

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Technical Notes 4 - Heat Transmission Coefficients of Brick Masonry Walls Rev [Jan. 1982] (Reissued Sept. 1997) Abstract: A procedure to analyze the heat flow through the opaque walls of a building envelope is provided. The design coefficients of heat transmission are provided for commonly used construction materials. Methods of calculating heat transmission coefficients and examples of heat loss calculations under steady-state conditions are provided for opaque wall assemblies. Key Words: brick, conductance, conductivity, energy, heat loss, rate of heat flow, resistance, resistivity, steady-state conditions, series and parallel path, thermal transmission. INTRODUCTION Because of the finite supply of fossil fuels and the high cost of energy, the need to design energy-efficient buildings that are also economical becomes important. Various industry groups are continually updating and refining energy conservation standards and guidelines for use in the design of new buildings. These standards and guidelines may be used to assist the building designers. The designer is confronted with the fact that no two buildings are exactly identical, nor are the methods or modes of operation similar. Thus, the energy performance of each building, as a whole, must be evaluated relative to the real performance of its materials, systems and equipment. This Technical Notes provides information and methods of calculating transmission coefficients and heat transfer values of brick masonry walls under static conditions. These may be used in energy conservation studies and comparisons for predicting thermal performance of building components. However, ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) cautions the designer that heat flow through a building envelope is actually not static, and although steady-state calculations provide an estimate of energy consumption, they do not take into account dynamic conditions such as the thermal storage capacity of materials, direct solar radiation, wind and other variables. The term "steady-state" means that all ambient conditions are assumed to be constant, which in the real world is virtually never the case. BUILDING THERMAL DESIGN The ASHRAE Handbook of Fundamentals states the following concerning heat transfer calculations: "Current methods for estimating the heat transferred through floors, walls and roofs of buildings are largely based on a steady-state or steady-periodic heat flow concept (Equivalent Temperature Difference Concept). The engineering application of these concepts is not complicated and has served well for many years in the process of design and selection of heating and cooling equipment for buildings. However, competitive practices of the building industry sometimes require more than the selection or design of a single heating or cooling system. Consultants are requested to present a detailed comparison of alternative heating and cooling systems for a given building, including initial costs as well as short- and long-term operating and maintenance costs. The degree of sophistication required for costs may make it necessary to calculate the heating and cooling load for estimating energy requirements in hourly increments for a year's time for given buildings at known geographic locations. Because of the number of calculations involved, computer processing becomes necessary. The hour-by-hour heating and cooling load calculations, when based upon a steady heat flow or steady-periodic heat flow concept, do not account for the heat storage effects of the building structure, especially with regard to net heat gain to the air-conditioned spaces." The Handbook of Fundamentals also suggests that the designer consider the following factors when performing heating load calculations: 1) building construction-heavy, medium or light; 2) presence of insulation; 3) infiltration and ventilation loads; 4) glass area-normal or greater than normal; 5) occupancy nature and schedule; 6) presence of auxiliary heating devices; and 7) expected cost of energy.

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Actual heat flow through a wall under normal weather conditions will involve daily cycles of solar radiation and air temperature, changing wind speeds and directions, and radiation to the night sky. In studies ("Effective U-Values", New Mexico Energy Institute, 1978) of dynamic heat transmission through a building envelope, it was found that consideration of solar heat gain and material thermal storage effects provided results significantly different from steady-state heat flow calculations. These studies also showed that the optimum economic insulation level varies with wall orientations, and that changing the color of East, West and South walls was more cost-effective in some instances than insulating. For a detailed description of the thermal storage effects of brick masonry walls, see Technical Notes 43 and 43D. The actual rate of heat flow through typical masonry building walls may be up to 20% less than the calculated rate based on published U-values. This is indicated by past research (Structural Clay Products Research Foundation, Studies of Heat Transfer.), which points out that the rate of heat transfer can be 20% to 60% greater than the calculated rate for wood frame walls and metal panel walls, respectively. Masonry walls have a more favorable rate of heat transfer because of their greater heat storage capacity, which is sometimes referred to as thermal mass, or capacity insulation. The heat flows calculated by steady-state methods are 29% to 60% greater than those measured under dynamic conditions for masonry walls. (Dynamic Thermal Performance of an Experimental Masonry Building, Building Science Series 45, National Bureau of Standards.) This means that massive masonry walls may be up to 60% better at retarding heat flow than steady-state U-values indicate. A method to modify the steady-state calculations, in order to account for the effect of mass, is provided in Technical Notes 4B. The overall coefficient of heat transmission (U-value) of various walls discussed in this Technical Notes is used in steady-state heat transfer and steady-periodic heat gain calculations. Computer programs, such as those used by the National Bureau of Standards, (National Bureau of Standards Loads Determination (NBSLD) Computer Program, T. Kasuda, "NBSLD-National Bureau of Standards Heating and Cooling Load Determination Program", Journal, Automated Procedures for Engineering Consultants (APEC), Winter 1973-1974.) give values much closer to the actual performance of walls than is possible under the steady-state concept of heat transfer. Government agencies and industry groups are continuing to examine simplified methods to calculate dynamic heat flow without the use of computers. TERMINOLOGY Commonly used terms relative to heat transmission are defined below in accordance with ASHRAE Standard 12-75, Refrigeration Terms and Definitions. All of these terms describe the same phenomenon, however, some are described as determined by material dimensions and boundaries. U = Overall Coefficient of Heat Transmission. The rate of heat flow through a unit area of building envelope material or assembly, including its boundary films, per unit of temperature difference between the inside and outside air. The term is commonly called the "U-value". The Overall Coefficient of Heat Transmission is expressed in Btu/(hr 0F ft2). Note that in computing U-values, the component heat transmissions are not additive, but the overall U-value is actually less (i.e., better) than any of its component layers. Normally, the U-value is calculated by determining the resistance (R, defined below) of each component, and then taking the reciprocal of the total resistance. k = Thermal Conductivity. The rate of heat flow through a homogeneous material, 1-in. thick, per unit of temperature difference between its two surfaces. A material is considered homogeneous when the value of its thermal conductivity does not depend on its dimensions (within the range normally used in construction). Thermal Conductivity is expressed in (Btu in)/(hr 0F ft2) C = Thermal Conductance. The rate of heat flow through a unit area of material per unit of temperature difference between its two surfaces for the thickness of construction given, not per in. of thickness. Note that the conductance of an air space is dependent on height, depth, position, character and temperature of the boundary surfaces. Therefore, the air space must be fully described if the values are to be meaningful. For a description of other than vertical air spaces, see the 1981 ASHRAE Handbook of Fundamentals, Chapter 23. Thermal Conductance is expressed in Btu/(hr 0F ft2) h = Film or Surface Conductance.

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The rate of heat exchange between a unit or surface area and the air it is in contact with. Subscripts i and o are used to denote inside and outside conductances, respectively. Film or surface conductance is expressed in Btu/(hr 0F ft2). R = Thermal Resistance. The reciprocal of a heat transfer coefficient, as expressed by U, C, or h. R is in (hr 0F ft2 )/Btu. For example, a wall with a U-value of 0.25 would have a resistance value of R = I/U = 1/0.25=4.0. The value of R is also used to represent Thermal Resistivity, the reciprocal of the thermal conductivity. Thermal Resistivity is expressed in (hr 0F ft2)/(Btu in) Btu = British Thermal Unit. It is the approximate heat required to raise 1 lb. of water 1 deg Fahrenheit, from 590F to 600F. The difference of thermally homogeneous materials and thermally heterogeneous materials is shown in Figure 1. There is a directly proportional relationship between the R and C of the thermally homogeneous material, at twice the thickness the R is twice as great and the C is halved. For the thermally heterogeneous material, there is no directly proportional relationship to the R or C and the material thickness. Fig. 1 also shows the horizontal path of heat flow through a 1 ft2 surface area of the wall component.

Thermal Transmittance Through Materialsa FIG. 1 aIt is important to note that not all materials are isotropic with respect to heat transmission. In such thermally heterogeneous materials, the specific thermal property under consideration could vary with temperature and material orientation. For this reason, care must be taken that the direction of heat flow through a material is suitable for the material's intended use. Materials in which heat flow is identical in all directions are considered thermally homogeneous.

CALCULATION OF OVERALL COEFFICIENTS General Conductance and resistance coefficients of various wall elements are listed in Table 1. These coefficients were taken from the 1981 ASHRAE Handbook of Fundamentals, Chapter 23, which states: "The most exact method of determining heat transmission coefficients for a given combination of building materials assembled as a building section is to test a representative section in a guarded hot box. However, it is not practicable to test all the combinations of interest. Experience has indicated that U-values for many constructions,

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when calculated by the methods given in this chapter using accurate values for component materials, and with corrections with framing member heat loss, are in good agreement with the values determined by guarded hot box measurements, when there are no free air cavities within the construction. "Remember, the values shown for materials in calculating overall heat transmission are representative of laboratory specimens tested under idealized conditions. In actual practice, if insulation is improperly installed (for example), shrinkage, settling, insulation compression, and similar factors may have a significant effect on the overall U-value numbers. Materials that are field fabricated and consequently especially sensitive to the skills of the mechanic, are especially prone to variations resulting in performance less than the idealized number." Calculation Methods Conductances and resistances of homogeneous material of any thickness can be obtained from the following formula: Cx=k/x, and Rx=x/k where: x=thickness of material in inches.

This calculation for a homogeneous material is shown in Fig. 1. The calculation only considers the brick component of the wall assembly. Whenever an opaque wall is to be analyzed, the wall assembly should include both the outside and inside air surfaces. The inclusion of these air surfaces makes all opaque wall assemblies layered construction. In computing the heat transmission coefficients of layered construction, the paths of heat flow should first be determined. If these are in series, the resistances are additive, but if the paths of heat flow are in parallel, then the thermal transmittances are averaged. The word "series" implies that in cross-section, each layer of building material is one continuous material. However, that is not always the case. For instance, in a longitudinal wall section, one layer could be composed of more than one material, such as wood studs and insulation, hence having parallel paths of heat flow within that layer. In this case, a weighted average of the thermal transmittances should be taken. For layered construction, with paths of heat flow in series, the total thermal resistance of the wall is obtained by:

R1=R1+R2+... and the overall coefficient of heat transmission is: U=1/R1

A solid 8-in. face brick wall would be a layered construction assembly in regard to thermal analysis:

R (hr * 0F * ft2) -------------BTU Outside Air Surface 0.17 8-in. Face Brick 0.88 Inside Air Surface 0.68 Total: R1=1.73 U = 1/R1 = 0.578 Btu/(hr * 0F * ft2 Average transmittances for parallel paths of heat flow may be obtained from the formula: uavg[AA(UA) + AB(UB) +

...] / At

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or

Uavg = [1/ (RA/AA) + 1/(RB/AB)...]/AT where:

AA, AB, etc. = area of heat flow path, in Ft2, UA,UB, etc.= transmission coefficients of the respective paths, RA, RB, etc.=thermal resistance of the respective paths. At= total area beign considered (AA+AB+...), in Ft2

Such an analysis is important for wall construction with parallel paths of heat flow when one path has a high heat transfer and the other a low heat transfer, or the paths involve large percentages of the total wall with small variations in the transfer coefficients for the paths. Thermal bridges built into a wall may increase heat transfer substantially above the calculated amount if the bridge is ignored. Thermal bridges occur in several types of walls. Three examples of these are shown. Different methods are used in calculating the Uavg for metallic and non-metallic bridges. Examples of both are shown. The brick veneer-frame wall shown in Fig. 2 has thermal bridges which occur at the wood studs. The parallel path method allows the average U-value of the wall to be calculated by first calculating the U-values in series of the two paths involved. Using the heat transmission coefficients for the various materials found in Table 1, the calculation is shown in Fig. 2. The path at the wood stud is Path A and the path at the insulation is Path B.

Brick Veneer/Wood Stud

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FIG. 2a

Brick Veneer/Wood Stud FIG. 2b This calculation reveals that, if the thermal bridge formed by the stud is considered, the Uavg exceeds the U of the wall having the insulation (Path B) by approximately 6 per cent. It is common practice to calculate the U-values for the insulation path by the series method and then multiply this value by 1.08 to obtain the Uavg for the wood frame walls. This method of correcting for wood framing in the walls is still used in many energy calculation guidelines procedures, although it is no longer provided in the ASHRAE Handbook of Fundamentals. It should be noted that the correction factor should be higher because this value properly predicts the Uavg for the studs, but does not appropriately adjust the U-value for jambs, heads, sills, and top and toe plates. Also, if 2 in. x 6 in. wood studs are used, the correction factor may no longer be appropriate. Most masonry walls have parallel paths of heat flow which result from bonding the separate wythes together. This may be by masonry bonders or metal ties. However, for conventional constructions, the effect of the bonders is not significant, because of the relatively small area of the metal ties per sq ft of wall, and the slight differences in conductivity or conductance of masonry units. However, if masonry bonded cavity walls with insulation in the cavity of walls with a large amount of headers are being considered, the parallel path method of calculation should be used. This is illustrated by the calculated U-values of the brick cavity wall, shown in Fig. 3.

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Brick Masonry Cavity Wall(Masonry Bonded) FIG. 3a

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Brick Masonry Cavity Wall(Masonry Bonded) FIG. 3b If the thermal bridge at the bonder were ignored, the U-value would be the same as UB, which is 0.088. This is approximately an 18 per cent differential between the series and parallel path calculated transmission coefficients. The metal-tied cavity wall shown in Fig. 4 requires the parallel path method of calculation. However, a slightly modified parallel path method should be used because the ASHRAE Handbook of Fundamentals requires that calculations for metallic thermal bridges be done by the Zone Method. Under this method a slightly larger area is assumed to be affected by the metallic bridge than just the area of the metal. The wall is divided into two zones, Zone A, containing the metal; and Zone B, the remaining portion of the wall.

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Brick Masonry Insulated Cavity Wall FIG. 4a

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Brick Masonry Insulated Cavity Wall FIG. 4b The Handbook of Fundamentals also prescribes a method for determining the size and shape of Zone A. The surface shape of Zone A in the case of a metal beam would be a strip of width, W, centered on the beam. In the wall shown in Fig. 4, the shape of Zone A, due to the circular tie, would be a circle of diameter W. W is calculated from the following formula:

where: W = width or diameter of the zone, in in., m = width or diameter of the metal heat path, in in., d = distance from the panel surface to the metal, in in. The value of d should not be taken as less than 0.5 in. Calculations for W should be run for both surfaces and the larger of the two values used.

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For the insulated cavity wall with one metal tie provided for each 4 1/2 sq ft of wall surface, the calculations in Fig. 4 show that there is about 3.2 per cent increase in the heat loss through the wall when the ties are considered as compared to the heat loss through the wall without consideration of the ties. For a cavity wall which does not contain any insulation, the effect of the metal ties is much less. By subtracting out the effects of the insulation and the metal ties through the insulation shown in Fig. 4, the effect of the wall tie through a 1-in. air space may be determined:

This calculation procedure shows that the effect of a metal tie across a 1-in. air space is negligible. Fig. 5 shows the calculations for an uninsulated cavity wall and again the effect is negligible. These calculations demonstrate that the effect of a metal tie would be negligible in the 1-in. air space in brick veneer construction and also in uninsulated cavity walls. There will be minor variations, depending on the type, size and spacing of metal ties, but the effect may usually be ignored. However, as demonstrated in the calculations in Fig. 4, if the metal tie passes through insulation, the effect of the metal tie on the thermal performance of the wall may become more significant. It should be noted that as the R-value of the material the metal tie penetrates in creases, the per cent of heat loss due to the metal tie also increases.

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Brick Masonry Cavity Wall FIG. 5a

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Brick Masonry Cavity Wall FIG. 5b Another factor which affects the thermal performance of walls containing metal is the location of the metal in the wall. The farther the metal is located from the face of the wall, the larger the area of the zone affected by the metal tie. This may be demonstrated with brick veneer/steel stud systems. Consider the brick veneer/steel stud system shown in Fig. 6. The steel stud backup system consists of 6-in., 20 gage steel studs at 24 in. o.c., with 6-in. batt insulation between the steel studs. The width of Zone A is determined from the exterior flange of the steel stud to the exterior face of the brick veneer, as shown in Fig. 6. The zone, including the metal, is quite wide for this type of construction. In accordance with steady-state analysis, assuming that the 1-in. air space is a material of the system, the width of the zone becomes 10.5359 in. The 1 5/8-in. wide flange of the metal studs, being relatively thin as compared to the wall section, is not considered in the analysis because it will not significantly affect the average thermal performance of the system.

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Brick Veneer/Steel Stud FIG. 6a

Brick Veneer/Steel Stud

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FIG. 6b Without consideration of sills, jambs, heads, and toe and top channels, the performance of the brick veneer/ steel stud system analyzed is almost 50 per cent less than the value calculated through the insulation. This performance is calculated using the procedures in the 1981 ASHRAE Handbook and Product Directory. However, actual tests of the heat transmission and more precise calculation procedures will probably demonstrate that the calculated heat loss is considerably higher than the actual heat loss. The intent of this example is simply to show that the thermal performance of brick veneer/metal stud systems is not the same as brick veneer over wood frame. The designer should be aware of this discrepancy and the accuracy, or inaccuracy of the approximation of thermal performance by simplified calculation procedures. The thermal performance of the brick veneer/metal stud system would require a correction factor for the framing which greatly exceeds the 8 per cent or the 1.08 U adjustment factor allowable for wood frame given in the previous brick veneer example. Even for the wood frame, because of the presence of fire stops, heads, jambs, sills and top and toe plates, it is recommended that the 1.08 factor for wood frame be increased to about 1.20, and that an even larger factor be used for metal studs. HEAT LOSS AND HEAT GAIN Building envelope heat losses and heat gains are calculated using the overall heat transmission coefficients and other known data. Even though heat losses and heat gains are calculated using U-values in the steady-state and steady-periodic formulae in lieu of the more accurate methods available, other factors greatly affect the performance of the building envelope in conserving energy. It should be remembered that the values obtained from the steady-state and steadyperiodic calculations are merely an estimate of the thermal performance of the envelope. The designer should be aware that several factors, other than U-values, determine the actual performance of the envelope in conserving energy. Some of these factors are: 1) building orientation and aspect ratio (The aspect ratio is the proportion of length to width. As the ratio approaches 1, the surface area to volume ratio decreases, and generally there will be less loss of thermal energy from interior spaces through the building envelope); 2) exterior surface color of envelope materials; 3) color of inside walls and ceilings; 4) mass and specific heat of envelope materials; 5) wind velocities; 6) infiltration through the envelope; and 7) orientation, area and external shading of glazing. These factors are not considered in the steady-state calculations. However, if their effects on heat transmission are kept foremost in the designer's mind, he can utilize the energy-conserving characteristics of each of these factors. The resulting structure will be more thermally efficient than is shown by the steady-state calculations. Note that some of these factors are accounted for by the CLTD values in heat gain calculations. The steady-state method of calculation for heat loss is straightforward and simple to perform. The outdoor design temperatures required can be found in the 1981 ASHRAE Handbook of Fundamentals. The inside design o temperature should be 72 F, or as prescribed by governing codes. The formula for calculating heat loss is as follows: where: H = heat loss transmitted through the walls or other elements of the building envelope, in Btu/hr, A = area of the walls or other elements, in ft2, o

U = overall coefficient of heat transmission of the walls or other elements, in Btu/(hr F ft2), o

ti = indoor design temperature, in F, to = outdoor design temperature, in oF.

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aFrom ASHRAE Handbook of Fundamentals, except as noted. bFace brick and common brick do not always have these specific densities. When the density is different from that shown, there will be a change in

the thermal conductivity. c

Calculated data based upon hollow brick (25% to 40% cored) of one manufacturer. Based upon coring and density given. R figures based upon coring and density of supplier using parallel path method. Vermiculite fill in cores. d From NCMA TEK 38 eValues for metal siding applied over flat surfaces vary widely depending upon the amount of ventilation of air space beneath the siding, whether the

air space is reflective or non-reflective, and on the thickness, type. and application of insulating backing-board used. Values given are averages intended for use as design guide values and were obtained from several guarded hot-box tests (ASTM C 236) on hollow-backed types and on types made using backer-board of wood-fiber, foamed plastic, and glass fiber. Departures of +/- 50%. or more, from the values given may occur.

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f

Thicknesses can vary. R values must be stamped on batt.

g

Based upon values as commercially produced. For calculations use specific manufacturer's specified values.

h

Time-aged values for board stock with gas-barrier quality (0.001 in thickness or greater) aluminum foil facers on two major surfaces.

CONCLUSION Present-day technology for heat transmission (steady-state and steady-periodic) does not permit the designer to take full advantage of the thermal mass of the element. While these design methods are relatively easy to understand and calculate, they are not a true measure of the performance of massive elements. These methods do give the designer an approximate solution which is on the conservative side in relation to the actual performance of massive walls. The designer should take into account the higher performance of massive construction which in many cases, may provide savings in operational costs, efficiency of operation and energy. To provide a more accurate prediction of these savings, a detailed computer study of the thermal performance of the structure is usually warranted. Other Technical Notes in this series discuss heat gain through opaque walls, thermal transmission corrections for dynamic conditions, balance point temperatures and energy conservation including worksheets, examples and data tables. METRIC CONVERSION Because of the possible confusion inherent in showing dual unit systems in calculations, the metric (Sl) units are not given in the data, equations or examples. Table 2 provides metric (Sl) conversion for the more commonly used heat transmission units. This table is provided so that the user may use the data and procedures with Sl units.

REFERENCES 1. 1997 ASHRAE Handbook and Product Directory, Fundamentals Volume. 2. 1981 ASHRAE Handbook and Product Directory, Fundamentals Volume.

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Technical Notes 4B Revised- Energy Code Compliance of Brick Masonry Walls February 2002

Abstract: All buildings designed today must comply with energy code requirements. Building energy performance requirements may be embodied in a model building code or in a separate energy standard. These documents typically contain requirements for the building envelope, including walls, windows, doors, roofs and floors. Brick masonry, as a high mass building material, has the inherent energy saving feature of thermal storage capacity (thermal mass). This Technical Notes describes how to quantify thermal mass and calculate the heat capacity of several brick masonry walls. The procedure for addressing thermal mass in residential and commercial construction when determining building envelope compliance with widely used energy standards and codes is also described. Key Words: brick, building codes, building envelope, energy, heat capacity, standards, thermal mass.

INTRODUCTION All buildings designed today must comply with energy code requirements. Energy performance requirements may be found in such documents as the 2000 International Residential Code [8], the 2000 International Energy Conservation Code [7], and the ASHRAE/IES Standard 90.1-1999: Energy Efficient Design of New Buildings Except New Low-Rise Residential Buildings [4]. These standards and codes specify energy efficient design through overall building performance criteria or by a component prescriptive approach. The element in overall building performance discussed in this Technical Notes is the building envelope. Brick masonry walls provide a uniquely energy efficient envelope due to their high thermal mass. Thermal mass is the characteristic of heat capacity and surface area capable of affecting building thermal loads by storing heat and releasing it at a later time. Materials with high thermal mass react more slowly to temperature fluctuations and thereby reduce peak energy loads. Economic, energy efficient designs may be achieved by recognizing this inherent aspect of brick masonry and incorporating it in the building envelope design. The benefits of thermal mass have been known for a long time. Research in 1975-76 during the energy crisis, sponsored by the Masonry Industry Committee, led to the development of a simplified method for quantifying thermal mass benefits [10]. This method, called the M Factor, was developed for use by designers to compare wall systems with respect to energy performance during the heating cycle. The M Factor was not intended for sizing of mechanical equipment, but rather as a comparative analysis tool. By knowing the weight of a wall and the annual heating degree days (HDD), a designer could determine the correction factor (M Factor) to convert the calculated U- or R-value of a wall to an equivalent U- or R-value accounting for thermal mass and its effect of slowing heat transmittance. The U- and R-values are measures of steady-state heat transmittance. The corrected U- or R-value was then used to comply with prescribed energy requirements. At that time codes and standards did not incorporate thermal storage concepts when prescribing limits on heat transfer. Today, energy codes and standards specify energy requirements as a function of wall type. Adjustment factors are included for masonry and other high mass walls as well as for walls built with steel studs that create thermal bridges. In the case of masonry walls, a higher maximum permissible value for the coefficient of thermal transmittance (U-value) for the building envelope is given depending upon where the insulation is located relative to the wall mass. Some codes additionally specify a maximum overall thermal transfer value for walls (OTTVw) of mechanically cooled spaces. The OTTVw is also a measure of heat transmittance and is a function of the wall temperature difference (TDEQ) which is also related to wall weight. This Technical Notes instructs the user on the methods for determining compliance of various brick masonry walls with the building envelope requirements of several energy standards and codes. Those included are the 1999 ASHRAE/IES Standard 90.1, the 2000 International Residential Code [8], and the 2000 International Energy Conservation Code [7]. The methods by which these energy standards and codes criteria reflect thermal mass properties of brick masonry are explained. The user of this Technical Notes is assumed to have a working knowledge of heat transmittance and familiarity with the

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energy codes and standards listed. Procedures for calculating the actual U-values for walls can be found in Technical Notes 4 Revised, Section 8.4 of ASHRAE/IES Standard 90.1, and in the ASHRAE Handbook of Fundamentals [5]. Because of the possible confusion inherent in showing dual unit systems in calculations, metric (SI) units are not given in the data, equations, or examples in this Technical Notes. Table 1 provides metric (SI) conversion factors for the more commonly used energy units.

NOTATION Ad

door area, ft2

Af

fenestration area, ft2

Ag

glazing area, ft2

Ao

gross wall area above grade, ft2

Aw

opaque wall area, ft2

c

specific heat, Btu/(lb -°F)

dt

temperature difference between exterior and interior design conditions, °F

HC

heat capacity, Btu/(ft2-°F)

HDD annual heating degree days HDD65

annual Fahrenheit heating degree days, 65 °F base

OTTVw

overall thermal transfer value - walls, Btu/(hr-ft2)

SC

shading coefficient of the fenestration, dimensionless

SF

solar factor value, Btu/(hr-ft2)

TDEQ temperature difference value, °F Ud

thermal transmittance of the door area, Btu/(hr-ft2-°F)

Uf

thermal transmittance of the fenestration area, Btu/(hr-ft2-°F)

Ug

thermal transmittance of the glazing area, Btu/(hr-ft2-°F)

Uo

average thermal transmittance of the gross wall area, Btu/(hr-ft2-°F)

Uow overall thermal transmittance of the wall assembly, Btu/(hr-ft2-°F) Uw

thermal transmittance of the opaque wall area, Btu/(hr-ft2-°F)

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w

weight, lb/ft2

HEAT CAPACITY In most energy codes, the thermal characteristics of high mass walls are quantified by measuring the heat capacity of the wall. Heat capacity represents the amount of thermal energy which may be stored by a material. For walls constructed of multiple materials, total heat capacity is calculated as the sum of the heat capacities of the individual components. In most energy codes and standards in the United States, heat capacity (HC) of a wall is calculated as the product of weight per unit area and specific heat (HC = w x c). Since the specific heats of most building materials are roughly equal, the heat capacity of a wall is directly proportional to its weight. Those materials which are relatively lightweight, such as insulation, do not have a significant effect on heat capacity and are often ignored when determining heat capacity. Use of the adjustment factors for mass walls in the 2000 International Residential Code [8] and the 2000 2

International Energy Conservation Code [7] is limited to walls having a heat capacity greater than or equal to 6 Btu/ft . Sample calculations of heat capacity for several brick walls are provided in Figure 1. Brick walls with a nominal thickness 2

or 4 in. or greater have heat capacities greater than or equal to 6 Btu/ft .

ENERGY CODE COMPLIANCE Each energy code and standard is slightly different in scope and criteria for compliance. The ASHRAE/IES Standard 90.1 is only applicable to non-residential buildings. Both residential and non-residential criteria may be found in the model building codes or the International Energy Conservation Code [7]. Each code and standard is discussed individually below.

ASHRAE/IES Standard 90.1 The ASHRAE/IES Standard 90.1 covers the energy performance design of new buildings except residential buildings of three stories or less. Compliance with this standard may follow one of two paths: the Building Energy Cost Budget Method or the System/Component Method. The Building Energy Cost Budget Method (BECBM) is to be used with innovative design concepts which cannot be accommodated by the System/Component Method or when a design fails the System/Component approach. The BECBM requires a detailed energy analysis to determine the estimated design energy cost. The BECBM permits any design whose design energy cost does not exceed the specified energy cost budget and meets the other requirements of the method. A complete description of this method can be found in Section 13 of the ASHRAE/IES Standard 90.1. The System/Component Method can be divided into two compliance paths for the building envelope: Prescriptive Criteria found in Section 8.5 and System Performance Criteria found in Section 8.6. These methods give minimum requirements to satisfy both heating and cooling cycle conditions. As the use of the ASHRAE/IES Standard 90.1 may be somewhat confusing, the National Codes and Standards Council of the Concrete and Masonry Industries has published a handbook which discusses the benefits of thermal mass and the design provisions of ASHRAE/IES Standard 90.1 [2]. In addition to the examples given in this Technical Notes, the reader is also urged to refer to this handbook. FIG. 1 Heat Capacities of Several Brick Walls _________________________________________________________________________________

(a) 4 IN. BRICK AND WOOD STUD WALL

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4 IN. BRICK w = (130 lb/ft3) x [(0.75)(3.63 in.) / 12in./ft] = 29.5 lb/ft2 (>75% SOLID)

c = 0.20 Btu/(lb-°F)

HC = 29.5 x 0.20 = 5.9 Btu/(ft2-°F) 4 IN. STUD w = 45 lb/ft3 x [(3.5 in. x 1.5 in.) / (144 in.2/ft2)] x (12 in./ft / 16 in.) = 1.23 lb/ft2 c = 0.30 Btu/(lb-°F) HC = 1.23 x 0.30 = 0.4 Btu/(ft2-°F) (2) 1/2 IN.

w = 50 lb/ft3 x [(2)(0.5 in.) / 12 in./ft] = 4.2 lb/ft2

GYPSUM BOARD c = 0.26 Btu/(lb-°F) HC = 4.2 x 0.26 = 1.1 Btu/(ft2-°F) INSULATION

NEGLIGIBLE TOTAL HC = 5.9 + 0.4 + 1.1 = 7.4 Btu/(ft2°F)

_________________________________________________________________________________

(b) 4 IN. BRICK AND 8 IN. LIGHTWEIGHT CMU WALL

4 IN. BRICK HC = 5.9 Btu/(ft3°F) 8 IN. LIGHTWEIGHT CMU (52% SOLID)

(from Fig. 1a)

w = 90 lb/ft3 x [(0.52)(7.63 in.) / 12in./ft] = 29.7 lb/ft2

c = 0.21 Btu/(lb-°F)

HC = 29.7 x 0.21 = 6.2 Btu/(ft2-°F) INSULATION

NEGLIGIBLE TOTAL HC = 5.9 + 6.2 = 12.1 Btu/(ft2-°F)

_________________________________________________________________________________

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(c) 4 IN. BRICK AND 6 IN. LIGHTWEIGHT CMU WALL

4 IN. BRICK HC = 5.9 Btu/(ft2-°F) (from Fig. 1a) 6 IN. LIGHTWEIGHT CMU (55% SOLID)

w = 90 lb/ft3 x [(0.55)(5.63 in.) / 12 in./ft] = 23.2 lb/ft2

c = 0.21 Btu/(lb-°F)

HC = 23.2 x 0.21 = 4.9 Btu/(ft2-°F) INSULATION

NEGLIGIBLE TOTAL HC = 5.9 + 4.9 = 10.8 Btu/(ft2-°F)

_________________________________________________________________________________

(d) 6 IN. HOLLOW BRICK WALL

6 IN. BRICK

w = 130 Ib/ft3 x [(0.60)(5.63 in.) / 12 in./ft] = 36.6 Ib/ft2

(60% SOLID)

c = 0.20 Btu/ (Ib-°F) TOTAL HC = 36.6 x 0.20 = 7.3 Btu/(ft2-°F) IF GROUTED, HC WOULD BE EVEN GREATER

_________________________________________________________________________________

Prescriptive Criteria. Section 8.5 of the ASHRAE/IES Standard 90.1 provides precalculated Alternate Component Package (ACP) tables based on the System Performance Criteria in Section 8.6 for a set of climate ranges. These ACP tables list the maximum permissible percentage of fenestration in a wall area, maximum thermal transmittance U-values, and minimum thermal resistance R-values as a function of the building's internal energy load, type and characteristics of fenestration and wall construction. The many climatic variables which influence the building envelope are grouped together in each ACP table for a range of climates. Thus, the criteria found in the ACP tables address a worst case condition and may be more stringent than the System Performance Criteria in Section 8.6.

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The maximum permissible overall thermal transmittance value of an opaque wall (Uow) using the prescriptive envelope criteria and the appropriate ACP table. The following example illustrates the benefits of using a thermal mass wall by comparing the maximum permissible Uow-value of a lightweight and a high mass wall. The U OW-value is a function of the wall weight (represented by HC); the building's internal cooling loads due to heat generated by lights, equipment, and people (ILD); the placement of the insulation either internal to or integral with the wall mass (INT INS) or outside the wall mass (EXT INS); and the percentage of total wall area consisting of doors, windows and other glazing (PCT FEN). Refer to Fig. 2 of this Technical Notes and Section 8.6 of the ASHRAE/IES Standard 90.1 for the tables and terms used in this example.

EXAMPLE 1: ASHRAE/IES Standard 90.1— Prescriptive Criteria Office Building Determine the maximum permissible overall wall thermal transmittance value (Uow) of a 12,000 ft2 office building located near Albuquerque, NM. The building is constructed of 4 in. nominal brick veneer with 8 in. nominal concrete masonry loadbearing walls with insulation as shown in Fig. 1b. The building's fenestration is 30 percent of the total wall area. To determine the maximum permissible Uow-value, use the following steps. Step 1: To use the Prescriptive Envelope Criteria, first determine the appropriate ACP table from the locations listed in Table 8A-0 in Attachment 8A of the Standard. Find Albuquerque, NM in Table 2 of this Technical Notes. From Table 2, determine that the appropriate ACP table is Table 8A-23 of the Standard. The ACP table for Albuquerque, NM (8A-23) is shown in Fig. 2 of this Technical Notes.

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1Table 8A-0, reprinted by permission from ASHRAE/IES Standard 90.1-1989 published by ASHRAE

FIG. 2

Step 2: Calculate the heat capacity (HC) of the wall in question. The HC of the brick and concrete masonry wall shown in Fig. 1b has already been calculated to be 12.1 Btu/(ft2-°F) . Step 3: Calculate internal load density (ILD) of the building. Section 8.5.5.2 of the Standard defines ILD as the sum of Lighting Power Density (LPD), Equipment Power Density (EPD) and Occupant Load Adjustment (OLA). Values for LPD are found in Table 6-5 of the Standard. (Note that Unit Lighting Power Allowance (ULPA) equals LPD.) For this office building example, LPD equals 1.81 W/ft2. The EPD can be selected from Table 8-4 of the Standard. For an office, EPD equals 0.75 W/ft2. OLA is a measure of the heat generated by living objects and is discussed in Section 8.5.5.2 of the Standard. For this example, assume OLA equals 0.0 W/ft2. Therefore,

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ILD = LPD + EPD + 0LA = 1.81 + 0.75 + 0.0 = 2.56 W/ft2.

Using the ACP table for Albuquerque, NM shown in Fig. 2, enter the appropriate row based on the ILD of the building. Since ILD for this example is 2.56 W/ft2, enter the row for ILD 1.51 - 3.00. Step 4: The ACP tables contain criteria for both fenestration and opaque portions of the building envelope. This example addresses only the opaque wall requirements. Therefore, to determine the maximum permissible U OW-value for the wall assembly in this example, move to the far right to the box under the heading OPAQUE WALL. Since HC of the wall in question is greater than 5 Btu/(ft2-F), go to the subheading MASS WALL and find the box corresponding to the ILD row found in Step 3. Step 5: The maximum U OW-value is also a function of the location of insulation in the wall assembly. The insulation in this example is placed between or integral with the wall mass. Therefore, select the column for interior or integral insulation, INT INS. See Section 8.5.5.3 of the Standard for a complete discussion of insulation location. Step 6: Find the appropriate rows under MASS WALL corresponding to the HC of the wall in question. In this example, HC equals 12.1 Btu/(ft2-F), so use the rows HC greater than or equal to 10. Follow these rows to where they intersect the INT INS column. There are two possible values of Uow based on the percentage of fenestration (PCT FEN) in the envelope. Step 7: Follow the rows for HC greater than or equal to 10 to PCT FEN equal to 11 and PCT FEN equal to 57. Recall that the building's fenestration (PCT FEN) equals 30 percent of the wall area in this example. The U OW-value corresponding to 11 percent equals 0.15 Btu/(hr-ft2-°F), and Uow-value corresponding to 57 percent equals 0.14 Btu/(hrft2-F). Linearly interpolate for PCT FEN equal to 30 or use the lower of the two values. Using the lower value as the maximum permissible value, Uow must be less than or equal to 0.14 Btu/(hr-ft2-F). Step 8: To comply with the Standard, the calculated U OW-value of the wall in question may not exceed the maximum permissible value as determined from the ACP table. Using the steps found in Technical Notes 4 Revised or the ASHRAE Hand/book of Fundamentals, the thermal transmittance of the wall in Fig. 1b is calculated to be 0.10 Btu/(hrft2-F). Since the calculated U OW-value is less than the maximum permissible value of 0.14 Btu/(hr-ft2-F), the wall construction complies with the Building Envelope Requirements of ASHRAE/IES Standard 90.1. Compare the maximum permissible Uow-value of the thermal mass wall in this example with the maximum permissible Uow-value for a lightweight wall with HC less than 5 Btu/(ft2-F). The box under the heading OPAQUE WALL shows that the maximum Uow-value is only 0.10 Btu/(hr-ft2-°F) for a lightweight wall. In terms of R-values, this thermal mass wall must have a minimum R-value of 7.1 (hr-ft2-F)/Btu, whereas a lightweight wall must have an R-value of at least 10.0 (hr-ft2-F)/Btu. System Performance Criteria. A system approach for compliance with envelope requirements is provided in Section 8.6 of the ASHRAE/IES Standard 90.1. This method is more flexible than the Prescriptive Criteria when considering thermal mass for several reasons. The external wall criteria are based on annual energy calculations for a specific location, rather than for a group of climates. Calculations allow for variations in internal loads and wall heat capacity by separating the building into zones. Furthermore, wall assemblies with HC greater than or equal to 7 Btu/(ft2-°F) do not have limits on the permissible Uow-value as they do in the ACP tables. Compliance with the System Performance Criteria is achieved if the calculated energy loads do not exceed the criteria specified in Section 8.6. The System Performance Criteria approach requires numerous mathematical calculations by hand or a computer program. Information on an acceptable computer program, ENVSTD, is part of Appendix D of the ASHRAE/IES Standard 90.1. The program models the building envelope's performance and fully accounts for the effects of thermal mass. For this reason, ENVSTD is recommended for use with the System Performance Criteria when determining energy compliance of brick masonry walls, particularly when passive solar technologies are employed in the design. International Residential Code The 2000 International Residential Code (IRC) covers all aspects of residential design and construction. Section N1102 of Chapter 11 - Energy Efficiency contains prescriptive requirements for energy compliance of the building envelope. This Code is only applicable for climates with Heating Degree Days (HDD) of less than 13,000. Further restrictions on the use of this Code limit the glazing area of Type A-1 Residential buildings to 15 percent or less and 25 percent or less for Type A-2 Residential buildings. Thermal performance criteria in the form of minimum required insulation R-values and maximum permissible U-factors are specified for each element in the building envelope. This Technical Notes covers the requirements for exterior walls only. Section N1102.1.1 contains tables with minimum R-values for walls, ceilings, floors, etc. based on the climates Heating

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Degree Days (HDD). Two tables are included specifically for mass walls. The first, Table N1102.1.1.1(1), specifies the minimum R-values for mass walls. The requirements vary depending upon the location of insulation and HDD. Walls with insulation placed on the exterior of the entire masonry mass are considered to have exterior insulation. An example of this type of construction is EIFS with a masonry backup. Walls that have insulation sandwiched between two roughly equal layers of masonry or mixed with the mass materials are considered to have integral insulation. Examples of this type of construction include masonry cavity walls and concrete masonry walls with insulated cores. Log walls are also considered to have integral insulation. Walls with interior insulation have the entire mass material on the exterior side of the insulation, such as in the case of brick veneer walls. The required R-values found in Table N1102.1.1.1(1) for mass walls with exterior or integral insulation are the same. Mass walls that do not meet the definitions for exterior or integral insulation are grouped into the “Other mass walls” category. The R-value requirements are lowest for walls having exterior or integral insulation. However, even “Other mass walls” reflect a considerable reduction in R-value as compared with non-mass walls. This savings is shown in Example 2(a). The second Table in this section provides a listing of the R-values of common mass wall assemblies. To comply with the minimum R-value requirements of Table N1102.1.1.1(1), find the R-value of the mass assembly from Table N1102.1.1.1(2) and add to it the R-value of any insulation or other layers in the wall assembly. See Example 2(b). EXAMPLE 2:

2000 International Residential Code - Mass Wall Requirements

Determine the required amount of insulation for the walls of a single family home in Raleigh, North Carolina framed with wood construction and a brick veneer. The glazing area is 12 percent. What is the required insulation R-value with vinyl siding instead of brick veneer? What is the required insulation R-value if the house is built with loadbearing brick masonry cavity walls? Ex. 2a: Determine the required R-values for brick veneer wall, a vinyl sided wall, and a loadbearing brick masonry cavity wall with integral insulation. Step 1: Determine the Climate Zone and annual Fahrenheit Heating Degree Days (HDD) for the location given. Climate Zones are listed in Table N1101.2 of the IRC. The Climate Zone for Raleigh, North Carolina which is located in Wake County is Zone 7. Step 2: Brick veneer construction is considered to have interior insulation. On Table N1102.1.1.1(1), Mass Wall Prescriptive Building Envelope Requirements, find Zone 7 and the column for “Other mass walls”. The required 2

mass wall assembly (insulation and masonry) R-value is 10.8 (hr·ft ·°F)/Btu. Step 3: For the vinyl-sided wall, use Table N1102.1. Zone 7 corresponds to HDD 3,000 - 3,499. From the walls column determine that R-13 insulation is required for the non-mass wall system. Step 4: For the loadbearing brick masonry cavity wall, use Table N1102.1.1.1(1). Under the column for integral insulation, find that the mass wall assembly (insulation and masonry) R-value must be R-8.9 (hr·ft2·°F)/Btu. Ex. 2b: Determine the required insulation values for the brick veneer wall and the loadbearing brick masonry cavity wall. Step 1: For the brick veneer wall, From Table N1102.1.1.1(2) determine that brick veneer alone has an R-value of 2

2

2.0(hr·ft ·°F)/Btu. The required insulation R-value is calculated as 10.8 - 2.0 = 8.8(hr·ft ·°F)/Btu Step 2: For the brick masonry cavity wall, assume ungrouted cells are not insulated and the only insulation is located in the cavity. From Table N1102.1.1.1(2) determine that the mass assembly R-value is equal to 3.7 2

2

(hr·ft ·°F)/Btu. Calculate the required insulation R-value as 8.9 - 3.7 = 5.2 (hr·ft ·°F)/Btu.

2000 International Energy Conservation Code The 2000 International Energy Conservation Code (IECC) prepared by the International Code Council, Inc. is applicable to residential dwellings as well as commercial, institutional and other buildings. This code sets limits on the permissible thermal transmission (U-value) of the building envelope. Residential buildings may comply with this code by adhering to one of three chapters : Chapter 4 - Residential Building Design by Systems Analysis and Design of Buildings Utilizing Renewable Energy Sources; Chapter 5 - Residential Building Design by Component Performance Approach; or Chapter 6 - Simplified Prescriptive Requirements for Residential Buildings, Type A-1 and A-2.

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RESIDENTIAL REQUIREMENTS - Chapters 4, 5, and 6 Chapter 4 - Systems Analysis and Renewable Energy Source Analysis. Chapter 4, as its title implies, is separated into two sections: Systems Analysis and Renewable Energy Source Analysis. Both sections require an analysis of the annual energy usage of the proposed system. Requirements and procedures for analysis are specified. Compliance is achieved if annual energy consumption is not greater than that of a similar residential building designed according to IECC Component Performance Approach found in Chapter 5. Chapter 5 - Component Performance Approach. The component performance approach presented in Chapter 5 of the IECC has requirements for residential building envelope (Section 502) as well as building mechanical systems, water heating, and electrical power and lighting. Residential requirements of Section 502 are divided into two types of residential construction, A-1 and A-2. Type A-1 are buildings with glazing areas that do not exceed 15 percent of the gross area of exterior walls. Detached one- and two-family dwellings are commonly Type A-1 buildings. Type A-2 have glazing areas that do not exceed 25 percent of the gross area of the exterior walls. Section 502.2, “Heating and Cooling Criteria”, specifies the maximum thermal transmission U-value for each building component (walls, roof, slab on grade, etc.). In residential construction, the maximum permissible UW-value for walls is a function of the heat capacity of the wall in question. The example that follows illustrates how the maximum permissible Uow-value may be increased if the HC of the wall in question is greater than or equal to 6 Btu/(ft2-°F). All 4 in. brick veneer walls have a HC of at least 6 Btu/(ft2-°F). This example utilizes the Compliance by Performance on an Individual Component Basis found in Section 502.2.1. Other provisions in this section contain criteria for compliance using Acceptable Practices (Section 502.2.3) and Prescriptive Criteria (502.2.4). EXAMPLE 3: International Energy Conservation Code — Component Performance Criteria Single Family Home Determine the maximum permissible thermal transmittance of the opaque wall area (UW-value) of a 2,000 ft2 two-story single family home located in a suburb of Washington, D.C. The house is brick veneer over wood frame constructed as shown in Fig. 1a. The home's fenestration is 20% of the total wall area: 15% glazing, 5% doors. Thermal transmittance values for the fenestration are: Ug = 0.48 and Ud = 0.48. The following steps are suggested to determine the maximum permissible UW-value. Step 1: Determine the annual Fahrenheit heating degree days (HDD, 65 °F base) for the location given. For Washington, D.C., HDD equals 4224. HDD for many U.S. cities can be found in the 2000 International Energy Conservation Code [7]. Other resources include Table B7.1 of Building Control Systems [1] or in the 1981 ASHRAE Handbook of Fundamentals [5]. A single family home with a glazing area of 20% is classified by IECC Section 101.3.1 as building Type A-2. Using this information, determine the maximum UO-value for the gross wall area from Fig. 3 of this Technical Notes to be 0.215 Btu/(hr-ft2-°F).

UO Walls—Type A-1 and A-2 Residential Buildings—Heating' FIG. 3

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Step 2: Calculate Uw using Eq. 1 and knowing the U-values of the glazing and door areas and the gross wall area (Uo). Equation 1 in this Technical Notes is Eq. 5-1 found in Section 502 of the IECC, solved for Uw.

Eq. 1

2

2

Uw = 0.118 Btu/(hr-ft -°F) or R ≥ 8.42 (hr-ft -°F)/Btu. This Uw-value is the maximum permissible value for wall constructions having a heat capacity less than 6 Btu/(ft2-F). Step 3: Determine the HC of the wall in question. The HC of the brick veneer and wood stud wall has already been calculated to be 7.4 Btu/(ft2-°F), see Fig. 1a. The maximum permissible Uw-value for a wall having a HC of 6 Btu/(ft2-°F) or greater may be increased to account for the effects of thermal mass using Tables 3a-3c in this Technical Notes. The values in these tables, taken from the IECC, are a function of climate (represented by HDD65); wall construction (HC greater than or equal to 6 Btu/(ft2-°F)); and the placement of insulation outside the thermal wall mass (Table 3a), on the interior of the wall mass (Table 3b) or integral with the wall mass (Table 3c). In this example, the insulation in the wall shown in Fig. 1a is placed interior of the wall mass. Therefore, Table 3b should be used. Enter the row in Table 3b for HDD equal to 4001-5500 and the column for Uw equal to 0.118 Btu/(hr-ft2-°F). Uw equal to 0.118 is between the columns in the table labeled 0.10 and 0.12. Linearly interpolate the table to determine the maximum permissible thermal transmittance, Uw, to be 0.137 Btu/(hr-ft2-°F). This U-value corresponds to an R-value greater than or equal to 7.30 (hr-ft2-°F)/Btu.

TABLE 3a Required Uw for Wall With a Heat Capacity Equal to or Exceeding 6 Btu/(ft2 oF) With Insulation Placed on the Exterior of the Wall Mass

TABLE 3b Required Uw for Wall With a Heat Capacity Equal to or Exceeding 6 Btu/(ft2 oF)

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With Insulation Placed on the Interior of the Wall Mass

TABLE 3c Required Uw for Wall With a Heat Capacity Equal to or Exceeding 6 Btu/(ft2 oF) With Integral Insulation (Insulation and Mass Mixed, Such as a Log Wall)

Step 4: To determine if the wall in question complies with Section 502 of the IECC, compare the maximum permissible thermal transmittance, Uw-value, determined in Step 3 with the calculated Uw-value. The calculated Uw-value, determined using the procedures contained in Technical Notes 4 Revised or the ASHRAE Handbook of Fundamentals, is 0.071 Btu/(hr-ft2-°F). Since the calculated Uw-value is less than the maximum Uw-value (0.157 Btu/(hr-ft2-°F)), this wall construction meets the requirements of the IECC Section 502. For comparison, in this example the maximum permissible Uw-value for a lightweight wall is 0.118 Btu/(hr-ft2-°F), but for a thermal mass wall, the maximum Uw-value is 0.137 Btu/(hr-ft2-°F). The allowable Uw-value for the thermal mass wall is 16 percent greater. Chapter 6 - Simplified Prescriptive Requirements for Residential Buildings, Type A-1 and A-2 Chapter 6 contains a simplified prescriptive approach that does not reflect different percentages of glazing or trade-offs between building envelope components. It does, however, allow for decreased R-value requirements for mass walls similar to those found in Chapter 5.

COMMERCIAL CONSTRUCTION - Chapters 7 and 8

Chapter 7 - Building Design for All Commercial Buildings. Chapter 7 of the IECC simply references the requirements of ASHRAE/IES Energy Code for Commercial and High-Rise Residential Buildings. All commercial buildings must meet

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the requirements of the ASHRAE/IES Energy Code or the requirements of Chapter 8 of the IECC. Chapter 8 - Design by Acceptable Practice for Commercial Buildings. Chapter 8 of the IECC is applicable to buildings that have a window and glazed door area not greater than 50 percent of the gross wall area. Buildings with glazing areas over 50 percent must comply with the ASHRAE/IEC Energy Code. Chapter 8 contains requirements for individual building components (walls, roof, floors). If any of these requirements are not met, the ASHRAE/IEC Energy Code can be used for that portion of the building envelope. Differences for mass walls are reflected in the required values for all but the warmest climates.

SUMMARY This Technical Notes continues the discussion of the energy efficiency of thermal mass brick masonry walls. Direction is provided on how to treat thermal mass when considering the envelope requirements of several energy codes or standards. Methods for complying with these requirements are described in detail. Sample calculations quantifying thermal mass as heat capacity (HC) are given. The information and suggestions contained in this Technical Notes are based on the available data and the experience of the engineering staff of the Brick Industry Association. The information contained herein must be used in conjunction with good technical judgment and a basic understanding of the properties of brick masonry. Final decisions on the use of the information contained in this Technical Notes are not within the purview of the Brick Industry Association and must rest with the project architect, engineer and owner.

REFERENCES 1. Bradshaw, V., Building Control Systems, John Wiley & Sons, New York, NY, 1985. 2. Thermal Mass Handbook, Concrete and Masonry Design Provisions Using the ASHRAE/IES Standard 90.1. National Codes and Standards Council of the Concrete and Masonry Industries, Herndon, VA, 1993. 3. Energy Conservation in New Building Design (ASHRAE Standard 90A), American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., Atlanta, GA, 1980. 4. Energy Efficient Design of New Buildings Except New Low-Rise Residential Buildings (ASHRAE/IES Standard 90.1-1989 and Addendum-1992), American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. and Illuminating Engineering Society of North America, Atlanta, GA. 5. Handbook of Fundamentals, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., Atlanta, GA, 1981 edition and 1997 edition. 6.

”Heat Transmission Coefficients of Brick Masonry Walls,” Technical Notes on Brick Construction 4 Revised,, Brick Industry Association, Reston, VA, January 1982.

7.

International Energy Conservation Code (IECC), International Code Council (ICC), Falls Church, VA, 2000.

8.

International Residential Code (IRC), International Code Council (ICC), Falls Church, VA, 2000.

9. "Report on the Effect of Wall Mass on the Storage of Thermal Energy," Hankins and Anderson, Inc., Richmond, VA and Boston, MA, 1976.

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Technical Notes 5A - Sound Insulation - Clay Masonry Walls (Reissued August 2000) INTRODUCTION The sound insulation or sound transmission loss of a wall is that property which enables it to resist the passage of noise or sound from one side to the other. This should not be confused with sound absorption which is that property of a material which permits sound waves to be absorbed, thus reducing the noise level within a given space and eliminating echoes or reverberations. Only sound insulation will be discussed in this Technical Notes. MEASUREMENT OF SOUND The sound insulation of a building assembly is expressed as a reduction factor in decibels (dB). The decibel is approximately the smallest change in energy the human ear can detect, and the decibel scale is used for measuring ratios of sound intensities. The reference sound intensity used to measure absolute noise levels is that corresponding to the faintest sound a human ear can hear (0 dB). However, a difference of 3 or less dB is not especially significant, because the human ear cannot detect a change in sounds of less than 3 dB. Figure 1 shows the intensity level of common sounds on the decibel scale. These data are reproduced from "How Loud is Loud? Noise, Acoustics and Health", by Lee E. Farr, M.D., published in the February 1970 issue of Architectural & Engineering News. SOUND TRANSMISSION LOSS It is desirable to have a single number rating as a means for describing the performance of building elements when exposed to an "average" noise. In the past it was customary to use the numerical average of the transmission loss values at nine frequencies. This rating, termed the nine-frequency average transmission loss, is often quite inaccurate in comparing an assembly of materials having widely differing TL-frequency characteristics. One single number rating method which has been recently proposed is the sound transmission class (STC). This rating is based on the requirements that the value of transmission loss at any of the eleven measuring frequencies does not fall below a specified TL-frequency contour. The shape of this contour is drawn to represent the more common types of noise, and generally covers the requirements for speech privacy.

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FIG. 1 The following are conclusions in a report entitled, "Measurements of Sound Transmission Loss in Masonry", by William Siekman of Riverbank Acoustical Laboratories, June 1969. "In conclusion, changes in results of transmission loss measurements have been studied. They indicate that deficiencies in earlier test methods and environments have apparently been corrected. Although data reported today are lower than ever before, they agree very well with data taken in field situations, and consequently provide

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assurance that laboratory tests can be relied upon to achieve the desired noise reductions. The performance of walls near the coincidence frequency cannot be predicted yet on a theoretical basis, nor can the performance of walls having a compound structure, but test specimen sizes are now large enough to be representative of typical walls and to provide data over the present frequency range of interest. "Since the principal deviation due to specimen size is apt to occur at the lower frequencies, users of transmission loss data are urged to avoid dependence upon single figure ratings, even such a relatively good one as is recommended by the Proposed Classification for Determination of Sound Transmission Class, ASTM RM 14-2 (1966). The decision to use a particular construction should always be based upon the total curve and the requirements at individual frequencies." DESCRIPTION OF SPECIMENS The specimens discussed in this issue of Technical Notes were constructed at the Riverbank Acoustical Laboratories in a testing frame having inside dimensions of 14 ft 4 in. wide by 9 ft 4 in. high. The joints were of typical thickness and were staggered. Mortar was mixed in a ratio by volume of 1 part cement, 2 parts lime and 9 parts sand. All specimens were constructed by a professional mason. The curing time was 28 days or more. The transmission area, S. used in the computations was generally 126 sq ft. Following are the descriptions of tests, performed at the Riverbank Acoustical Laboratories starting with the lowest Sound Transmission Class (STC): STC 39. 4-in. Structural Clay Tile Wall Tile dimensions: 3-9/16 by 4-7/8 by 11-3/4 in Wall thickness: 3-9/16 in. Average weight: 22.3 psf Test: TL 67-59 STC 41. 4 in. Structural Clay Tile Wall, with 5/8-in. plaster one face Tile dimensions: 3-9/16 by 4-7/8 by 11-3/4 in. Wall thickness: 4-3/16 in. Average weight: 25.3 psf Test: TL 67-82 STC 45. 8-in. Structural Clay Tile Wall Tile dimensions: 7-5/8 by 4-7/8 by 11-3/4 in. Wall thickness: 7-5/8 in. Average weight: 40.6 psf Test: TL 67-69 STC 45. 4-in. Face Brick Wall Brick dimensions: 2-1/4 by 3-3/4 by 8-1/4 in. Wall thickness: 3-3/4 in.

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Average weight: 38.7 psf Test: TL 67-70 STC 49. 6-in. "SCR brick" (Reg. U.S. Pat. Off., SCPI) Wall, with 3/8-in. gypsum board over 1-in. styrofoam insulation one face Brick dimensions: 2-1/4 by 5-1/2 by 11-1/2. Wall thickness: 6-7/8 in. Average weight: 57.7 psf Test: TL 70-39 NOTE: The styrofoam was placed with adhesive, spot applied 12 in. o.c. both vertically and horizontally, to the brick wall on one side. A single layer of 3/8 in. gypsum board was applied vertically over the foam with adhesive, spot applied 12 in. o.c. vertically and horizontally in the field and 6 in. o.c. at the joints. The external joints were finished with a typical drywall joint system. STC 50. 8-in. Face Brick and Structural Clay Tile Composite Wall Brick dimensions: 2-1/4 by 3-3/4 by 8-1/4 in. Tile dimensions: 4 in. nominal thickness Wall thickness: 8 in. Average weight: 63.8 psf Test: TL 67-65 STC 50. 10-in. Face Brick Cavity Wall, with 2-in. air space Brick dimensions: 2-1/4 by 3-3/4 by 8-1/4 in. Wall thickness: 10 in. Average weight: 81.0 psf Test: TL 68-31 NOTE: The 2 wythes of masonry were tied together with metal wall ties. STC 50. 4-in. Brick Wall, with 1/2-in. sanded plaster, two-coat one face Brick dimensions: 2-1/4 by 3-5/8 by 7-5/8 in. Wall thickness: 4-1/8 in. Average weight: 42.4 psf Test: TL 69-283 STC 51. 6-in. "SCR brick" (Reg. U.S. Pat. Off., SCPI) Wall Brick dimensions: 2-1/4 by 5-1/2 by 11-1/2 in.

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Wall thickness: 5-1/2 in. Average weight: 55.8 psf Test: TL 69-286 STC 52. 8-in. Solid Face Brick Wall Brick dimensions: 2-1/4 by 3-3/4 by 8-1/4 in. Wall thickness: 8 in. Average weight: 83.3 psf Test: TL 67-68 STC 53. 8-in. Solid Brick Wall, with 1/2-in. gypsum board on furring strips one face Brick dimensions: 2-1/4 by 3-5/8 by 7-5/8 in. Wall thickness: 9-1/4 in. Average weight: 86.7 psf Test: TL 69-287 NOTE: The 3/4-in. collar joint was filled with mortar. Metal Z ties were used between wythes spaced at 24 in. o.c. both vertically and horizontally. The 1 by 3 wood vertical furring strips were spaced at 16 in. o.c. and nailed at the mortar joints approximately 12 in. o.c. The gypsum board was applied vertically and attached with nails spaced 12 in. o.c. in the field and 8 in. o.c. along the edges. The joints and nail heads were finished with standard drywall system. STC 53. 6-in. "SCR brick" (Reg. U.S. Pat. Off., SCPI) Wall, with 1/2-in. plaster one face Brick dimensions: 2-1/4 by 5-1/2 by 11-1/2 in. Wall thickness: 6 in. Average weight: 60.8 psf Test: TL 70-70 STC 55. 12-in. Face Brick and Structural Clay Tile Composite Wall Brick dimensions: 2-1/4 by 3-3/4 by 8-1/4 in. Tile dimensions: 7-5/8 by 4-7/8 by 11-3/4 in. Wall thickness: 12 in. Average weight: 84.1 psf Test: TL 67-62 STC 59. 12-in. Solid Brick Wall Brick dimensions:

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Face: 2-1/4 by 3-3/4 by 8-1/4 in. Building: 2-1/4 by 3-5/8 by 8 in. Wall thickness: 12 in. Average weight: 116.7 psf Test: TL 67-32 NOTE: The outside wythes were of face brick. The interior wythe was of common brick. STC 59. 10-in. Reinforced Brick Masonry Wall (RBM) Brick dimensions: 2-1/4 by 3-5/8 by 7-5/8 in Wall thickness: 9-1/2 in. Average weight: 94.2 psf Test: TL 70-6 NOTE: The 2-1/4-in. grouted cavity contained No. 6 bars at 48 in. o.c. vertically and No. 5 bars at 30 in. o.c. horizontally. SOUND TRANSMISSION CLASS Sound transmission class contours (see Fig. 2) may be constructed in accordance with ASTM RM 14-2 on conventional semi-logarithmic paper as follows: a horizontal line segment from 1250 to 4000 Hz (cycles per second); a middle line segment decreasing 5 dB in the interval 1250 to 400 Hz; and a low frequency segment decreasing 15 dB in the interval 400 to 125 Hz.

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The sound transmission loss of the tested specimen is shown by the curved line in the above graph. The broken line is the limiting sound transmission class contour. The theoretical transmission loss of that limp mass having the same weight per square foot as the specimen can be located by drawing a straight line between the two slash marks on the edges of the grid. This was derived from the equation: TL = 20 log W + 20 log F - 33, where W is weight in pounds per square foot, and F is frequency in Hertz (cycles per second). FIG. 2 The STC contour is shifted vertically relative to the test curve until some of the measured TL values for the test specimen fall below those of the STC contour and the following conditions are fulfilled: The sum of the deficiencies (that is; the deficiencies of test points below the contour) shall not be greater than 32 dB, and the maximum deficiency of any single test point shall not exceed 8 dB. The sound transmission class for the specimen is the TL (transmission loss) value corresponding to the intersection of the sound transmission class contour and the 500-Hz ordinate. Table 1 shows the decibel losses for 18 frequencies of test specimens listed above. Deficiencies or deviations from the contour (see graph) are tabulated to correspond with the proper frequencies. These measurements were made using a one-third octave bank of pink noise, swept in 13 min from 100 to 5000 Hz. Runs were made before and after a system interchange, during which the ratio of sound pressure levels in the two rooms was directly recorded graphically. The final results were obtained by averaging the runs, with a resultant precision within a 90 per cent confidence limit of ±1 dB. The sound transmission class is computed in accordance with the Tentative Recommended Practice for Laboratory Measurement of Airborne Sound Transmission Loss of Building Partitions, ASTM E 90-66T, and ASTM RM 14-2. The STC number is intended to be used as a preliminary estimate of the acoustical properties of the specimen. Final decisions for design use should be based upon the entire TL curve for the values at all the test frequencies.

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1Transmission Loss, decibels 2Deficiencies, decibels

MASKING EFFECT The sound insulation required in a structure to give satisfactory results depends not only upon the noise level outside of the building or in adjoining rooms, but also upon the noise level within the room under consideration. If it is to be assumed that there is no noise within the room to be insulated against sound transmission and the noise level in the adjoining room is 60 dB, it will require a partition having a reduction factor of 60 dB to render the noise in the adjoining room inaudible. However, if the noise level in the room under consideration is 30 dB, a partition having a sound reduction factor of approximately 40 dB (see Fig. 3) will make the sound in the adjoining room inaudible. Experiments have shown that for one sound to mask another, there must be at least 10 dB difference between the two sounds. This effect of the sound within the room under consideration is known as the "masking effect". Figure 3 illustrates this "masking effect" principle.

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Effect of Masking Noise on "Listening" Side of Wall FIG. 3 CONCLUSION This issue of Technical Notes has discussed recent test data for, and sound insulation performance of, brick and tile walls and partitions. Future issues of Technical Notes will contain some suggestions and recommendations for the control of sound transmission through brick and tile walls and partitions.

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Technical Notes 6 - Painting Brick Masonry Rev [May 1972] (Reissued December 1985) INTRODUCTION Although some masonry walls require protective coatings to impart color and help in resisting rain penetration, clay masonry requires no painting or surface treatment. Brick are generally selected because, among other characteristics, they have integral and durable color and, when properly constructed, are resistant to rain penetration. Clay masonry walls may be painted to increase light reflection or for decorative purposes. Most paint authorities agree that, once painted, exterior masonry will require repainting every three to five years. This issue of Technical Notes discusses general applications of paint to interior and exterior brick walls, and a brief discussion on specific paints suitable for brick masonry. GENERAL It is often erroneously assumed that brick masonry walls that are to be painted can be built with less durable materials and, in some instances, with less than extreme care in workmanship than would normally be used for unpainted brick walls. This is not the case. When a brick wall is to be painted, the selection of materials, both brick units and mortar, and the workmanship used in constructing the wall should all be of the highest quality; at least as good in quality as when the walls are to be left exposed. Every care should be taken to see that joints are properly filled with mortar to avoid the entrance of moisture into the wall, since it may become trapped behind the paint and cause problems. Every care should be taken to see that there are no efflorescing materials in the wall, either in the mortar, brick units or in the backup, since efflorescence beneath the paint film can also cause problems. See Technical Notes 23 Series. Brick. Brick units to be used for walls that are to be painted should conform to the applicable requirements of the ASTM Specifications for Building Brick or Facing Brick, C 62 or C 216, respectively. The grade of units (which designates their durability) should not be lower than would be used if the wall were not to be painted. Grade SW is recommended. It may be acceptable to use brick units which are durable but differ in color in a wall to be painted. However, care should be taken that the units have similar absorption and suction characteristics so that the paint applied will adhere to all of the surfaces and have a uniform acceptable appearance. Mortar. Mortar for brick masonry walls to be painted should conform to the Specifications for Mortar for Unit Masonry, ASTM C 270, Proportion Specifications. It is suggested that the mortar consist of portland cement and lime, and that the mortar type be selected on the basis of the structural requirements of the wall. See Technical Notes 8. Paint. Paint for application to brick masonry walls should be durable, easy to apply and have good adhesive characteristics. It should be porous if applied on exterior masonry, thereby permitting the wall to breathe and preventing the trapping of free moisture behind the paint film. CONSIDERATIONS FOR PAINTING CLAY MASONRY In selecting a paint system for a brick masonry wall, the primary concern should be the characteristics of the surface and the exposure conditions of the wall. A primer coat may be of particular importance, especially where unusual or severe conditions exist. Alkalinity. The chemical property of masonry which may have a significant effect on paint durability and performance

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is the alkalinity of the wall. Brick are normally neutral, but are set in mortars which are chemically basic. Paint products, which are based on drying oils, may be attacked by free alkali and the oils can become saponified. To prevent this occurrence, an alkaline-resistant primer is recommended. Efflorescence. The deposit of water-soluble salts on the surface of masonry, efflorescence, is another factor that can hamper the performance of painted masonry. Efflorescence, which is present on the surface, should be removed and, once removed, the surface should be observed for reoccurrence prior to being painted. Methods of preventing and removing efflorescence are discussed in Technical Notes 23 Series, "Efflorescence-Causes, Prevention and Control". Water and Moisture. Water or moisture in a masonry system will generally hamper the satisfactory performance of the painted surface. Moisture may enter masonry walls in any of several ways; through the pores of the material, through incompletely bonded or only partially filled mortar joints, copings, sills and projections, through incomplete caulked joints and improperly installed flashing or where flashing is omitted. In general, brick wall surfaces should be dry for painting. Acceptable moisture conditions for masonry walls to receive paint are listed in Table 1. The use of an electrical moisture meter may be used to measure the moisture content of a wall

1

Some manufacturers offer special porous, highly pigmented emulsion paints which may give somewhat better results in very adverse conditions where delay is not acceptable.

SURFACE PREPARATION General. Proper surface preparation is as important as paint selection. Because each coat is the foundation for all future coats, success or failure depends largely upon surface preparation. Thoroughly examine all surfaces to determine the required preparation. Previously painted surfaces often require the greatest effort. Before painting, remove all loose matter. Take special care when cleaning surfaces for emulsion paints and primers. They are nonpenetrating and require cleaner surfaces than solvent-based paints. Some paints can or should be applied to damp surfaces. Others must not. Be sure to follow directions accompanying proprietary brands. New Masonry. As a general rule, new clay masonry is seldom painted. It is difficult to justify the extra expenditure for initial and future painting. However, if for any reason painting new masonry is desired, there are a few precautions necessary for reasonable success. Do not wash new clay masonry walls with acid cleaning solutions. Acid reactions can result in paint failures. Use alkali-resistant paints. If low-alkali portland cement is not used in the mortar, it may be necessary to neutralize the wall to reduce the possibility of alkali-caused failures. Zinc chloride or zinc sulfate solution, 2 to 3 1/2 lb per gal of

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water, is often used for this purpose. Existing Masonry. Examine older unpainted masonry for evidence of efflorescence, mildew, mold and moss. While these conditions are not common, they all indicate the presence of moisture. Examine all possible entry points for water. Where necessary, repair flashing and caulking; tuckpoint defective mortar joints. Remove all efflorescence by scrubbing with clear water and a stiff brush. A wall which has effloresced for a long time may present difficulties. The presence of moisture, the deposition of salts and the probable presence of alkalies are all factors which may contribute to the deterioration of paints. If moss has accumulated on damp, shaded masonry, apply an ordinary weed killer. Wet the wall with clear water before applying weed killers to prevent them from being drawn into the wall. Chemical weed killers may contain solubles which can contribute to efflorescence or react unfavorably with paint, and should be removed after being used by scrubbing the wall with a stiff brush while rinsing with clear water. Mildew seldom occurs on unpainted masonry. However, where present, treat it the same as on painted surfaces, discussed in the following paragraphs. Be sure to wet the wall before applying any cleaning solution. Clean small areas and rinse thoroughly. For further discussion on cleaning brick see Technical Notes 20 Revised, "Cleaning Clay Products Masonry". Painted Surfaces. Previously painted surfaces normally require extensive preparation prior to repainting (refer to Table 2 for typical paint failures). Under humid conditions, mildew may have developed. Mildew may feed on a paint film or on particles trapped by the painted surface. If present, remove it completely before applying paint. Otherwise, growth will continue, damaging new paint. Mildew has been successfully removed by steam cleaning and sand blasting. The following is also effective: 3 oz trisodium phosphate (Soilax, Spic and Span, etc.), plus 1 oz detergent (Tide, All, etc.), plus 1 qt 5 per cent sodium hyperchlorite (Chlorox, Purex, etc.), plus 3 qt warm water, or enough to make 1 gal of solution. Use this solution to remove mildew and dirt. Scrub with a medium soft brush until the surface is clean; then rinse thoroughly with fresh water. For small areas, use an ordinary household cleanser. Scrub with a medium soft brush and then rinse thoroughly. Use masonry paints containing a mildewcide to help prevent molds from recurring. Remove all peeled, cracked, flaked or blistered paint by scraping, wire brushing or sand blasting. In some instances, old paint may be burned off, but this should be done only by skilled operators. Like efflorescence, paint blistering is caused by water within the masonry. Search for the water's source and take the necessary corrective measures to keep water out of the wall. If alligatoring exists, remove the entire finish. There is no other means of correction. If slight chalking has occurred, brush the surface thoroughly. However, if chalking is deep, remove by scrubbing with a stiff fiber brush and a solution of trisodium phosphate and water. Rinse the surface thoroughly afterwards. Use a penetrating primer to improve adhesion of the final coat. Excessive paint buildup results from too many coats or excessively thick coats. Where it occurs, remove all paint and treat as a new surface. Completely remove cement-based paints before repainting with other types. An exception to this rule is the use of cement-based paints as primers which will be covered by another paint within a relatively short time. If the wall will be repainted with another cement-based paint, wire brushing and scrubbing will suffice, providing treatments for mildew, efflorescence, etc. are not required.

TABLE 2 Types of Paint Failure

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MASONRY PAINTS Because all paints have distinct properties and because surfaces vary considerably, even the most experienced painting contractors carefully examine a surface before making recommendations. However, the following will generally indicate the proper use of masonry paints. CEMENT-BASED PAINTS For many years, cement-based paints have been satisfactory coatings for masonry surfaces. They achieved popularity because they have relatively good adherence and tendency to make a wall less permeable to free water. Cement-based paints are permeable, permitting the wall to breathe. Their main components are portland cement, lime and pigments. Additives, binders and sands may be added. Although cement-based paints are more difficult to apply than other types, good surface protection results when properly applied. While they are not complete waterproofers, cement-based paints help to seal and fill porous areas, excluding large amounts of free water. White and light colors tend to be the most satisfactory. It is difficult to obtain a uniform coating with darker shades. Lighter colors tend to become translucent when wet, and dark colors become darker. Color returns to normal as the wall surface dries. Cement-based paints can provide a good base for other paints applied within a relatively short time. The following procedure for applying paint on a properly prepared surface generally applies: 1. Cure new masonry walls for approximately one month before applying cement-based paints. 2. Dampen wall surfaces thoroughly by spraying with water. 3. Cement-based paints are packaged in powdered form. Because their cementitious components begin to hydrate upon contact with water, mix immediately prior to application for optimum results. 4. Apply heavy coats with a stiff brush, allowing at least 24 hr to elapse between coats. 5. During this time, keep the wall damp by periodically spraying it with water.

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6. Apply additional coats in the same manner. 7. Keep the final coat damp for several days to properly cure. WATER-THINNED EMULSION PAINTS General Characteristics. Water-thinned emulsion paints, commonly referred to as latex paints, are relatively easy to apply. Water-thinned emulsions may be brush, roller or spray-applied. However, brush application is preferable, especially on coarse-textured masonry. Emulsion paints dry quickly, have practically no odor and present no fire hazard. They may be applied to damp surfaces, permitting painting shortly after a rain or on walls damp with condensation. As a group, these paints are alkali-resistant. Hence, neutralizing washes and curing periods are not usually necessary before painting. Water emulsion paints possess high water vapor permeability and are known to have performed well on brick substrates that have been properly prepared. Emulsion paints will not adhere well to moderately chalky surfaces. If possible, repainting should be done before the previous coat chalks excessively. However, specifically formulated latex paints are available containing emulsified oils or emulsified alkyds which facilitate wetting of chalky surfaces. This property enables the paint to bond the chalk together and to the substrate. The principal water-thinned emulsion paint types are: butadiene-styrene, vinyl, acrylic, alkyd and multicolored lacquers. Butadiene-Styrene Paints. These relatively low-cost, rubber-based latex paints develop water resistance more slowly than vinyl or acrylic emulsions. They are most satisfactory in light tints as chalking rate may be excessive in deep colors. Vinyl Paints. Polyvinyl acetate emulsion paints dry faster, have improved color retention and a more uniform, lower sheen than rubber-based latex paints. Acrylic Emulsion Paints. Acrylic emulsions have excellent color retention, permit recoating in 30 min or less, and have good alkali resistance. Acrylics have high resistance to water spotting and may be scrubbed easily. Alkyd Emulsion Paints. Alkyd emulsions are related to solvent-thinned alkyd types, but have all the general characteristics of latex paints. They do have more penetration than most water-thinned emulsions, achieving better adhesion on chalky surfaces. Compared to other emulsion paints, these are rather slow to dry, have more odor, are not as resistant to alkalies, and have poorer color retention. Under normal exposure conditions, alkyd emulsions can serve as a finished coat over a suitable primer. Multicolored Lacquers. A specialized paint group, multicolored lacquers are applied only by spray gun. The finished film appears as a base color with separate dots or particles of contrasting colors. These paints will cover many surface defects and irregularities. However, they must be applied over a base coat of another type; for example, polyvinyl acetate or acrylic emulsion paints. FILL COATS Fill coats are base coats for exterior masonry. They are similar in composition, application and uses to cement-based paints. However, fill coats contain an emulsion paint in place of some water, giving improved adhesion and a tougher film than unmodified cement paints. Fill coats have greater water retention, giving the cement a better chance to cure. This is particularly valuable in arid areas where it is difficult to keep the painted surface moist during the curing period. SOLVENT-THINNED PAINTS The five major solvent-thinned paints are oil-based, alkyd (synthetic resin), synthetic rubber, chlorinated rubber and epoxy. Oil-based and alkyd paints are not recommended for exterior masonry. Solvent-thinned paints should be applied only to completely dry, clean surfaces. They produce relatively nonporous films and should be used only on interior masonry walls not susceptible to moisture penetration. The exception to this is special purpose paint, such as

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synthetic rubber, chlorinated rubber and epoxy paints. Oil-Based Paints. Oil-based paints have been used for many years. They are relatively non-porous and recommended for interior use only. Although several coats may be required for uniform color and good appearance, they bind well to porous masonry. As with most solvent-based paints, they have good penetration on relatively chalky surfaces, but are highly susceptible to alkalies. New masonry must be thoroughly neutralized to avoid saponification. Available in a wide color range, oil-based paints are moderately easy to apply. Several days' drying is generally required between coats. Alkyd Paints. Alkyd paints are similar to oil-based paints in most general characteristics. They may have slightly less penetration, resulting in somewhat better color uniformity at the cost of adhering power. Alkyd paints are more difficult to brush, dry faster and give a harder film than oil-based paints. These, too, are nonpermeable and are recommended for interior use only. Synthetic Rubber and Chlorinated Rubber Paints. These paints have excellent penetration and good adhesion to previously painted, moderately chalky surfaces as well as new surfaces. They are reported to be more resistant to efflorescence and are generally good in alkali resistance. They may be applied directly to alkaline masonry surfaces, but are more difficult to brush on than oil paints. Darker colored synthetic rubber paints lack color uniformity. Both types have high resistance to corrosive fumes and chemicals. For this reason, they are often specified for industrial applications. Both types require very strong volatile solvents, a fire hazard which may prove undesirable. Epoxy Paints. Epoxy paints are of synthetic resins generally composed of two parts, a resin base and a liquid activator. They must be used within a relatively short time after mixing. Epoxies can be applied over alkaline surfaces, have very good adhering power, and good corrosion and fume resistance. However, some types chalk excessively if used outdoors. Epoxies are relatively expensive and somewhat difficult to apply. "HIGH-BUILD" PAINT COATINGS High-build paint coatings are generally used on interiors to give the effect of glazed brick. Some coatings are based on two-component urethane polyesters and epoxies. Others are of an emulsion-based coat with acrylic lacquer. These paint systems usually include fillers to smooth out surface irregularities. OTHER COATINGS Heavily applied coatings of the so-called "breathing type" are available with either a water or solvent base. They are generally composed of asbestos fiber and sand, and applied thickly to hide minor surface imperfections. The presence of moisture on the surface of a masonry wall generally will not harm the latex type. Lower application temperatures of 35 F to 50 F on the other hand are less damaging to the solvent type. For both types, adhesion is mostly mechanical because of low binder and high pigment content. Some coatings require special primers to insure adhesion. Although these coatings are reported to have given good performance on masonry, they tend to show stains where water runoff occurs. These coatings are capable of allowing passage of water vapor, but cannot transmit large quantities of water that may enter through construction defects. Failure may occur as a result of freezing of water accumulation behind the film. PAINTING NEAR UNPAINTED MASONRY Often windows and trim of masonry buildings are painted with self-cleaning paints to keep surfaces fresh and clean. Unfortunately, self-cleaning is generally achieved through chalking. The theory is that rain will wash away chalked paint, constantly exposing a fresh paint surface. The theory works well, but too often no provision is made to keep chalk-contaminated rain water away from masonry surfaces. The result is usually more unsightly than dirty paint on trim or windows. Avoid this staining by choosing nonchalking paints for windows and trim and by providing a means of draining water away from wall surfaces. REFERENCES

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1. Manual on the Selection and Use of Paints, Technical Report #6, National Research Council of Canada, Division of Building Research, 1950, Ottawa, Canada. 2. Paints for Exterior Masonry Walls, BMS110, National Bureau of Standards, 1947, Washington, D.C. 3. Field Applied Paints and Coatings, Publication 653, Building Research Institute, 1959, Washington, D.C. 4. Paints and Coatings, Publication 706, Building Research Institute, 1960, Washington, D.C. 5. Painting Walls; 1, Building Research Station Digest (2nd Series), No. 55, Building Research Station, 1965, Garston, Herts., England. 6. Coatings for Masonry Surfaces, by H. E. Ashton, Canadian Building Digest, CBD 131, November 1970, Ottawa, Canada. 7. Coatings for Masonry and Cementitious Materials, by Walter Bayer, Construction Specifier, November 1970, Washington D.C.

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TECHNICAL NOTES on Brick Construction 6A 1850 Centennial Park Drive, Reston, Virginia 20191 | www.gobrick.com | 703-620-0010

August 2008

Colorless Coatings for Brick Masonry Abstract: This Technical Note discusses common reasons for applying colorless coatings to above-grade brick masonry and the appropriateness of such actions. The types of products often used and the advantages and disadvantages of each are presented. Issues to consider prior to application of a clear coating to brick masonry are provided.

Key Words: clear, colorless coatings, film former, graffiti-resistant, penetrant, silane, siloxane, water penetration, water repellent.

SUMMARY OF RECOMMENDATIONS: General • Application of a water repellent coating is not necessary to achieve water resistance in brickwork subjected to normal exposures where proper material selection, detailing, construction and maintenance have been executed • Application is not recommended on newly constructed brick veneer or cavity walls or on new or existing pavements using clay pavers • Correct conditions contributing to water penetration before applying a coating to brickwork • Consider providing vents at top of drainage spaces when a water repellent coating is applied

General Selection Criteria • Consult the brick manufacturer prior to the selection of a coating • Select only coatings intended for use on clay brickwork • Consider the effects of all coating properties on brickwork, not just the desired property • Select coatings that have demonstrated consistent performance on similar installations, materials and exposures for a minimum period of five years

• Except for anti-graffiti applications, use only breathable coatings with a water vapor permeability of 0.98 or greater as measured by ASTM E96 • Consider the use of a siloxane or siloxane/silane preblended coating • Use comparative testing of treated and untreated walls using ASTM E514 or ASTM C1601 to determine coating effectiveness • Do not apply film-forming coatings to brickwork located in freeze-thaw environments

Specific Selection Criteria

• For exterior brickwork, consider a condensation analysis to determine whether coating affects the dew point location within the wall • For paving, consider the effects of coating on pavement slip resistance and the abrasion resistance of the coating

Application • Use a contractor with a minimum of five years experience installing selected coating on similar installations • Apply the coating according to the coating manufacturer directions

INTRODUCTION Colorless coatings are available in many types and are designed for a variety of uses. When needed, colorless coatings for brick masonry should be selected based on their intended use, documented performance and chemical and physical properties [Refs. 4, 6, 10, 13]. Clear coatings formulated for use on other masonry materials may not be appropriate for brick masonry and may in fact be detrimental to brick. Clay brick masonry has physical and chemical properties that are different from stone, concrete or concrete masonry. Brick masonry has a different pore structure and is generally less absorptive, less permeable and less alkaline than concrete masonry. The recommendations included herein are applicable only to clay brick masonry. The type of exposure the brickwork is subject to also plays an important role in coating selection. Coatings suitable for interior brick masonry may not be suitable for exterior exposures. Similarly, coatings applied to floors or pavements are subject to conditions different from those in brick walls. Specific recommendations regarding the reasons for, selection of and use of colorless coatings are found throughout this Technical Note. Opaque coatings, such as damp-proofing or waterproofing coatings, are not addressed. For further information about opaque coatings, refer to Technical Note 6, which covers painting of brick masonry.

© 2008 Brick Industry Association, Reston, Virginia

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REASONS FOR USE Clear coatings may be applied to brick masonry in an effort to facilitate cleaning, to resist graffiti, to provide gloss or to reduce water absorption or penetration. Often, a single product is used to achieve several of these objectives. Selection of a coating should be based on the desired appearance, resistance to water penetration, application of brickwork, material substrate, economics, life span or other criteria set by the designer or user. The disadvantages of using colorless coatings should also be considered during selection.

Water Penetration Resistance It is desirable to minimize the penetration and absorption of water in brickwork to avoid problems encountered in walls. Problems caused by excessive water penetration include freezing and thawing deterioration; corrosion of metal ties, metal studs and other items; rotting of wood members; mold growth; and damage to interior finishes. The most effective means of minimizing water penetration include exercising care during material selection, designing and detailing brick masonry properly, constructing high-quality brickwork, and performing proper maintenance. Detailed discussions of these issues are provided in the Technical Note 7 Series. Drainage-type walls, such as brick veneer and cavity walls, are designed to accommodate water penetration of the exterior brickwork without damage to the interior components of the wall system through its drainage system. Nonetheless, water-repellent coatings are sometimes suggested to reduce the amount of water that penetrates brickwork. Research indicates varied effectiveness of clear water repellents in reducing water leakage through a brick masonry wythe. [Refs. 3, 7, 11] Water-repellent coatings are most effective at reducing the amount of water absorbed by brick masonry. But water usually penetrates brick masonry at separations and cracks between brick and mortar or at junctures with other materials. Thus, a change in the absorption properties of brick masonry provided by a water-repellent coating may not significantly reduce water penetration through brickwork. Waterrepellent coatings cannot stop water penetration caused by design or construction deficiencies such as ineffective sills, caps or copings, or incompletely filled mortar joints. Penetrating water-repellent coatings seldom stop water penetration through cracks more than 0.02 in. (0.5 mm) wide, and their effectiveness under conditions of winddriven rain is limited. As a result, the use of water-repellent coatings to eliminate water penetration in a wall with existing defects can be futile. Water repellents can be useful for barrier walls, chimneys, parapets and other brickwork that is particularly vulnerable to water absorption and penetration, especially in climates that receive large amounts of rain. When a water-repellent coating is considered for use on these elements, the benefits must be weighed against the possible disadvantages. Past successful performance of the proposed coating, for a number of years in the same exposure conditions and on the same type of brick and mortar, should be required. In climates that experience freezing and thawing cycles, the effect of a coating on the durability of the brickwork is of particular concern. The age of construction and limitations of different types of water repellents are described in the sections that follow. Methods for evaluating the effectiveness of water repellents are discussed under Performance Criteria. New Construction Use. Water repellents sometimes are specified for newly constructed brick masonry to protect against water penetration due to imperfections in construction. As discussed previously, water repellents have limited effectiveness and cannot compensate for poor construction or design. Furthermore, most brick masonry wall systems do not require a water repellent to effectively manage water and prevent water intrusion into the interior of a building. For these reasons, the use of water repellents on newly constructed drainage walls is not recommended. Remedial Use. Water-repellent coatings most often are applied in an attempt to reduce or eliminate water penetration in existing brickwork experiencing water penetration problems. As noted previously, water repellents cannot prevent water from penetrating cracks wider than 0.02 in. (0.5 mm). Therefore, the source of water penetration should be determined and necessary repairs completed prior to the application of a water-repellent coating. Exterior walls should be inspected to determine the condition of caps and copings, flashing, weeps, sealant joints, mortar joints, brick units and general execution of details. Technical Note 46 provides an inspection checklist for areas of concern. Repair and replacement of missing, broken, failed or disintegrating items identified during the inspection and essential to the water resistance of the brickwork should be completed prior to

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application of a water repellent. The application of a water repellent is rarely effective and is not recommended in lieu of the following common repairs: 1. Removal of failed sealant, and cleaning, priming and replacement with an appropriate grade of elastomeric sealant at all windows, copings, sills, expansion joints and between brick masonry and other materials. 2. Repointing of incompletely filled, cracked or disintegrated mortar joints. 3. Removal and replacement of brick with spalled faces or cracks extending through the face shell. 4. Surface grouting of separations between the brick units and the mortar. These remedial measures are described in Technical Note 46. Other repairs, which are generally more difficult and costly to complete, include the following: 1. Clearing of mortar blockage from weeps and the air space or cavity. 2. Removal and replacement of damaged, omitted or improperly installed flashing. The latter repairs are considered by some to be unnecessary or uneconomical if a water repellent is applied. However, these repair techniques provide long-term solutions to water penetration problems. Not completing them may allow water within a wall to become trapped, resulting in failure of the coating or deterioration of brickwork. After remedial repairs have been completed and inspected, it is advisable to wait a period of several months to determine whether a water repellent is necessary. Moisture penetration problems often will be corrected by these initial repairs, and further consideration of coatings can be dismissed. If water penetration remains a problem, or long-term solutions are judged to be too costly despite their benefits, the application of a water repellent can be considered. If water absorption appears to be the problem, a water repellent can be particularly effective. However, water repellents are not a permanent solution and will require reapplication. See the discussion under Durability of Coating for further information on the life span of coatings.

Stain Resistance and Efflorescence Prevention By reducing the amount of water absorbed by brickwork, colorless coatings may help reduce staining and efflorescence. As a result, colorless coatings are sometimes used on brickwork that is subject to severe exposures or on units that have a relatively high absorption. Brick manufacturers sometimes apply colorless coatings to units during manufacture to reduce staining or initial rate of absorption. ASTM standards for face brick require that the brick manufacturer report the presence of such coatings. Selection of a coating for any of these uses should be based on demonstrated successful performance on similar brick with comparable exposures. Staining and efflorescence may not be completely eliminated by application of a coating. If staining or efflorescence occur on masonry treated with a colorless coating, the stains and salts may be difficult or impossible to remove. Further, for film-forming coatings and water repellents with a vapor permeability less than 0.98, efflorescing salts may become trapped under the coating, causing damage to the brick.

Appearance Change Another common reason for using a colorless coating is to achieve a darker, wet or glossy appearance. In some cases, a colorless coating may result in an undesired sheen or gloss. Such gloss may be an indication of an improperly applied coating or of poor coating selection (see Photo 1). Satisfactory appearance of a treated surface is best judged by examining a sample panel or test area of masonry before and after treatment.

Graffiti Resistance Resistance to graffiti and ease of cleaning can be important attributes for public structures such as schools, government buildings, libraries and noise barrier walls, where brick masonry is chosen for its

Photo 1 Undesired Gloss Due to a Colorless Coating

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appearance and low maintenance. Colorless coatings are sometimes applied to brick masonry to keep graffiti or dirt on the surface of the brickwork for easier removal. Glazed brick often are used in similar installations to provide the same benefits. Note that some coatings used for graffiti resistance are sacrificial, meaning that the coating itself is removed when the graffiti is removed.

TYPES OF COLORLESS COATINGS Colorless coatings for brick masonry can be classified into two general categories: film formers and penetrants. The two types have significantly different physical properties and performance. As the name implies, film formers produce a continuous film on the surface of the masonry. Penetrants enter up to ⅜ in. (10 mm) into the brick masonry and do not form a surface film. Colorless coatings may be either waterborne or solvent-borne. Carrier type influences permissible application conditions. Originally, better penetration and performance were attained using solvent-borne solutions. However, manufacturers are increasingly producing waterborne solutions that have lower volatile organic compound (VOC) content. Coatings with higher solids content also may have lower VOC content. VOC content is regulated by the Environmental Protection Agency nationwide because of its connection with poor air quality. In addition, many green building guidelines have limits on VOC content in coatings. Product data and test results should be examined carefully to compare performance. Temperature range, substrate moisture content, environmental regulations and effects on adjacent materials and vegetation must be considered. Colorless coatings are discussed in the following sections according to generic chemical type. Most colorless coating manufacturers will provide information on the generic chemical composition of their products. In addition, handbooks are available that classify many proprietary coatings according to their generic chemical composition.

Film Formers Typically, film-forming products adhere to the brick masonry and form a film on the surface. Surface preparation can be important in achieving satisfactory adhesion of a film-forming coating. Film-forming products should be applied only to dry surfaces. Film materials, continuity and product concentration determine the performance characteristics. Film-forming products are effective at preventing water from penetrating into brick masonry. Film formers can bridge the small, hairline cracks that are commonly the source of water penetration. If the crack is active, such as one created by wind load or thermal fluctuations, a film-forming product may also crack. This obviously reduces its effectiveness. However, a film-forming product's ability to exclude water from the exterior also inhibits evaporation of water within the masonry through the exterior face and can result in clouding (see Photo 2) and spalling (see Photo 3) if the source of moisture is not addressed. The reduced water vapor transmission rate, or lack of “breathability,” is of special concern in exterior brick masonry subject to freezing and thawing cycles. Thus, filmforming products are not recommended for brick masonry in such environments.

Photo 2 Clouding of Brick Masonry Wall with a Film-Forming Coating

Photo 3 Spalling of Brick Masonry Wall with a Film-Forming Coating

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A film on a masonry wall may facilitate cleaning by keeping surface contaminants from penetrating into the masonry. This characteristic leads to such products' use as graffiti-resistant coatings. When an appearance change is desired, film formers typically are used. Film-forming products, by their nature, tend to produce a sheen or gloss when applied. When used in high concentrations, they may darken the appearance of a wall (the “wet look”). Acrylics, stearates, mineral gum waxes and urethanes are among the products that form a film when applied to brick masonry. The large molecular size of these products prevents them from penetrating into the masonry. Acrylics. Acrylics can be effective as water repellents. They often are used when a high gloss is desired. Acrylics are available in two forms, waterborne and solvent-borne. Acrylic emulsions are waterborne. Acrylic solutions are solvent-borne. Because of increasing regulation of solvent-borne products, acrylic emulsions are more widely used. Coating manufacturers typically recommend that acrylics be applied to substrates that are thoroughly dry. If applied to a damp substrate, the acrylic film can separate from the masonry, giving it a cloudy, or whitened, appearance. Some acrylics can create a slippery surface, which is a concern in pavements. However, some acrylics increase slip resistance. When stabilized against degradation in ultraviolet (UV) light, acrylics can last approximately five to seven years. Stearates. Stearates promoted for use on masonry are generally aluminum or calcium stearates. They are sometimes known as metallic soaps. Stearates form a water-repellent surface by reacting with free salts in mineral building materials and plugging the pores. Some formulations are used as integral water repellents in concrete masonry and mortar. Their effectiveness as applied water repellents varies, and typically film-forming stearates must be reapplied every year. Stearates also have the potential to turn cloudy if moisture gets behind the coating. Mineral Gum Waxes. Paraffin wax and polyethylene wax are commonly referred to as mineral gum waxes. These products are typically solvent-borne and can be good water repellents, able to bridge hairline cracks. As with other coating types, mineral gum waxes can be used to protect units from staining. However, they have been known to darken the substrate and, in cases where moisture gets behind the coating, turn the surface a milky white. If the sources of moisture are not addressed, clouding and eventual spalling of the masonry may occur. Urethanes. Urethanes, chemically referred to as polyurethanes, are isocyanate resins. They are classified as either aromatic or aliphatic, depending on the resulting chemical. They are considered one-part urethanes if cured by moisture in the substrate or air and two-part if they require a chemical catalyst to cure. While urethanes can be excellent water repellents and provide good gloss, they can break down under UV light and have very low vapor permeability. Chemical additives often are used in urethanes to prevent UV degradation and yellowing and to improve gloss retention. Urethanes with such additives usually last from one to three years.

Penetrants Penetrating type coatings are characterized by their penetration into the substrate, typically to depths up to ⅜ in. (10 mm). They repel water by changing the capillary force, or contact angle with water, of the pores in the face of the masonry from positive (suction) to negative (repellency). Penetrating coatings are typically more resistant to UV degradation because of their chemical composition and because they penetrate below the masonry surface. Because they coat the pores rather than bridge them, penetrants tend to have better water vapor transmission characteristics. The solids content of these materials commonly ranges from 5 to 40 percent by weight. Higher solid content typically indicates better water penetration resistance. Penetrants can be categorized into six groups — siloxanes, silanes, silicates, methyl siliconates silicone resins and RTV silicone rubber — and blends of these. Siloxanes. Siloxanes have a larger molecular structure than silanes and provide good penetration and water repellency. Siloxanes bond chemically with silica- or alumina-containing materials, such as brick and mortar, to make the material water-repellent. This results in a long life, up to 10 years or more, and makes the coating more difficult to remove. Some siloxanes can also be applied to slightly damp surfaces. Siloxanes are less volatile than silanes and react with chemically neutral substrates without a chemical catalyst. Siloxanes are typically used in solutions having 5 to 12 percent solids by weight. Siloxanes have been known to work well on certain brick

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masonry installations. However, siloxanes are highly reactive with silica and will bond with glass that is not properly protected. Silanes. Silanes used as clear water repellents have a smaller molecular structure than siloxanes, which allows good penetration on dense substrates. They are used in relatively high concentrations (typically 20 percent or greater solids content). Like siloxanes, silanes bond chemically with silica- or alumina-containing materials and can bond with unprotected glass. Silanes can be applied to slightly damp substrates. An alkaline substrate, such as concrete or concrete masonry, acts as a catalyst to speed the reaction to form a water-repellent surface. Chemical catalysts also are used with silanes to improve the chemical reaction on less alkaline substrates such as brick. Silicates. Ethyl silicates are commonly used in restoration of deteriorated masonry as consolidants for natural stone and occasionally brick masonry. Consolidants are designed to react with and stabilize the substrate to which they are applied. Their use on brick is uncommon. None are effective water repellents, and they are not recommended for this use on brick masonry. Methyl Siliconates. Methyl siliconates are alkaline solutions that react with silica-containing materials in the presence of carbon dioxide to form a water-repellent surface. Siliconates are sometimes injected into brick masonry to form a horizontal barrier to rising damp. Silicone Resins. Silicone resins come in many weights and forms. The 5 percent silicone resin is the most common penetrating formula. Silicones do not chemically bond with the substrate and as a result have a short life. Many silicones require reapplication on a yearly basis, although some last longer. RTV Silicone Rubber. Room temperature vulcanizing (RTV) silicone rubber is a penetrating water repellent that contains petroleum distillates. It does not require the presence of alkali to react with the substrate. Once cured, RTV silicone rubber retains its elasticity, helping it to bridge hairline cracks. Asphalt, plastic rubber and glass surfaces must be protected from contact with it. RTV silicone rubber is commonly used in anti-graffiti coatings. Blends. Colorless coatings also are made from blends of the materials listed above. Blends are created to produce products with the benefits of the constituent materials. As such, they reflect the properties of the constituent materials, but the properties will be modified somewhat. Thus, it is important to review product data and test results for products, especially blended ones. For quality assurance that a blend is formulated in the correct proportions, select a product that is pre-blended by the manufacturer.

PERFORMANCE CRITERIA Any coating applied to brick masonry will change the physical properties of the masonry. The most critical properties of colorless coatings to be evaluated are water vapor transmission, water penetration and repellency, durability, compatibility with the substrate, gloss, slip resistance, graffiti resistance, VOC content and environmental considerations. A variety of industry standard tests for evaluating these properties exist; however, it can be difficult to compare products because the reported performance characteristics of each product may be based on a different set of tests. Another difficulty exists in correlating test results with in-service performance of coatings applied to brickwork. For example, one method of evaluating water repellency of a coating is by comparing the cold water absorption of an untreated brick to that of a treated brick, using the method described in ASTM C67, Test Methods of Sampling and Testing Brick and Structural Clay Tile. Although such a test may indicate the ability of a coating to reduce the amount of water absorbed through the faces of individual brick, it neglects the effect of mortar joints on the water penetration resistance of brickwork. The presence of partially filled mortar joints, hairline cracks and minute separations that occur in brickwork will often reduce, and sometimes completely negate, the “tested” effectiveness of a coating.

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Until standard tests better correlate with performance of brickwork in service, good judgment and experience are necessary in establishing performance criteria. The properties discussed in the following sections can be useful in comparing colorless coating alternatives. Table 1 presents a relative comparison of several colorless coating properties. TABLE 1 Typical Properties of Colorless Coatings for Brick Masonry1 Water Vapor Transmission

Water Repellency

Life Span, Years

Available with Glossy Finish

Graffiti Resistance

Acrylics

Poor

Very good

5 to 7

Yes

Yes

Stearates

Poor

Varies

1

No

No

Mineral gum waxes

Poor

Good

Varies

No

No

Urethanes

Poor

Very good

1 to 3

Yes

Yes

Siloxanes

Very good

Very good

10+

No

No

Silanes

Very good

Very good

10+

No

No

Silicates

Poor

Poor

Varies

No

No

Methyl siliconates

Good

Fair

Varies

No

No

Fair

Varies

1

Yes

No

RTV silicone rubber

Good

Good

5 to 10

No

Yes

Blends

Varies

Varies

Varies

No

No

Film Formers

Penetrants

Silicone resins

1. Refs. 6, 14

Water Vapor Transmission Rate and Permeability

Low water vapor transmission may also result in the premature deterioration of brickwork. Water that is unable to pass through a coating increases risks of masonry deterioration due to freeze-thaw cycles and deposition of water-soluble salts behind the coating. As these salts crystallize, they grow significantly in size and can create enough expansive pressure to cause spalling of brick.

Mike Dickey, Frieze & Associates

The most important property to consider when selecting a coating for application on exterior brick masonry is the water vapor transmission rate. The water vapor transmission, or breathability, determines the rate and amount of water that can evaporate through the face of the brickwork. Coatings that have low water vapor transmission rates inhibit evaporation and can trap water within the brickwork, leading to clouding of the coating, as shown in Photo 2 and Photo 4.

Photo 4 Clouding of a Colorless Coating on a Brick Pavement

For these reasons, the effect of a coating on the water vapor transmission rate of brickwork should be carefully considered, particularly for walls exposed to freezing and when moisture problems such as rising damp and condensation are known to exist. Coatings with a water vapor permeability of 0.98 or higher allow natural evaporation to occur, thus reducing the potential for problems. However, even a highly breathable coating may lower the vapor transmission of a wall by preventing moisture migration to the exterior surface where evaporation occurs. A condensation analysis, as described in Technical Note 47, should be performed before applying a coating to determine the effect of the coating on the location of condensation within the wall system. www.gobrick.com | Brick Industry Association | TN 6A | Colorless Coatings for Brick Masonry | Page 7 of 14

At present, there is no definitive test establishing the effect of colorless coatings on the water vapor transmission rate and durability of brick masonry. However, the water vapor transmission rate of a coating can be measured using ASTM E96, Test Methods for Water Vapor Transmission of Materials. To accurately replicate field conditions (air rather than water on one side of the brick), the desiccant method is preferred. Using this test, the effect of a coating can be evaluated through a comparative measurement between an untreated and a treated brick. For comparative testing, a maximum 10 percent reduction in the rate of vapor transmission is the recommended limit. Another method to evaluate the potential of a colorless coating to entrap damaging salts and cause spalling is proposed by Binda [Ref. 2]. Individual brick are treated with the colorless coating on their exposed faces. The sides of the units are sealed with rubber to prevent evaporation except through the treated face. The units are subjected to cycles of immersion in a salt solution for four hours and air drying for 44 hours. The cross-sectional size is measured after each cycle. Deterioration is typically by delaminations of the treated brick face, hence a reduction in brick cross section. A correlation of the number of cycles to deterioration in this test to the durability of a masonry assemblage has not yet been established. However, this method is one means of assessing salt crystallization damage potential when evaluating colorless coatings.

Water Repellency Water repellency is an important criterion when a coating is intended to reduce water penetration resistance. However, water repellency of most coatings is based on reducing the amount of water absorbed by a substrate. Water repellency is often evaluated by comparing the absorptions of treated and untreated brick using the ASTM C67 test for cold water absorption. As discussed previously, this approach has significant limitations. Because most water penetrates brickwork through voids or cracks in mortar joints and minute separations between brick and mortar, tests of water repellents on individual brick cannot accurately indicate the performance of a water repellent on brickwork. The effectiveness of water-repellent coatings in reducing water penetration through brickwork is more accurately evaluated by using representative brickwork panels. ASTM E514, Test Method for Water Penetration and Leakage Through Masonry, is the preferred laboratory test for evaluating the ability of a coating to reduce the water penetration of brickwork. The test can be used to compare the water penetration resistance of brickwork treated with water-repellent coatings to untreated brickwork. Testing should be performed on a minimum of three identical wall specimens of the intended materials and construction. The amount of water penetration should be measured on each specimen in accordance with ASTM E514 before and after coating with the clear water repellent. The percentage reduction in water penetration is a measure of the water repellent effectiveness. A 90 percent reduction in maximum leakage rate; and a 75 percent reduction in percent area of dampness on the back face of the wall and total water collected after 24 hours of testing [Ref. 3] as compared to the untreated wall panel is recommended. ASTM E514 has its limitations. Performance of coatings in laboratory tests may differ from results on actual brickwork due to the variables inherent in construction. Thus, a tested percent reduction rate for a laboratory test does not automatically translate into the same percent reduction in water leakage through the exterior brickwork of a constructed building. ASTM C1602, Test Method for Field Determination of Water Penetration of Masonry Wall Surfaces, provides a means to evaluate the effectiveness of a coating in the field. The test can be used on existing masonry walls or field mock-ups. A sheet of water is to be developed and maintained on the wall surface during testing. If the sheet of water does not consistently form, the results of this test may be inaccurate. After a preconditioning period, a specified water flow rate and air pressure are maintained. The amount of water applied to the face of the wall during the test is measured and the water loss calculated. Again, a coating should provide at least a 75 percent reduction in loss of water.

Durability of Coating The durability of a coating is an important selection criterion. Greater depth of penetration or film thickness and greater resistance to degradation in UV light and harmful environments imply longer life for coatings applied to exterior brickwork. Durability of coatings applied to brick pavements may also depend on resistance to abrasion. A coating’s durability also determines how often it must be reapplied, which may have permeability and ongoing maintenance implications. Most coatings must be reapplied every five to 15 years, and some last considerably shorter periods of time. Many coatings are warranted by the manufacturer to last 10 years or more. It is common for film-forming products to require reapplication more often than penetrants, particularly if they are applied to brick floors subject to significant www.gobrick.com | Brick Industry Association | TN 6A | Colorless Coatings for Brick Masonry | Page 8 of 14

amounts of traffic. Evaluation of a coating’s resistance to abrasion is difficult, because there are no direct test methods for measurement on brick. Reapplication of a coating (especially if carried out prematurely) may decrease the vapor permeability of the brickwork. This may be a concern for exterior brick masonry walls, particularly in climates subject to freezing and thawing. One way to evaluate the durability of a coating is with laboratory tests that simulate outdoor exposure. ASTM G154, Practice for Operating Fluorescent Light Apparatus for UV Exposure of Nonmetallic Materials, is one often specified. The difficulty with using laboratory tests to measure the life span of a coating is trying to correlate laboratory test results to field performance. Coating characteristics, such as gloss or water repellency, can be measured before and after exposure and the results compared, but such tests have not been correlated to the actual life expectancy of the coating. Periodic evaluations of field performance can also be used to determine whether a coating continues to be effective. Results of field tests conducted on a specified area of a newly treated wall can be compared to tests performed in the same location after some period of service. Such evaluation will indicate if the coating has met its warranted life and help to determine when reapplication may be necessary. Compatibility. Compatibility of a coating with the brickwork and its existing surface treatments should be determined prior to application. Only coatings specifically formulated for use on brickwork should be selected. Incompatibility of a coating with the brickwork or an existing coating may adversely affect durability, appearance or otherwise prevent the coating from performing as intended. Penetrating coatings are typically incompatible with existing film-forming coatings. In some cases, reapplication of a coating may cause clouding and may be difficult or impossible to remove. It may be necessary to remove any existing coating, following the coating manufacturer’s recommendations before reapplication or application of a different coating. This procedure may involve hazardous chemicals often regulated or restricted from use by local, state or federal environmental regulations. Thus, an existing coating may have to remain in place until it wears off, even if deterioration of the masonry calls for its removal.

Environmental Considerations Possible environmental hazards are also of concern when considering a colorless coating. Often the chemicals used in colorless coatings are highly reactive and can etch glass, damage paint, kill vegetation and emit harmful vapors. This requires attention to worker safety and proper protection of adjacent surfaces.

Appearance Some coatings, particularly film-formers, may impart a gloss, sheen or darkening to brickwork. Acceptable appearance is a subjective matter and should be determined by the designer or owner prior to application. Gloss is best evaluated by treating half of a test area representing the entire range of brick colors and textures and comparing the treated half to the untreated half. An accepted test area should be retained as a means of judging acceptability of other treated areas. When necessary, a number of ASTM test methods can be used to evaluate differences and to establish tolerances [Ref. 1, Volume 6.01].

Slip Resistance A coating can adversely affect the slip resistance of a brick floor or pavement. The slip resistance of coated floors or pavements should be evaluated for safety reasons, especially in public access areas and in areas where water may contact the floor or pavement. The slip resistance of coatings often is measured in the laboratory using ASTM D2047, Test Method for Static Coefficient of Friction of Polish-Coated Floor Surfaces as Measured by the James Machine [Ref. 1]. A value of 0.5, measured by the James machine, is the recognized minimum value for slipresistant walking surfaces in courts of law in the United States. Slip resistance can be measured in the field using portable devices such as the NBS-Brungraber machine (also known as the Mark I Slip Tester). The United States Access Board recommends coefficient of friction values of 0.6 for a level surface and 0.8 for ramps, as measured using the NBS-Brungraber machine [Ref. 14].

Graffiti Resistance Effective graffiti resistance depends on the ability of a coating to prevent penetration of unwanted markings into brickwork and facilitate their removal. Often, water repellency, appearance, durability and other properties are also www.gobrick.com | Brick Industry Association | TN 6A | Colorless Coatings for Brick Masonry | Page 9 of 14

important selection criteria for anti-graffiti coatings. A method for determining the effectiveness of an anti-graffiti coating is described in ASTM D7089, Practice for Determination of the Effectiveness of Anti-Graffiti Coating for Use on Concrete, Masonry and Natural Stone Surfaces by Pressure Washing [Ref. 1]. Satisfactory performance is indicated by successful removal of intentionally applied graffiti. Always consult the coating manufacturer prior to testing, as reactions between the cleaner and the coating may be hazardous. Anti-graffiti coatings generally employ either a “barrier” or “sacrificial” strategy to resist graffiti. Barrier or permanent coatings must be resistant to cleaning chemicals so that they remain on the surface of brickwork after graffiti is removed. Conversely, sacrificial coatings should be easy to remove. Removal of graffiti should always follow coating manufacturers’ recommendations, because many anti-graffiti coatings are intended to be used with a particular removal method or cleaning product. As anti-graffiti coatings provide a barrier to paint and other staining, they also provide a barrier to water evaporation through the outer face of the brick, similar to that of glazed brick. Therefore, most of the drying of the brickwork occurs by evaporation through the back face of the brick, into the air space. It is important that when an anti-graffiti coating is used, the cavity behind the brick be vented at top and bottom to help remove the excess moisture in the air space created by this evaporation.

CONSIDERATIONS PRIOR TO COATING Selection of a colorless coating for use on brick masonry should be based on the desired performance, the information discussed in this Technical Note and literature from the coating manufacturer. Additional items to be considered prior to application of a colorless coating follow. Whenever possible, consult with the brick manufacturer for specific recommendations regarding coating of a particular brick. Properties of each brick are unique and can affect coating performance. 1. It is suggested that the designer or user require test reports for relevant performance criteria and a written warranty from the coating manufacturer for the performance of the coating over a designated period of time. 2. The coating should be that of a well-known manufacturer who has been in business for at least five years. It is suggested that a brand name be used that has a good track record over a period of at least five years. References of projects with similar installations, materials and exposure should be investigated. 3. The coating should be applied at the application rate and under the climatic conditions recommended for clay brick masonry substrates by the coating manufacturer. Typically, temperatures above 40 °F (4 °C) and below 100 °F (38 °C) are required. Application on windy days should be avoided when possible. 4. Repair and replacement of brick and mortar joints and other necessary repairs should be completed prior to applying a colorless coating. 5. A minimum of one month should pass after close-in of the building before a water repellent is applied to newly constructed brickwork. This period allows the evaporation of moisture from the building materials to occur naturally, unimpeded by a coating on the brickwork, and permits the walls to cure sufficiently. In fact, many colorless coating manufacturers recommend application only to a relatively dry substrate. A delay of one year is preferred so that efflorescence due to water absorbed during construction, often known as “new building bloom,” is not entrapped by the coating. For a more complete discussion of efflorescence, refer to the Technical Note 23 Series. 6. There should have been no efflorescence or, at the maximum only a minor occurrence of efflorescence, on the brick masonry to be treated. Walls with a history of efflorescence should be coated only after the source of moisture has been addressed. 7. The wall must be clean at the time of application [Ref. 9]. Heavy accumulations of dirt will interfere with proper penetration or adhesion of the coating and result in poor performance and shorter life. See ASTM D5703, Practice for Preparatory Surface Cleaning for Clay Brick Masonry [Ref. 1], for a discussion of cleaning techniques that may be required. In addition, freshly repointed mortar and repaired sealant joints should cure for a minimum of 72 hours before a coating is applied [Ref. 11]. 8. The brickwork should have a moisture content consistent with that recommended by the coating manufacturer. Moisture content of the brick masonry should be checked at several locations by the method recommended by the coating manufacturer. 9. Apply samples of the selected coating to test areas of at least 10 ft² (1 m²) on the building at a location representative of the area to be treated or on a sample panel. Allow these test areas to cure as recommended by the coating manufacturer. Inspect and test them to determine satisfactory performance with respect to the performance criteria established. www.gobrick.com | Brick Industry Association | TN 6A | Colorless Coatings for Brick Masonry | Page 10 of 14

10. The application contractor should know the work to be performed and should protect adjacent and surrounding surfaces from over-spray as necessary. Qualifications of the contractor should be verified. These steps must be taken in conjunction with the recommendations contained within the applicable sections of this Technical Note. They cannot guarantee successful performance but will greatly increase the likelihood that the colorless coating will perform as intended. The coating manufacturer often will have additional recommendations regarding coating selection, substrate preparation, curing, application methods and coverage rates. The coverage rate is especially critical, because over-application of the coating can reduce its breathability. Failure to consider these items can result in poor performance of the coating and can cause severe harm to the masonry or surrounding elements.

RECOMMENDATIONS FOR USE Selection of a specific product should be based on recommended performance criteria described herein and any other criteria set by the designer to address the particular conditions involved. In addition, the brick manufacturer should be consulted for recommendations on the use of colorless coatings prior to coating selection. There are a variety of reasons that colorless coatings may be considered for application to brickwork. However, it is important to recognize that coatings change the physical properties of the brickwork to which they are applied. Therefore, the potential advantages of colorless coatings should be carefully weighed against their disadvantages.

Exterior Walls Penetrating coatings are preferred for exterior brick masonry walls because they permit water vapor transmission. Only coatings with a water vapor permeability of 0.98 or greater as measured by ASTM E96 should be used. If a water repellent is to be used, siloxanes are recommended. Siloxanes provide the advantage of good water repellency and long-term performance and have been shown to be effective on many brick masonry walls. Silanes containing chemical catalysts also have been used successfully. Because of the effect of a film on the breathability of masonry, use of film-forming coatings is discouraged, particularly in freezing climates. Some film-forming coatings have been known to perform successfully; however, there can be significant risks. If use of a film-forming coating, such as an anti-graffiti coating, is necessary, select only products known to successfully perform in a similar climate, wall type and exposure on brick masonry with similar physical properties. When a drainage wall is treated with a colorless coating, the use of vents at the top and bottom of wall cavities can promote evaporation of moisture from the brickwork. Chimneys and Parapets. These elements can be subject to premature deterioration because of severe exposure. They are often exposed to wind-driven rain and water rundown on the exterior walls from the crown or coping. Because of the large amount of moisture that can contact the surface of a chimney or parapet wall, a clear water-repellent coating can sometimes be effective in reducing water-related problems. Conditions in which a clear water repellent may be recommended on chimneys and parapet walls include climates with a driving rain index above 3 (see Figure 1) and on sloped or horizontal projections of such elements where water and snow can accumulate.

0

1

2

3

4

5 >5

Driving Rain Index

Figure 1 Driving Rain Index Map [Ref. 9]

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Interior Walls Colorless coatings are generally applied to interior walls to facilitate cleaning or to provide a gloss. Water repellency and breathability of interior walls is generally not a concern. Film-forming products, specifically waterborne acrylics (acrylic emulsions) and urethanes, typically will give the best results when gloss and ease of cleaning are desired. However, some penetrating coatings may also provide this effect. Acrylics in particular are known to provide a high gloss. Both acrylics and urethanes are durable in installations with no UV exposure. In the case of exterior brick masonry walls that have their interior faces exposed, water vapor transmission may be a concern. Film-forming products should be used cautiously, only after the effect of the film on the water vapor transmission of the wall system has been evaluated.

Pavements and Floors Coatings may be desired on brick pavements to resist staining or to decrease moss and mildew growth. The exposure and construction of brick pavements are significantly different from those of vertical brickwork. Lack of a drainage cavity or air space to aid in drying increases the severity of exposure. There are several disadvantages associated with the use of a colorless coating on pavement surfaces. Colorless coatings can decrease the slip resistance of the pavement or floor, especially when wet. Also, pavements and interior floors are subject to abrasion due to foot traffic, which shortens the life expectancy of most coatings compared to vertical installations. Exterior brick pavements are subjected to more severe weathering exposures than exterior vertical walls. Pavements often have prolonged contact with moisture due to their horizontal orientation and are seldom protected by overhangs. Any joint sand stabilizers needed to protect sand in joints from erosion are typically applied before coatings. For more information about these products, refer to Technical Note 14A. Exterior Pavements. By the nature of their construction, pavements allow evaporation of moisture from the masonry through only one face, the wearing surface. As a result, the potential for problems associated with reduced water vapor transmission are significant. These disadvantages usually outweigh any potential benefit. For this reason, colorless coatings are not recommended for use on exterior brick pavements subject to freezing and thawing. In exterior environments not subject to freezing, the water vapor transmission rate of the coating must be high. Clouding of the coating is a particularly common problem (see Photo 4). Interior Floors. Colorless coatings are often applied to interior brick floors to provide a glossy finish and to facilitate cleaning. Mortarless brick pavements also can be coated to help retain the jointing sand in the joints. Urethanes, acrylics, waxes and some penetrating coatings that meet the performance criteria discussed herein, and those set by the designer, can be used on interior brick masonry floors not subject to freezing. The primary disadvantage of most colorless coatings used on floors is their tendency to reduce the skid resistance of the floor. New epoxy-based coatings show promise in this area. Film-forming coatings may separate from the brick paving and turn cloudy if moisture from the brickwork or supporting members migrates through the brick floor. Consequently, film-forming coatings should be applied only when the brick floor and supporting members are dry. Past successful performance is the best measure of a satisfactory coating.

SUMMARY This Technical Note has discussed both the reasons for and the suitability of colorless coatings for brick masonry. For most exterior brick masonry, use of colorless coatings is discouraged. Furthermore, clear water repellents are not necessary on properly designed and constructed brick masonry. However, under certain conditions, clear water repellents and other colorless coatings may be beneficial. The information and suggestions contained in this Technical Note are based on the available data and the experience of the engineering staff and members of the Brick Industry Association. The information contained herein must be used in conjunction with good technical judgment and a basic understanding of the properties of brick masonry. Final decisions on the use of the information contained in this Technical Note are not within the purview of the Brick Industry Association and must rest with the project architect, engineer and owner.

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REFERENCES 1. Annual Book of ASTM Standards, ASTM International, West Conshohocken, PA, 2007: Volume 4.05 C67 C1601 E514

“Standard Test Methods for Sampling and Testing Brick and Structural Clay Tile” “Standard Test Method for Field Determination of Water Penetration of Masonry Wall Surfaces” “Standard Test Method for Water Penetration and Leakage Through Masonry”

Volume 4.06 E96/E96M “Standard Test Methods for Water Vapor Transmission of Materials” Volume 6.01 D523 D3134 D4449 Volume 6.02 D5703 D7089 Volume 15.04 D2047 G154

“Standard Test Method for Specular Gloss” “Standard Practice for Establishing Color and Gloss Tolerances” “Standard Test Method for Visual Evaluation of Gloss Differences Between Surfaces of Similar Appearance” “Standard Practice for Preparatory Surface Cleaning of Clay Brick Masonry” “Standard Practice for Determination of the Effectiveness of Anti-Graffiti Coating for Use on Concrete, Masonry and Natural Stone Surfaces by Pressure Washing" “Standard Test Method for Static Coefficient of Friction of Polish-Coated Floor Surfaces as Measured by the James Machine” “Standard Practice for Operating Fluorescent Light Apparatus for UV Exposure of Nonmetallic Materials”

2. Binda, L., “Experimental Study on the Durability of Preservation Treatments of Masonry Surfaces: Use of Outdoor Physical Models,” Proceedings of the Workshop – The Degradation of Brick and Stone Masonries Due to Moisture and Salt Content and the Durability of Surface Treatments, Politecnico di Milano, Milan, Italy, January 1991, pp. 1-8. 3. Brown, R.H., “Initial Effects of Clear Coatings on Water Permeance of Masonry,” Masonry: Materials, Properties, and Performance, ASTM STP 778, J.G. Borchelt, ed., ASTM International, West Conshohocken PA, 1982, pp. 221-236. 4. Clark, E.J., Campbell, P.G., and Frohnsdorff, G., “Waterproofing Materials for Masonry,” NBS Technical Note 883, National Bureau of Standards, Gaithersburg, MD, October 1975. 5. Clear Water Repellents for Above Grade Masonry and Horizontal Concrete, Sealant, Waterproofing & Restoration Institute, Kansas City, MO, 1994. 6. Clear Water Repellent Treatments for Concrete Masonry, Concrete Masonry Association of California and Nevada and the Masonry Institute of America, Los Angeles, CA, 1993, pp. 38-40. 7. Coney, W.B., and Stockbridge, J.G., “The Effectiveness of Waterproofing Coatings, Surface Grouting, and Tuckpointing on a Specific Project,” Masonry: Materials, Design, Construction, and Maintenance, ASTM STP 992, H.A. Harris, ed., ASTM International, West Conshohocken, PA, 1988, pp. 220-224. 8. Grimm, C.T., “A Driving Rain Index for Masonry Walls,” Masonry Materials, Properties, and Performance, ASTM STP 778, American Society for Testing and Materials, West Conshohocken, PA, 1982, pp. 171177. 9. Mack, R.C., and Grimmer, A., “Assessing Cleaning and Water-Repellent Treatments for Historic Masonry Buildings,” Preservation Briefs, No. 1, U.S. National Park Service, Washington, DC, November 2000. 10. McGettigan, E., “Selecting Clear Water Repellents,” The Construction Specifier, Vol. 47, No. 6, Construction Specifications Institute, Alexandria, VA, June 1994, pp. 121-132.

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11.

Roller, Sandra, “A Comparison of ASTM E 514 and MAT Tube Water Penetration Testing Methods Including an Evaluation of Saver Systems Water Repellents,” Department of Civil and Architectural Engineering, University of Wyoming, Laramie, WY, October 1994.

12.

Roth, M., “Comparison of Silicone Resins, Siliconates, Silanes and Siloxanes as Water Repellent Treatments for Masonry,” Technical Bulletin 983-1, ProSoCo, Inc., Kansas City, KS, 1985.

13.

Suprenant, B.A., “Water Repellents: Selection and Usage,” Magazine of Masonry Construction, Aberdeen Group, Addison, IL, December 1993, pp. 527-532.

14.

“Technical Bulletin: Ground and Floor Surfaces,” United States Access Board, Washington, DC, August 2003.

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TECHNICAL NOTES on Brick Construction

7

1850 Centennial Park Drive, Reston, Virginia 20191 | www.gobrick.com | 703-620-0010

December 2005

Water Penetration Resistance Design and Detailing Abstract: Proper design, detailing and construction of brick masonry walls are necessary to minimize water penetration into or through a wall system. Many aspects of design, construction and maintenance can influence a wall's resistance to water penetration. The selection of the proper type of wall is of utmost importance in the design process as is the need for complete and accurate detailing. In addition to discussing various wall types, this Technical Note deals with proper design of brick masonry walls and illustrates suggested details which have been found to be resistant to water penetration.

Key Words: barrier, design, detailing, drainage, flashing, installation, rain, wall types, weeps.

SUMMARY OF RECOMMENDATIONS: Wall System Selection:

Through-Wall Flashing Installation:

• Drainage walls provide maximum protection against water penetration • Barrier walls are designed to provide a solid barrier to water penetration and provide good water penetration resistance • Single wythe masonry walls require careful detailing and construction practices to provide adequate water penetration resistance

• Lap continuous flashing pieces at least 6 in. (152 mm) and seal laps • Turn up the ends of discontinuous flashing to form end dams • Extend flashing beyond the exterior wall face • Terminate UV sensitive flashings with a drip edge

Through Wall Flashing Locations: • Install at wall bases, window sills, heads of openings, shelf angles, tops of walls and roofs, parapets, above projections, such as bay windows, and at other discontinuities in the cavity

Weeps: • Open head joint weeps spaced at no more than 24 in. (610 mm) o.c. recommended • Most building codes permit weeps no less than 3/16 in. (4.8 mm) diameter and spaced no more than 33 in. (838 mm) o.c. • Wick and tube weep spacing recommended at no more than 16 in. (406 mm) o.c.

INTRODUCTION This Technical Note is the first in a series addressing water resistance of brick masonry. Design considerations and details are provided to illustrate the principles involved in addressing water penetration issues. The other Technical Notes in this series provide detailed guidance in the areas of material selection (7A) and construction (7B). Technical Notes 7C and 7D provide information on condensation. When masonry walls encounter problems, water-related issues are often one of the primary factors. If a wall is saturated with water, freezing and thawing may cause cracking, crazing, spalling and disintegration over time. Water can cause masonry to experience dimensional changes, metals to corrode, insulation to lose its effectiveness, interior finishes to deteriorate and efflorescence to appear on exterior surfaces. Water penetration may also provide the moisture necessary for the development of mold growth on susceptible wall elements. Water resistance of a masonry wall depends on four key factors: design, including detailing; materials; construction; and maintenance. Attention to all four is necessary to produce a satisfactorily performing wall. Failure to properly address any one factor can result in water penetration problems. Water is abundant in many forms. Rain and snow contact building materials, wetting them. Water vapor is present in the air from many sources. As a result, since water cannot be completely eliminated, water penetration must be controlled. When water passes through brick masonry walls, it typically does so through minute separations between the brick units and the mortar joints. Under normal exposures, it is virtually impossible for significant amounts of water to pass directly through the brick units or through the mortar. Highly absorbent brick will absorb some water, but certainly do not contribute to an outright flow of water through a wall. Before brick veneer became popular, masonry walls usually functioned as both the structural system and as the exterior skin of the building. As a result, these masonry walls were quite massive, ranging in thickness from 12 in. Page 1 of 9

(305 mm) up to 6 ft (1.83 m) of solid brick. These masonry walls, both because of their thickness and their being in constant compression due to the structural loads, worked quite well in keeping water out of the interior of the building. Many older masonry walls were built with cornices and other ornamentation which helped to protect the faces of the buildings from excessive water rundown and subsequent water penetration to the interior. Walls used today are much less massive, and the masonry may be only 3 in. (76 mm) or less in thickness. In many cases, they have minimal overhang at the top, allowing sheeting of the rain water from the roof or parapet down to the ground. As a result of these newer wall systems, rain water is allowed to be in contact with the masonry in larger quantities and for longer periods of time, thus leading to more opportunity for water penetration problems. The successful performance of a masonry wall depends on limiting the amount of water penetration and controlling any water that enters the wall system. If water penetration can be minimized, for all practical purposes, the wall system will perform well.

DESIGN The first factor in evaluating water penetration resistance of masonry is that of design. Proper design of masonry does not mean just proper structural design. Design includes fire resistance, heat transmission, structural integrity, material compatibility, sound reduction, aesthetics and water resistance. Other Technical Notes provide guidance on each of these different design factors. Design for water resistance requires evaluation of several items, including: (1) sources of moisture; (2) selection of wall type; and (3) flashing and weeps. Each of these items will be addressed separately.

Sources of Moisture Moisture is present almost everywhere in various forms, i.e., rain, snow, condensation, ground water, construction water, etc. Some of these lend themselves to control; some do not. This section deals with wind-driven rain. Interstitial condensation and its control are discussed in Technical Notes 7C and 7D. Wind-Driven Rain. The exposure to which a masonry wall will be subjected is very important to the proper design of the wall. No single standard design can be expected to perform equally well under all exposures. Exposures vary greatly throughout the United States, from severe on the Atlantic Seaboard and Gulf Coast, where rains of several hours' duration may be accompanied by high velocity winds; to moderate in the Midwest and Mississippi Valley, where wind velocities are usually lower; to slight in the arid areas of the West. Refer to Figure 1.

Selection of Wall Type The selection of the proper wall type to use in any given situation is very important. Under normal conditions, it is nearly impossible to keep a heavy wind-driven rain from penetrating a single wythe of brickwork, regardless of the quality of the materials or the degree of workmanship used. The best approach to designing a water resistant wall is to design the wall assuming some water penetrates the surface. Therefore, the objective is

Source: National Climatic Data Center

Figure 1 Wind Speed and Precipitation

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to control the moisture once it begins to penetrate the wall. Two basic wall systems are used for this purpose: the drainage wall and the barrier wall. Drainage Wall Systems. Drainage wall systems include cavity walls (metal-tied and masonry-bonded hollow walls in historical applications), and anchored veneer walls as shown in Figures 2 through 5. The basic concept behind the drainage wall assumes a heavy, wind-driven rain will penetrate the exterior wythe of brickwork. When it does, the wall is designed to allow the water to flow inward to the air space or cavity between the wythes. The water then flows down the back face of the outer brick wythe, where it is collected on the flashing and redirected out of the wall system through the weeps. Properly designed, detailed and constructed drainage wall systems are excellent with respect to water penetration resistance. Specific detailed information on all aspects of cavity wall systems can be found in the Technical Notes 21 Series. The Technical Notes 28 Series addresses anchored veneer wall systems. Barrier Wall Systems. Barrier wall systems, such as the one shown in Figure 6, include multi-wythe walls with mortar- or grout-filled collar joints (including composite brick and concrete block walls), reinforced brick masonry walls and adhered veneer walls. The basic concept is that when a wind-driven rain penetrates the exterior wythe of

Figure 2 Brick Veneer/Wood Stud Wall

Figure 3 Brick Veneer/Steel Stud Wall

Figure 4 Insulated Brick/CMU Wall

Figure 5 Masonry Bonded Hollow Wall

Figure 6 Reinforced Barrier Wall

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masonry it migrates inward toward a filled collar joint that acts as a barrier to prevent further inward movement. The water then migrates back out of the wall system. The key item is that the collar joint must be completely filled with grout or mortar to provide a monolithic barrier to moisture. Grouting is the most effective method of ensuring that collar joints are completely filled. However, grouting spaces less than 3/4 in. (19.1 mm) is not recommended. In these instances, the face of the inner masonry wythe should be parged and the back of brick in the exterior wythe buttered in order to fill the collar joint. Placing mortar in the collar joint with a trowel after the individual wythes are laid, commonly referred to as "slushing", does not result in completely filled joints, and is not recommended. Flashing is also integrated into barrier walls to aid in controlling water that penetrates the exterior wythe. Properly designed, detailed and constructed barrier wall systems work well with respect to water penetration resistance. Single-Wythe Walls. Single-wythe masonry walls can be considered a variation of a barrier wall system. Singlewythe brick masonry construction can be designed with either solid or hollow units. In single-wythe walls, the masonry wythe usually exceeds the thickness of a nominal 4 in. (102 mm) exterior brick wythe. In addition to the added thickness, grouted cells help to prevent water from penetrating to the interior of the wall system. The singlewythe wall design is not inherently as resistant to water penetration as are drainage wall systems or multi-wythe barrier wall systems and may not be appropriate for some severe exposures. With careful detailing and good construction practices however, they can perform well. For example vertically reinforced and grouted brickwork often provides good water penetration resistance. With single-wythe masonry, it is especially important to use a mortar joint profile that sheds, rather than collects water. Concave and "V" joints are preferred over raked joints, for example. See Technical Note 7B for further information. Penetrating water repellents can increase the water resistance of single-wythe walls. See Technical Note 6A for further information.

DETAILING Through-Wall Flashing Through-wall flashing is a membrane, installed in a masonry wall system, that collects water that has penetrated the exterior wythe and facilitates its drainage back to the exterior. Such flashing is essential in a drainage wall system, and is required as a second line of defense in a barrier wall system. Proper design requires flashing at wall bases, window sills, heads of openings, shelf angles, projections, recesses, bay windows, chimneys, tops of walls and at roofs. Flashing should extend vertically up the backing a minimum of 8 in. (203 mm). The water-resistant barrier on the backing should lap the top of the flashing. Examples of water-resistant membranes include No. 15 asphalt felt, building paper, certain high-density polyethylene or polypropylene plastics (housewraps) and certain water-resistant sheathings. Various types of flashing materials which may be used in the design of brick masonry and composite walls are covered in Technical Note 7A. In regard to flashing, the designer must also address the following considerations: Extension Through Wall. When possible, flashing should extend beyond the face of the wall to form a drip as shown in Figure 7. When using a flashing that deteriorates with UV exposure, a metal or stainless steel drip edge can accomplish this. It is imperative that flashing be extended at least to the face of the brickwork. Continuity. Flashing is not usually installed in one long, continuous sheet. As a result, pieces must be fitted together on the job. Flashing pieces should be lapped at least 6 in. (152 mm) and the laps sealed with mastic or an adhesive compatible with the flashing material. Self-adhesive flashing should be considered as an alternate. Flashing Around Corners. To achieve flashing continuity around corners, preformed corner pieces are available or the pieces of flashing may be cut, lapped and sealed to conform to the shape of the structure.

Figure 7 Shelf Angle Flashing

End Dams. Where the flashing is not continuous, such as over and under openings in the wall and on each side of vertical expansion joints, the ends of the flashing should be extended beyond the jamb lines on both

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sides and turned up into the head joint at least 1 in. (25.4 mm) at each end to form a dam. Preformed end dams may also be used. Refer to Figure 8. Flashing at Vertical Supports. In some cases, connections that support shelf angles make it necessary to cut, puncture or otherwise interrupt the flashing. When this occurs, it is important to make sure that all openings in the flashing are tightly sealed, and that the flashing is attached to these supports with mastic.

Weeps In order to properly drain any water collected on the flashing, weeps are required immediately above the flashing at all locations. An open head joint, formed by leaving mortar out of a joint, is the recommended type of weep. Open head joint weeps should be at least 2 in. (51 mm) high. Weep openings are permitted by most building codes to have a minimum diameter of 3/16 in. (4.8 mm). The practice of placing weeps in one or more courses of brick above the flashing can cause a backup of water and is not recommended. Non-corrosive metal, mesh or plastic screens can be installed in open head joint weeps if desired. Refer to Figure 9.

Figure 8 End Dam Detail

Spacing of open head joint weeps is recommended at no more than 24 in. (610 mm) on center. Spacing of wick and tube weeps is recommended at no more than 16 in. (406 mm) on center. Weep spacing is permitted by most building codes at up to 33 in. (838 mm) on center. Wicks should be at least 16 in. (406 mm) long and extend through the brick, into the air space and along the back of the brick.

Drainage The air space must be kept clear of mortar and mortar droppings to allow proper drainage. Drainage materials may be specified that prevent mortar from entering the air space or catch mortar droppings at the wall base. These materials are usually made of a plastic mesh or fabric porous enough to allow passage of water, but catch or deter mortar from collecting at the base of the air space. The effects of mortar collection devices should be considered carefully as they may require modifications to typical details such as extending flashing more than 8 in. (203 mm) vertically up the backing. While it is not mandatory to include drainage materials, they may help to keep the air space open for drainage. However, the use of drainage materials should not preclude good workmanship and an effort to keep the air space clean.

Figure 9 Flashing and Weeps

Critical Locations Wall Base. Moisture that enters a wall gradually travels downward. Continuous flashing must be placed above grade at the base of walls to divert this water to the exterior. In addition, base flashing prevents water from rising up into the wall system due to capillary action and helps prevent efflorescence. The elevation of flashing and weeps should be above planting beds, ground covering, sidewalks, etc. that are placed immediately adjacent to the wall. Once the designer has determined the level for placing flashing in the wall in accordance with the gradwww.gobrick.com | Brick Industry Association | TN 7 | Water Penetration Resistance - Design and Detailing | Page 5 of 9

ing plans, care should be taken that field modifications do not result in any section of flashing being below grade. Refer to Figure 10. The top of the foundation stem wall should be above the elevation of the base flashing to prevent water from being directed toward the building interior. The cavity below base wall flashing should be solidly filled with mortar or grout. Window Sills. Window sills should be sloped to drain; 15 degrees is recommended. Through-wall flashing must be placed under all sills as shown in Figures 11 through 13 and turned up at the ends to form dams. Soffits and deep reveals may require special flashing considerations. The Technical Notes 36 Series contains further details and information. Steel Lintels. Through-wall flashing should be installed over all openings including door and window heads as shown in Figure 14. An exception may be those completely protected by overhangs. The flashing should be placed on a thin bed of mortar directly on top of the lintels and turned up at the ends to form dams. Figure 15 shows several examples of lintels. Weeps are recommended above all lintels which require flashing.

(b)

(a)

(c)

Figure 10

(d)

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Figure 11 Window Sill in Brick Veneer/Frame Wall

Figure 12 Window Sill in Cavity Wall

Double Angle Solid Wall

Double Angle Hollow Wall

Steel Shape Suspended Plate

Steel Shape Attached Plate

Figure 13 Precast Concrete or Stone Sill

Figure 14 Window Head in Brick Veneer/Frame Wall

Figure 15 Structural Steel Lintels

Shelf Angles. In concrete or steel frame buildings with the brick wythe supported on shelf angles, the entire face of spandrel beam may be flashed or the flashing may be inserted in a continuous reglet installed in the spandrel beam or integrated with moisture-proofing on the spandrel beam. Refer to Figure 8. Projections, Recesses and Caps. Projections, recesses and caps tend to collect rain water and snow. They should be sloped away from the wall to drain and be flashed where possible as shown in Figure 16. Other details and information can be found in the Technical Notes 36 Series. Tops of Walls and Parapets. The tops of all walls and parapets should have an adequate cap or coping, and there should be flashing beneath the coping. Drainage-type parapet walls as shown in Figures 17 and 18 are recwww.gobrick.com | Brick Industry Association | TN 7 | Water Penetration Resistance - Design and Detailing | Page 7 of 9

Figure 17 Precast Concrete or Stone Coping on Cavity Wall

Figure 16 Projections and Caps Precast or Stone Coping Anchorage Varies Overhang, Min. 11/2 in. (38 mm) Recommended Sealant (Typ.) Through-Wall Flashing Flashing Counter Flashing Air Space, Min. 2 in. (51 mm) Recommended Joint Reinforcement with Eye & Pintle

Figure 18 Metal Coping on Cavity Wall Parapet

Figure 19 Non-Parapet Wall

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ommended as the best parapet system for resistance to water penetration. The Technical Notes 36 Series provide more details and information on these subjects. Metal copings, as shown in Figure 19, are preferable to brick, cast stone, concrete or stone copings. Metal copings should extend down the face of the wall at least 8 in. (203 mm) with the bottom edge sealed against the masonry to prevent wind-blown rain from entering the wall. Copings of cast stone, concrete or stone must have joints between each element closed with sealants. Roof Flashing. Because roof flashing is placed at very vulnerable points, it must be designed and installed with great care. Roof flashing design may depend upon the type of roofing used. Where the roof flashing is metal, the counter-flashing should also be metal, extending into the wall and overlapping the roof flashing a minimum of 3 in. (76 mm). Refer to Figures 17 and 18.

SUMMARY Masonry walls constructed of brickwork have performed well for centuries and are a testament to the performance and durability of brick. Design and detailing that maximizes the water penetration resistance of brickwork is needed to achieve this level of service. Selection of the wall type should be based on the project's location, environmental conditions and building use. Water penetration resistance of brickwork is enhanced by including appropriate details that reduce water penetration at key points in the brickwork. The information and suggestions contained in this Technical Note are based on the available data and the combined experience of engineering staff and members of the Brick Industry Association. The information contained herein must be used in conjunction with good technical judgment and a basic understanding of the properties of brick masonry. Final decisions on the use of the information contained in this Technical Note are not within the purview of the Brick Industry Association and must rest with the project architect, engineer and owner.

REFERENCES 1. ASTM E 2266, " Standard Guide for Design and Construction of Low-Rise Frame Building Wall Systems to Resist Water Intrusion", Annual Book of Standards, Vol. 04.12, ASTM International, West Conshohocken, PA, 2005.

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TECHNICAL NOTES on Brick Construction

7A

1850 Centennial Park Drive, Reston, Virginia 20191 | www.gobrick.com | 703-620-0010

December 2005

Water Penetration Resistance - Materials Abstract: This Technical Note discusses considerations for the selection of materials used in brickwork and their impact on its resistance to water penetration. Minimum recommended property requirements and performance characteristics of typical materials are described. Key Words: anchors, brick, coatings, corrosion resistance, flashing, grout, lintels, mortar, sealants, shelf angles, ties, waterresistant barrier, weeps

SUMMARY OF RECOMMENDATIONS: Brick and Mortar:

• Select brick from the appropriate ASTM standard, designated for exterior exposures • Choose mortar materials and types that are compatible with the brick selected • Use mortar type with lowest compressive strength meeting project requirements

Ties and Anchors:

• Use galvanizing, stainless steel or epoxy coatings to provide corrosion resistance

Water-Resistant Barriers:

• Install when brick veneer is anchored to wood or steel studs • Protect from or avoid prolonged ultraviolet (UV) exposure • Use No. 15 asphalt felt conforming to ASTM D 226 or building paper, polymeric films (building wraps) or waterresistant sheathings deemed equivalent or conforming to AC 38

• Tape or seal all joints of insulation or sheathings with facings intended to act as a water-resistant barrier

Flashing:

• Select flashing that is waterproof, durable, UV resistant and compatible with adjacent materials • Flashing materials should conform to applicable ASTM specifications • Do not use aluminum, sheet lead, polyethylene sheeting or asphalt-saturated felt, building paper or house wraps • Use a metal drip edge to extend flashings that degrade when exposed to UV light

Weeps:

• Open head joint weeps recommended

Sealant Joints:

• Use backer rods in joints wide enough to accommodate them. • Use sealants meeting the requirements of ASTM C 920 for joints subject to large movements

INTRODUCTION This Technical Note is the second in a series addressing water resistance of brick masonry and provides guidance regarding material selection of brick masonry components. Other Technical Notes in the series address brickwork design and details (7), construction techniques and workmanship (7B) and condensation (7C and 7D). The use of quality construction materials in brickwork is of prime importance in attaining a satisfactory degree of water resistance. Requiring that materials meet the minimum criteria of appropriate material specifications helps to ensure that they are of an acceptable quality. The most recognized and widely used building material specifications for the determination of quality construction materials are those developed by ASTM International (ASTM). The requirements of ASTM specifications alone cannot predict performance levels of products because they are also affected by design, detailing and workmanship. However, the requirements are based on laboratory tests and field experience and, in the case of brick, are the result of experience gained over a time span exceeding 100 years.

BRICK UNITS Selection of quality brick is very important. Units are normally chosen based on color, texture, size and cost. However, characteristics that can affect water penetration resistance should also be considered. These include durability and those properties that influence brick/mortar compatibility. Under normal exposures, it is virtually impossible for significant amounts of water to pass directly through brick units. Brick may absorb some water, but this does not contribute to an outright flow of water through the brickwork.

Durability Because exterior masonry will be exposed to moisture and the elements, durability is a primary concern. Durability Page 1 of 10

of the brickwork is affected not only by the durability of individual materials, but also the compatibility of materials, how the assembly is designed, how materials are installed and the conditions to which the masonry is exposed. The ASTM specifications for brick are written to provide guidance in choosing a suitable quality of brick based on specific exposure conditions. The requirements for compressive strength, absorption and saturation coefficient are established to indicate the resistance of the brick to damage by freezing and thawing when saturated. Cracking, crazing, spalling and disintegration can occur if an improper choice of brick is made. The ASTM requirements are not intended to serve as an indicator of the degree of water resistance of the masonry. The degree of water resistance is related to the durability of the masonry insofar as the more water that enters the system, the greater the probability that the masonry will be in a saturated condition during freeze/thaw cycles. Brick Standards. Each kind of brick currently in use has its own designated ASTM standard, with specific requirements for durability stipulated by physical properties of the brick. The most commonly used brick standards and the classification for the most severe exposures are: ASTM C 216, Grade SW - Facing Brick (Solid Masonry Units Made From Clay or Shale) ASTM C 652, Grade SW - Hollow Brick (Hollow Masonry Units Made From Clay or Shale) ASTM C 62, Grade SW - Building Brick (Solid Masonry Units Made From Clay or Shale) ASTM C 1405, Class Exterior - Glazed Brick (Single Fired, Brick Units) ASTM C 126, (does not include physical requirements for the brick body, use Grade SW within ASTM C 216 or C 652) - Ceramic Glazed Structural Clay Facing Tile, Facing Brick, and Solid Masonry Units

MORTAR AND GROUT Choosing the proper type of mortar or grout to use in a particular application is very important. To minimize water penetration the primary concern is to choose a mortar and/or grout that will result in the most complete bond with the masonry units chosen. The Technical Notes 8 Series provides detailed information on mortar. Technical Note 3A provides further information on grout.

Mortar The most commonly used standard for specifying mortars for unit masonry is ASTM C 270. Four types of mortar (M, S, N and O) are covered in the standard, although building codes typically require the use of Types M, S or N. ASTM C 270 addresses mortars made with portland cement-lime combinations and those made with mortar cements and masonry cements. Detailed information on ASTM C 270, mortar types and properties can be found in Technical Note 8. No single type of mortar is best for all purposes. The basic rule for the selection of a mortar for a particular project is: Always select the mortar type with the lowest compressive strength that meets the performance requirements of the project. This general rule must be tempered with good judgment. For example, it would be uneconomical and unwise to continuously change mortar types for various parts of a structure. However, the general intent of the rule should be followed, using good judgment and economic sense. For most brick veneer applications, Type N mortar is appropriate.

Grout In some barrier masonry walls, grout is used to form a collar joint that bonds the outer and inner masonry wythes together. Collar joints are the primary means of providing water penetration resistance in contemporary barrier wall construction. When properly constructed, collar joints provide a solid cementitious layer deterring water entry into the inner masonry wythe. Grout for brickwork should conform to ASTM C 476. Two types of grout, fine and coarse, are addressed in this standard. Coarse grout differs from fine grout in that, in addition to sand, it contains coarse aggregates such as pea gravel. Grout may be specified by proportions or by strength requirements. Specification by proportions is recommended for grout used in brickwork. Volumes of materials used in grout specified by proportions should be consistently measured throughout the project. www.gobrick.com | Brick Industry Association | TN 7A | Water Penetration Resistance - Materials | Page 2 of 10

Specification for Masonry Structures [Ref. 9] contains requirements for the maximum height of grout pour, the minimum width of grout space and the minimum dimensions of cells receiving grout for each grout type. Fine grout requires a minimum grout space width of ¾ in. (19.1 mm) and any cells receiving grout to be a minimum dimension of 1½ x 2 in. (38 x 51 mm). Coarse grout requires a minimum grout space width of 1½ in. (38 mm) and any cells receiving grout to be a minimum dimension of 1½ x 3 in. (38 x 76 mm).

BRICK/MORTAR COMPATIBILITY When water passes through brick masonry walls, it does so through separations that form between the brick and the mortar at the time of laying or through cracks that form after the mortar has cured. The dominant property affecting the amount of water entering brickwork from a materials selection standpoint is the extent of bond between the brick and the mortar. Extent of bond is a measure of the area of contact at the interface between brick and mortar surfaces. Not to be confused with extent of bond, bond strength is a measure of the adhesion between brick and mortar. Bond strength is one factor that determines if cracks form after the mortar cures. Brick and mortar combinations that have high bond strengths may not have an extent of bond that would provide high resistance to water penetration. Consequently, extent of bond is more important to water penetration resistance of brick masonry than bond strength. Extent of bond is influenced by both brick and mortar properties and is best achieved when both are considered. Initial rate of absorption is the key property of the brick related to brick/mortar compatibility. Mortar properties include water retention, air content and workability. The initial rate of absorption (IRA) of a brick is a measure of the amount of water taken into a 30 in.2 (194 cm2) brick surface area within one minute. A brick’s IRA can be measured in the laboratory under controlled drying conditions or in the field. The field IRA of a brick will vary depending on its moisture condition at the time it is measured. Tests over the years have shown that the most complete bond is achieved when the initial rate of absorption (IRA) of a brick, at the time of laying, is below 30 g/min•30 in.2 (30 g/min•194 cm2). As a result, Specification for Masonry Structures requires brick with initial rates of absorption in excess of this value to be wetted prior to laying. Water penetration tests of masonry built with low and high IRA brick [Ref. 4 and 5] indicate that water penetration generally increases as brick IRA increases and as mortar water retention decreases. Thus, low IRA brick should be combined with mortars that exhibit low water retention and high IRA brick should be combined with mortars with high water retention, See Technical Note 8B for mortar recommendations with brick of various IRAs. Mortar air content will also affect extent of bond. Higher air content mortars such as masonry cement mortars and those made with air-entrained cements or lime are more likely to increase water penetration. Several studies have shown that workmanship is critical with respect to water penetration. Thus, mortars with better workability should be used. There are no recognized tests to determine mortar workability, but it typically increases with air content and lower compressive strength mortars.

TIES AND ANCHORS Ties and anchors in a masonry wall system connect two or more wythes together or attach the brick veneer to a structural backing. Ties and anchors do not directly influence water penetration, except when related to cracking of the brickwork and resulting water entry. All ties and anchors must be corrosion-resistant. Applicable ASTM standards for corrosion-resistance of masonry ties and anchors are discussed later in this Technical Note. More detailed information on ties and anchors can be found in Technical Note 44B. Truss-type joint reinforcement that engages the brick wythe with fixed diagonal cross wires is only permitted in multiwythe walls with a filled collar joint. In other walls, it can restrict differential in-plane movement between masonry wythes, which can lead to cracking and subsequent water penetration.

Additional Considerations Drips. A drip is a bend or crimp in a tie or anchor that helps any moisture traveling across the tie to drip off before reaching the interior masonry wythe or backing. Ties and anchors with drips are not permitted [Ref. 6] because the drips reduce the compressive and tensile capacity of the ties when transferring the lateral loads between the wythes. www.gobrick.com | Brick Industry Association | TN 7A | Water Penetration Resistance - Materials | Page 3 of 10

Corrosion Resistance. Corrosion resistance is usually provided by zinc coatings or by using stainless steel. The level of corrosion protection required for wall ties and anchors varies with their intended exposure conditions, as follows [Ref. 6]: - when exposed to earth or weather or to a mean relative humidity exceeding 75%, ties and anchors are required to be stainless steel, hot-dip galvanized or epoxy-coated - in other exposures, ties and anchors must be mill galvanized, hot-dip galvanized or stainless steel. In addition, the designer should consider the potential for corrosion due to contact between dissimilar metals. Items protected by zinc coatings may be hot-dip or mill galvanized. With mill galvanizing, the steel is galvanized before the joint reinforcement or wall tie is fabricated. Therefore, ends cut during or after the manufacturing process are not coated. With hot-dip galvanizing, the finished item is galvanized, providing more complete coverage. Stainless steel items should be AISI Type 304 or Type 316 and conform to the appropriate specification listed below. Building Code Requirements for Masonry Structures, also known as the MSJC Code [Ref. 6] also allows epoxy coatings to be used as corrosion protection. To ensure adequate resistance to corrosion, coatings or materials should conform to the following: Zinc Coatings -

ASTM A 123 or A 153 Class B (for sheet metal ties and sheet metal anchors) or 1.50 oz/ft2 (458 g/m2) (for joint reinforcement, wire ties and wire anchors) ASTM A 641, 0.1 oz/ft2 (0.031 kg/m2) (minimum for joint reinforcement) ASTM A 653, Coating designation G60 (for sheet metal ties and sheet metal anchors)

Stainless Steel - ASTM A 240 (for sheet metal anchors and sheet metal ties) ASTM A 480 (for sheet metal anchors and sheet metal ties and for plate and bent-bar anchors) ASTM A 580 (for joint reinforcement, wire anchors and wire ties) ASTM A 666 (for plate and bent-bar anchors) Epoxy Coatings - ASTM A 884 Class A, Type 1- less than or equal to 7 mils (175 μm) (for joint reinforcement) ASTM A 899, Class C – 20 mils (508 μm) (for wire ties and wire anchors)

MASONRY HEADERS A header is a masonry unit laid perpendicular to the wythe that may be used to connect two wythes of masonry. Although the MSJC Code allows wythes of masonry designed for composite action to be bonded by masonry headers, they are not commonly used in contemporary construction. These units provide a direct path for water penetration from the outside of the wall to the interior along the head and bed joints. As a result, they are not recommended.

WATER-RESISTANT BARRIERS Water-resistant barriers are membranes placed behind claddings as a secondary measure to prevent the passage of liquid water to underlying materials such as sheathing and other wall elements susceptible to moisture damage. This function is distinct from those provided by vapor retarders, intended to prevent water vapor diffusion, and air barriers, intended to prevent air flow through the wall system. However, some materials can serve all three functions. A water-resistant barrier should keep out any water which finds its way across the air space via anchors, mortar bridging or splashing. A water-resistant barrier is required in exterior walls when brick veneer is anchored to wood or steel framing and can be provided by No. 15 asphalt felt or other approved materials as described below. While a membrane is preferred, sheathing or rigid insulation boards with an inherent resistance to moisture penetration may serve as the water-resistant barrier when all edges and joints are completely taped or sealed.

Sheet Membranes Typically, mechanically attached membranes should not be left exposed to UV light for an extended period of time, as they deteriorate and become less water-resistant. www.gobrick.com | Brick Industry Association | TN 7A | Water Penetration Resistance - Materials | Page 4 of 10

Asphalt Saturated Felt. One layer of No. 15 asphalt felt is prescribed by most codes as the material for waterresistant barriers. The felt should conform to Type I of ASTM D 226, Specification for Asphalt-Saturated Organic Felt Used in Roofing and Waterproofing. The durability of asphalt-saturated felt is adequate; however it may be torn during or after installation. Asphalt-saturated felt typically has a high water vapor permeability. Building Paper. Asphalt saturated kraft paper (generally referred to as building paper) has a long history as an approved and common substitution for No. 15 asphalt felt. Building paper for use as a water-resistant barrier should conform to the requirements of Federal Specification UU-B-790a, Type I, Grade D. Characteristics of building paper are similar to those of asphalt saturated felt. Building paper typically has less asphalt and lower permeance than felts and can offer better resistance to bending damage. Polymeric Films. Some plastic films (building-wraps) have been approved for use as water-resistant barriers. These films may have qualities similar to those of other water-resistant barriers, but ascertaining the effectiveness of a particular plastic as a water-resistant barrier can be difficult as a standard specification is yet to be developed. Some plastic membranes act as vapor retarders and can potentially trap water vapor inside the stud wall where it can condense if the temperature in the wall drops below the dew point. Thus, all plastic membranes should not be considered suitable and caution should be exercised when specifying them as water-resistant barriers. AC38, Acceptance Criteria for Water-Resistive Barriers [Ref. 1], developed by the International Code Council Evaluation Service, Inc., is typically used to establish the suitability of a polymeric film as a water-resistant barrier. Perforated films are not recommended because they do not consistently resist water penetration in commonly used performance tests. PVC is not recommended because of its tendency to become brittle with age. Polymeric films are highly resistant to tearing and often function concurrently as air barriers; however, they do not tend to seal themselves when penetrated by fasteners as felts sometimes do. Some manufacturers suggest fasteners with large heads or plastic caps be used rather than standard fasteners to enhance water penetration resistance at fastener locations. Polymeric films can often be installed with fewer lap joints than felt and building paper, as they are supplied in larger rolls up to 10 feet (3.1 m) wide.

Liquid Applied Films Liquid applied films often have the capability of serving as vapor and air barriers and sometimes thermal insulation, in addition to providing water resistance. These coatings are varied in type and may be spray, roller or trowel applied; however they generally have the benefit of providing a seamless, monolithic membrane that adheres to most substrates. Although these materials can be applied rapidly, they require skilled applicators to ensure quality and performance. These membranes have a unique set of service requirements as a result of being bonded to a substrate. The effects of wet substrates, expansion and contraction at substrate joints, volume changes of building materials, and stresses caused by lateral loads must be considered so that the membrane performs successfully during its life. Quality installations are more difficult to achieve on substrates with rough surfaces and may require increased thicknesses.

Board Products Sheathings and other board products that are inherently water-resistant or have water-resistant facings are permitted to serve as water-resistant barriers when the edges and joints of boards are completely taped or sealed. To perform successfully, the materials providing this seal must maintain their integrity and performance when subjected to moisture and other environmental conditions for the entire service life of the wall. Board products that act as water-resistant barriers should be vapor permeable except when they are also intended to serve as a vapor retarder.

SHELF ANGLES AND LINTELS Although similar, shelf angles and lintels differ in the way each is incorporated into brickwork. A shelf angle supports brick veneer and is anchored to the structure. A lintel, on the other hand, is a structural beam placed over an opening to carry superimposed loads. As such, it is supported by the masonry on each side of the opening and is not attached to the structure. Lintels may be loose steel angles, stone, precast concrete or reinforced masonry. The proper specification of material for lintels is important for both structural and serviceability requirements. www.gobrick.com | Brick Industry Association | TN 7A | Water Penetration Resistance - Materials | Page 5 of 10

Nongalvanized and non-stainless steel angles and lintels should be primed and painted as a minimum to inhibit corrosion. For severe climates and exposures, such as coastal areas, consideration should be given to the use of galvanized or stainless steel shelf angles and lintels. Even where galvanized or stainless steel shelf angles and lintels are used, continuous flashing should be installed to protect the angle. To ensure adequate resistance to corrosion, shelf angles should be protected by a zinc coating conforming to ASTM A 123, or be made of stainless steel conforming to ASTM A 167, Type 304. Additional discussion and details of shelf angles and lintels may be found in Technical Notes 21, 21A, 28B, 31 and 31B.

FLASHING Selection of a proper flashing material is of utmost importance because the flashing is a critical element to the drainage of water that may penetrate the wall system. Flashing materials should be waterproof, durable and resist puncture and cracking during and after construction. Because flashing may be installed in advance of the exterior brick wythe, it should be able to endure some exposure to ultraviolet (UV) light without significant deterioration. The flashing should also resist damage from contact with metal, mortar or water and be compatible with adjacent adhesives and sealants. Minimum recommended flashing thicknesses are included below for each type of flashing. In general, thicker flashings are more durable, but may be more difficult to form. Flashing materials generally fall into three categories: sheet metals, composite materials (combination flashings) and plastic or rubber compounds. The selection is largely determined by cost and suitability. It is suggested that only superior quality materials be selected, since replacement in the event of failure may be expensive. Materials such as polyethylene sheeting, asphalt-impregnated building felt, building paper and house wraps should not be used as flashing materials. These materials are easily damaged during installation and in many cases, turn brittle and decay over time.

Sheet Metals Stainless Steel. Stainless steel is an excellent flashing material that has excellent chemical resistance and does not stain masonry. Stainless steel flashing should conform to ASTM A 167, Type 304. The minimum thickness should be at least 0.01 in. (0.25 mm). Because it is difficult to form, preformed shapes are commonly used, although these are difficult to bend on-site if field adjustments are required. Mastic can be used to seal joints between individual flashing pieces, as stainless steel can be difficult to solder. Copper. Copper is another excellent flashing material that is durable, easy to form and solder, and is available in preformed shapes. Exposed copper may stain adjacent masonry, but it is not damaged by the caustic alkalies present in masonry mortars. It can be safely embedded in fresh mortar and will not deteriorate in continuously saturated, hardened mortar, unless excessive chlorides are present. When using copper flashing, prohibit the use of mortar admixtures containing even small amounts of chloride ions. Copper flashing should conform to ASTM B 370, Standard Specification for Copper Sheet and Strip for Building Construction, or B 882, Specification for Pre-Patinated Copper for Architectural Applications. The Copper Development Association recommends minimum weights of 12 oz./ft2 and 16 oz./ft2 for “High Yield” and standard cold rolled copper, respectively, used as through-wall flashing. If copper flashing is used adjacent to other metals, proper care should be taken to account for separation of the materials. Laminated copper flashing and combinations of copper sheet and other materials are discussed below in the Composites section. Galvanized Steel and Zinc Alloys. Galvanized coatings are subject to corrosion in fresh mortar, thus the use of galvanized steel as through wall flashing is not recommended. Although corrosion forms a very compact film around zinc, its extent cannot be accurately predicted. Bending steel items cracks the galvanized coating, thereby reducing its durability. Some zinc-alloy flashings are available, but, like many alloys, these may have properties considerably different from those of the pure metal. Aluminum. Aluminum should not be used as a flashing material in brick masonry. The caustic alkalies in fresh, unhardened mortar will attack aluminum. Although dry, seasoned mortar will not affect aluminum, corrosion can continue if the adjacent mortar becomes wet. Sheet Leads. Thin lead sheet is not recommended as a flashing material in brick masonry. Lead, like aluminum, is susceptible to corrosion in fresh mortar. Furthermore, where lead is partially embedded in mortar with moisture present, galvanic action can occur resulting in the gradual disintegration of the lead. www.gobrick.com | Brick Industry Association | TN 7A | Water Penetration Resistance - Materials | Page 6 of 10

Plastic and Rubber Flashing Plastic and rubber flashings are resilient, corrosion resistant materials that are easy to form and join. However, because the chemical compositions of these products vary widely, the durability of these materials is variable. Thus, it is necessary to rely on performance records of the material, the reputation of the manufacturer, and where possible, test data to ensure satisfactory performance. Some of the critical areas are: (1) resistance to degradation in UV light; (2) compatibility with alkaline masonry mortars; (3) compatibility with joint sealants and (4) resistance to tear and puncture during construction. A minimum thickness of 30 mil (0.76 mm) is recommended for plastic and rubber flashings. Polyvinyl chloride (PVC). PVC degrades under exposure to UV light and should be cut flush with the face of the wall or used with a metal drip edge to extend beyond the wall face. Ethylene Propylene Diene Monomer (EPDM). EPDM is a synthetic rubber that is used as a single ply roofing membrane as well as flashing. It has better low temperature performance the PVC, and better weathering resistance than butyl rubber. It is commonly available in a thickness of 40 mils (1.0 mm) or greater, reducing concerns of fragility during construction. Dimensional stability may be a concern. Self-Adhesive Rubberized Asphalt. Self-adhesive rubberized asphalt flashing adheres to other building materials and itself, thus speeding flashing installation and making it easier to seal flashing laps and terminations. These flashings are also self-healing, making them less susceptible to small punctures. Substrates should be dry and clean for proper adhesion. In addition, when self-adhesive flashings are used, care should be taken to ensure compatibility between the flashing adhesive and sealants used in the wall. Primers may be necessary to ensure adequate adhesion of self-adhering flashings to some substrates.

Composites The most common type of composite or combination flashing is a thin layer of metal sandwiched between one or two layers of another material, such as bitumen, kraft paper or various fabrics. The metal layer is usually copper, lead or aluminum. Composite flashings utilize the better properties of each of their component materials. In the case of lead and aluminum composite flashings, the paper and fabric laminates reduce the potential for corrosion resulting from the metal foil contacting the mortar or adjacent dissimilar metals. These flashings also allow the use of thinner metal sheet, making them less expensive and easier to form, but also more prone to tearing and punctures. The laminate must either be durable and stable under UV exposure or these flashings should be used with stainless steel drip edges. It is beyond the scope of this Technical Note to describe the various types of composite flashing and their properties. The manufacturer's literature should be consulted for the various types of composite flashing available.

DRAINAGE MATERIALS AND MORTAR DIVERTERS When a high probability of mortar falling into the air space exists, such as for tall brick veneer without shelf angles, drainage materials and mortar diverters may be useful to help prevent mortar from bridging the air space or blocking weeps. It is beyond the scope of this Technical Note to characterize the widely varying types of materials used for these purposes. Manufacturers’ literature should be used to compare and determine the suitability of drainage materials and mortar diverters. The use of drainage materials should not preclude good workmanship and an effort to keep the air space clean of excess mortar droppings.

WEEPS Although open head joint weeps are the recommended type of weep, some weeps are made using plastic or metal tubes, or using rope wicks. These alternate weeps should be spaced more closely as they do not drain water as quickly. Weep openings are permitted by most building codes to have a minimum diameter of 3/16 in (4.8 mm). Rope wicks should be at least 16 in. (406 mm) long and made from cotton sash cord or other materials that wick. Items used to form weeps should not easily deteriorate or stain the brickwork. Open head joint weeps may have non-corrosive plastic, mesh or metal screens installed if desired. Vent-type weeps can serve a dual function of allowing water to drain, but can also allow air to enter the cavity resulting in more drying action. There is no single method that produces the best weep for all situations.

SEALANTS Sealants are an important element in preventing water penetration around openings in masonry walls. Too frewww.gobrick.com | Brick Industry Association | TN 7A | Water Penetration Resistance - Materials | Page 7 of 10

quently, sealants are relied on as a means of correcting or hiding poor workmanship rather than as an integral part of construction. A discussion of the characteristics of joint sealants is beyond the scope of this Technical Note, but a few comments are in order. Sealants should be selected for their durability, extensibility, compressibility and their compatibility with other materials. Other important considerations in sealant selection may include curing time, UV resistance, color stability, resistance to staining and the ability to handle a broad range of joint sizes. A sealant should be able to maintain these qualities under the temperature extremes of the climate in which the building is located. Trial applications of sealants under consideration are always helpful in determining suitability for a particular application. Additional discussion of sealants may be found in Technical Notes 18 and 18A. Oil-based caulks and acetoxic silicone sealants that attack cement in mortar should not be applied to masonry. Solvent-based acrylic sealant or a butyl caulk should only be used where little or no movement is expected, such as joints around windows and other openings. For joints subject to large movements, such as expansion joints, an elastomeric joint sealant conforming to the requirements of ASTM C 920 should be used. This includes silicones, urethanes and polysulfides. Application of a sealant primer may be required to preclude staining of some sealants on certain brick. Backer rods are recommended behind sealants in joints large enough to accommodate them. Backer rods should be plastic foam or sponge rubber. Backer rods should be capable of resisting permanent deformation before and during sealant application, non-absorbent to liquid water and gas, and should not emit gas which may cause bubbling of the sealant. A bond breaking tape may be used when there is not sufficient space for a backer rod. For further information on sealants, refer to ASTM C 1193, Guide for Use of Joint Sealants.

COATINGS The use of external coatings, such as paint or clear coatings, on brick masonry should be considered only after a detailed evaluation of the possible consequences. Although coatings are not required on properly designed, specified and constructed brick masonry, they may be used successfully to correct certain deficiencies or alter the wall’s appearance. Coatings intended to reduce water penetration (water repellents) are most effective when their intended use corresponds with the nature of the water penetration problem. Use of coatings for reasons outside their intended application rarely reduces water penetration and often leads to more serious problems. Considerations in the choice of coating include: compatibility with brick masonry, water and air permeability, ability to span cracks, applicability to exterior exposure, potential lifespan and aesthetic considerations. Technical Notes 6 and 6A should be consulted when considering a coating for brick masonry.

SUMMARY This, the second in a series of Technical Notes on water resistance of brick masonry, has provided information on properly selecting quality materials for masonry work. This Technical Note cannot cover all available materials or all conditions. Lack of specific reference to a material should not preclude its use providing that it results in waterresistant brick masonry. The information and suggestions contained in this Technical Note are based on the available data and the combined experience of engineering staff and members of the Brick Industry Association. The information contained herein must be used in conjunction with good technical judgment and a basic understanding of the properties of brick masonry. Final decisions on the use of the information contained in this Technical Note are not within the purview of the Brick Industry Association and must rest with the project architect, engineer and owner.

REFERENCES 1.

Acceptance Criteria for Water Resistive Barriers, AC38, ICC Evaluation Service, Inc., Whittier CA, 2004.

2. Annual Book of ASTM Standards, ASTM International, West Conshohocken, PA, 2005: Volume 1.03 - A 167, Standard Specification for Stainless and Heat-Resisting Chromium-Nickel Steel Plate, Sheet, and Strip

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A 240/A 240M, Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels and for General Applications A 480/A 480M, Standard Specification for General Requirements for Flat-Rolled Stainless and Heat-Resisting Steel Plate, Sheet, and Strip A 580/A 580M, Standard Specification for Stainless Steel Wire A 666, Standard Specification for Annealed or Cold-Worked Austenitic Stainless Steel Sheet, Strip, Plate, and Flat Bar A 884/A 884M, Standard Specification for Epoxy-Coated Steel Wire and Welded Wire Reinforcement A 899, Standard Specification for Steel Wire, Epoxy-Coated Volume 1.06 - A 123/A 123M, Standard Specification for Zinc (Hot-Dipped Galvanized) Coatings on Iron and Steel Products A 153/A 153M, Standard Specification for Zinc Coating (Hot-Dip) on Iron and Steel Hardware A 641/A 641M, Standard Specification for Zinc-Coated (Galvanized) Carbon Steel Wire A 653/A 653M, Standard Specification for Steel Sheet, Zinc-Coated (Galvanized) or ZincIron Alloy-Coated (Galvannealed) by the Hot-Dip Process Volume 2.01 - B 370, Standard Specification for Copper Sheet and Strip for Building Construction B 882, Specification for Pre-Patinated Copper for Architectural Applications Volume 4.04 - D 226, Standard Specification for Asphalt-Saturated Organic Felt Used in Roofing and Waterproofing Volume 4.05 - C 62, Standard Specification for Building Brick (Solid Masonry Units Made From Clay or Shale C126, Standard Specification for Ceramic Glazed Structural Clay Facing Tile, Facing Brick, and Solid Masonry Units C 216, Standard Specification for Facing Brick (Solid Masonry Units Made from Clay or Shale) C 270, Standard Specification for Mortar for Unit Masonry C 476, Standard Specification for Grout for Masonry C 652, Standard Specification for Hollow Brick (Hollow Masonry Units Made From Clay or Shale) C 1405, Standard Specification for Glazed Brick (Single Fired, Brick Units) Volume 4.07 - C 920, Standard Specification for Elastomeric Joint Sealants C 1193, Standard Guide for Use of Joint Sealants 2. Beall, C., "Selecting a Joint Sealant", Masonry Construction, Hanley Wood, LLC, December 1996. 3. Bomberg, M. and Onysko D., "Characterization of Exterior Sheathing Membranes," Symposium on Membranes in Enclosure Wall Systems, Building Environment and Thermal Envelope Council, June 1011, 2004. 4. Borchelt, J.G. and Tann, J.A., ”Bond Strength and Water Penetration of Low IRA Brick and Mortar”, Proceedings of the Seventh North American Masonry Conference, South Bend, IN, The Masonry Society, June 1996.

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5. Borchelt, J.G., Melander, J.M. and Nelson, R.L., “Bond Strength and Water Penetration of High IRA Brick and Mortar” Proceedings of the Eight North American Masonry Conference, Austin, TX, The Masonry Society, June 1999. 6. Building Code Requirements for Masonry Structures (ACI 530-05/ASCE 5-05/TMS 402-05), The Masonry Society, Boulder, CO, 2005. 7. Lies, K.M., "Weather Resistant Barrier Performance and Selection", Symposium on Membranes in Enclosure Wall Systems, Building Environment and Thermal Envelope Council, June 10-11, 2004. 8. Pickett, M., "Fluid Applied Wall Membrane Systems", Symposium on Membranes in Enclosure Wall Systems, Building Environment and Thermal Envelope Council, June 10-11, 2004. 9. Specification for Masonry Structures (ACI 530.1-05/ASCE 6-05/TMS 602-05), The Masonry Society, Boulder, CO, 2005. 10. Yorkdale, A.H. , “Initial Rate of Absorption and Mortar Bond”, Masonry: Materials, Properties and Performance, STP 778, J.G. Borchelt, Ed., ASTM, September, 1982.

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TECHNICAL NOTES on Brick Construction 7B 1850 Centennial Park Drive, Reston, Virginia 20191 | www.gobrick.com | 703-620-0010

December 2005

Water Penetration Resistance Construction and Workmanship Abstract: This Technical Note covers essential construction practices needed to assure water-resistant brick masonry. Procedures for preparing materials to be used in brick construction are recommended, including proper storage, handling and preparation of brick, mortar, grout and flashing. Good workmanship practices are described, including the complete filling of all mortar joints, tooling of mortar joints for exterior exposure and covering unfinished brick masonry walls to protect them from moisture. Key Words: air space, brick, construction, flashing, initial rate of absorption, joints, mortar, tooling, weeps, workmanship.

SUMMARY OF RECOMMENDATIONS: General

Joints

• Store materials on the job site to avoid wetting and contamination • For drainage walls, keep the air space free of excessive mortar droppings • Do not disturb newly laid masonry • Cover tops of unfinished walls until adjacent construction protects them from water entry

• In exterior wythes, completely fill all mortar joints intended to have mortar • Minimize furrowing of bed joints and prohibit slushing of head joints • Fill collar joints completely with grout or mortar, preferably grout; do not slush collar joints • Tool mortar joints when thumbprint hard with a concave, “V” or grapevine jointer

Brick • Pre-wet brick with a field measured initial rate of absorption (IRA) exceeding 30 g/min•30 in.2 (30 g/min•194 cm2)

Mortar • When mixing mortar, use accurate batching measurements and maximum amount of water that produces a workable mortar • For brick with an IRA exceeding 30 g/min•30 in.2 (30 g/ min•194 cm2), increase water or maximize water retention by increasing lime proportions within limits of ASTM C 270 • For brick with an IRA lower than 5 g/min•30 in.2 (5 g/min•194 cm2), reduce water or minimize water retention by decreasing lime proportions within limits of ASTM C 270

Flashing and Weeps • Do not stop flashing behind face of brickwork • Where required, turn up flashing ends into head joint a minimum of 1 in. (25.4 mm) to form end dams • Lap continuous flashing pieces at least 6 in. (152 mm) and seal laps • Where installed flashing is pierced, make watertight with sealant or mastic compatible with flashing • Install weeps immediately above flashing

INTRODUCTION The best design, detailing and materials will not compensate for poor construction practices and workmanship. Proper construction practices, including preparation of materials and workmanship, are essential to achieve a water-resistant brick masonry wall. This Technical Note discusses construction techniques and workmanship and is the third in a series of Technical Notes addressing water penetration resistance of brick masonry. Other Technical Notes in the series address brickwork design and details (7), materials (7A) and condensation (7C and 7D). Maintenance of brick masonry is addressed in Technical Note 46. All of these items are essential to obtain water-resistant brick masonry walls.

PREPARATION OF MATERIALS Preparation of masonry materials before bricklaying begins is very important. Specific procedures must be followed to ensure satisfactory performance and avoid future problems. Preparation includes material storage, mixing mortar and grout and, in some cases, wetting the brick.

Storage of Materials All materials at the jobsite should be stored to avoid contamination. Masonry units, mortar materials, ties and reinforcement should be stored off the ground, preferably in a dry location. In addition, all materials should be covered with tarpaulins or other weather-resistant materials to protect them from the elements. Page 1 of 7

Wetting Brick Brick with an initial rate of absorption (IRA) greater than 30 g/min•30 in.2 (30 g/min•194 cm2) at the time of laying tend to draw too much moisture from the mortar before initial set. As a result, construction practices should be altered when using brick with high IRA to achieve strong, water-resistant masonry. The IRA of brick in the field will typically be less than that reported in laboratory tests. Laboratory test results may be used to determine if measuring IRA in the field is necessary. ASTM C 67, Test Methods for Sampling and Testing Brick and Structural Clay Tile, includes a standard procedure for measuring IRA in the field. A crude method of indicating whether brick need to be wetted prior to placement consists of drawing, with a wax pencil, a circle 1 in. (25.4 mm) in diameter on the brick surface that will be in contact with the mortar. A quarter can be used as a guide for the circle. With a medicine dropper, place 20 drops of water inside this circle and note the time required for the water to be absorbed. If the time exceeds 11/2 minutes, the brick should not need wetting; if less than 11/2 minutes, adjustments to typical construction practice are recommended. Specification for Masonry Structures [Ref. 4] requires that brick with an IRA exceeding 30 g/min•30 in.2 (30 g/min•194 cm2) be wetted prior to laying to produce an IRA less than 30 g/min•30 in.2 (30 g/min•194 cm2) when the units are placed. However, execution of this method may be impractical on large-scale construction projects and the contractor may consider other alternatives, as discussed in the following section, Mixing of Mortar and Grout. If brick are to be wetted, the method of wetting is very important. Sprinkling or dipping the brick in a bucket of water just before laying would produce the surface wet condition which may not be sufficient, as shown in Figure 1b. The units should have a saturated interior, but be surface dry at the time of laying, as shown in Figure 1d. Satisfactory procedures for wetting the brick consist of letting water run on the cubes or pallets of brick, or placing them in a large tank of water. This should be done the day before the units are laid, or not later than several hours before the units will be used so that the surfaces have an opportunity to dry before the brick are laid. Wetting low-absorption brick or excessive wetting of brick may result in saturation, as shown in Figure 1c. This can cause “bleeding” of the mortar joints and “floating” of the brick.

a) Dry

b) Surface Wet

c) Saturated

d) Surface Dry

Figure 1 Moisture Content of Brick

Mixing of Mortar and Grout Typically, a high water content in the mortar is necessary to obtain complete and strong bond between mortar and brick. In general the mortar should be mixed with the maximum amount of water that produces a workable mortar. Factors such as the jobsite environment and the IRA of the brick should be considered when determining the proper amount of water to include in the mortar. Mortar to be used with brick that have an IRA greater than 30 g/min•30 in.2 (30 g/min•194 cm2) should be mixed to maximize water retention by increasing mixing water or lime content within the limits of ASTM C 270. This is particularly important when pre-wetting the brick to reduce their IRA is impossible or impractical. Admixtures designed to increase the water retention of the mortar may also be used to improve the compatibility of mortar with high IRA brick. Only admixtures with test data showing no deleterious effects should be used. Mortar for use with brick that have an IRA less than 5 g/min•30 in2 (5 g/min•194 cm2) should be mixed with reduced amounts of water or lime to minimize water retention. Lime proportions should remain within the limits of ASTM C 270. When brick with widely different absorption rates are used together in brickwork, it is important to maintain the correct water content in the mortar used with the different brick. All cementitious materials and aggregates must be mixed for at least 3 minutes and not more than 5 minutes in a mechanical batch mixer. If, after initial mixing, the mortar stiffens due to the loss of water by evaporation, addiwww.gobrick.com | Brick Industry Association | TN 7B | Water Penetration Resistance - Construction and Workmanship | Page 2 of 7

tional water should be added and the mortar remixed (retempered). All mortar should be used within 21/2 hr (2 hr in hot weather conditions, see Technical Note 1) of initial mixing and grout should be used within 11/2 hour of introducing water into the mix. No mortar or grout should be used after it has begun to set. One of the most common problems with mortar is oversanding. Oversanded mortar is harsh, unworkable and results in poor extent of bond and reduced bond strength, thus increasing the potential for water penetration problems. The cause of oversanding is frequently the use of the shovel method of measuring the sand. The amount of sand that a shovel will hold varies depending on the moisture content of the sand, the person doing the shoveling and the different size of shovels used on the jobsite. To alleviate this problem, proper batching methods must be used. Measurement of sand by shovel should not be permitted without periodically gauging the shovel count using a bucket or box of known volume. Technical Note 8B provides detailed guidelines for various methods of more accurately batching mortar.

Blending of Brick While not related to water penetration resistance, blending of brick at the jobsite is an important preparation task related to workmanship and the acceptable appearance of brickwork. Because brick is made from natural materials that vary in physical properties, variations in color may occur between production runs and occasionally within the same run. Modern manufacturing processes use automatic equipment which may not permit inspection of each brick, also resulting in minor color and texture variations. For these reasons, straps of brick from different cubes should be placed together around the wall. The mason should then select brick from adjacent straps when laying a given section of brickwork. By blending the brick throughout the wall in this manner, the effect of potential color variations on the finished brickwork is minimized.

WORKMANSHIP

Termination Bar

The importance of good workmanship to attain quality brickwork cannot be overemphasized. While design and the quality of materials contribute to the water penetration resistance of brickwork, workmanship is a highly important factor in the construction of water-resistant masonry.

Flashing

Placing Flashing and Weeps

Water-Resistant Barrier on Exterior Sheathing

Weep Filled Cavity Beneath Flashing

Figure 2 Wall Base Flashing Detail

Flashing must be installed properly and integrated with adjacent materials to form an impervious barrier to moisture movement. The flashing should be wide enough to start outside the exterior face of the brick wythe, extend across the cavity, and turn up vertically against the backing or interior wythe at least 8 in. (203 mm). The top (vertical) edge should be placed in a mortar joint of the backing wythe, in a reglet in concrete backing, or attached to sheathing with a termination bar, as shown in Figure 2. Sections of flashing are to be overlapped at least 6 in. (152 mm) and the lap sealed with a compatible adhesive. Water-resistant sheet membranes should overlap the flashing in a shingle fashion by at least 6 in. (152 mm). Flashing that is placed so that the outside edge projects from the face of the wall may be cut flush with the face of the brickwork. In no circumstances should the flashing be stopped behind the face of the brickwork. Continuity at corners and returns is achieved by cutting and folding straight sections or using preformed corner pieces. Discontinuous flashing should terminate with an end dam in a head joint, rising at least 1 in. (25.4 mm) as shown in Figure 3.

End Dam Flashing

Figure 3 End Dam Detail

Flashing must be placed without punctures or tears. Openings created for reinforcement or anchors must be closed with a compatible sealant. Protection may be needed around bolts fastening shelf angles to the structure.

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Weeps are required, and should be formed in mortar joints immediately above the flashing. Open head joints, formed by leaving mortar out of a joint, are the recommended type of weep. Open head joint weeps should be at least 2 in. (51 mm) high. Weep openings are permitted by most building codes to have a minimum diameter of 3/16 in. (4.8 mm). The practice of specifying the installation of weeps one or more courses of brick above the flashing can cause a backup of water and is not recommended. Noncorrosive metal, mesh or plastic screens can be installed in open head joint weeps if desired. Spacing of open head joint weeps at no more than 24 in. (610 mm) on center is recommended. Spacing of wick and tube weeps is recommended at no more than 16 in. (406 mm) on center. Weep spacing is permitted by most building codes up to 33 in. (838 mm) on center. If other than an open head joint weep is used, be sure the weep is clear of all mortar to allow the wall to drain (see Technical Note 21C). Rope wicks should be flush with, or extend 1/2 in. (12.7 mm) beyond the face of the wall to promote evaporation. The rope should continue into the bottom of the air space, placed along the back of the brick and be at least 16 in. (406 mm) long.

Photo 1 Shoving Brick into Place

Filling Mortar Joints To reduce water penetration, there is no substitute for proper filling of all mortar joints that are designed to receive mortar. Improperly filled mortar joints can result in leaky walls, reduce the strength of masonry, and may contribute to disintegration and cracking due to water penetration and subsequent freezing and thawing.

Photo 2 Cutting Excess Mortar

A uniform bed of mortar should be spread over only a few brick, and furrowed lightly, if at all. Filled joints result when plenty of mortar is placed on the end of the brick to be laid and it is shoved into place so that mortar is squeezed out of the top of the head joint, as shown in Photo 1. After placement, mortar squeezed out of bed joint should be cut off prior to tooling, as shown in Photo 2. When placing closures, plenty of mortar is needed on the ends of brick in place and on the ends of the brick to be laid. The closure should be shoved into place without disturbing brick on either side, as shown in Photo 3.

Photo 3 Placing the Closure

Bed Joints. A bed joint is the horizontal layer of mortar on which a brick is laid. The length of time between placing the bed joint mortar and laying the succeeding brick influences the resulting bond. If too long a time elapses, poor extent of bond will result. Brick should be laid within 1 minute or so after the mortar is placed. For solid brick, bed joints should be constructed without deep furrowing of the mortar, as full bed joints (covering the entire bedding surface) are an inherent requirement for water-resistant brick masonry construction. For hollow brick, bed joints may be laid with face shell bedding (mortar placed only on the front and back face shells). Both face shells must be completely covered with mortar.

Bad

Bad

Good

Figure 4 Head Joints

Head Joints. A head joint, sometimes called a cross joint, is the vertical mortar joint between two brick. For both solid and hollow brick it is important that head joints be completely filled. The best head joints are formed by completely buttering the ends of the brick with mortar and shoving the brick into place against previously laid brick. www.gobrick.com | Brick Industry Association | TN 7B | Water Penetration Resistance - Construction and Workmanship | Page 4 of 7

Photo 4 Concave Mortar Joints

Photo 5 "V" Mortar Joints “Slushing” (“throwing” mortar into the joint with the edge of a trowel) does not adequately fill joints or compact the mortar, resulting in joints that are less resistant to water penetration. The results of head joint forming are shown in Figure 4.

Tooling of Mortar Joints Proper tooling, or “striking”, of mortar joints helps seal the wall surface against moisture penetration. Mortar joints should be tooled when they are “thumbprint” hard, (pressing the thumb into the mortar leaves an indentation, but no mortar is transferred to the thumb) with a jointer slightly larger than the joint. It is important that joints are tooled at the appropriate time as this affects both their effectiveness and appearance. Joints that are tooled too early often smear and result in rough joints. If tooling is delayed too long the surface of the joint cannot be properly compressed and sealed to the adjacent brick. Each portion of the completed brickwork should be allowed to set for the same amount of time before tooling in order to ensure a uniform mortar shade. Early tooling often results in joints of a lighter color. Later tooling results in darker shades.

Figure 5 Typical Mortar Joints

Concave, “V” and grapevine joints best resist water penetration in exterior brickwork. These joints produce a more dense and weathertight surface, as the mortar is pressed against the brick, as shown in Photos 4 and 5. For interior masonry work, other joints such as the weathered, beaded, struck, flush, raked or extruded joints shown in Figure 5 can also be used.

Collar Joints The vertical, longitudinal joint between wythes of masonry is called a collar joint. The manner in which these joints are filled is very important. Grouting is the most effective method of ensuring that collar joints are completely filled. However, grouting spaces less than 3/4 in. (19.1 mm) is not permitted. Mortar protrusions (fins) that extend more than 1/2 in. (12.7 mm) into a cell or cavity that will be grouted must be removed prior to grouting. For mortar-filled collar joints, the outer face of the inner masonry wythe should be parged and the back of brick in the exterior wythe buttered in order to fill the collar joint. Photo 6 Poorly Filled Collar Joint

“Slushing” of collar joints is not effective since it does not completely fill all voids in the joint, as shown in Photo 6. Frequently, the mortar is

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caught and held before it reaches the bottom of the joint, leaving openings between the face brick and the backing. Even when this space is filled, there is no way to compact the mortar. The mortar does not bond with the brick over its entire surface and channels are left between the mortar and the brick. Some of these channels may allow water to reach the back of the wall. A properly constructed collar joint is completely filled with grout or mortar.

Parging Parging is the process of applying a coat of portland cement mortar to masonry. Parging the outer face of the inner wythe of a multiwythe wall with Type M or S mortar as damp proofing may help resist rain penetration and can also reduce air leakage. Membranes or liquid-applied materials usually provide superior performance to parging, which will crack if the wythe cracks. However, parging can provide a smooth base for these materials. If parging alone is to resist water penetration, proper curing is necessary to reduce shrinkage cracks. Parging the back side of the exterior wythe is not recommended for drainage-type walls, as this may result in more debris in the air space or break the brick/mortar bond. The face of the wall to be parged must not have any mortar protrusions. Protruding mortar can cause bond breaks in the parge coat, resulting in a leaky wall. When applied in multiple layers, each should be a minimum thickness of ¼ in. (6.4 mm). The first coat should be allowed to partially set, roughened, and allowed to cure for 24 hours. It is then moistened for application of the second coat. The parged surface should be troweled smooth so that it sheds water easily. When completed in adjacent areas, the edges of the parging should be feathered and new parging should overlap existing parging by a minimum of 6 in. (152 mm). Lap joints should be spaced no closer than 6 feet (1.83 m).

Keeping Air Spaces Clean In a drainage wall system, such as a cavity wall or an anchored veneer wall, it is essential that the air space be kept clean. If it is not, mortar droppings may clog the weeps, protrusions may span the air space and water penetration to the interior may occur. To the greatest extent possible, mortar droppings should be prevented from falling into the air space or cavity. An aid to prevent this is to bevel the bed joint away from the air space or cavity, as shown in Figure 6. When brick are laid on a beveled bed joint, a minimum of mortar is squeezed out of the joint, as shown in Photo 7. The mortar squeezed from the joints on the air space or cavity side may be troweled onto the units. This same procedure may be used for laying the exterior wythes of grouted and reinforced brick cavity walls.

Beveled Bed Joints

a b

(a) Beveled Joint; (b) Conventional Joint Figure 6 Beveled Bed Joints

Photo 7 Beveled and Conventional Mortar Joints

Another method allows access to the base of the cavity for cleaning. When the brickwork is initially constructed, every third brick or so in the course above the flashing of the exterior wythe is omitted. Once the brickwork is complete, mortar droppings at the base of the cavity can be easily removed and weeps provided when the omitted brick are placed in the wall with mortar. Alternately, a wooden or metal strip, slightly smaller than the cavity width, can be placed in the air space. This strip rests on the wall ties as the wall is built. Wire or rope is attached to the strip so the strip can be lifted out as the mason builds the wall. Care should be taken when raising or removing the strip to not disturb the brickwork. www.gobrick.com | Brick Industry Association | TN 7B | Water Penetration Resistance - Construction and Workmanship | Page 6 of 7

Drainage materials and mortar dropping control devices may also be used to keep the air space adjacent to the weeps free from mortar. Use of these devices does not guarantee that bridging of the air space will not occur, thus the amount of mortar droppings should be limited as much as possible.

Disturbance of Newly Laid Masonry Newly laid brick should never be pushed, shoved, tapped or otherwise disturbed once they are laid in their final position and the mortar has begun to set. Any disturbance at this point will break the bond and may lead to a leak. If adjustments are necessary, the incorrectly placed brick should be removed and re-laid in fresh mortar.

Protection of Unfinished Brickwork Covering of masonry walls at the end of each work day, and especially in times of inclement weather, is essential for satisfactory performance. Covering unfinished walls with tarpaulins or other water-resistant materials, securely tied or weighted in position, should be rigorously enforced. Mortar boards, scaffold planks and light plastic sheets weighted with brick should not be accepted as suitable cover. Metal clamps, similar to bicycle clips, are commercially available in a variety of sizes to meet various wall thicknesses. These are used in conjunction with plastic sheets or water-repellent tarpaulins and offer excellent protection for extended periods of time. Tops of walls should also be covered after the mason’s work is finished if a permanent coping is not attached immediately after the brickwork is completed. Protection of openings in brickwork such as those for windows, movement joints, etc. should also be considered as they may allow moisture ingress from rain and snow and can lead to moisture-related problems such as efflorescence, and in some cases could affect the final mortar color.

SUMMARY Quality construction practices and good workmanship are essential to achieve brickwork that is resistant to water penetration. This Technical Note does not cover all construction practices, but describes material storage and preparation procedures, construction practices and installation techniques that are indicative of high quality and, when combined with proper design, detailing and materials, result in brickwork that is resistant to water penetration. The information and suggestions contained in this Technical Note are based on the available data and the combined experience of engineering staff and members of the Brick Industry Association. The information contained herein must be used in conjunction with good technical judgment and a basic understanding of the properties of brick masonry. Final decisions on the use of the information contained in this Technical Note are not within the purview of the Brick Industry Association and must rest with the project architect, engineer and owner.

REFERENCES 1. The BDA Guide to Successful Brickwork, Second Edition, The Brick Development Association, Arnold (a member of the Hodder Headline Group), London, England, 2000. 2. Drysdale, R.G., Hamid, A.A., and Baker, L.R., Masonry Structures: Behavior and Design, Second Edition, The Masonry Society, Boulder, CO, 1999. 3. Koski, J.A., “Waterproof the Backup Wythe,” Masonry Construction, August 1992. 4. Specification for Masonry Structures, ACI 530.1-05/ASCE 6-05/TMS 602-05, The Masonry Society, Boulder, CO, 2005.

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TECHNICAL NOTES on Brick Construction

8

1850 Centennial Park Drive, Reston, Virginia 20191 | www.gobrick.com | 703-620-0010

January 2008

Mortars for Brickwork Abstract: This Technical Note addresses mortars for brickwork. The major ingredients of mortar are identified. Means of specifying mortar are covered. Mortar properties are described, as well as their effect on brickwork. Information is provided for selection of the appropriate materials for mortar and properties of mortars.

Key Words: hardened mortar properties, mortar, plastic mortar properties, specifications, Types of mortar.

SUMMARY OF RECOMMENDATIONS: General • Use mortar complying with ASTM C270 • For typical project requirements, use proportion specifications of ASTM C270 • Select mortar Type using recommendations of Technical Note 8B • Use Type N mortar for normal use, including most veneer applications • Avoid combining two air-entraining agents in mortar

Mortar Materials Cementitious: • Use cement complying with ASTM C150 (portland cement), ASTM C595 (blended hydraulic cement), or ASTM C1157 (hydraulic cement) in combination with either hydrated lime complying with ASTM C207, Type S, or lime putty complying with ASTM C1489 • Use mortar cement complying with ASTM C1329 • Use masonry cement complying with ASTM C91 Aggregate: • Use natural or manufactured sand complying with ASTM C144

Water: • Use potable water free of deleterious materials

Mortar Admixtures • Use admixtures complying with ASTM C1384 • When using a bond enhancer admixture, do not use an air-entraining agent • When using a set retarding admixture, do not retemper mortar • Do not use water-repellent admixtures

Pigments • Use pigments complying with ASTM C979 • Use as little pigment as possible • For metallic oxide pigments, limit quantity to 10 percent of cement content by weight • For carbon black pigment, limit quantity to 2 percent of cement content by weight • Avoid using pigments containing Prussian blue, cadmium lithopone and zinc and lead chromates • Premix cement and coloring agents in large, controlled quantities • Do not retemper colored mortar

INTRODUCTION Mortar is the bonding agent that integrates brick into a masonry assembly. Mortar must be strong, durable and capable of keeping the masonry intact, and it must help to create a water-resistant barrier. Also, mortar accommodates dimensional variations and physical properties of the brick when laid. These requirements are influenced by the composition, proportions and properties of mortar ingredients. Because concrete and mortar contain the same principal ingredients, it is often erroneously assumed that good concrete practice is also good mortar practice. In reality, mortar differs from concrete in working consistencies, methods of placement and structural performance. Mortar is used to bind masonry units into a single element, developing a complete, strong and durable bond. Concrete, however, is usually a structural element in itself. Mortar is usually placed between absorbent masonry units and loses water upon contact with the units. Concrete is usually placed in nonabsorbent metal or wooden forms, which absorb little if any water. The importance of the water/cement ratio for concrete is significant, whereas for mortar it is less important. Mortar has a high water/ cement ratio when mixed, but this ratio changes to a lower value when the mortar comes in contact with the absorbent units. The most frequently used means of specifying mortar is ASTM C270, Standard Specification for Mortar for Unit Masonry [Ref. 1]. This standard contains information on specifying and using mortar. This Technical Note uses ASTM C270 as a basis and addresses the materials, properties and means of specifying mortars. The other Technical Note in this series addresses the selection and quality control of mortars.

© 2008 Brick Industry Association, Reston, Virginia

Page 1 of 11

MATERIALS Historically, mortar has been made from a variety of materials. Burned gypsum and sand were used to make mortar in ancient Egypt, while lime and sand were used extensively in this country before the 1900s. Currently, the basic dry ingredients for mortar include some type of cement, hydrated lime and sand. Each of these materials makes a definite contribution to mortar performance.

Portland and Other Hydraulic Cements Portland cement, a hydraulic cement, is the principal cementitious ingredient for cement-lime mortar. It contributes to durability, high strength and early setting of the mortar. Portland cement used in masonry mortar should conform to ASTM C150, Standard Specification for Portland Cement [Ref. 1]. Of the eight portland cement Types covered by ASTM C150, only three are recommended for use in masonry mortars: Type I - For general use when the special properties of Types II and III are not required. Type II - For use when moderate sulfate resistance or moderate heat of hydration is desired. Type III - For use when high early strength is desired. ASTM C270 permits the use of other hydraulic cements in mortar. Some of these materials may slow the strength gain or may affect the color of mortar. The material standards for these cements are ASTM C595, Standard Specification for Blended Hydraulic Cements [Ref. 1], such as portland blast-furnace slag cement, portlandpozzolan cement and slag cement; and ASTM C1157, Standard Performance Specification for Hydraulic Cement [Ref. 1]. The use of blended hydraulic cements is not recommended unless the mortar containing such cements meets the property specifications of ASTM C270. Because high air entrainment can significantly reduce the bond between the mortar and brick or reinforcement, the use of air-entrained portland, blended hydraulic or hydraulic cements is not recommended. Most building codes have lower allowable flexural tensile stress values for mortar made with air-entrained cementitious materials.

Masonry Cements Masonry cements are proprietary cementitious materials for mortar. They are widely used because of their convenience and good workability. ASTM C91, Standard Specification for Masonry Cement [Ref. 1], defines masonry cement as “a hydraulic cement, primarily used in masonry and plastering construction, consisting of a mixture of portland or blended hydraulic cement and plasticizing materials (such as limestone, hydrated or hydraulic lime) together with other materials introduced to enhance one or more properties such as setting time, workability, water retention, and durability.” ASTM C91 provides specific criteria for physical requirements and performance properties of masonry cements. The constituents of masonry cement may vary depending on the manufacturer, local construction practices and climatic conditions. Masonry cements are classified into three Types by ASTM C91: Types M, S and N. The current edition of ASTM C91 requires a minimum air content of 8 percent (by volume) and limits the maximum air content to 21 percent for Type N masonry cement and 19 percent for Types S and M masonry cements. Mortar prepared in the field will typically have an air content that is 2 to 3 percent lower than mortar tested under laboratory conditions. In the model building codes, allowable flexural tensile stress values for masonry built with masonry cement mortar are lower than those for masonry built with non-air-entrained portland cement-lime mortar. Therefore, the use of masonry cement should be based on the requirements of the specific application.

Mortar Cements Mortar cements are hydraulic cements, consisting of a mixture of portland or blended hydraulic cement, plasticizing materials such as limestone or hydrated or hydraulic lime, and other materials intended to enhance one or more of the properties of mortar. In this respect, mortar cement is similar to masonry cement. However, ASTM C1329, Standard Specification for Mortar Cement [Ref. 1], includes requirements for maximum air content and minimum flexural bond strength that are not found in the masonry cement specification. Because of the strict controls on air content and the minimum strength requirement, mortar cement and portland cement-lime mortars are treated similarly in the Building Code Requirements for Masonry Structures (ACI 530-05/ASCE 5-05/TMS 402-05) [Ref. 5].

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Three Types of mortar cements are specified in ASTM C1329: Types M, S and N. Physical requirements vary depending upon mortar cement Type. Air content for all three Types must be a minimum of 8 percent. The maximum air content is 14 percent for Types M and S and 16 percent for Type N. Flexural bond strength, as measured by the test method in ASTM C1072, Standard Test Method for Measurement of Masonry Flexural Bond Strength [Ref. 1], is also specified. The minimum flexural bond strength for these mortar cements is 115 psi (0.8 MPa) for Type M, 100 psi (0.7 MPa) for Type S and 70 psi (0.5 MPa) for Type N.

Hydrated Lime and Lime Putty Hydrated lime is a derivative of limestone that has been through two chemical reactions to produce calcium hydroxide. Lime contributes to extent of bond, workability, water retention and elasticity. Hydrated lime in ASTM C207, Standard Specification for Hydrated Lime for Masonry Purposes [Ref. 1], is available in four Types. Only Type S hydrated lime should be used in mortar. Type N hydrated lime contains no limits on the quantity of unhydrated oxides. Types NA and SA lime contain air-entraining additives that reduce the extent of bond between the mortar and masonry units or reinforcement, and are therefore not recommended for mortar. ASTM C1489, Standard Specification for Lime Putty for Structural Purposes [Ref. 1], is prepared from hydrated lime and is often used in restoration projects. Because lime hardens only upon contact with carbon dioxide in the air, hardening occurs over a long period of time. However, if small hairline cracks develop, water and carbon dioxide that penetrate the joint will react with calcium hydroxide from the mortar and form calcium carbonate. The newly developed calcium carbonate will seal the cracks, limiting further water penetration. This process is known as autogenous healing.

Aggregates Aggregates (sand) act as a filler material in mortar, providing for an economical mix and controlling shrinkage. Either natural sand or manufactured sand may be used. Gradation limits are given in ASTM C144, Standard Specification for Aggregates for Masonry Mortar [Ref. 1]. Gradation can be easily and inexpensively altered by adding fine or coarse sands. Sometimes the most feasible method requires proportioning the mortar mix to suit the available sand, rather than requiring sand to meet a particular gradation. However, if the sand does not meet the grading requirement of ASTM C144, it can only be used provided the mortar meets the property specifications of ASTM C270.

Water Water that is clean, potable and free of deleterious acids, alkalis or organic materials is suitable for masonry mortars.

Admixtures Admixtures are sometimes used in mortar to obtain a specific mortar color, increase workability, decrease setting time, increase setting time, increase flexural bond strength or act as a water repellent [Ref. 2]. Admixtures to achieve a desired color of the mortar are the most widely used. Although some admixtures are harmless, some are detrimental to mortar and the resulting brickwork. Because the properties of both plastic and hardened mortars are highly dependent on mortar ingredients, the use of admixtures should not be considered unless their effect on the mortar is known. Admixtures also should be examined for their effect on the masonry, masonry units and items embedded in the brickwork. For example, admixtures containing chlorides promote corrosion of embedded metal anchors and therefore should not be used. ASTM C1384, Standard Specification for Admixtures for Masonry Mortars [Ref. 1], provides methods to evaluate the effect of admixtures on mortar properties. The admixtures represented in ASTM C1384 are as follows: Bond Enhancers. Bond enhancers improve flexural bond strength, surface density and freeze-thaw resistance. They are typically used to increase bond strength to smooth, dense surface units and applications such as copings and pavers. Bond enhancers should not be used with air-entraining agents.

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Set Accelerators. Set accelerators shorten the time required for cement hydration to occur and typically reduce the setting time by 30 to 40 percent. They are typically used to reduce the time required for cold weather protective measures. Set accelerators typically increase short-term compressive strengths and may affect color. Set Retarders. Set retarders increase the board life of fresh mortar by increasing the time required for cement hydration to occur. They are typically used in conjunction with hot weather protective measures or to aid in reducing the rapid suction associated with high initial rate of absorption (IRA) brick. Mortar with set retarders should not be retempered, and severely retarded mortar may require moist curing to maintain hydration. Set retarders typically reduce short-term compressive strength and may affect color. Water Repellents. Water repellent admixtures are typically used in conjunction with concrete masonry units where the admixture is added to both the mortar and to the concrete masonry units. When water-repellent admixtures are used in the mortar alone, they may inhibit bond and are not recommended for use with brick. Workability Enhancers. Workability enhancers add viscosity to mortar mixes, allowing easier placement of mortar on masonry units. The benefits of workability enhancers are subjective, and their use is more to suit the liking of the mason. They should be reviewed to ensure that there are no deleterious effects on the mortar.

Colored Mortar Colored mortars may be obtained through the use of colored aggregates or suitable pigments. The use of colored aggregates is preferable when the desired mortar color can be obtained. White sand, ground granite, marble or stone usually have permanent color and do not weaken the mortar. For white joints, use white sand, ground limestone or ground marble with white portland cement and lime. Most pigments that conform to ASTM C979, Standard Specification for Pigments for Integrally Colored Concrete [Ref. 1], are suitable for mortar. Mortar pigments must be sufficiently fine to disperse throughout the mix, capable of imparting the desired color when used in permissible quantities, and must not react with other ingredients to the detriment of the mortar. These requirements are generally met by metallic oxide pigments. Carbon black and ultramarine blue also have been used successfully as mortar colors. Avoid using organic colors and, in particular, those colors containing Prussian blue, cadmium lithopone and zinc and lead chromates. Paint pigments may not be suitable for mortars. Use as little pigment as is needed to produce the desired results; an excess may seriously impair strength and durability. The maximum permissible quantity of most metallic oxide pigments is 10 percent of the cement content by weight. Although carbon black is a very effective coloring agent, it will greatly reduce mortar strength when used in greater proportions. Therefore, limit carbon black to 2 percent of the cement content by weight. For best results, use cement and coloring agents premixed in large, controlled quantities. Premixing large quantities will ensure more uniform color than can be obtained by mixing smaller batches in the field. A consistent mixing sequence is essential for color consistency when mixing smaller batches in the field. Further, use the same source of mortar materials throughout the project. Color uniformity varies with the amount of mixing water, the moisture content of the brick when laid and whether the mortar is retempered. The time and degree of tooling and cleaning techniques also will influence final mortar color. Color permanence depends upon the quality of pigments and the weathering and efflorescing qualities of the mortar.

SPECIFYING MORTAR Masonry mortars are classified by ASTM C270 into four Types: M, S, N and O. Each mortar Type consists of aggregate, water and one or more of the four cementitious materials (portland or hydraulic cement, mortar cement, masonry cement and lime) listed in the previous section. There are two methods of specifying mortar by Type in ASTM C270: proportion specifications and property specifications. A cement-lime mortar, a mortar cement mortar, or a masonry cement mortar is permitted. The type of cementitious material desired should be specified.

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Proportion Specifications The proportion specifications require that mortar materials be mixed according to given volumetric proportions. If mortar is specified by this method, no laboratory testing is required, either before or during construction. Table 1 lists proportion requirements of the various mortar Types. Note that masonry cement and mortar cement may be used alone to produce Type M, S, N or O mortars. Additionally, Type N mortar cement or masonry cement may be combined with portland cement to produce a Type M or Type S mortar. TABLE 1 Proportion Specification Requirements Note: Two air-entraining materials shall not be combined in mortar Proportions by Volume (Cementitious Materials) Mortar

Cement – Lime

Mortar Cement

Masonry Cement

Mortar Cement

Masonry Cement

Portland or Blended Cement

M

S

N

M

S

N

Hydrated Lime or Lime Putty

M

1

…

…

…

…

…

…

¼

S

1

…

…

…

…

…

…

over ¼ to ½

N

1

…

…

…

…

…

…

over ½ to 1¼

O

1

…

…

…

…

…

…

over 1¼ to 2½

M

1

…

…

1

…

…

…

…

M

…

1

…

…

…

…

…

…

S

½

…

…

1

…

…

…

…

S

…

…

1

…

…

…

…

…

N

…

…

…

1

…

…

…

…

O

…

…

…

1

…

…

…

…

M

1

…

…

…

…

…

1

…

M

…

…

…

…

1

…

…

…

S

½

…

…

…

…

…

1

…

S

…

…

…

…

…

1

…

…

N

…

…

…

…

…

…

1

…

O

…

…

…

…

…

…

1

…

Type

Aggregate Ratio (Measured in Damp, Loose Conditions)

Not less than 2¼ and not more than 3 times the sum of the separate volumes of cementitious materials

The volumetric proportions given in Table 1 can be converted to weight proportions using assumed weights per cubic foot (cubic meter) for the materials as follows: Portland cement Masonry, mortar and blended cements Hydrated lime Lime putty Sand, damp and loose

94 lb (1506 kg) Varies, use weight printed on bag 40 lb (641 kg) 80 lb (1281 kg) 80 lb (1281 kg) of dry sand

Property Specifications The property specifications require a mortar mix of the materials to be used for construction to meet the specified properties under laboratory testing conditions. If mortar is specified by the property specifications, compressive strength, water retention and air content tests must be performed prior to construction on mortar mixed in the laboratory with a controlled amount of water. The material quantities determined from the laboratory testing are

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then used in the field with the amount of water determined by the mason. Table 2 lists property requirements of the various mortar Types. Properties of field-mixed mortar cannot be compared to the requirements of the property specifications because of the different amounts of water used in the mortars, the use of different mixers and the different curing conditions. Field sampling of mortar, where specified, is typically performed for tracking project consistency from beginning to end. It is not to be used for compliance with property specifications. Additional information about this type of quality assurance testing can be found in Technical Note 8B. TABLE 2 Property Specification Requirements1

Mortar

Type

Average Compressive Strength at 28 Days, min. psi (MPa)

Water Retention, min. %

Air Content, max. %

M

2500 (17.2)

75

122

S

1800 (12.4)

75

122

N

750 (5.2)

75

142

O

350 (2.4)

75

142

M

2500 (17.2)

75

122

S

1800 (12.4)

75

122

N

750 (5.2)

75

142

O

350 (2.4)

75

142

M

2500 (17.2)

75

182

S

1800 (12.4)

75

182

N

750 (5.2)

75

203

O

350 (2.4)

75

203

Cement – Lime

Mortar Cement

Masonry Cement

Aggregate Ratio (Measured in Damp, Loose Conditions)

Not less than 2¼ and not more than 3½ times the sum of the separate volumes of cementitious materials

1. Laboratory prepared mortar only. 2. When structural reinforcement is incorporated in cement-lime or mortar-cement mortar, the maximum air content shall be 12 percent. 3. When structural reinforcement is incorporated in masonry-cement mortar, the maximum air content shall be 18 percent.

Proportion vs. Property Specifications The specifier should indicate in the project specifications whether the proportion or the property specifications are to be used. If the specifier does not indicate which should be used, then the proportion specifications govern by default. The specifier also should confirm that the mortar Types selected and the materials indicated in the project specifications are consistent with the structural design requirements of the masonry. Mortar prepared by the proportion specifications is not to be compared to mortar of the same Type prepared by the property specifications. A mortar that is mixed according to the proportion specification will have a higher laboratory compressive strength than that of the corresponding mortar Type under the property specification [Ref. 7].

PHYSICAL PROPERTIES OF MORTAR Mortars have two distinct, important sets of properties: those in the plastic state and those in the hardened state. The plastic properties help to determine the mortar’s compatibility with brick and its construction suitability. Properties of plastic mortar include workability, water retention, initial flow and flow after suction. Properties of hardened mortars help determine the performance of the finished brickwork. Hardened properties include flexural bond strength, durability, extensibility and compressive strength. Properties of plastic mortar are more important to the mason, while the properties of hardened mortar are more important to the designer and owner.

Workability Workability is the most important physical property of plastic mortar. A mortar is workable if its consistency allows it to be spread with little effort and if it will readily adhere to vertical masonry surfaces. This results in good extent of bond between the mortar and the brick, which provides resistance to water penetration. Although experienced masons are good judges of the workability of a mortar and have developed various methods to determine suitability, there is no standard laboratory or field test for measuring this property. www.gobrick.com | Brick Industry Association | TN 8 | Mortars for Brickwork | Page 6 of 11

Water retention, flow and resistance to segregation affect workability. In turn, these are affected by properties of the mortar ingredients. Because of this complex relationship, quantitative estimates of workability are difficult to obtain. Until a test is developed, the requirements for water retention and aggregate gradation must be relied upon to provide a quantitative measure of workability.

Water Content Water content is possibly the most misunderstood aspect of masonry mortar, probably due to the similarity between mortar and concrete materials. Many designers mistakenly base mortar specifications on the assumption that mortar requirements are similar to concrete requirements, especially with regard to the water/cement ratio. Many specifications incorrectly require mortar to be mixed with the minimum amount of water consistent with workability. Often, retempering of the mortar is prohibited. These provisions result in mortars that have higher compressive strengths but lower bond strengths. Mixing mortar with the maximum amount of water consistent with workability will provide maximum bond strength within the capacity of the mortar. As a result, water content normally should be determined by the mason or bricklayer to produce the best workability. Retempering is permitted, but only to replace water lost by evaporation. This is usually controlled by the requirement that all mortar be used within 2½ hours after initial mixing, or as determined for hot weather construction.

Water Retention Water retention is the ability of a mortar to hold water when placed in contact with absorbent masonry units. The laboratory value of water retention is the ratio of flow after suction to the initial flow, expressed in a percentage. Flow after suction, as described in ASTM C91, is determined by subjecting the mortar to a vacuum and remeasuring the flow of the mortar. A mortar that has low water retention will lose moisture more rapidly. This is used in conjunction with the IRA of the brick to select mortar materials and Type. In general, the following will increase water retention: 1. Addition of sand fines within allowable gradation limits. 2. Use of highly plastic lime (Type S lime). 3. Increased air content. 4. Use of hydraulic cement containing very fine pozzolans.

Initial Flow Initial flow is essentially a measure of the mortar’s water content. It can be measured by either of two methods: ASTM C109, Standard Test Method for Compressive Strength of Hydraulic Cement Mortars [Ref. 1], or ASTM C780, Standard Test Method for Preconstruction and Construction Evaluation of Mortars for Plain and Reinforced Unit Masonry [Ref. 1]. In ASTM C109, a truncated cone of mortar is formed on a flow table, which is then mechanically raised 1 in. (25.4 mm) and dropped 25 times in 15 seconds. During this test, the mortar will flow, increasing the diameter of the mortar specimen. The initial flow is the ratio of the increase in diameter from the initial 4 in. (102 mm) cone base diameter, expressed in a percentage. Flow rates are laboratory tests. In ASTM C780, a 3½ in. (89 mm) high hollow cylinder is filled with mortar, and a cone-shaped plunger, whose point is placed at the top of the cylinder, is dropped into the mortar. The depth of the cone penetration into the mortar is measured in millimeters. The greater the penetration of the cone into the mortar, the greater its flow or water content. Cone penetration can be measured in the laboratory or in the field. Laboratory mortars are mixed to have an initial flow of only 105 to 115 percent. Construction mortars normally have initial flows in the range of 130 to 150 percent (sometimes higher in hot weather) to produce workability satisfactory to the mason. Requirements for laboratory-prepared mortar should not be applied to field-prepared mortar. Test results of laboratory-prepared mortar should not be compared to test results of field-prepared mortar without considering the initial flow of each. The lower initial flow requirements for laboratory mortars were set to allow for more consistent test results on most available laboratory equipment, and to compensate for water absorbed by the units.

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Extensibility and Plastic Flow Extensibility is another term for maximum tensile strain at failure. It reflects the maximum elongation possible under tensile forces. High-lime mortars exhibit greater plastic flow than low-lime mortars. Plastic flow, or creep, acting with extensibility will impart some flexibility to the masonry, permitting slight movement. Where greater resiliency for movement is desirable, the lime content may be increased while still satisfying other requirements.

Flexural Bond Strength Flexural bond strength is perhaps the most important physical property of hardened mortar. For veneer applications, the bond strength of mortar to brick units provides the ability to transfer lateral loads to veneer anchors. For loadbearing applications, the bond influences the overall strength of the wall for resisting lateral and flexural loads. Variables that affect the bond strength include texture of the brick, suction of the brick, air content of the mortar, water retention of the mortar, pressure applied to the joint during forming, mortar proportions and methods of curing. Brick Texture. The texture of a brick affects the mechanical bond between the brick and mortar [Ref. 8]. Mortar bond is greater to roughened surfaces, such as wire-cut surfaces, than to smooth surfaces, such as die-skin surfaces. Sanded and coated surfaces can reduce the bond strength depending upon the amount and type of material on the surface and its adherence to the surface. Brick IRA (Suction). The laboratory-measured initial rate of absorption (IRA) of brick indicates the brick’s suction and whether it should be considered for wetting before use. It is the IRA at the time of laying that influences bond strength. In practically all cases, mortar bonds best to brick with an IRA less than 30 g/min/30 in.2 (30 g/min/ 194 cm2) when laid. If the brick’s IRA exceeds this value, then the brick should be wetted three to 24 hours before laying. Wetted brick should be surface dry when they are laid in mortar. Several researchers have shown that IRA appears to have little influence on bond strength when the appropriate mortar is used [Refs. 3, 4 and 9]. Air Content. Available information indicates a definite relationship between air content and bond strength of mortar. Provided that other parameters are held constant, as air content is increased, compressive strength and bond strength are reduced, while workability and resistance to freeze-thaw deterioration are increased [Ref. 10]. Water Content. Mortar with a high water content, or flow, at the time of use is beneficial because it can satisfy the suction of the brick and can allow greater control of the mortar for the bricklayer. For all mortars, and with minor exceptions for all brick suction rates, bond strength increases as flow increases. However, excessive water can reduce both workability and bond strength. The time lapse between spreading mortar and placing brick will affect mortar flow, particularly when mortar is spread on brick with high suction rates, or when construction takes place during hot, dry weather. In such cases, mortar will have less flow by the time brick are placed than when it was first spread. Conceivably, bond to brick placed on this mortar could be materially reduced. For highest bond strength, reduce the time interval between spreading the mortar and laying brick on top of it to a minimum. Because not all mortar is used immediately after mixing, some of its water may evaporate while it is on the mortar board. The addition of water to mortar (retempering) to replace water lost by evaporation should be encouraged, when necessary. Although compressive strength may be slightly reduced and mortar color lightened if mortar is retempered, bond strength may be lowered if it is not. ASTM C270 requires that all mortar be used within 2½ hours after mixing since the mortar will begin to set. This time may be affected by hot or cold weather, as discussed in Technical Note 1. Materials and Proportions. There is no precise combination of materials that will always produce optimum bond. Mortars made with cement-lime and mortar cement cementitious materials typically have higher flexural bond strengths than do masonry cement mortars [Refs. 3, 4, 6]. Building codes prescribe the same bond strength values to Type S and M mortars [Ref. 5]. Test Methods. Because many variables affect bond, it may be desirable to achieve reproducible results from a small-scale laboratory test. The bond wrench test, ASTM C1072, Standard Test Method for Measurement of Masonry Flexural Bond Strength [Ref. 1], appears to fulfill this need. It evaluates the flexural bond strength of each

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joint in a masonry prism. The apparatus shown in Figure 1 consists of a stack-bonded prism clamped in a stationary frame. A cantilevered arm is clamped to the top brick over the joint to be tested. The free end of the cantilevered arm is loaded until failure, which occurs when the clamped brick is “wrenched” off. The bond wrench test has replaced previous tests of fullsized wall specimens and prisms in which only one joint was tested.

Load Bearing Plate

Clamping Bolts

Adjustable Base Support

Test Specimen

In general, to increase the flexural bond strength: 1. Bond mortar to a wire-cut or roughened surface rather than a die-skin surface. 2. Wet brick with an IRA greater than 30 grams/min/30 in.2 (30 g/min/194 cm2) when Figure 1 laid. Bond Wrench Test Apparatus 3. Use Type S portland cement-lime mortar, Type S mortar cement or Type S masonry cement mortar with air content in the low to mid-range of ASTM C91 limits. 4. Mix mortar to the maximum flow compatible with workmanship. Use maximum mixing water and permit retempering.

Compressive Strength As with concrete, the compressive strength of mortar primarily depends upon the cement content and the water/ cement ratio. However, because compressive strength of masonry mortar is less important than bond strength, workability and water retention, the latter properties should be given principal consideration in mortar selection. The water/cement ratio of mortar as mixed in the field is reduced due to absorption of water by the adjacent brick. Proportions. Compressive strength increases with an increase in cement content of mortar and decreases with an increase in water content, lime content or over-sanding. Occasionally air entrainment is introduced to obtain higher flows with lower water content. The reasoning here is that lower water/cement ratios will provide higher compressive strengths. However, this generally proves futile since compressive strength decreases with an increase in air content. Test Methods. Compressive strength is measured by testing 2 in. (51 mm) mortar cubes or 2 in. (51 mm) or 3 in. (76 mm) diameter cylinders. Procedures for molding and testing cubes appear in ASTM C109, and procedures for molding and testing both cubes and cylinders appear in ASTM C780.

Durability The durability of mortar in unsaturated masonry is not a serious problem. The durability of mortar is shown in the number of masonry structures that have been in service for many years. In general, mortar contains sufficient entrapped and entrained air to resist freeze-thaw damage. Though increasing air content may theoretically increase the durability of masonry mortar, a decrease in bond strength, compressive strength and other desirable properties will result. For this reason, the use of air-entraining admixtures to increase air content is not recommended.

Volume Change Volume changes in mortars can result from four causes: chemical reactions in hardening, temperature changes, wetting and drying, and unsound ingredients that chemically expand. Differential volume change between brick and mortar in a given wythe has no significant effect on performance. However, total volume change can be significant. Volume change caused by cement hydration (hardening) is often termed shrinkage and depends upon curing conditions, mix proportions and water content. Mortars hardened in contact with brick exhibit considerably less shrinkage than those hardened in nonabsorbent molds. An increase in water content will cause an increase in www.gobrick.com | Brick Industry Association | TN 8 | Mortars for Brickwork | Page 9 of 11

shrinkage during hardening of mortar if the excess water is not removed. Change in temperature will lead to expansion or contraction of mortar. Thermal expansion and contraction of masonry and means to accommodate the expected movement are discussed in the Technical Note 18 Series. Mortar swells as its moisture content increases and shrinks as it decreases. Moisture content changes with normal cycles of wetting and drying. The magnitude of volume change due to this effect is smaller than that from shrinkage. Unsound ingredients or impurities such as unhydrated lime oxides or gypsum can cause significant volume change and are thus limited by ASTM C207.

Efflorescence Efflorescence is a crystalline deposit of water-soluble salts on the surface of masonry. Mortar may be a major contributor to efflorescence since it is a primary source of calcium hydroxide. This chemical can produce efflorescence on its own and can react with carbon dioxide in the air or solutions from the brick to form insoluble compounds. Mortar can contain other soluble constituents, including alkalis, sulfates and magnesium hydroxide. Currently there is no standard test method to determine the efflorescence potential of mortar or of a brick/mortar combination. Researchers have concluded that mortars will effloresce under any standard test.

RECOMMENDED MORTAR USES Selection of a particular mortar Type and materials is usually a function of the needs of the finished masonry element. Type N mortar is recommended for normal use and in most veneer applications. In applications where high lateral strength is required, mortar with high flexural bond strength should be chosen. For loadbearing walls and reinforced brick masonry, high compressive strength may be the governing factor. In some projects, considerations of durability, color and flexibility may be of utmost concern. Factors that improve one property of mortar often do so at the expense of others. For this reason, when selecting a mortar, evaluate properties of each Type and materials and choose the combination that will best meet the particular end-use requirements. No single mortar Type is best for all purposes. Refer to Technical Note 8B for more information on selection of mortar Type.

GREEN BUILDING/SUSTAINABILITY Sustainability or “Green Building” is a movement to use resources efficiently, create healthier environments and enhance the quality of buildings while minimizing social and environmental impacts on future generations. For further information about the sustainability of brick masonry, refer to Technical Note 48. While materials used to make mortar are readily abundant and produce a durable material, sustainability can be improved further by using recycled products such as blast furnace slag cement and cements with fly ash in the mortar to partially replace portland cement. Blast furnace slag is a by-product from the production of iron. The waste from the production is processed to produce slag cement. When slag cement is used in mortar, it typically makes the cement hydration process more efficient, increases long-term compressive strength, produces a tighter pore structure and increases workability of mortar during placement. Fly ash comes from coal-fired plants used in generating electrical power. It can replace a portion of the cement in mortar materials. Fly ash increases strength and durability by increasing density.

SUMMARY Mortar requirements differ from concrete requirements, principally because the primary function of mortar is to bond masonry units into an integral element. Properties of both plastic and hardened mortars are important. Plastic properties determine construction suitability; hardened properties determine performance of finished elements. When selecting a mortar, evaluate all properties, and then select the mortar providing the best results overall for the particular requirements. The information and suggestions contained in this Technical Note are based on the available data and the combined experience of engineering staff and members of the Brick Industry Association. The information contained herein must be used in conjunction with good technical judgment and a basic understanding of the properties of brick masonry. Final decisions on the use of the information contained in this Technical Note are not within the purview of the Brick Industry Association and must rest with the project architect, engineer and owner.

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REFERENCES 1. Annual Book of ASTM Standards, ASTM International, West Conshohocken, PA, 2007: Volume 4.01 C91 “Standard Specification for Masonry Cement” C109 “Standard Test Method for Compressive Strength of Hydraulic Cement Mortars (Using 2-in. or [50-mm] Cube Specimens)” C150 “Standard Specification for Portland Cement” C207 “Standard Specification for Hydrated Lime for Masonry Purposes” C595 “Standard Specification for Blended Hydraulic Cements” C1157 “Standard Performance Specification for Hydraulic Cement” C1489 “Standard Specification for Lime Putty for Structural Purposes” C1329 “Standard Specification for Mortar Cement” Volume 4.02 C979 “Standard Specification for Pigments for Integrally Colored Concrete” Volume 4.05 C144 “Standard Specification for Aggregate for Masonry Mortar” C270 “Standard Specification for Mortar for Unit Masonry” C780 “Standard Test Method for Preconstruction and Construction Evaluation of Mortars for Plain and Reinforced Unit Masonry” C1072 “Standard Test Method for Measurement of Masonry Flexural Bond Strength” C1384 “Standard Specification for Admixtures for Masonry Mortars” 2. Beall, Christine, “A Guide to Mortar Admixtures,” Magazine of Masonry Construction, October 1989, pp. 436-438. 3. Borchelt, J.G., Melander, J.M., and Nelson, R.L., “Bond Strength and Water Penetration of High IRA Brick and Mortar,” Proceedings of the Eighth North American Masonry Conference, The Masonry Society, Boulder, CO, June 1999, pp. 304-315. 4. Borchelt, J.G., and Tann, J.A., “Bond Strength and Water Penetration of Low IRA Brick and Mortar,” Proceedings of the Seventh North American Masonry Conference, The Masonry Society, Boulder, CO, June 1996, pp. 206-216. 5. Building Code Requirements for Masonry Structures (ACI 530-05/ASCE 5-05/TMS 402-05), The Masonry Society, Boulder, CO, 2005. 6. Matthys, J.H., “Brick Masonry Flexural Bond Strength Using Conventional Masonry Mortar,” Proceedings of the Fifth Canadian Masonry Symposium, University of Vancouver, Vancouver, BC, 1992, pp. 745-756. 7. Melander, J.M., and Conway, J.T., “Compressive Strengths and Bond Strengths of Portland Cement-Lime Mortars,” Masonry, Design and Construction, Problems and Repair, ASTM STP 1180, American Society for Testing and Materials, Philadelphia, PA, 1993, pp. 105-120. 8. Ribar, J.W., and Dubovoy, V.S., “Investigation of Masonry Bond and Surface Profile of Brick,” Masonry: Materials, Design, Construction and Maintenance, ASTM STP 992, American Society for Testing and Materials, Philadelphia, PA, 1988, pp. 33-37. 9. Wood, S.L., “Flexural Bond Strength of Clay Brick Masonry,” The Masonry Society Journal, Vol. 13, No. 2, The Masonry Society, Boulder, CO, February 1995, pp. 45-55. 10. Wright, B.T., Wilkin, R.D., and John, G.W., “Variables Affecting the Strength of Masonry Mortars,” Masonry, Design and Construction, Problems and Repair, ASTM STP 1180, American Society for Testing and Materials, Philadelphia, PA, 1993, pp. 197-210.

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TECHNICAL NOTES on Brick Construction

8B

1850 Centennial Park Drive, Reston, Virginia 20191 | www.gobrick.com | 703-620-0010

October 2006

Mortars for Brickwork Selection and Quality Assurance Abstract: This Technical Note discusses the selection and specification of mortar Type. Key Words: bond strength, extent of bond, lime, masonry cement, mortar, mortar cement, portland cement, quality assurance, sand, testing, workability.

SUMMARY OF RECOMMENDATIONS: • Select a mortar Type with the lowest compressive strength meeting project requirements • Select mortar appropriate for application, project conditions and workability • Type N mortar is recommended for normal use, including most veneer applications

• Create a quality assurance program, where appropriate, to obtain consistent mortar • Follow recommended procedure and sequence for mixing mortar • Measure mortar materials by volume

INTRODUCTION Selection of an appropriate mortar helps to ensure durable brickwork that meets performance expectations. Mortar Type and mortar material selection should consider multiple aspects of a project, including design, brick or masonry materials, exposure and required level of workmanship. Improper mortar selection may lead to lower performance of the finished project. This Technical Note provides guidance for selecting the appropriate mortar Type. It also describes a quality assurance program to ensure the desired results. Technical Note 8 addresses specific properties of mortar, mortar materials and their selection as well as the specification of mortar.

SELECTION OF MORTAR Mortar bonds individual brick together to function as a single element. In its hardened state, mortar must be durable and must help resist moisture penetration. Mortar also must have certain properties in its plastic state so that it is both economical and easy to place. One property of mortar that is often overemphasized is compressive strength. Stronger is not necessarily better when specifying mortar. In fact, the opposite is often true. Mortar selection should be based on properties such as durability and workability in addition to compressive strength. Mortar for each project should be selected to balance the construction requirements with the performance of the completed masonry. High lateral loads from wind or seismic activity may require a mortar that develops high flexural tensile strength. Allowable flexural tensile and compressive stresses for unreinforced structural masonry are given in the building code. Building code requirements may limit the use of some mortar Types under certain conditions. For example, Building Code Requirements for Masonry Structures (ACI 530/ASCE 5/TMS 402) [Ref. 8] does not permit the use of Type N or masonry cement mortars in any part of the lateral force-resisting system for structures located in Seismic Design Categories D, E or F. Other considerations may include durability (below grade or in retaining walls), color uniformity, flexibility, workability or other desired properties. The combination of the mortar and brick properties may dictate the selection of a certain mortar.

© 2006 Brick Industry Association, Reston, Virginia

Page 1 of 6

These are the fundamental guidelines of mortar selection: • No single mortar is best for all purposes. • Select a mortar Type with the lowest compressive strength meeting the project requirements. Of course, these guidelines must be used with good judgment. For example, it could be uneconomical and unwise to use different mortars for various portions of the same structure.

Mortar Type Characteristics Mortars are classified by ASTM C 270, Standard Specification for Mortar for Unit Masonry [Ref. 2], into four Types: M, S, N and O. These four Types of mortar can be made with portland cement, masonry cement, mortar cement or blended cements some of which are combined with hydrated lime. Each mortar Type has some basic characteristics: • • • •

Type N mortar - General all-purpose mortar with good bonding capabilities and workability Type S mortar - General all-purpose mortar with higher flexural bond strength Type M mortar - High compressive-strength mortar, but not very workable Type O mortar - Low-strength mortar, used mostly for interior applications and restoration

Although the descriptions above provide basic mortar characteristics, each mortar Type can be used in a variety of applications. No single mortar is best for all purposes.

Simplistic Mortar Selection The easiest method to select mortar is to remember the following mnemonic: • Type N for normal brickwork applications • Type S for stronger brickwork applications Normal applications include most veneer. Stronger applications are needed in high seismic and high wind areas and in reinforced brickwork.

Mortar Selection Based on Use More explicit guidance on mortar selection based on the location and use of the building segment is given in Table 1. More durable mortar Types are recommended for more severe exposures. TABLE 1 Mortar Recommendations Based on Use Mortar Type Location

Building Segment Recommended

Alternate

Exterior, above grade

Reinforced or Loadbearing walls Veneer or Non-loadbearing walls Parapets, Chimneys

S N N

N S S

Exterior, at or below grade

Foundation walls, Retaining walls Sewers, Manholes

M

S

Interior

Loadbearing walls Partitions

N N

S O or S

Brick Properties Influencing Mortar Selection In general, the bond between brick and mortar is the most important property to consider when selecting mortar Type. Bond actually has two components: extent of bond and bond strength. Extent of bond refers to the amount of intimate contact between the mortar and brick, which is enhanced by good mortar workability. Good extent of bond provides durability and resistance to water penetration. Bond strength refers to the force required to separate the mortar from the brick. Good bond strength provides resistance to cracking.

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Brick properties, particularly the initial rate of absorption (IRA), also can affect bond. Brick with a high IRA should be used with mortar that has a greater ability to retain mixing water. Conversely, brick with a low IRA should be used with mortar that does not retain water as easily. Bed joint surface texture also may influence bond strength and extent of bond, but to a lesser degree than IRA. Table 2 can be used to select a mortar based on IRA. These recommendations are based on Bond Strength and Water Penetration of Low IRA Brick and Mortar [Ref. 6] and Bond Strength and Water Penetration of High IRA Brick and Mortar [Ref. 7]. The mortar recommendations in Table 2 are applicable for construction in temperatures from 40° to 100 °F (4° to 37.8 °C). Under colder or hotter temperatures, other brick and mortar combinations may be preferable. Refer to Technical Note 1 for hot and cold weather construction recommendations. In addition, there may be other brick/mortar combinations that perform as well. Bond strength of particular combinations can be tested using ASTM C 1357, Standard Test Methods for Evaluating Masonry Bond Strength [Ref. 4]. TABLE 2 Mortar Recommendations Based on Brick Unit IRA1 Initial Rate of Absorption Range of Brick

Portland or Blended Cement: Lime Mortar

Mortar Cement Mortar

Masonry Cement Mortar

Up to 10 g/min/30 in.² (Up to 0.0005 g/min/mm²)

Type S (Type N)

Type S (Type N)

Type S (Type N)

10 to 30 g/min/30 in.² (0.0005 to 0.0016 g/min/mm²)

Type N or S

Type N or S

Type N or S

Above 30 g/min/30 in.² (Above 0.0016 g/min/mm²) Dry when laid

Type N (Type S)

Above 30 g/min/30 in.² (Above 0.0016 g/min/mm²) Wetted prior to laying

Type N (Type S)

1

Alternate Types listed in parentheses

2

Not recommended unless verified with testing

__

2

Type N (Type S)

__

2

Type S (Type N)

Mortars for Special Applications Certain applications may require special considerations for mortar selection. Several of these follow: Repointing Mortars. Repointing mortars are used in maintenance and restoration projects. Compatibility between existing brick and mortar is the most important consideration in selecting a repointing mortar. Hence, it may be necessary to use a weaker mortar for older masonry than would be used for new construction. In general, the compressive strength of a repointing mortar should not exceed that of the existing mortar. If necessary, the existing mortar can be tested to determine proportions of ingredients for the repointing mortar. Type O mortar often is used for repointing older brickwork. Type N mortar may be suitable for repointing newer brickwork. Repointing mortars should be pre-hydrated. In this process the mortar materials are mixed dry, and then just enough water is added to produce a damp mix which will retain its shape when formed into a ball. After one to one and half hours, additional water should be added to bring the mortar to the proper consistency for placement. Refer to Technical Note 46 for more information about repointing. Paving. Paving applications are more likely to be in a saturated condition than walls. Because of this, the mortar typically must be more durable to resist the harsher exposure. Type M mortar is recommended with Type S as the alternate. A mortar with a latex modifier conforming to ANSI A118.4, Specification for Latex-Portland Cement Mortar [Ref. 1], may provide a more durable assembly. Flexible brick paving, which uses sand rather than mortar to fill joints between pavers, is less susceptible to damage from exposure and should be considered as an alternative to mortared paving. Refer to Technical Note 14A for more information about paving materials.

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Stain-Resistant Mortar. Where resistance to staining is desired, aluminum tristearate, calcium stearate or ammonium stearate may be added to the mortar. Where maximum stain resistance is desired, use mortar consisting of one part portland cement, one-eighth part lime and two parts graded fine (80 mesh) sand, proportioned by volume. To this, add aluminum tristearate, calcium stearate or ammonium stearate equal to 2 percent of the portland cement by weight. Chemical-Resistant Mortar. Chemical-resistant masonry often is used in food processing plants, refineries or breweries. Chemical-resistant mortars may include silicate mortars, sulfur mortars, various resin mortars or cementitious mortars. For further information on chemical-resistant mortar, refer to Corrosion & Chemical Resistant Masonry Materials Handbook [Ref. 9].

MIXING REQUIREMENTS Although most mortar is mixed on-site, preblended mortar also is available. Preblended mortar is supplied in consistent proportions without the need for on-site batching and measurement controls. While each mortar Type has specified ranges of material quantities, accurate and consistent material quantities are desired throughout the job. Material measuring and batching should be by volume or by weight to ensure that the specified mortar proportions are accurately controlled and maintained. For material weights and recommended proportions, refer to ASTM C 270 or Technical Note 8. When using a mechanical mixer, the ingredients should be added in such a manner that the mix remains damp. Typically, about half the mix water is added to the mixer, followed by about half of the sand, then any and all lime. The cement and the remainder of the sand are then added, followed by the remainder of the water. These materials should be mixed for three to five minutes. If admixtures are to be used, they should consistently be added at the same stage in the mixing process. The same quantities of materials should be added in the same order from batch to batch to help ensure uniform results throughout the job. Every effort should be made to keep the materials agitated by the paddles. This may require changing the sequence in which water is added. If ingredients are added too fast or if not enough water is added to the mixer before the dry ingredients, the mixer may not be able to combine them, and the dry materials will stick around the bowl.

Photo 1 Obtaining Accurate Sand Quantities

Cement and lime should be placed in the mixer in whole (preferable) or half bags. The mixer should be sized accordingly, also depending upon the project requirements and the size of the masonry crew.

Photo 1 shows an example of batching and measurement controls that are both economical and accurate. Sand can be measured with a 1-cubic foot (0.028 m3) box or a 5-gallon bucket equal to 2/3-cubic-feet (0.019 m3). Alternatively, the number of shovels of sand required to fill the box or bucket can be calibrated. Shovel count calibration should be done every morning and afternoon or whenever the shovel size or individual shovelling sand is changed.

QUALITY ASSURANCE A quality assurance program provides policies, procedures and requirements intended to ensure compliance with the contract documents. Quality assurance requirements may be set by the owner, designer or governing building code. Quality control is a part of the quality assurance program that may involve testing, inspection, or both. Some quality assurance programs require the contractor to submit documentation showing conformance to the contract documents. Building Code Requirements for Masonry Structures [Ref. 8] assumes that all masonry is constructed under a quality assurance program. www.gobrick.com | Brick Industry Association | TN 8B | Mortars for Brickwork - Selection and Quality Assurance | Page 4 of 6

For mortar specified by ASTM C 270, the key to quality assurance is adherence to the material proportions added to the mixer. ASTM C 270 prescribes the volumes of the materials in each mortar Type when the proportion specification is used. When the property specification is used, laboratory testing establishes the material proportions that will be used in the field. Observation during measuring and mixing is thus an essential component of the quality assurance program. Testing may be included as a second component. ASTM C 1586, Standard Guide for Quality Assurance for Mortars [Ref. 5], explains how to use ASTM C 270 and ASTM C 780 for evaluating laboratory-prepared and field-prepared mortars.

Inspection Inspection is often a part of the quality assurance programs required by the contract documents or building code. Mortar inspection typically entails verifying that the specified materials are used and that they are in the proper proportions. Inspection also may include verifying proper mix time, retempering, mortar placement and tooling.

Testing Field testing of mortar is not necessary on most projects. When the ASTM C 270 property specification is used, however, laboratory testing is necessary to establish mortar mix proportions, which are then used to prepare mortar in the field. If inspection during mixing is not possible, some physical testing of the mortar may be appropriate. ASTM C 780, Standard Test Method for Preconstruction and Construction Evaluation of Mortars for Plain and Reinforced Unit Masonry [Ref. 3], provides methods for sampling and testing mortar in the laboratory and in the field. It defines procedures for measuring properties of plastic mortar such as consistency, the aggregate ratio, air content and water content. Finally, it defines procedures for measuring properties of hardened mortar, such as compressive strength. These test results are used to verify mortar consistency from batch to batch. For test results to be useful there must be a basis of comparison. Preconstruction testing with the materials to be used during the actual construction provides the benchmark for field testing results. Proper interpretation of mortar test results requires a thorough knowledge of mortar specifications and test methods. For example, compressive strength test results from field-sampled mortar cannot be compared with the minimum requirements of the ASTM C 270 property specification. The different sampling and mixing requirements of ASTM C 780 will yield different results from those determined according to ASTM C 270. ASTM C 270 is for laboratoryprepared and tested mortars, while ASTM C 780 is mainly for field sampling and testing. Compressive strength results obtained according to ASTM C 780 can be expected to be lower and more variable than ASTM C 270 laboratory test results; the two are not comparable. ASTM C 780 can be used to determine whether the proper proportions are being used in the field. Freshly sampled mortar is placed in a jar with isopropyl or methyl alcohol to prevent hydration. The sand used in the mortar also is sampled to determine its gradation. After weighing the materials, the fine material is filtered out of the mortar using a sieve. The remaining material is assumed to be sand, from which the sand to cement ratio can be determined. This can be compared with the specified proportions.

Interpreting Test Results If ASTM C 780 field test methods are used, the results must be properly interpreted and compared with preconstruction test results. Observations should include mortar sampling, test specimen preparation, specimen handling during transportation, storage at the test facility and test procedures. If there is a substantial difference between preconstruction and field results, the following should be investigated: • Change of mortar materials or proportions • Change in brick properties (different brick or wet brick) resulting in a change to the amount of water added to the mortar • Change in time between mortar mixing and sampling • Proper construction of specimens • Unusual curing conditions • Damage to specimens during transit or storage • Proper adherence to test procedures • Accuracy of calculations www.gobrick.com | Brick Industry Association | TN 8B | Mortars for Brickwork - Selection and Quality Assurance | Page 5 of 6

This information can be used to help identify the possible cause(s) of inconsistent test results. If questions about mortar quality remain, additional masonry testing may be required. In some cases, prism tests of masonry specimens from the project can be conducted to determine the structural capacity of the masonry.

SUMMARY Mortar, although it comprises a relatively small portion of brickwork, has a significant impact on overall performance. A range of mortars is available to suit the needs of all brick projects. Taking into consideration the brick unit properties as well as the project requirements when specifying mortar Type will contribute to a properly performing brick structure, as will implementing a good quality assurance plan. The information and suggestions contained in this Technical Note are based on the available data and the combined experience of engineering staff and members of the Brick Industry Association. The information contained herein must be used in conjunction with good technical judgment and a basic understanding of the properties of brick masonry. Final decisions on the use of the information contained in this Technical Note are not within the purview of the Brick Industry Association and must rest with the project architect, engineer and owner.

REFERENCES 1. ANSI A118.4, Specification for Latex-Portland Cement Mortar, American National Standards Institute, Washington, DC, 2006. 2. ASTM C 270, Standard Specification for Mortar for Unit Masonry, Annual Book of Standards, Vol. 04.05, ASTM International, West Conshohocken, PA, 2006. 3. ASTM C 780, Standard Test Method for Preconstruction and Construction Evaluation of Mortars for Plain and Reinforced Unit Masonry, Annual Book of Standards, Vol. 04.05, ASTM International, West Conshohocken, PA, 2006. 4. ASTM C 1357, Standard Test Methods for Evaluating Masonry Bond Strength, Annual Book of Standards, Vol. 04.05, ASTM International, West Conshohocken, PA, 2006. 5. ASTM C 1586, Standard Guide for Quality Assurance for Mortars, Annual Book of Standards, Vol. 04.05, ASTM International, West Conshohocken, PA, 2006. 6. Borchelt, J.G. and Tann, J.A., “Bond Strength and Water Penetration of Low IRA Brick and Mortar,” Proceedings of the Seventh North American Masonry Conference, The Masonry Society, Boulder, CO, 1996. 7. Borchelt, J.G., Melander, J.M., and Nelson, R.L., “Bond Strength and Water Penetration of High IRA Brick and Mortar,” Proceedings of the Eighth North American Masonry Conference, The Masonry Society, Boulder, CO, 1999. 8. Building Code Requirements for Masonry Structures (ACI 530/ASCE 5/TMS 402) and Specification for Masonry Structures (ACI 530.1/ASCE 6/TMS 602), The Masonry Society, Boulder, CO, 2005. 9. Sheppard, Walter Lee Jr., Editor, Corrosion and Chemical Resistant Masonry Materials Handbook, Noyes Publications, Park Ridge, NJ, 1986.

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TECHNICAL NOTES on Brick Construction

9

1850 Centennial Park Drive, Reston, Virginia 20191 | www.gobrick.com | 703-620-0010

December 2006

Manufacturing of Brick Abstract: This Technical Note presents fundamental procedures for the manufacture of clay brick. The types of clay used, the three principal processes for forming brick and the various phases of manufacturing, from mining through storage, are discussed. Information is provided regarding brick durability, color, texture (including coatings and glazes), size variation, compressive strength and absorption. Key Words: absorption, clays, color, cooling, compressive strength, de-hacking, drying, durability, firing, forming, hacking, manufacturing, mining, preparation, shales, size variation, texture.

SUMMARY: • Brick is made of clay or shale formed, dried and fired into a durable ceramic product. • There are three ways to form the shape and size of a brick: extruded (stiff mud), molded (soft mud) and drypressed. The majority of brick are made by the extrusion method. • Brick achieves its color through the minerals in the fired clay or through coatings that are applied before or after the firing process. This provides a durable color that never fades or diminishes. • Brick shrink during the manufacturing process as vitrification occurs. Brick will vary in size due to the

manufacturing process. These variations are addressed by ASTM standards. • The method used to form a brick has a major impact on its texture. Sand-finished surfaces are typical with molded brick. A variety of textures can be achieved with extruded brick. • Brick manufacturers address sustainability by locating manufacturing facilities near clay sources to reduce transportation, by recycling of process waste, by reclaiming land where mining has occurred, and by taking measures to reduce plant emissions. Most brick are used within 500 miles of a brick manufacturing facility.

INTRODUCTION The fundamentals of brick manufacturing have not changed over time. However, technological advancements have made contemporary brick plants substantially more efficient and have improved the overall quality of the products. A more complete knowledge of raw materials and their properties, better control of firing, improved kiln designs and more advanced mechanization have all contributed to advancing the brick industry. Other Technical Notes in this series address the classification and selection of brick considering the use, exposure and required durability of the finished brickwork.

RAW MATERIALS Clay is one of the most abundant natural mineral materials on earth. For brick manufacturing, clay must possess some specific properties and characteristics. Such clays must have plasticity, which permits them to be shaped or molded when mixed with water; they must have sufficient wet and air-dried strength to maintain their shape after forming. Also, when subjected to appropriate temperatures, the clay particles must fuse together.

Types of Clay Clays occur in three principal forms, all of which have similar chemical compositions but different physical characteristics. Surface Clays. Surface clays may be the upthrusts of older deposits or of more recent sedimentary formations. As the name implies, they are found near the surface of the earth. Shales. Shales are clays that have been subjected to high pressures until they have nearly hardened into slate. Fire Clays. Fire clays are usually mined at deeper levels than other clays and have refractory qualities. Surface and fire clays have a different physical structure from shales but are similar in chemical composition. All © 2006 Brick Industry Association, Reston, Virginia

Page 1 of 7

three types of clay are composed of silica and alumina with varying amounts of metallic oxides. Metallic oxides act as fluxes promoting fusion of the particles at lower temperatures. Metallic oxides (particularly those of iron, magnesium and calcium) influence the color of the fired brick. The manufacturer minimizes variations in chemical composition and physical properties by mixing clays from different sources and different locations in the pit. Chemical composition varies within the pit, and the differences are compensated for by varying manufacturing processes. As a result, brick from the same manufacturer will have slightly different properties in subsequent production runs. Further, brick from different manufacturers that have the same appearance may differ in other properties.

MANUFACTURING Although the basic principles of manufacture are fairly uniform, individual manufacturing plants tailor their production to fit their particular raw materials and operation. Essentially, brick are produced by mixing ground clay with water, forming the clay into the desired shape, and drying and firing. In ancient times, all molding was performed by hand. However, since the invention of brick-making machines during the latter part of the 19th century, the majority of brick produced in the United States have been machine made.

Phases of Manufacturing The manufacturing process has six general phases: 1) mining and storage of raw materials, 2) preparing raw materials, 3) forming the brick, 4) drying, 5) firing and cooling and 6) de-hacking and storing finished products (see Figure 1).

Figure 1 Diagrammatic Representation of Manufacturing Process Mining and Storage. Surface clays, shales and some fire clays are mined in open pits with power equipment. Then the clay or shale mixtures are transported to plant storage areas (see Photo 1). Continuous brick production regardless of weather conditions is ensured by storing sufficient quantities of raw materials required for many days of plant operation. Normally, several storage areas (one for each source) are used to facilitate blending of the clays. Blending produces more uniform raw materials, helps control color and allows raw material control for manufacturing a certain brick body.

Photo 1 Clay or Shale Being Crushed and Transported to Storage Area

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Photo 2

Photo 3

Clay is Thoroughly Mixed with Water in Pug Mill Before Extrusion

After Mining, Clay is Extruded Through a Die and Trimmed to Specified Dimension Before Firing

Preparation. To break up large clay lumps and stones, the material is processed through size-reduction machines before mixing the raw material. Usually the material is processed through inclined vibrating screens to control particle size. Forming. Tempering, the first step in the forming process, produces a homogeneous, plastic clay mass. Usually, this is achieved by adding water to the clay in a pug mill (see Photo 2), a mixing chamber with one or more revolving shafts with blade extensions. After pugging, the plastic clay mass is ready for forming. There are three principal processes for forming brick: stiff-mud, soft-mud and dry-press. Stiff-Mud Process - In the stiff-mud or extrusion process (see Photo 3), water in the range of 10 to 15 percent is mixed into the clay to produce plasticity. After pugging, the tempered clay goes through a deairing chamber that maintains a vacuum of 15 to 29 in. (375 to 725 mm) of mercury. De-airing removes air holes and bubbles, giving the clay increased workability and plasticity, resulting in greater strength. Next, the clay is extruded through a die to produce a column of clay. As the clay column leaves the die, textures or surface coatings may be applied (see PROPERTIES, Textures, Coatings and Glazes). An automatic cutter then slices through the clay column to create the individual brick. Cutter spacings and die sizes must be carefully calculated to compensate for normal shrinkage that occurs during drying and firing (see PROPERTIES, Size Variation). About 90 percent of brick in the United States are produced by the extrusion process. Soft-Mud Process - The soft-mud or molded process is particularly suitable for clays containing too much water to be extruded by the stiff-mud process. Clays are mixed to contain 20 to 30 percent water and then formed into brick in molds. To prevent clay from sticking, the molds are lubricated with either sand or water to produce “sand-struck” or “water-struck” brick. Brick may be produced in this manner by machine or by hand. Dry-Press Process - This process is particularly suited to clays of very low plasticity. Clay is mixed with a minimal amount of water (up to 10 percent), then pressed into steel molds under pressures from 500 to 1500 psi (3.4 to 10.3 MPa) by hydraulic or compressed air rams. Drying. Wet brick from molding or cutting machines contain 7 to 30 percent moisture, depending upon the forming method. Before the firing process begins, most of this water is evaporated in dryer chambers at temperatures ranging from about 100 ºF to 400 ºF (38 ºC to 204 ºC). The extent of drying time, which varies with different clays, usually is between 24 to 48 hours. Although heat may be generated specifically for dryer chambers, it usually is supplied from the exhaust heat of kilns to maximize thermal efficiency. In all cases, heat and humidity must be carefully regulated to avoid cracking in the brick. Hacking. Hacking is the process of loading a kiln car or kiln with brick. The number of brick on the kiln car is determined by kiln size. The brick are typically placed by robots or mechanical means. The setting pattern has www.gobrick.com | Brick Industry Association | TN 9 | Manufacturing of Brick | Page 3 of 7

some influence on appearance. Brick placed face-toface will have a more uniform color than brick that are cross-set or placed face-to-back. Firing. Brick are fired between 10 and 40 hours, depending upon kiln type and other variables. There are several types of kilns used by manufacturers. The most common type is a tunnel kiln, followed by periodic kilns. Fuel may be natural gas, coal, sawdust, methane gas from landfills or a combination of these fuels. In a tunnel kiln (see Photo 4), brick are loaded onto kiln cars, which pass through various temperature zones as they travel through the tunnel. The heat conditions in each zone are carefully controlled, and the kiln is continuously operated. A periodic kiln is one that is loaded, fired, allowed to cool and unloaded, after which the same steps are repeated. Dried brick are set in periodic kilns according to a prescribed pattern that permits circulation of hot kiln gases.

Photo 4 Brick Enter Tunnel Kiln for Firing

Firing may be divided into five general stages: 1) final drying (evaporating free water); 2) dehydration; 3) oxidation; 4) vitrification; and 5) flashing or reduction firing. All except flashing are associated with rising temperatures in the kiln. Although the actual temperatures will differ with clay or shale, final drying takes place at temperatures up to about 400 ºF (204 ºC), dehydration from about 300 ºF to 1800 ºF (149 ºC to 982 ºC), oxidation from 1000 ºF to 1800 ºF (538 ºC to 982 ºC) and vitrification from 1600 ºF to 2400 ºF (871 ºC to 1316 ºC). Photo 5 Clay, unlike metal, softens slowly and melts or vitrifies Robotic Arm Unloading Brick After Firing gradually when subjected to rising temperatures. Vitrification allows clay to become a hard, solid mass with relatively low absorption. Melting takes place in three stages: 1) incipient fusion, when the clay particles become sufficiently soft to stick together in a mass when cooled; 2) vitrification, when extensive fluxing occurs and the mass becomes tight, solid and nonabsorbent; and 3) viscous fusion, when the clay mass breaks down and becomes molten, leading to a deformed shape. The key to the firing process is to control the temperature in the kiln so that incipient fusion and partial vitrification occur but viscous fusion is avoided. The rate of temperature change must be carefully controlled and is dependent on the raw materials, as well as the size and coring of the brick being produced. Kilns are normally equipped with temperature sensors to control firing temperatures in the various stages. Near the end, the brick may be “flashed” to produce color variations (see PROPERTIES, Color). Cooling. After the temperature has peaked and is maintained for a prescribed time, the cooling process begins. Cooling time rarely exceeds 10 hours for tunnel kilns and from 5 to 24 hours in periodic kilns. Cooling is an important stage in brick manufacturing because the rate of cooling has a direct effect on color. De-hacking. De-hacking is the process of unloading a kiln or kiln car after the brick have cooled, a job often performed by robots (see Photo 5). Brick are sorted, graded and packaged. Then they are placed in a storage yard or loaded onto rail cars or trucks for delivery. The majority of brick today are packaged in self-contained, strapped cubes, which can be broken down into individual strapped packages for ease of handling on the jobsite. The packages and cubes are configured to provide openings for handling by forklifts. www.gobrick.com | Brick Industry Association | TN 9 | Manufacturing of Brick | Page 4 of 7

PROPERTIES All properties of brick are affected by raw material composition and the manufacturing process. Most manufacturers blend different clays to achieve the desired properties of the raw materials and of the fired brick. This improves the overall quality of the finished product. The quality control during the manufacturing process permits the manufacturer to limit variations due to processing and to produce a more uniform product. The most important properties of brick are 1) durability, 2) color, 3) texture, 4) size variation, 5) compressive strength and 6) absorption.

Durability The durability of brick depends upon achieving incipient fusion and partial vitrification during firing. Because compressive strength and absorption values are also related to the firing temperatures, these properties, together with saturation coefficient, are currently taken as predictors of durability in brick specifications. However, because of differences in raw materials and manufacturing methods, a single set of values of compressive strength and absorption will not reliably indicate the degree of firing.

Color The color of fired clay depends upon its chemical composition, the firing temperatures and the method of firing control. Of all the oxides commonly found in clays, iron probably has the greatest effect on color. Regardless of its natural color, clay containing iron in practically any form will exhibit a shade of red when exposed to an oxidizing fire because of the formation of ferrous oxide. When fired in a reducing atmosphere, the same clay will assume a dark (or black) hue. Creating a reducing atmosphere in the kiln is known as flashing or reduction firing. Given the same raw material and manufacturing method, darker colors are associated with higher firing temperatures, lower absorption values and higher compressive strength values. However, for products made from different raw materials, there is no direct relationship between strength and color or absorption and color.

Texture, Coatings and Glazes Many brick have smooth or sand-finished textures produced by the dies or molds used in forming. A smooth texture, commonly referred to as a die skin, results from pressure exerted by the steel die as the clay passes through it in the extrusion process. Most extruded brick have the die skin removed and the surface further treated to produce other textures using devices that cut, scratch, roll, brush or otherwise roughen the surface as the clay column leaves the die (see Photo 6). Brick may be tumbled before or after firing to achieve an antique appearance. Many manufacturing plants apply engobes (slurries) of finely ground clay or colorants to the column. Engobes are clay slips that are fired onto the ceramic body and develop hardness, but are not impervious to moisture or water vapor. Sands, with or without coloring agents, can be rolled into an engobe or applied directly to the brick faces to create interesting and distinctive patterns in the finished product.

Photo 6 Some Brick Textures are Applied by Passing Under a Roller After Extrusion

Although not produced by all manufacturers, glazed brick are made through a carefully controlled ceramic glazing procedure. There are two basic variations of glazing; single-fired and double-fired. Single-fired glazes are sprayed on brick before or after drying and then kiln-fired at the normal firing temperatures of the brick. Double-fired glazes are used to obtain colors that cannot be produced at higher temperatures. Such a glaze is applied after the brick body has been fired and cooled, then refired at temperatures less than 1800 ºF (982 ºC). Glazes are available in a wide variety of colors and reflectances. Unlike engobes, glazes are impervious to water and water vapor. www.gobrick.com | Brick Industry Association | TN 9 | Manufacturing of Brick | Page 5 of 7

Size Variation Because clays shrink during both drying and firing, allowances are made in the forming process to achieve the desired size of the finished brick. Both drying shrinkage and firing shrinkage vary for different clays, usually falling within the following ranges: • Drying shrinkage: 2 to 4 percent • Firing shrinkage: 2.5 to 4 percent Firing shrinkage increases with higher temperatures, which produce darker shades. When a wide range of colors is desired, some variation between the sizes of the dark and light units is inevitable. To obtain products of uniform size, manufacturers control factors contributing to shrinkage. Because of normal variations in raw materials and temperature variations within kilns, absolute uniformity is impossible. Consequently, specifications for brick allow size variations.

Compressive Strength and Absorption Both compressive strength and absorption are affected by properties of the clay, method of manufacture and degree of firing. For a given clay and method of manufacture, higher compressive strength values and lower absorption values are associated with higher firing temperatures. Although absorption and compressive strength can be controlled by manufacturing and firing methods, these properties depend largely upon the properties of the raw materials.

ENVIRONMENTAL ISSUES Brick manufacturing is one of the most efficient uses of materials to produce a product. Brick plants are typically located close to raw material sources. Processed clay and shale removed in the forming process before firing are returned to the production stream. Brick not meeting standards after firing are culled from the process and ground to be used as grog in manufacturing brick or crushed to be used as landscaping material. There is virtually no waste of raw materials in manufacturing brick. Brick manufacturing uses readily available raw materials, including some waste products. The primary ingredient, clay, has been termed an “abundant resource” by many authorities including the American Institute of Architects [Ref. 1], confirming that depletion of clay is not a concern. Nonhazardous waste products from other industries are sometimes used. Examples include using bottom- and fly-ash from coal-fired generators, using other ceramic materials as grog, using lubricants derived from processing organic materials in the forming of brick, and using sawdust as a burnout material. The brick industry’s goal is to reduce resources used in the manufacturing process. Although water is used in brick manufacturing, it is not chemically altered but is evaporated into the atmosphere. By using storage tanks to recirculate and reuse water, potable water demand can be cut dramatically. Brick manufacturers are continuously looking for ways to minimize use of water. Photo 7 shows one plant using a storage tank to hold recirculated water for reuse in brick production.

Photo 7 Left Storage Tank Captures Used Water from Manufacturing Process; Water is Cleaned, Cooled and Moved to Holding Tank for Reuse

While natural gas is the most frequently used energy source for brick manufacturing, many manufacturers are using waste products, such as methane gas from landfills and sawdust, for brick firing. The brick industry recognizes the need for compliance with state and federal regulations for clean air and the environment. Air emissions are minimized with controls such as scrubbers installed on kiln exhausts. Dust in plants

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is controlled through the use of filtering systems, vacuums, additives and water mists. Mined areas are reclaimed by replacing overburden and topsoil so the resulting property can be used for a wide variety of functions, including farmland, residential and commercial sites, and even wetlands. Current manufacturing processes for brick are similar in scope to those used for the past 3500 years. Over this period of time, it has been demonstrated that brick are safe and durable products for society. The long service life of brickwork is a key component of sustainable structures and pavements. The Brick Industry Association has adopted the following environmental policy statement: The brick industry recognizes that the stewardship of our planet lies in the hands of our generation. Our goal is to continually seek out innovative, environmentally friendly opportunities in the manufacturing process and for the end use of clay brick products. As demonstrated over time, we are committed to manufacturing products that provide exceptional energy efficiency, durability, recyclability, and low maintenance with minimal impact on the environment from which they originate. We will ensure that our facilities meet or exceed state and federal environmental regulations, and we will continue to partner with building professionals to help them in using our products to create environmentally responsible living and working spaces for today’s and future generations.

SUMMARY This Technical Note on manufacturing brick is the first in a series covering the manufacturing, classification and selection of brick. It provides a synopsis of the manufacturing process and discusses the various properties that are a function of this process. More detailed descriptions of the ceramic properties of brick are not within the purview of the Brick Industry Association. This type of information is more readily available through the National Brick Research Center, ceramic engineers and educators. The information and suggestions contained in this Technical Note are based on the available data and the combined experience of engineering staff and members of the Brick Industry Association. The information contained herein must be used in conjunction with good technical judgment and a basic understanding of the properties of brick masonry. Final decisions on the use of the information contained in this Technical Note are not within the purview of the Brick Industry Association and must rest with the project architect, engineer and owner.

REFERENCES 1. American Institute of Architects, Environmental Resource Guide, The American Institute of Architects, Canada, 1998. 2. Campbell, J. W. P. and Pryce, W., Brick, A World History, Thames and Hudson, New York, NY, 2003.

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TECHNICAL NOTES on Brick Construction 9A 1850 Centennial Park Drive, Reston, Virginia 20191 | www.gobrick.com | 703-620-0010

October 2007

Specifications for and Classification of Brick Abstract: This Technical Note describes the predominant-consensus standard specifications for brick and the various classifications used in each. Specific requirements — including physical properties, appearance features and coring — are described. Additional requirements for each brick specification also are covered.

Key Words: appearance, ASTM standards, brick, chippage, classification, CSA standard, dimensions, distortion, durability, exposure, grade, physical properties, specification, tolerances, type, use.

SUMMARY OF RECOMMENDATIONS: • Identify the appropriate brick specification for the intended use • Specify each classification in the specification or verify that the default classification is valid • Specify each required action of the purchaser and specifier

• Evaluate and specify any optional requirement • Use requirements in consensus-based specifications; deviate from them only with consideration of effect on performance and cost

INTRODUCTION Brick selection is made according to the specific application in which the brick will be used. Standards for brick cover specific uses of brick and classify the brick by performance characteristics. The performance criteria include strength, durability and aesthetic requirements. Selection of the proper specification and classification within that specification, along with proper design and construction, should result in expected performance. ASTM International (ASTM) publishes the most widely accepted standards on brick. These standards are voluntary consensus standards that are reviewed and updated periodically to contain the most recent information. All have been through a thorough review process by a balanced committee of interested ASTM members classified as producers, users and general interest. All of the model building codes in the United States reference ASTM standards for brick. Standards used in Canadian building codes are prepared by the Canadian Standards Association (CSA). The process used to prepare and revise CSA standards is similar to ASTM’s. The sole CSA standard for brick, A82 Fired Masonry Brick Made from Clay or Shale, is similar in content to the ASTM standards for face brick and hollow brick. It also includes test methods. This Technical Note identifies the standards for brick and the specific requirements for its various classifications. Other Technical Notes in this series address the fundamentals of brick manufacturing and the proper selection of brick.

© 2007 Brick Industry Association, Reston, Virginia

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BRICK SPECIFICATIONS Depending on its use, brick is covered by one of several specifications. See Table 1. Because firebox brick, chemical resistant brick, sewer and manhole brick, and industrial floor brick are special uses, they will not be addressed in this Technical Note. TABLE 1 Specifications for Brick ASTM Designation1

CSA Designation2

Building Brick

C 62

—

Facing Brick

C 216

A82

Hollow Brick

C 652

A82

Thin Veneer Brick Units Made from Clay or Shale

C 1088

—

Pedestrian and Light Traffic Paving Brick

C 902

—

Heavy Vehicular Paving Brick

C 1272

—

Ceramic Glazed Structural Clay Facing Tile, Facing Brick, and Solid Masonry Units

C 126

—

Glazed Brick, Single Fired

C 1405

—

Firebox Brick, Residential Fireplaces

C 1261

—

Chemical-Resistant Masonry Units

C 279

—

Sewer and Manhole Brick

C 32

—

Industrial Floor Brick

C 410

—

Title of Specification

1. ASTM International, 100 Bar Harbor Drive, West Conshohocken, PA 19428. 2. Canadian Standards Association, 5060 Spectrum Way, Suite 100, Mississauga, Ontario, L4W 5N6 Canada.

Beginning with the 2007a edition of ASTM C 216, an appendix has been added. The appendix is designed to explain the specification, noting subtleties and relationships that might not otherwise be clear. In many instances the use of brick is similar to the title of its ASTM specification.

Facing Brick Facing brick are intended for use in both structural and nonstructural masonry, including veneer, where appearance is a requirement.

Hollow Brick Hollow brick are used as either building or facing brick but have a greater void area. Most hollow brick are used as facing brick in anchored veneer. Hollow brick with very large cores are used in reinforced brickwork and contain steel reinforcement and grout.

Building Brick Building brick are intended for use in both structural and nonstructural brickwork where appearance is not a requirement. Building brick are typically used as a backing material.

Thin Brick Thin veneer brick have normal face dimensions but a reduced thickness. They are used in adhered veneer applications.

Paving Brick Paving brick are intended for use as the wearing surface on clay paving systems. As such they are subject to pedestrian and light or heavy vehicular traffic.

Glazed Brick Glazed brick have a ceramic glaze finish fused to the brick body. The glaze can be applied before or after the firing of the brick body. These brick may be used as structural or facing components in masonry. www.gobrick.com | Brick Industry Association | TN 9A | Specifications for and Classification of Brick | Page 2 of 13

CLASSIFICATIONS There are several classifications used in each standard. Classifications include grade, class, type, application and use. The criteria for these classifications may include exposure or use conditions; appearance items; physical properties needed for performance; tolerances on dimensions and distortion; chippage; and void area. Brick qualify for a particular classification based on their properties after manufacturing. While most brick can be manufactured to attain all the attributes desired by a user, certain attributes may be dictated by the production method, durability classification or appearance classification designated by the user. For example, a molded brick cannot be made to meet the classification for the tightest dimensional tolerances since the production method uses a higher percentage of water that may result in greater shrinkage. Brick manufactured by the extrusion process can be made to meet the classification for tight or loose dimensional tolerances. When specifying brick each classification should be designated. Some ASTM brick specifications default to a certain classification if it is not designated. The default classification may not be suitable for the intended use. Table 2 contains a listing of the classifications in ASTM and CSA brick specifications. TABLE 2 Classifications in Specifications for Brick Classification Durability

Appearance

Void Area

Use

ASTM Specification C 62 Building Brick

Grade

None

None

None

C 216 Facing Brick

Grade

Type

None

None

C 652 Hollow Brick

Grade

Type

Class

None

C 1088 Thin Veneer Brick

Grade

Type

None

None

Class and Type

Application

None

Type

C 1272 Heavy Vehicular Paving Brick

Type

Application

None

Type

C 126 Ceramic Glazed Facing Brick

None

Grade and Type

None

None

C 1405 Single Fired Glazed Brick

Class

Grade and Type

Division

None

None1

None

C 902 Pedestrian and Light Traffic Paving Brick

CSA Specification A82 Fired Masonry Brick Made from Clay or Shale

Grade

Type

1. No classification given, but solid, cored and hollow brick are defined. See Void Area.

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Durability and Exposure Since the environmental and service conditions that brick are subjected to vary, each brick specification classifies brick for its specific durability. The classification is based on the severity of weather and the exposure of the brick. The classification assigned to the brick is typically based on physical properties of the brick. See Technical Note 9B for selection of the appropriate level of durability. The durability classifications for each specification are listed in Table 3. TABLE 3 Durability Classifications Durability Classification

More Severe Exposure

Less Severe Exposure

ASTM Specification C 62 Building Brick

Grade

SW

C 216 Facing Brick

Grade

SW

MW

C 652 Hollow Brick

Grade

SW

MW

C 1088 Thin Veneer Brick

Grade

Exterior

Class

SX

MX

NX

Type

I

II

III

C 1272 Heavy Vehicular Paving Brick

Type

F

C 126 Ceramic Glazed Facing Brick

None

C 1405 Single Fired Glazed Brick

Class

C 902 Pedestrian and Light Traffic Paving Brick

MW

NW

Interior

R —

Exterior

Interior

Exterior (EG)

Interior (IG)

CSA Specification A82 Fired Masonry Brick Made from Clay or Shale

Grade

For durability classifications the letters S, M and N in C 62, C 216, C 652 and C 902 indicate the following exposure conditions: S indicates severe weathering. M indicates moderate weathering. N indicates negligible or no weathering. Physical Property Requirements. The physical property requirements in most specifications are compressive strength, water absorption and saturation coefficient. These properties must be determined in accordance with ASTM C 67, Standard Methods of Sampling and Testing Brick and Structural Clay Tile [Ref. 1] or CSA A82 [Ref. 3]. The minimum compressive strength, maximum water absorption and maximum saturation coefficient are used in combination to predict the durability of the bricks in use. The saturation coefficient, also referred to as the C/B ratio, is the ratio of 24-hour cold water absorption to the five-hour boiling absorption. The physical property requirements for each standard are listed in Table 4. Some brick are durable but cannot be classified under the physical requirements shown in Table 4. Using alternates and alternatives in the specifications allows brick that are known to perform well to meet the durability requirement. A brick qualifying for a classification by an alternate or alternative does not signify that it is of a lower quality. The Absorption Alternate is found in ASTM C 62, C 216, C 652, C 1088, C 902 and C 1405. The Freezing and Thawing Alternative is found in ASTM C 62, C 216, C 652, C 1088, C 902, C 1272 and C 1405. The Low Weathering Index Alternative is found in ASTM C 62, C 216 and C 1088. CSA A82 includes a freeze-thaw test as an alternative if the brick does not meet the physical property requirements. Other unit specifications include alternates as well. These are discussed in the Additional Requirements section. Absorption Alternate- The saturation coefficient requirement does not apply, provided the cold water absorption of any single brick of a random sample of five brick does not exceed 8 percent.

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TABLE 4 Physical Properties in Brick Specifications Minimum Compressive Strength, Gross Area1 psi (MPa) Average of 5 brick

Individual

Maximum Cold Water Absorption, % Average of 5 brick

Individual

Maximum Five-Hour Boiling Absorption, % Average of 5 brick

Individual

Maximum Saturation Coefficient

Minimum Breaking Load, lb/in. (kN/mm)

Average of 5 brick

Individual

Average of 5 brick

Individual

ASTM Specification and Classification

C 62 Grade

C 216 Grade

C 652 Grade C 1088 Grade

C 902 Class

C 1272 Type

C 126 Coring

C 1405 Class

SW

3000 (20.7)

2500 (17.2)

—

—

17.0

20.0

0.78

0.80

—

—

MW

2500 (17.2)

2200 (15.2)

—

—

22.0

25.0

0.88

0.90

—

—

NW

1500 (10.3)

1250 (8.6)

—

—

No limit

No limit

No limit

No limit

—

—

SW

3000 (20.7)

2500 (17.2)

—

—

17.0

20.0

0.78

0.80

—

—

MW

2500 (17.2)

2200 (15.2)

—

—

22.0

25.0

0.88

0.90

—

—

SW

3000 (20.7)

2500 (17.2)

—

—

17.0

20.0

0.78

0.80

—

—

MW

2500 (17.2)

2200 (15.2)

—

—

22.0

25.0

0.88

0.90

—

—

Ext.

—

—

—

—

17.0

20.0

0.78

0.80

—

—

Int.

—

—

—

—

22.0

25.0

0.88

0.90

—

—

SX

8000 [4000]2 (55.2) [(27.6)]2

7000 [3500]2 (48.3) [(24.1)]2

8.0 [16.0]2

11.0 [18.0]2

—

—

0.78

0.80

—

—

MX

3000 (20.7)

2500 (17.2)

14.0

17.0

—

—

No limit

No limit

—

—

NX

3000 (20.7)

2500 (17.2)

No limit

No limit

—

—

No limit

No limit

—

—

F

10,000 (69.0)

8800 (60.7)

6.0

7.0

—

—

—

—

475 (83)

333 (58)

R

8000 (55.2)

7000 (48.3)

6.0

7.0

—

—

—

—

—

—

Vert.

3000 (20.7)

2500 (17.2)

—

—

—

—

—

—

—

—

Horiz.

2000 (13.8)

1500 (10.3)

—

—

—

—

—

—

—

—

Ext.

6000 (41.4)

5600 (34.8)

—

7.0

—

—

0.78

0.80

—

—

Int.

3000 (20.7)

2500 (17.2)

—

—

—

—

—

—

—

—

Ext.

3000 (20.7)

2500 (17.2)

—

8.03

—

17.0

—

0.783

—

—

Int.

2500 (17.2)

2200 (15.2)

—

—

22.0

25.0

0.88

0.90

—

—

CSA Specification and Classification

A82

1. Brick in bearing position or loaded in the same direction as in service. 2. Numbers in brackets are for molded brick and apply provided the requirements for saturation coefficient are met. 3. Either of these requirements must be met, not both.

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Freezing and Thawing Alternative- The requirements for five-hour boiling water absorption and saturation coefficient do not apply, provided a sample of five brick, meeting the strength requirements, passes the freezing and thawing test as described in the Rating section of the Freezing and Thawing test procedures of ASTM C 67 with a weight loss not greater than 0.5 percent in dry weight of any individual brick (for Grade SW). Unlike ASTM C 67, CSA A 82 stipulates that brick must be kept in a frozen state during any interruption of the freeze-thaw test. Low Weathering Index Alternative- If the brick are intended for use where the weathering index is less than 50 and have a minimum average compressive strength of 2500 psi (17.2 MPa), the requirements given for five-hour boiling water absorption and for saturation coefficient shall not apply. Consult the appropriate ASTM specification for specific alternates.

Appearance Classification related to the appearance may include limits tolerances on dimensions, distortion, out-of-square and chippage. The appearance classification is established on the size and precision attained in manufacturing. The classifications for appearance of brick for each specification are listed in Table 5, and requirements for size variation, distortion and chippage are listed in Table 6, Table 7 and Table 8, respectively. There are no color-related tolerances in the ASTM standards for brick. Those are dictated by the sample panel or project specification. TABLE 5 Appearance Classifications Appearance Classifications

More Stringent Requirements

Less Stringent Requirements

ASTM Specification C 62 Building Brick

None

C 216 Facing Brick

Type

FBX

C 652 Hollow Brick

Type

HBX

C 1088 Thin Veneer Brick

Type

TBX

TBS

TBA

C 902 Pedestrian and Light Traffic Paving Brick

Application

PX

PS

PA

C 1272 Heavy Vehicular Paving Brick

Application

PX

PS

PA

Grade

SS

S

Type

II

I

Grade

SS

S

Type

II

I

C 126 Ceramic Glazed Facing Brick C 1405 Single Fired Glazed Brick

— FBS HBS

FBA HBA

HBB

CSA Specification A82 Fired Masonry Brick Made from Clay or Shale

Type

X

S

A

For appearance classifications the letters X, S and A have the following meanings: X indicates extreme or extra control in the criteria. S indicates standard production. A indicates architectural or aesthetic criteria that must be specified and in many specifications must be less stringent than the S designation. Dimensional Tolerances. Variations in raw materials and the manufacturing process will result in brick that vary in size. Permitted size variation is based on the brick classification and the relative dimensional range measured. These permitted variations in size are listed in Table 6A, Table 6B and Table 6C. The variation is plus or minus from the specified dimension. Size variation becomes important when vertical alignment of brick (stack bond) is used, when bands of brick from different production runs are combined, or when a short horizontal extent of brickwork is constructed, such as between closely spaced window openings.

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TABLE 6A Dimensional Tolerances for ASTM C 216 and CSA A821 Maximum Permissible Variation, in. (mm), plus or minus from: Specified Dimension or Average Brick Size in Job Lot Sample, in. (mm)

Column A (for Specified Dimension)

Column B (for Average Brick Size in Job Lot Sample)2

Type FBX

Type FBS

Type FBX

Type FBS Smooth3

Type FBS Rough4

3 (76) and under

1/16 (1.6)

3/32 (2.4)

1/16 (1.6)

1/16 (1.6)

3/32 (2.4)

Over 3 to 4 (76 to 102), inclusive

3/32 (2.4)

1/8 (3.2)

1/16 (1.6)

3/32 (2.4)

1/8 (3.2)

Over 4 to 6 (102 to 152), inclusive

1/8 (3.2)

3/16 (4.8)

3/32 (2.4)

3/32 (2.4)

3/16 (4.8)

Over 6 to 8 (152 to 203), inclusive

5/32 (4.0)

1/4 (6.4)

3/32 (2.4)

1/8 (3.2)

1/4 (6.4)

Over 8 to 12 (203 to 305), inclusive

7/32 (5.6)

5/16 (7.9)

1/8 (3.2)

3/16 (4.8)

5/16 (7.9)

Over 12 to 16 (305 to 406), inclusive

9/32 (7.1)

3/8 (9.5)

3/16 (4.8)

1/4 (6.4)

3/8 (9.5)

1. Dimensional tolerances for Type FBA and A in C 216 and A82, respectively, shall be as specified by the purchaser, but not more restrictive than Type FBS and S (Rough), respectively. 2. Lot size shall be determined by agreement between purchaser and seller. If not specified, lot size shall be understood to include all brick of one size and color in the job order.

3. Type FBS Smooth brick have relatively fine texture and smooth edges, including wire cut surfaces. These definitions relate to dimensional tolerances only. 4. Type FBS Rough bricks are molded brick or extruded brick with textured, rounded or tumbled edges or faces. These definitions apply to dimensional tolerances only.

TABLE 6B Dimensional Tolerances ASTM Specification and Classification C 62

C 652

Maximum Permissible Variation, in. (mm), plus or minus 3 (76) and under

1/8 (3.2)

3/16 (4.8)

1/4 (6.4)

5/16 (8.0)

3/8 (9.5)

HBX

1/16 (1.6)

3/32 (2.4)

1/8 (3.2)

5/32 (4.0)

7/32 (5.6)

9/32 (7.1)

HBS and HBB

3/32 (2.4)

1/8 (3.2)

3/16 (4.8)

1/4 (6.4)

5/16 (7.9)

3/8 (9.5)

As specified by the purchaser, but not more restrictive than HBS and HBB

TBX

1/16 (1.6)

3/32 (2.4)

1/8 (3.2)

5/32 (4.0)

7/32 (5.6)

9/32 (7.2)

TBS

3/32 (2.4)

1/8 (3.3)

3/16 (4.8)

1/4 (6.4)

5/16 (8.0)

3/8 (9.5)

TBA

As specified by the purchaser

C 126 C 902 and C 1272

Over 12 to 16 (408) inclusive

3/32 (2.4)

HBA C 1088

Over 3 to 4 Over 4 to 6 Over 6 to 8 Over 8 to 12 (102) inclusive (152) inclusive (204) inclusive (306) inclusive

See ASTM C 126 PX

1/16 (1.6)

3/32 (2.4)

—

1/8 (3.2)

7/32 (5.6)

—

PS

1/8 (3.2)

3/16 (4.8)

—

1/4 (6.4)

5/16 (8.0)

—

PA

No limit

No limit

—

No limit

No limit

—

TABLE 6C Dimensional Tolerances for ASTM C 1405 Maximum Permissible Variation in Dimensions, in. (mm) plus or minus from: Specified Dimension or Average Brick Size in Job Lot Sample, in. (mm)

Column A (for Specified Dimension)

Column B (for Average Brick Size in Job Lot Sample)1

Grade S

Grade SS

Grade S

Grade SS

3 (76) and under

1/16 (1.6)

1/16 (1.6)

1/16 (1.6)

1/16 (1.6)

Over 3 to 4 (76-102), inclusive

3/32 (2.4)

1/16 (1.6)

1/16 (1.6)

1/16 (1.6)

Over 4 to 6 (102-152), inclusive

1/8 (3.2)

1/16 (1.6)

3/32 (2.4)

1/16 (1.6)

Over 6 to 8 (152-203), inclusive

5/32 (4.0)

1/16 (1.6)

3/32 (2.4)

1/16 (1.6)

Over 8 to 12 (203-305), inclusive

7/32 (5.6)

1/16 (1.6)

1/8 (3.2)

1/16 (1.6)

Over 12 to 16 (305-406), inclusive

9/32 (7.1)

1/16 (1.6)

3/16 (4.8)

1/16 (1.6)

1. Lot size shall be determined by agreement between purchaser and seller. If not specified, lot size shall be understood to include all brick of one size and color in the job order.

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TABLE 7 Distortion Tolerances Maximum Permissible Distortion, in. (mm) Over 8 to 12 (306), inclusive

8 (204) and under

Over 12 to 16 (408), inclusive

ASTM Specification and Classification C 62 C 216

No limit

No limit

No limit

FBX

1/16 (1.6)

3/32 (2.4)

1/8 (3.2)

FBS

3/32 (2.4)

1/8 (3.2)

5/32 (4.0)

FBA C 652

As specified by the purchaser

HBX

1/16 (1.6)

3/32 (2.4)

1/8 (3.2)

HBS

3/32 (2.4)

1/8 (3.2)

5/32 (4.0)

HBA C 1088

As specified by the purchaser

TBX

1/16 (1.6)

3/32 (2.4)

1/8 (3.2)

TBS

3/32 (2.4)

1/8 (3.2)

5/32 (4.0)

TBA C 902 and C1272

As specified by the purchaser

PX

1/16 (1.6)

3/32 (2.4)

1/8 (3.2)

PS

3/32 (2.4)

1/8 (3.3)

5/32 (4.0)

PA

No limit.

C 126 C 1405

Special requirements – see ASTM C 126 SS

1/16 (1.6)

3/32 (2.4)

3/32 (2.4)

S

1/16 (1.6)

3/32 (2.4)

1/8 (3.2)

CSA Specification and Classification A82

X

(1.5)

(2.5)

(3.0)

S

(2.5)

(3.0)

(4.0)

A

As specified by purchaser, but not more restrictive than Type S (Rough)

Distortion. Permitted distortion, or warpage, of brick is listed in Table 7. The amount of distortion is based on the brick specification and face dimension. Distortion may be convex or concave and may be in the plane of the wall or perpendicular to it, as illustrated in Figure 1. Other terms for distortion are “bowed” or “banana” brick. A brick that is over the distortion limitations is difficult to lay and is easily noticeable in the brickwork.

Maximum Concave Edge

Maximum Convex Edge

Maximum

Average of 4 Corners Concave Surface

Convex Surface

Figure 1 Distortion Measurements

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Chippage. Brick may be damaged or chipped during packaging, shipping or on the job site. Limitations to the size and number of chips on individual brick are listed in Table 8. The amount of chippage is based upon the brick specification and classification. A delivery of brick may contain up to 5 percent broken brick or brick chipped beyond the limits in Table 8. The chippage requirements in Table 8 are based on the remaining 95 percent of the shipment. The chips are measured from an edge or a corner, and the total length of these chips may not be greater than 10 percent of the perimeter of the face of the brick. Chips are more noticeable on brick that have a surface color different from the body of the brick. Chips on “through-body” color brick are less noticeable. TABLE 8 Maximum Permissible Range of Chippage1 Specification and Type or Application ASTM C 216

ASTM C 652

FBX

HBX

TBX

—

—

X

FBS2

HBS2

TBS2

—

—

FBS3

HBS3

TBS3

—

TBA

PA

FBA

ASTM ASTM ASTM C 1088 C 902 C 1272

HBA HBB

—

—

—

PS

—

—

—

PX

Chippage in From Edge, in. (mm)

Corner, in. (mm)

95 to 100%

0 to 1/8 (0 to 3.2)

0 to 1/4 (0 to 6.4)

S2

90 to 100%

0 to 1/4 (0 to 6.4)

—

S3

85 to 100%

PA4

A

PS PX —

CSA A82

Percent Allowed

Percent Allowed

Chippage in From Edge, in. (mm)

Corner, in. (mm)

5% or less

1/8 to 1/4 (3.2 to 6.4)

1/4 to 3/8 (6.4 to 9.5)

0 to 3/8 (0 to 9.5)

10% or less

1/4 to 5/16 (6.4 to 7.9)

3/8 to 1/2 (9.5 to 12.7)

0 to 5/16 0 to 1/2 (0 to 7.9) (0 to 12.7)

15% or less

5/16 to 7/16 (7.9 to 11.1)

1/2 to 3/4 (12.7 to 9.1)

As specified by the purchaser5

—

100%

5/16 (7.9)

1/2 (12.7)

—

—

—

—

100%

1/4 (6.4)

3/8 (9.5)

—

—

—

1. There are no chippage requirements for C 62, C 126 or C 1405. 2. Extruded brick with unbroken natural die finish face and dry-pressed brick. 3. Extruded brick with finished face sanded, combed, scratched, scarified, or broken by mechanical means such as wire cutting or wire brushing, and molded brick. 4. No limit. 5. Not more restrictive than FBS (Textured) in C 216 or HBS (altered).

ADDITIONAL REQUIREMENTS Void Area In ASTM standards brick are generally classified as solid or hollow. A solid brick is defined as a unit whose net cross-sectional area in every plane parallel to the bearing surface is 75 percent or more of its gross cross-sectional area measured in the same plane. Thus, a solid brick has a maximum coring or void area of 25 percent. A hollow brick is defined as a unit whose net cross-sectional area in every plane parallel to the bearing surface is less than 75 percent of its gross cross-sectional area measured in the same plane. A hollow brick has a minimum coring or void area greater than 25 percent, and a maximum of 60 percent. Brick are cored or frogged at the option of the manufacturer. Cores. Holes in brick less than or equal to 1½ square inches (9.68 cm2) in cross-sectional area, referred to as cores, are used to aid in the manufacturing process and shipping of brick. The cores permit better utilization of raw materials, create more uniform drying and firing of the brick, reduce the amount of fuel necessary to fire the brick and reduce shipping costs by reducing weight. Additional advantages, such as aiding in mechanical bond in a wall, easier laying of the brick, etc., also may result from brick manufactured with cores. Cores are found only in brick manufactured by the extrusion or dry-press process. Limits to the amount of coring allowed in brick, the distance from a core to a face, and web thickness where applicable are listed in Table 9. www.gobrick.com | Brick Industry Association | TN 9A | Specifications for and Classification of Brick | Page 9 of 13

Cells. Cells are similar to cores except that a cell is larger in minimum dimension and has a cross-sectional area greater than 1½ square inches (9.68 cm2). Some requirements for cells are shown in Table 9. Additional requirements for cells can be found in ASTM C 652, C 126 and C 1405 and CSA A82. Frogs. Frogs are depressions in brick, usually located on one bed surface, and are included for the same reasons as cores and cells. Frogs are found in brick manufactured by the molded process. Panel frogs are limited to a specified depth and a specified distance from a face. Requirements for panel frogs are listed in Table 9. Deep frogs are depressions deeper than 3/8 in. (10 mm), and must conform to the requirements for coring, hollow spaces and void area of the applicable standard. The Canadian Standards Association takes a different approach. CSA A82 defines a solid brick as one without cores, cells or frogs deeper than 3/8 in. (10 mm); cored brick as those of which the net cross-sectional area in any plane parallel to the bed face shall be at least 75 percent of the gross cross-sectional area measured in the same plane; and hollow brick as brick whose net cross-sectional area in a plane parallel to the bed face is not less than 40 percent and not more than 75 percent of its gross cross-sectional area measured in the same plane. Further, there is a required minimum dimension of 1/2 in. (6 mm) between cores; 1 in. (13 mm) between cells; and 3/4 in. (19 mm) to an edge from a core, cell or frog. TABLE 9 Requirements for Void Areas1

a

b c

A

f

h E

e g

Cores

Cells

a

A

b

c

E

e

f

g

h

in. (mm), min.

in.² (cm²), max.

in. (mm), min.

in. (mm), min.

in.² (cm²), max.

in. (mm), min.

in. (mm), min.

in. (mm), min.

in. (mm), min.

ASTM Specification

Void Area, %

C 62

< 25

3/4 (19.1)

—

3/4 (19.1)

3/8 (9.5)

No Requirements for Cells

C 216

< 25

3/4 (19.1)

—

3/4 (19.1)

3/8 (9.5)

No Requirements for Cells

H40V

> 25, ≤ 40

5/8 (16)

≤ 1½ (9.68)

5/8 (16)

3/8 (9.5)

< 1½ (9.68)

3/4 (19.1)

3/4 (19.1)

1/2 (13)

—

H60V3

> 40, ≤ 60

5/8 (16)

≤ 1½ (9.68)

5/8 (16)

3/8 (9.5)

> 1½ (9.68)

3/4 (19.1)

3/4 (19.1)

1/2 (13)

—

1/2 (13)5

1/2 (13)

C 6522 C 1088

—

No Requirements for Cores, Frogs or Cells

C 902

—

No Requirements for Cores, Frogs or Cells

C 1272

—

C 1264

C 14052

1. 2. 3. 4. 5.

Frogs

Cores and Cells Not Permitted No Requirements for Cores or Frogs

—

> 1½ (9.68)

3/4 (19.1)

3/4 (19.1)

Solid

≤ 25

3/4 (19.1)

—

3/4 (19.1)

3/8 (9.5)

H40V

> 25, ≤ 40

5/8 (16)

1½ (9.68)

5/8 (16)

3/8 (9.5)

> 1½ (9.68)

3/4 (19.1)

3/4 (19.1)

1/2 (13)

—

H60V3

> 40, ≤ 60

—

5/8 (16)

1½ (9.68)

5/8 (16)

3/8 (9.5)

1½ (9.68)

3/4 (19.1)

3/4 (19.1)

1/2 (13)

No Requirements for Cells

Deep frogs shall meet coring requirements of the applicable specification (see ASTM C 62, C216, C 652 and C 1405). Cored-shell and double-shell hollow brick shall meet additional coring requirements of applicable specification in ASTM C 652 and C 1405. Based on 3 in. (76 mm) and 4 in. (102 mm) nominal width (for larger dimensions see C 652 and C 1405). Cells shall meet additional requirements of ASTM C 126. Web thickness in cored brick shall meet additional requirements of ASTM C 126.

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Efflorescence Efflorescence is a crystalline deposit of water-soluble salts that can form on the surface of some brickwork. The principal objection is an unsightly appearance, though it typically is not harmful to brick. The test for efflorescence is described in ASTM C 67 and CSA A82. Brick tested under C 67 are given a rating of “effloresced” or “not effloresced.” The specifier must invoke this part of the standard for the requirement of “not effloresced” to apply. CSA A82 also includes a rating of “slightly effloresced,” and it is this rating that must be met if efflorescence testing is invoked. Requirements on efflorescence are not included in C 62 and C 126.

Strength Brickwork may be used as a structural material, so there may be instances when it is important to specify a minimum compressive strength of the brick. This possibility is noted in ASTM C 62, C 216, C 652 and C 1405. Most brick have compressive strengths considerably higher than the minimum compressive strengths required for durability and abrasion resistance.

Initial Rate of Absorption The initial rate of absorption (IRA) is a measure of how quickly the brick will remove water from mortar spread on it. IRA is not a qualifying property or condition of brick in the ASTM or CSA specifications. IRA values may be of interest when selecting mortar and in use of the brick on the jobsite. If the purchaser wishes to learn the IRA of the brick, the IRA test must be requested. Initial rate of absorption information is included in ASTM C 62, C 216, C 652 and C 1405.

Sampling and Testing All brick under ASTM specifications are sampled and tested in accordance with ASTM C 67. The purchaser designates the place of selection of the brick for testing when the order is placed. Brick for efflorescence testing must be sampled at the point of manufacturer. This is because the brick may be contaminated by efflorescing materials after leaving the brick plant. Brick are sampled and tested for compliance to their specification prior to use. ASTM C 126 and C 1405 include additional tests for properties of the glaze. These are described in the following section on Glazed Brick. CSA A82 includes sampling and test methods as part of the standard.

Facing Brick, ASTM C 216 and CSA A82 An additional tolerance is found in the ASTM standard for solid facing brick specification and in CSA A82. The amount that the exposed face of a brick can be “out-of-square” is limited. This is more critical as brick height increases. The maximum permitted dimension for out-of-square of the exposed face of the brick in C 216 is 1/8 in. (3.2 mm) for Type FBS brick and 3/32 in. (2.4 mm) for Type FBX brick. Tolerances on out-of-square for Type FBA brick shall be specified by the purchaser. CSA A82 contains similar requirements: Type S of 3.0 mm and Type X of 2.5 mm. Tolerances on out-of-square for Type A brick shall be specified be specified but shall not be more restrictive than for Type S (Rough) brick.

Paving Brick, ASTM C 902 and C 1272 Not only must paving brick conform to the physical properties required in Table 4, but they also must have additional alternatives for durability and must meet requirements for abrasion resistance. Alternative Performance Requirements. If information on the performance of brick in a pavement subject to similar exposure and traffic conditions is documented, then the physical property requirements in Table 4 may be waived. This is identified as the Performance Alternative. An optional test for the freeze and thaw test is ASTM C 88 Test Method for Soundness of Aggregates by Use of Sodium Sulfate. The sulfate soundness test, like the freeze and thaw test, is not required unless the paving brick do not meet the saturation coefficient and absorption requirements.

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Abrasion Resistance. Since paving brick are used in a horizontal application and are exposed to traffic, they must meet a specified abrasion limit. Pedestrian and light traffic paving brick (C 902) are assigned a Type by the traffic or abrasion expected. Type I pavers are exposed to extensive abrasion, such as driveways or public entries. Type II pavers are exposed to high levels of pedestrian traffic, such as in stores, restaurant floors or exterior walkways. Type III pavers are exposed to light pedestrian traffic, such as floors or patios in homes. Heavy vehicular paving brick (C 1272) are assigned a Type depending on their intended installation. Type R pavers are intended to be set in a mortar or asphalt setting bed supported by an adequate base. Type R pavers must be at least 2¼ in. (57.2 mm) thick. Type F pavers are intended to be set in a sand setting bed, with sand joints, and supported by an adequate base. Type F pavers must be at least 2⅝ in. (66.7 mm) thick. The abrasion requirements are the same for Type F and Type R pavers. The abrasion resistance index can be determined in either of two ways: 1) by dividing the absorption by the compressive strength and multiplying by 100, or 2) by determining the volume abrasion loss in accordance with ASTM C 418 Test Method for Abrasion Resistance of Concrete by Sandblasting. The abrasion requirements are listed in Table 10. TABLE 10 Abrasion Resistance Requirements for Pavers ASTM Specification C 902 Pedestrian and Light Traffic Paving Brick C 1272 Heavy Vehicular Paving Brick

Traffic Type

Abrasion Index, Max.

Volume Abrasion Loss, Max. (cm3/cm2)

Type I

0.11

1.7

Type II

0.25

2.7

Type III

0.50

4.0

Types F and R

0.11

1.7

Glazed Brick, ASTM C 126 and C 1405 ASTM C 126 and C 1405 are specifications for glazed brick and contain requirements for properties of the glaze. These properties include imperviousness, opacity, resistance to fading, resistance to crazing, flame spread, fuel contribution and smoke density, toxic fumes, hardness, and abrasion resistance.

SUMMARY This Technical Note identifies brick specifications used in the United States and Canada. Classification designations for each brick specification and the criteria used to qualify for them are explained. Potential performance issues can be minimized by designating the proper brick specification and applicable classifications based on the environmental and service conditions of the project. The information and suggestions contained in this Technical Note are based on the available data and the experience of engineering staff and members of the Brick Industry Association. The information contained herein should be used in conjunction with good technical judgment and a basic understanding of the properties of brick masonry. Final decisions on the use of the information discussed in this Technical Note are not within the purview of the Brick Industry Association and must rest with the project architect, engineer and owner.

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REFERENCES 1. Annual Book of ASTM Standards, ASTM International, West Conshohocken, PA 2006: Volume 04.02 – Concrete and Aggregate ASTM C 88 Test Method for Soundness of Aggregates by Use of Sodium Sulfate ASTM C 418 Test Method for Abrasion Resistance of Concrete by Sandblasting Volume 4.05 – Chemical Resistant Nonmetallic Materials; Vitrified Clay Pipe; Concrete Pipe; Fiber-Reinforced Cement Products; Mortars and Grouts; Masonry; Precast Concrete C 32, Standard Specification for Sewer and Manhole Brick (Made From Clay or Shale) C 62, Standard Specification for Building Brick (Solid Masonry Units Made From Clay or Shale) C 67, Standard Test Methods for Sampling and Testing Brick and Structural Clay Tile C 126, Standard Specification for Ceramic Glazed Structural Clay Facing Tile, Facing Brick, and Solid Masonry Units C 216, Standard Specification for Facing Brick (Solid Masonry Units Made from Clay or Shale) C 279, Standard Specification for Chemical-Resistant Masonry Units C 410, Standard Specification for Industrial Floor Brick C 652, Standard Specification for Hollow Brick (Hollow Masonry Units Made from Clay or Shale) C 902, Standard Specification for Pedestrian and Light Traffic Paving Brick C 1088, Standard Specification for Thin Veneer Brick Units Made from Clay or Shale C 1261, Standard Specification for Firebox Brick for Residential Fireplaces C 1272, Standard Specification for Heavy Vehicular Paving Brick C 1405, Standard Specification for Glazed Brick (Single Fired, Brick Units) 2. Borchelt, J. G., Danforth, L.. Jr., and Hunsicker, R., “Specifying Brick: Getting what you want for appearance and function,” The Construction Specifier, Construction Specifications Institute, Alexandria, VA, January 2006, pp. 20-28. 3. CSA A82, Fired Masonry Brick Made from Clay or Shale, Canadian Standards Association, Mississauga, Ontario, Canada, 2006.

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Technical Notes 9B - Manufacturing, Classification, and Selection of Brick, Selection, Part 3 Revised December 2003 Abstract: This Technical Notes addresses the selection of brick. Evaluation of the properties and applications of brick determines the durability, appearance, and impression of a project. Information is provided regarding aesthetics, cost and availability. Key Words: abrasion, absorption, aesthetics, availability, brick, color, compressive strength, cost, durability, size, texture. INTRODUCTION The selection of brick is important in that it determines a project's durability and appearance, and results in a lasting impression. It is necessary to identify which qualities and properties of brick are appropriate to consider in selecting a brick. Brick with a wide variety of strength, color, texture, size, shape and cost are available. The owner or designer must decide which characteristics of brick are most critical. This selection process can dictate the success of any project. This Technical Notes addresses the properties and characteristics which must be considered in the selection of the appropriate brick for a project. Other Technical Notes in this series provide the fundamentals of brick manufacturing and classification of brick. GENERAL Brick selection is based on a number of factors. Not only are aesthetics and durability important, but strength, absorption, availability and cost are important to the owner, designers and contractors. The selection process can be difficult since each group is trying to satisfy different requirements. Typically, the final selection is based on a compromise from all parties involved. Aesthetics The use of brick as a building material dates back centuries. Because of brick's enduring qualities and limitless appearances, designers can satisfy their creative styles with brick. Brick is readily available in many sizes, colors, textures and shapes. These can be adapted to achieve virtually any desired style or expression. A variety of common brick sizes are shown in Figure 1. Brick's small module can be related to the scale of the wall. These sizes can be combined in such a way as to create different appearances and patterns. Not only does brick size influence scale and appearance, but the size of brick influences wall cost because larger units require fewer brick, normally resulting in less labor. When specifying the size of units, dimensions should be listed in the following order: thickness (width) by height by length.

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Brick Sizes (Nominal Dimensions) FIG. 1 Brick manufacturers also offer a wide variety of colors to choose from. Units whose colors range from reds and burgundies to whites and buffs are manufactured today. Many manufacturers produce over 100 colors. Many of these color variations are created during the firing process. Temperature variations and the order in which the units are stacked in the kiln determine shades of light and dark. Ceramic glazes, slurries or sand coatings can be applied to the surface to achieve colors not possible with some clays. The possibilities of using units of contrasting colors in bands or other patterns are endless. Sample panels, or mockups, can aid in selecting the desired color by showing the finished appearance. Another aesthetic feature to consider when selecting brick is the texture. Textures on brick can be smooth, wirecut (velour), stippled, tumbled, brushed, rolled, and more. The texture interacts with light and creates differing and interesting shadows. Unique design features can easily be achieved by using special brick shapes. Brick can be molded and formed into any shape, from simple sloped sill shapes to fancy watertable brick. For most manufacturers, molded shapes are easier to produce than extruded shapes, because the molded, or soft-mud process is more adaptable to making brick shapes than the extruded process. Making very large shapes can be difficult in either process because of problems with proper drying and firing. Physical Properties There are many physical properties which may influence the selection of brick. Some of these include durability, absorption, compressive strength and abrasion resistance. This Technical Notes will provide a basic understanding of these properties to aid in selection of the proper brick. Physical properties required for proper performance are given in the appropriate American Society for Testing and Materials (ASTM) specification for brick. Durability. Currently, there are two accepted methods for demonstrating durability under ASTM standards: 1) durability as predicted by compressive strength, absorption, and saturation coefficient, or 2) durability as determined by compressive strength and passing 50 cycles of the freeze and thaw test. Criteria in each ASTM specification determine grade or class designations. Because of the varying climates and applications of brick, specific physical properties are required. Brick are classified into these grades or classes according to their resistance to freezing when wet. Table 1 gives the recommended grade of facing, building and hollow brick, based on weathering index and exposure. Fig. 2 indicates the approximate weathering indices of areas across the U.S. Technical Notes 9A describes this in more detail. Most manufacturers make brick to meet the designation for the most severe weathering exposure, SW or SX, so they

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may ship brick to all parts of the country. Some manufacturers produce brick complying only with the designation for moderate weathering, MW or MX. Grade NW or NX brick are typically confined to interior applications, or where they are protected from water absorption and freezing. Brick manufacturers can furnish certification that their product will meet a certain grade or class.

Weathering Indices in the United FIG. 2

States

Absorption. Absorption can be broken into two distinct categories - absorption and initial rate of absorption (IRA). Both are important in selecting the appropriate brick. Absorption of a brick is expressed as a percentage, and defined as the ratio of the weight of water that is taken up into its body divided by the dry weight of the unit. Water absorption is measured in two ways: 1) submerging the test specimen in room temperature water for a period of 24 hours, and 2)

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submerging the test specimen in boiling water for five hours. These are known as the 24 hour cold water absorption, and the 5 hour boiling water absorption, respectively. These two are used to calculate the saturation coefficient by dividing the 24 hour cold water absorption by the 5 hour boiling. The saturation coefficient is used to help predict durability. The initial rate of absorption (IRA) or suction is the rate of how much water a brick draws (sucks) in during the first minute after contact of the bed surface with water. The suction has a direct bearing on the bond between brick and mortar. It has been shown by test results that when a brick has high suction (over 30 grams/min/30 in2 [30 2 grams/min./194 cm ]), a strong, watertight joint may not be achieved. Therefore, high suction brick should be wetted prior (3 hrs to 24 hrs) to laying to reduce the suction and allow the brick's surface to dry. Very low suction brick should be covered and kept dry on the jobsite. Brick manufacturers can furnish values of IRA and saturation coefficient of the selected units. The material specifier or supplier should inform the mason contractor about the suction of the brick prior to construction. Compressive Strength. The strength of a unit is used to determine durability and also compressive strength of the resulting brick masonry. Typically, most materials are judged on the basis of strength. However, it is important not to sacrifice properties of durability and bond for higher compressive strengths. Most brick currently produced have strengths ranging from 3,000 psi (20.7MPa) to over 20,000 psi (138 MPa), averaging around 10,000 psi (68.9 MPa). Achieving sufficient compressive strength with brick is seldom a problem. Abrasion Resistance. This property is important when brick is used as paving. The resistance to abrasion is affected by the degree of firing and by the nature of the raw material. Abrasion resistance is predicted in two manners. It is evaluated in terms of cold water absorption and compressive strength. These two properties produce an abrasion index which is used to determine the type of traffic which is suitable for a particular brick. Alternately, volume loss is determined by sand blasting the paver surface. Application A building must perform the functions for which it is designed. The materials selected for a project must also perform as intended. The designer must consider all factors which a wall or material must withstand. Some of the more important factors include moisture penetration, temperature variations and structural loads. No one standard assembly is suitable for all localities, occupancies, or designs; therefore, the designer must evaluate each factor and its relative effect on the selection of a material or assembly. Moisture Penetration. The use of quality materials and workmanship is essential in obtaining a satisfactory degree of water resistance. When water passes through brick masonry walls, it invariably does so through separations or cracks between the brick units and the mortar. It is virtually impossible for significant amounts of water to pass directly through a brick unit. Therefore, brick units which develop a complete bond with mortar offer the best moisture resistance. Brick and mortar properties should be compared to provide compatible materials which result in more watertight walls. Currently, there are no requirements for the degree of water resistance of a wall. Temperature Variations. Brick must withstand daily temperature cycles and seasonal extremes (-30°F to 120°F [-34°C to 49°C]) depending on location, throughout its life. Thermal expansion and contraction of brick is not critical to the selection of brick, but it is important to designers and this movement should be provided for in design and construction. Brick also withstands temperature extremes in fires. Since brick is a fired material, it will not burn and acts as an excellent barrier to fire because it is non-combustible. Structural Loads. Ability to withstand either gravity or lateral loads relies heavily on brick strength, mortar strength and dimensions of the wall assembly. Compressive strength requirements found in the ASTM specifications for brick are based on durability performance. Structural analysis may require a higher compressive strength in order to resist the applied loads. Compressive strength of masonry may be a governing criterion in loadbearing or reinforced brick masonry projects. Cost Material selection is often based on cost, usually initial cost only. Although initial cost is important, lifecycle cost is a better tool for making critical decisions. When deciding between different materials, all costs involved including labor and maintenance costs, future value and life expectancy should be considered. The selling price of brick is governed by many factors, including manufacturing methods and appearance of the unit.

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When considering different brick, one must take into account shipping costs. Since most prices quoted are plant prices, distance between the manufacturing plant and the jobsite is a major determinant of these shipping costs. Brick manufacturers and distributors can supply brick prices and shipping prices. Brick price is only one part of the in-place costs. Labor and overhead costs are approximately twice the brick and mortar costs. Many of the Masonry Institutes throughout the country provide cost comparisons between different materials. Availability The availability of brick fluctuates with the time of the year and current construction trends and demands. On the average, brick production time runs about 5 days, from pugging of the clay to the finished, fired product. This can change depending on many factors such as variations in raw materials, forming process, and kiln types. Many brick manufacturers have stockpiles of brick, but usually only a small quantity of each brick type. This may satisfy smaller jobs, but for large projects requiring large quantities of brick, a special production run must be made for the job. Most manufacturers have a set schedule as to when they produce a certain brick shade. It is at this time that the size of the run will be increased to accommodate the large order. It is wise to determine the brick's availability from the manufacturer. It is best to purchase all brick from the same production run because there are typically slight color variations between runs. All manufacturers have quality controls to keep this at a minimum.

SUMMARY This Technical Notes has described which characteristics of brick are important in selecting a particular unit. There is a wide selection of brick from which to choose. Selecting the appropriate material is important to the project's longevity and appearance. The remainder of this Technical Notes is "Recommended Practices Relating to the Responsibilities and Relationships in Brick Construction". This document, developed jointly by the Brick Industry Association and the Mason Contractors Association of America, explains some potential problems that may occur during and after the selection process, and how to avoid them. The information and suggestions contained in this Technical Notes are based on the available data and the experience of the technical staff of the Brick Industry Association. The information and recommendations contained herein must be used along with good technical judgment and a basic understanding of the properties of brick masonry. Final decisions on the use of the information discussed in this Technical Notes are not within the purview of the Brick Industry Association and must rest with the project architect, engineer and owner. REFERENCES More detailed information on subjects discussed here can be found in the following publications: 1. Brick Industry Association Technical Notes 7 Series - Water Resistance of Brick Masonry 2. ASTM Standard Specifications for Brick.

Most brick construction projects are completed with the result that the building owner, architect, general contractor, mason contractor, brick distributor, and brick manufacturer are completely satisfied with the final product. On rare occasions, however, a mistake is made or a misunderstanding occurs that spoils what would otherwise be a rewarding and profitable experience for all concerned. Recognizing this fact, representatives from the manufacturing, sales and distribution, and installation segments have

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developed these “Recommended Practices” which identify the areas in which misunderstandings are most likely to occur and suggest procedures to be followed that will minimize the effects when mistakes do occur. The “Recommended Practices Relating to the Responsibilities and Relationships in Brick Construction” was developed through the cooperative efforts of the Brick Industry Association and the Mason Contractors Association of America. Draft copies of the complete document were distributed to other construction industry associations for review and, where appropriate, their advice was included in these final “Recommended Practices”. INTRODUCTION The purpose of these recommended practices is to prevent misunderstandings that might result from improper sampling procedures, ordering, or examination of the field work. As in all business relationships, there are responsibilities among all parties involved - manufacturers, distributors, general contractors, mason contractors, construction managers, architects, engineers, owners and/or their respective representatives or agents - in producing an acceptable masonry project. It is to the mutual advantage of all concerned that problems, when encountered, be identified and addressed in a timely manner. Contract Allowances The practice of using only dollar value allowances for brick in construction documents is not recommended because this method does not provide sufficient information to make an informed bid. Items such as special shapes often are too complicated to use an allowance. However, if an allowance is used, the following variables should be included: unit specification (ASTM standard), grade, type and size (width by height by length). The construction documents should clearly state whether taxes, delivery, handling, and/or installation are included in the allowance. In the initial establishment of an allowance, the parties should take into consideration the extra cost of special shapes and any other special units required by the project. Ordering All brick orders should be submitted in writing by the purchaser to the distributor or manufacturer, whichever is appropriate. The order should include and clearly identify the following: A. Job name and type; B. Location; C. Owner; D. Architect; General contractor and/or mason contractor; E. F. Material quantities, including types and quantities of special or non-standard items, should be accurately determined so that the order may be shipped in its entirety. Brick should be described by specified dimensions (width by height by length) rather than by generic or trade name; G. Unit prices, including conditions such as escalation of prices, freight rates and terms; H. Delivery schedules, including anticipated start date and quantity of each shipment; Other information pertinent to the order, such as a copy of that portion of the specifications which applies to the I. brickwork. If special shapes are required, detailed large-scale drawings should be supplied by the purchaser through appropriate channels at the earliest possible time. Most orders are processed through a chain of purchasing which begins with the signing of the owner-general contractor agreement and ends with the receipt of an order by the manufacturer. Other parties may be involved in this process as intermediaries or secondary parties, including, among others, the owner's representative, the general contractor, the mason contractor and the distributor. Each party in the chain should endeavor to promptly process the order and give approvals as necessary so as to cause minimal delays in the schedule of the project. Upon receipt of the order, the manufacturer typically acknowledges the order and should promptly advise the parties through the chain of purchasing about any unacceptable or impractical terms. The acknowledgement should then be thoroughly scrutinized by the responsible parties. It should also be understood by all parties that by the placement of a written order the purchaser incurs the specific payment responsibility for all special and/or non-standard items.

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Certificates and Testing Contract documents may require a letter of certification from the manufacturer to verify that the quality and characteristics of the brick meet ASTM standards. Test reports from an independent testing laboratory, supplied by the manufacturer, should be considered current if they are 24 months old or less. The cost of such tests is borne by the seller. If testing of the production run that is intended for shipment to the project is required, the cost of testing is typically borne as follows: if the results of the tests show that the brick do not conform to the requirements of the product specification, the cost is typically borne by the seller; if the results of the tests show that the brick conform to the requirements of the products specification, the cost is typically borne by the purchaser. The cost of any additional testing is typically borne by the purchaser. All testing shall be done in accordance with ASTM procedures and specifications. Selection and Sampling Brick is subject to variations in color between production runs and occasionally within the same run. Modern manufacturing processes encompass the use of automatic equipment, which may also result in minor differences in color and texture of the brick. The selection of the size, color, texture and type of brick is the responsibility of the owner and/or owner's representative. Usually, small samples are used for the preliminary selection and may not exactly represent the complete range of colors and textures encountered in production runs. Sometimes, a small sample is sufficient for determining the final selection. However, when large quantities of brick are to be erected, the prudent owner, general contractor, mason contractor, distributor and/or manufacturer should direct or request that the final selection be made from a field panel (also known as a field sample or mock-up). A field panel is typically constructed as a freestanding element that will later be torn down when the project is complete. Usually, a quantity of brick equal to 100 modular-size brick (approximately 15 square feet) will be used for the construction of the freestanding field panel. If an owner or the owner's representative requires the field panel, the distributor or manufacturer may not have control over the actual erection that is frequently performed by a mason contractor. The party or parties who have control over the work of the mason contractor (either by direct contract or by other powers) should take appropriate action during the erection of the field panel to assure that no additions or deletions are made to the brick supplied by the distributor and manufacturer, unless written approval has been received from the manufacturer for such a change. Field panels should be constructed from the production run that is intended for shipment to the project. In the event that the field panel has to be constructed for inspection and final selection before the production run for that project, the owner and the manufacturer should agree in writing upon such a use. The manufacturer may reserve the right to resample from the actual run before shipment commences. The owner or owner's representative should inspect and approve the new panel. When the field panel has been formally approved, it is the manufacturer's responsibility to provide brick as represented in the field panel. A strap or control sample may be retained at the plant. Typically, the general contractor and mason contractor are responsible for preserving and maintaining the integrity of the field panel which is considered the project standard for bond, mortar, workmanship and appearance and as the standard for comparison until the masonry has been completed and accepted by the owner or the owner's representative. If the owner or owner's representative elects not to have a field panel erected, the first 100 square feet of actual construction shall serve as the field panel. Inspection and Examination The general contractor or mason contractor normally receives the brick when they are delivered to the job site. The general contractor or mason contractor should properly protect the brick from the weather and damage. It is critical that the contractor inspect the brick before they are placed in the wall. If there are any discrepancies, the manufacturer or distributor should be notified immediately. The owner or the owner's representative is responsible for acceptance of the work and, therefore, should inspect, as necessary, while the work progresses. This is especially critical at the start of the project to ensure that the color, texture and workmanship are representative of the field panel and are acceptable.

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The selling party, whether the manufacturer or distributor should visit the job site, as necessary, and, in addition, should be available for meetings and consultation in the event the owner or the owner's representative discovers a problem. In the event the work does not meet with the approval of the owner or the owner's representative, the owner should immediately notify the general contractor, and appropriate action should be taken to correct the problem. If necessary, this may require that the work be stopped and that all interested parties meet to resolve the problem. References Brick Industry Association, 11490 Commerce Park Dr., Reston, VA 20191, (703) 620-0010, www.gobrick.com. Mason Contractors Association of America, 33 S. Roselle Rd., Schaumburg, IL 60193, (800) 536-2225, www.masonryshowcase.com.

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TECHNICAL NOTES on Brick Construction 10 1850 Centennial Park Drive, Reston, Virginia 20191 | www.gobrick.com | 703-620-0010

February 2009

Dimensioning and Estimating Brick Masonry Abstract: This Technical Note presents information for determining the basic layout of brick masonry walls, including both structural and veneer applications. Modular and non-modular brick masonry is discussed, including overall dimensioning of masonry walls using various brick unit sizes. Finally, guidelines are presented to aid the designer in estimating the amount of materials needed for brick masonry. Key Words: actual dimension, construction, estimating, modular masonry, nominal dimension, size, specified dimension.

SUMMARY OF RECOMMENDATIONS: Brick and Mortar Joint Sizes:

• Specify brick using standardized nomenclature and specified size (width by height by length) • For modular brick, specify mortar joint thicknesses such that when added to the specified brick size, the intended modular dimensions result • When possible, select brick size to minimize cutting

Bond Pattern:

• Select one-half running bond for applications when brick width is one-half of brick length; select one-third running bond when brick width is one-third of brick length

Dimensioning:

• When using modular brick sizes, use multiples of brick dimension plus mortar joint to determine nominal dimensions • For horizontal dimensions of elements longer than four

brick lengths, use nominal dimensions as intended constructed dimensions • When nominal dimensions are used on plans but are not intended to be used for construction, note plans accordingly

Estimating: • Use wall area method and tables to determine number of brick and quantity of mortar per wall area • Modify brick estimates for bond pattern, breakage and waste • Modify mortar estimates for bond pattern, collar joints and waste • Include partial brick in estimates to maintain bond at corners • Determine approximate mortar material quantities based on brick size and bond pattern

INTRODUCTION Brick are made in a number of sizes and laid in a variety of patterns. Most patterns of brickwork will adhere to a common module that facilitates the dimensioning of the brickwork and any masonry openings. Generally, designers can minimize the number of cuts of whole brick by dimensioning to a module. Knowing the size of the brick and bond pattern will allow an estimate of the number of brick and amount of mortar needed for the project. This Technical Note presents information to help the designer to choose a brick size, lay out modular dimensions using the chosen size, and develop a materials estimate for brick and mortar.

Metric Measurements Throughout this Technical Note, dimensions are based on the inch-pound system with conversions given for the metric system. The measurements and dimensions correspond to brick manufactured primarily in the United States to a typical module of 4 in. (102 mm). Brick manufactured for projects requiring metric dimensions typically conform to a module of 100 mm (3.94 in.). Although the principles presented here are the same for either system, care should be used when using the conversions given here for metric modular units and construction.

BRICK SIZES Brick is a building material with a human scale. Brick sizes have varied over the centuries but have always been similar to present-day sizes. Some sizes were developed to meet specific design, production or construction needs. For example, larger brick were developed to increase bricklaying economy, and thinner brick help conserve resources. © 2009 Brick Industry Association, Reston, Virginia

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Brick Orientation A brick has three dimensions: width (sometimes referred to as thickness), height and length. Although brick can be laid in six different orientations (see Figure 1), these dimensions as referenced apply to a brick laid as a stretcher. Height and length are sometimes called face dimensions, because these are the dimensions exposed when the brick is laid as a stretcher.

Stretcher

Soldier

Header

Rowlock Stretcher

Sailor

Rowlock

Brick Dimensions There are three different sets of dimensions used with brick: nominal, specified and actual. Each must be used with care and accuracy to avoid confusion during design and construction.

Exposed faces shaded.

Nominal dimensions. Nominal dimensions apply Figure 1 to modular brick and are the result of the specified dimension of the brick plus the intended thickness of Brick Positions in a Wall its intended mortar joint. Generally, these dimensions will fall into “round” numbers to produce modules of 4 in. or 8 in. for imperial units or 100 mm for SI units. They are also a quick way to refer to a given brick size without having to include fractions.

Specified dimensions. Specified dimensions are the anticipated manufactured dimensions of the brick, without consideration for mortar, which are to be used in project specifications and purchase orders. They are also used by the structural engineer in rational design of brick masonry. In non-modular construction, only the specified dimensions are used; thus the absence of corresponding nominal dimensions in Table 2. Actual dimensions. Actual dimensions are the measurements of the brick as manufactured. Generally the actual dimensions will be within a tolerance of the specified dimensions. The allowable tolerances are dependent upon the type and size of the brick and are given within the applicable ASTM standard specifications, such as those in ASTM C216, Standard Specification for Facing Brick and C652, Standard Specification for Hollow Brick [Ref. 1].

Bond Pattern For most brick sizes, one-half running bond is the basic pattern when laying a wall or pavement; i.e., approximately half of the brick’s length overlaps the brick below. This pattern is the most frequently used pattern in homes, schools and offices. However, some sizes lend themselves best to other bond patterns. As an example, a utility-sized brick has a nominal length three times its nominal thickness. At corners, where the thickness of the wythe is exposed as the brickwork turns the corner, laying a one-half running bond with utility-sized brick would require cutting at least one brick in every course to maintain bond around the corner. So for utility-sized brick, onethird running bond is much easier to install. These two patterns, as well as some of the more historic patterns that use headers to tie together multiple wythes of masonry, are presented in greater detail in Technical Note 30.

Modular and Non-Modular Brick Modular brick are sized such that the specified dimension plus the intended mortar joint thickness equal a modular dimension. Generally, modular dimensions are whole numbers without fractions that result in modules of 4 in. or 8 in. for imperial units or 100 mm for SI units. A modular brick has a set of nominal, specified and actual dimensions as referenced above. A non-modular brick has a set of specified and actual dimensions but does not have nominal dimensions. Brick are available in many sizes and are referred to by many different names, depending on region. In addition, the name of a brick and its size, whether modular or non-modular, can vary depending on the manufacturer. Modular brick and their nominal and specified dimensions are shown in Table 1 and Figure 2. Non-modular brick and their specified sizes are shown in Table 2 and Figure 3. www.gobrick.com | Brick Industry Association | TN 10 | Dimensioning and Estimating Brick Masonry | Page 2 of 11

31/5"

22/3" 8"

4"

4"

8"

2”

Utility

Engineer Norman 4"

12"

6"

12"

4"

Norman

31/5"

12"

31/5"

12"

4"

Roman 4"

4"

22/3"

12"

4"

8"

4"

Closure Modular

8"

8"

6"

8"

4"

Engineer Modular

Modular

4"

4"

4"

12"

6"

12"

8"

8" 4"

22/3" 16"

16"

4"

16"

4"

4"

Double Meridian

Meridian

8" 4" 16"

6"

6-in. ThroughWall Meridian

4" 16"

8"

16"

8"

8-in. ThroughWall Meridian

Double ThroughWall Meridian

Figure 2 Modular Brick Sizes (Nominal Dimensions)

2 5/8" - 2 3/4"

2 3/4" 2 3/4" - 3"

7 5/8" - 8"

9 5/8" - 9 3/4"

2 3/4" - 3"

Queen

3"

8 5/8"

King 2 3/4" - 213/16"

21/4" 31/2"- 3 5/8"

2 5/8" - 2 3/4"

8"

Standard

31/2"- 3 5/8"

8"

Engineer Standard

31/2"- 3 5/8" 31/2"- 3 5/8"

8"

Closure Standard

Figure 3 Non-modular Brick Sizes (Specified Dimensions) www.gobrick.com | Brick Industry Association | TN 10 | Dimensioning and Estimating Brick Masonry | Page 3 of 11

Although a size not listed in Table 1 or Table 2 might be desired for a specific project, special sizes are typically avoided where possible in order to not increase costs unnecessarily. The use of specified dimensions when ordering and specifying brick is strongly recommended, since a brick name can vary from manufacturer to manufacturer, and a non-modular brick will not have nominal dimensions. To avoid confusion, specify brick using the stretcher position with width first, followed by height, then length. In other words, a modular brick would be specified as 3⅝ in. × 2¼ in. × 7⅝ in. (92 mm × 57 mm × 194 mm). TABLE 1 Modular Brick Sizes Nominal Dimensions, in. (mm)

Joint 3 Thickness, in. (mm)

4

Specified Dimensions, in. (mm) W

H

L

Vertical Coursing

⅜ (9.5) ½ (12.7)

3⅝ (92) 3½ (89)

2¼ (57)

7⅝ (194) 7½ (191)

3C = 8 in. (203 mm)

⅜ (9.5) ½ (12.7)

3⅝ (92) 3½ (89)

213⁄16 (71) 2¾ (70)

7⅝ (194) 7½ (191)

5C = 16 in. (406 mm)

⅜ (9.5) ½ (12.7) ⅜ (9.5) ½ (12.7) ⅜ (9.5) ½ (12.7) ⅜ (9.5) ½ (12.7)

3⅝ (92) 3½ (89) 3⅝ (92) 3½ (89) 3⅝ (92) 3½ (89) 3⅝ (92) 3½ (89)

3⅝ (92) 3½ (89) 5⅝ (143) 5½ (140) 7⅝ (194) 7½ (191) 1⅝ (41) 1½ (38)

7⅝ (194) 7½ (191) 7⅝ (194) 7½ (191) 7⅝ (194) 7½ (191) 11⅝ (295) 11½ (292)

1C = 4 in. (102 mm) 2C = 12 in. (305 mm) 1C = 8 in. (203 mm) 2C = 4 in. (102 mm)

12 (305)

⅜ (9.5) ½ (12.7)

3⅝ (92) 3½ (89)

2¼ (57)

11⅝ (295) 11½ (292)

3C = 8 in. (203 mm)

31⁄5 (81)

12 (305)

⅜ (9.5) ½ (12.7)

3⅝ (92) 3½ (89)

213⁄16 (71) 2¾ (70)

11⅝ (295) 11½ (292)

5C = 16 in. (406 mm)

4 (102)

4 (102)

12 (305)

2

6 (152)

31⁄5 (81)

12 (305)

2

6 (152)

4 (102)

12 (305)

2

8 (203)

4 (102)

12 (305)

4 (102)

2⅔ (68)

16 (406)

3⅝ (92) 3½ (89) 5⅝ (143) 5½ (140) 5⅝ (143) 5½ (140) 7⅝ (194) 7½ (191) 3⅝ (92) 3½ (89)

3⅝ (92) 3½ (89) 213⁄16 (71) 2¾ (70) 3⅝ (92) 3½ (89) 3⅝ (92) 3½ (89)

2

⅜ (9.5) ½ (12.7) ⅜ (9.5) ½ (12.7) ⅜ (9.5) ½ (12.7) ⅜ (9.5) ½ (12.7) ⅜ (9.5) ½ (12.7)

11⅝ (295) 11½ (292) 11⅝ (295) 11½ (292) 11⅝ (295) 11½ (292) 11⅝ (295) 11½ (292) 15⅝ (397) 15½ (394)

1C = 4 in. (102 mm) 5C = 16 in. (406 mm) 1C = 4 in. (102 mm) 1C = 4 in. (102 mm) 3C = 8 in. (203 mm)

Meridian

4 (102)

4 (102)

16 (406)

⅜ (9.5) ½ (12.7)

3⅝ (92) 3½ (89)

3⅝ (92) 3½ (89)

15⅝ (397) 15½ (394)

1C = 4 in. (102 mm)

Double Meridian

4 (102)

8 (203)

16 (406)

⅜ (9.5) ½ (12.7)

3⅝ (92) 3½ (89)

7⅝ (194) 7½ (191)

15⅝ (397) 15½ (394)

1C = 8 in. (203 mm)

6-in. Through-Wall Meridian

6 (152)

4 (102)

16 (406)

⅜ (9.5) ½ (12.7)

5⅝ (143) 5½ (140)

3⅝ (92) 3½ (89)

15⅝ (397) 15½ (394)

1C = 4 in. (102 mm)

8-in. Through-Wall Meridian

8 (203)

4 (102)

16 (406)

⅜ (9.5) ½ (12.7)

7⅝ (194) 7½ (191)

3⅝ (92) 3½ (89)

15⅝ (397) 15½ (394)

1C = 4 in. (102 mm)

Double ThroughWall Meridian

8 (203)

8 (203)

16 (406)

⅜ (9.5) ½ (12.7)

7⅝ (194) 7½ (191)

7⅝ (194) 7½ (191)

15⅝ (397) 15½ (394)

1C = 8 in. (203 mm)

1

Brick Designation

W

H

L

Modular

4 (102)

2⅔ (68)

8 (203)

Engineer Modular

4 (102)

31⁄5 (81)

8 (203)

Closure Modular

4 (102)

4 (102)

8 (203)

2

4 (102)

6 (152)

8 (203)

2

4 (102)

8 (203)

8 (203)

Roman

4 (102)

2 (51)

12 (305)

Norman

4 (102)

2⅔ (68)

Engineer Norman

4 (102)

Utility

—

—

— —

— —

2¼ (57)

1. Some manufacturers may use a brick designation different from that shown. 2. No brick designation is provided due to inadequate consensus among manufacturers. 3. Common joint sizes used with length and width dimensions. Actual bed joint thicknesses vary based on vertical coursing and actual brick height. 4. Specified dimensions may vary within this range from manufacturer to manufacturer.

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TABLE 2 Non-Modular Brick Sizes

Brick

Designation1

Queen King 2

—

Standard Engineer Standard Closure Standard

Joint Thickness,3 in. (mm) ⅜ (9.5) ½ (12.7) ⅜ (9.5) ½ (12.7) ⅜ (9.5) ½ (12.7) ⅜ (9.5) ½ (12.7) ⅜ (9.5) ½ (12.7) ⅜ (9.5) ½ (12.7)

Specified Dimensions,4 in. (mm) W

2¾ (70) 3 (76) 2¾ (70) 3 (76) 3 (76) 3⅝ (92) 3½ (89) 3⅝ (92) 3½ (89) 3⅝ (92) 3½ (89)

H

L

2¾ (70) 2⅝ (67) 2¾ (70) 2⅝ (67) 2¾ (70) 2¼ (57) 213⁄16 (71) 2¾ (70) 3⅝ (92) 3½ (89)

7⅝ (194) 8 (203) 9⅝ (244) 9¾ (248) 8⅝ (219) 8 (203) 8 (203) 8 (203)

Vertical Coursing 5C = 16 in. (406 mm) 5C = 16 in. (406 mm) 5C = 16 in. (406 mm) 3C = 8 in. (203 mm) 5C = 16 in. (406 mm) 1C = 4 in. (102 mm)

1. Some manufacturers may use a brick designation different from that shown. 2. No brick designation is provided due to inadequate consensus among manufacturers. 3. Common joint sizes used with length and width dimensions. Actual bed joint thicknesses vary based on vertical coursing and actual brick height. 4. Specified dimensions may vary within this range from manufacturer to manufacturer.

MODULAR MASONRY There are relationships between the width, height and length of brick that were developed as brick masonry construction began. The most common of these dimensional relationships are: • •

two brick widths plus one mortar joint equal one brick length, and three brick heights plus two mortar joints equal one brick length.

Because of greater ease in design and construction, the vast majority of contemporary brickwork uses modular-sized brick and modular dimensioning. The most common modular dimension system for brickwork utilizes a 4 in. (102 mm) grid. The 4 in. (102 mm) grid is used in modular coordination between brick and concrete masonry units [Ref. 1] and fits the modular dimensions of other construction materials.

Architect: DiMella Shaffer

Use of these relationships allows corners and openings in brick walls to be constructed with little waste and limited cutting of brick. These relationships allow rowlocks and headers to tie adjacent wythes together and courses of brick in different orientations to align vertically (see Photo 1). This has given rise to the rich variety of detailing that is part of the architectural vernacular of brickwork.

Photo 1 Dimensional Relationships

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Modular dimensions are sometimes called nominal dimensions, because they represent round numbers without accounting for the fractions of an inch represented by mortar joint thicknesses. For masonry elements, the relationship between modular dimensions and the actual dimensions constructed in the field can depend upon the overall length of the masonry element. For longer masonry wall lengths made of modular-sized brick and about four or more brick lengths long, the actual constructed length of the element often will be the modular dimension. This is possible because during construction, the mason typically will adjust the horizontal layout of the brick to allow slightly larger or smaller head joints so that the brickwork meets the required dimension. For shorter masonry wall lengths made of modular-sized brick and less than about four brick lengths long, the designer may want to consider the specified dimension of the brick and joint thickness when dimensioning the wall. This is because the amount of adjustment necessary to the thickness of head joints between brick will be larger. Additionally, the mason will adjust the number of courses and the bed joint thicknesses in order to meet fixed vertical dimensions. When the completed elevation is viewed, any slight deviation in mortar joint width or the number of courses generally is not obvious in the brickwork.

Overall Dimensioning The choice of whether nominal or specified dimensions are to be used on drawings is often determined by the type of information that the drawing provides. For drawings that cover large areas, such as elevations and floor plans, use of nominal dimensions is recommended. The overall intent and appearance of the project can be presented without the precision of specified dimensions. When nominal dimensions are used on plans, the drawings must be clearly noted to advise the mason of the intended actual size of the completed masonry elements. For drawings that provide specific information to other trades, those that coordinate the installation of materials, and for shop drawings, the use of specified dimensions is recommended. An easy manner to remember this is to use nominal dimensions for drawings in which the scale is smaller than ¼ in. per foot. Use specified dimensions for drawings shown in ¼ in. per foot and larger, Of course Computer Aided Drafting (CAD) and Building Information Modeling (BIM) programs often have the specified dimensions of the brick and mortar joint as input options. Thus, at the designer’s discretion, specified dimensions that utilize fractions can be used throughout the drawings to indicate the desired constructed dimensions of the brickwork. However, doing so involves fractions and may complicate the dimensioning process. Non-Modular Horizontal Dimensioning. Non-modular brick by definition do not conform to a 4 in. (203 mm) module. However, all non-modular brick of a certain size create a module equal to the sum of one brick length and one mortar joint width. This module can be used to establish modular dimensioning for the brickwork in a fashion similar to that used for modular brick. Non-modular brick that are approximately three times as long as they are wide are usually laid in one-third running bond. When laid in one-half running bond, brick near wall ends and openings must usually be cut to maintain the bond. Vertical Dimensioning. The vertical coursing of both modular and non-modular sized brick is similar. A certain number of courses will correspond to 4, 8, 12 or 16 in. (102, 203, 305 or 406 mm) in height. This dimension establishes the vertical modular grid used on the brickwork. For example, for a non-modular engineer standard brick, a vertical grid of 16 in. (406 mm) is used since five courses of brick equal 16 in. (406 mm). For a wall constructed of modular brick, a vertical grid is established by three courses (three brick and three mortar joints) equaling 8 in. (203 mm). Table 3 gives the vertical dimensions for numbers of courses (stretcher or header positions) and corresponding mortar joints using various sized brick, rounded to the nearest 1⁄16 in.

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TABLE 3 Vertical Coursing Vertical Coursing of Unit No. of Courses

2C = 4 in. (102 mm)

3C = 8 in. (203 mm) ft – in.

5C = 16 in. (406 mm) m

ft – in.

1C = 4 in. (102 mm)

ft – in.

m

m

ft – in.

m

1

0 2

0.051

0 211⁄16

0.068

0 33⁄16

0.081

0 4

0.102

2

0 4

0.102

0 55⁄16

0.135

0 6⅜

0.163

0 8

0.203

3

0 6

0.152

0 8

0.203

0 9⅝

0.244

1 0

0.305

4

0 8

0.203

0 1011⁄16

0.271

1

13

0.325

1 4

0.406

5

0 10

0.254

1 1 ⁄16

0.339

1 4

0.406

1 8

0.508

6

1 0

0.305

1 4

0.406

1 7 ⁄16

0.488

2 0

0.61

7

1 2

0.356

1 611⁄16

0.474

1 10⅜

0.569

2 4

0.711

8

1 4

0.406

1 95⁄16

0.542

2 1⅝

0.65

2 8

0.813

5

⁄16

3

9

1 6

0.457

2 0

0.61

2 4 ⁄16

0.732

3 0

0.914

10

1 8

0.508

2 211⁄16

0.677

2 8

0.813

3 4

1.02

3

13

11

1 10

0.559

2 5 ⁄16

0.745

2 11 ⁄16

0.894

3 8

1.12

12

2 0

0.61

2 8

0.813

3 2⅜

0.975

4 0

1.22

13

2 2

0.66

11

2 10 ⁄16

0.881

3 5⅝

1.06

4 4

1.32

14

2 4

0.711

3 1 ⁄16

0.948

3 8 ⁄16

1.14

4 8

1.42

15

2 6

0.762

3 4

1.02

4 0

1.22

5 0

1.52

16

2 8

0.813

3 611⁄16

1.08

4 33⁄16

1.3

5 4

1.63

17

2 10

0.864

3 9 ⁄16

1.15

4 6⅜

1.38

5 8

1.78

18

3 0

0.914

4 0

1.22

4 9⅝

1.46

6 0

1.83

19

3 2

0.965

4 211⁄16

1.29

5

13

1.54

6 4

1.93

20

3 4

1.02

4 5 ⁄16

1.36

5 4

1.63

6 8

2.03

21

3 6

1.07

4 8

1.42

5 73⁄16

1.71

7 0

2.13

11

5

5

5

5

13

⁄16

22

3 8

1.12

4 10 ⁄16

1.49

5 10⅜

1.79

7 4

2.24

23

3 10

1.17

5 15⁄16

1.56

6 1⅝

1.87

7 8

2.34

24

4 0

1.22

5 4

1.63

6 4 ⁄16

1.95

8 0

2.44

25

4 2

1.27

5 6 ⁄16

1.69

6 8

2.03

8 4

2.54

26

4 4

1.32

5 95⁄16

1.76

6 113⁄16

2.11

8 8

2.64

27

4 6

1.37

6 0

1.83

7 2⅜

2.2

9 0

2.74

11

13

28

4 8

1.42

6 2 ⁄16

1.9

7 5⅝

2.28

9 4

2.85

29

4 10

1.47

6 55⁄16

1.96

7 813⁄16

2.36

9 8

2.95

30

5 0

1.52

6 8

2.03

8 0

2.44

10 0

3.05

31

5 2

1.58

6 10 ⁄16

2.1

8 3 ⁄16

2.52

10 4

3.15

32

5 4

1.63

7 15⁄16

2.17

8 6⅜

2.6

10 8

3.25

33

5 6

1.68

7 4

2.24

8 9⅝

2.68

11 0

3.35

11

11

3

34

5 8

1.73

7 6 ⁄16

2.3

9

2.76

11 4

3.45

35

5 10

1.78

7 95⁄16

2.37

9 4

2.85

11 8

3.56

36

6 0

1.83

8 0

2.44

9 73⁄16

2.93

12 0

3.66

37

6 2

1.88

8 211⁄16

2.51

9 10⅜

3.01

12 4

3.76

38

6 4

1.93

8 5 ⁄16

2.57

10 1⅝

3.09

12 8

3.86

39

6 6

1.98

8 8

2.64

10 4 ⁄16

3.17

13 0

3.96

40

6 8

2.03

8 10 ⁄16

2.71

10 8

3.25

13 4

4.06

11

5

11

13

⁄16

13

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3 TABLETABLE 3 (continued) Vertical Coursing Vertical Coursing of Unit No. of Courses 41

2C = 4 in. (102 mm)

3C = 8 in. (203 mm)

ft – in.

m

6 10

2.08

ft – in.

5C = 16 in. (406 mm) m

ft – in.

1C = 4 in. (102 mm) m

ft – in.

m

9 15⁄16

2.78

10 113⁄16

3.33

13 8

4.17

42

7 0

2.13

9 4

2.85

11 2⅜

3.41

14 0

4.27

43

7 2

2.18

9 611⁄16

2.91

11 5⅝

3.5

14 4

4.37

44

7 4

2.24

9 9 ⁄16

2.98

11 8 ⁄16

3.58

14 8

4.47

45

7 6

2.29

10 0

3.05

12 0

3.66

15 0

4.57

46

7 8

2.34

10 211⁄16

3.12

12 33⁄16

3.74

15 4

4.67

47

7 10

2.39

10 5 ⁄16

3.18

12 6⅜

3.82

15 8

4.78

5

5

3

48

8 0

2.44

10 8

3.25

12 9⅝

3.9

16 0

4.88

49

8 2

2.49

10 1011⁄16

3.32

13

13

3.98

16 4

4.98

50

8 4

2.54

11 15⁄16

3.39

13 4

4.06

16 8

5.08

100

16 8

5.08

22 2 ⁄16

6.77

26 8

8.13

33 4

10.2

11

⁄16

Masonry Openings The edges of masonry openings are defined by brick units rather than mortar joints. Vertical dimensions are based on the number of courses plus an extra bed joint thickness. Figure 4 shows an example of dimensions for a punched window opening for modular sized brick units. Note that the height is for the opening before the installation of the sill and extends up to the bottom of the brick above, not to the bottom of the lintel supporting the brick.

Modular Brick,

3/ 8 inch (9.5 mm) Joints

ESTIMATING BRICK MASONRY There are various methods to estimate material quantities on a project. Hand calculations and computer programs have been used depending on the complexity of the building. Because of its simplicity and accuracy, the most widely used estimating procedure is the “wall-area” method. It consists simply of multiplying the net wall area (gross areas less areas of openings) by known quantities of material required per square foot (square meter). Determining the area of brick and mortar within each unit area of wall depends on both brick size and joint width. For non-modular masonry, both dimensions must be known to make accurate estimates. In modular masonry, mortar joint sizes are dictated by the size of the brick, simplifying the estimating process.

5’-4” (1.63 m) M.O. Approx. 5’-4 3/8” (1.64 m) actual 24 Nom. Brick Courses + 1 Joint

2’-8” (813 mm) M.O. Approx. 2’-83/ 8” (822 mm) actual 4 Nom. Brick Lengths + 1 Joint

Figure 4 Example of Determining Dimensions for a Masonry Opening

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Brick and Mortar Quantities Masons frequently use a rule of thumb that eight bags of masonry cement will lay 1000 modular brick. This is a very rough estimate and includes an unspecified amount of waste. Table 4 presents the estimated quantities of brick and mortar (not including waste) required for brick masonry according to the size of brick used in the wall. The mortar quantities are based on theoretical dimensions of the mortar in the wall. Estimates made using Table 4 should also include applicable correction factors listed in the Correction Factor section. For guidance on the volume of each solid material required for a specific mortar type, refer to ASTM C270, Standard Specification for Mortar for Unit Masonry [Ref. 1]. The commonly used “rule of thumb” is appropriate: 1 cubic foot (cubic meter) of loose, damp sand will yield about one cubic foot (cubic meter) of mortar. TABLE 4 Quantity Estimates for Brick Masonry MODULAR BRICK SIZES Nominal Dimensions, in. (mm)

Brick Designation

W

H

L

Modular

4 (102)

2⅔ (68)

8 (203)

Engineer Modular

4 (102)

31⁄5 (81)

8 (203)

Closure Modular

4 (102)

4 (102)

8 (203)

—

4 (102)

6 (152)

8 (203)

—

4 (102)

8 (203)

8 (203)

Roman

4 (102)

2 (51)

12 (305)

Norman

4 (102)

2⅔ (68)

12 (305)

Engineer Norman

4 (102)

31⁄5 (81)

12 (305)

Utility

4 (102)

4 (102)

12 (305)

—

6 (152)

31⁄5 (81)

12 (305)

—

6 (152)

4 (102)

12 (305)

—

8 (203)

4 (102)

12 (305)

—

4 (102)

2⅔ (68)

16 (406)

Meridian

4 (102)

4 (102)

16 (406)

Double Meridian

4 (102)

8 (203)

16 (406)

6 (152)

4 (102)

16 (406)

8 (203)

4 (102)

16 (406)

8 (203)

8 (203)

16 (406)

6-in. ThroughWall Meridian 8-in. ThroughWall Meridian Double ThroughWall Meridian

Joint Thickness, in. (mm) ⅜ (9.5) ½ (12.7) ⅜ (9.5) ½ (12.7) ⅜ (9.5) ½ (12.7) ⅜ (9.5) ½ (12.7) ⅜ (9.5) ½ (12.7) ⅜ (9.5) ½ (12.7) ⅜ (9.5) ½ (12.7) ⅜ (9.5) ½ (12.7) ⅜ (9.5) ½ (12.7) ⅜ (9.5) ½ (12.7) ⅜ (9.5) ½ (12.7) ⅜ (9.5) ½ (12.7) ⅜ (9.5) ½ (12.7) ⅜ (9.5) ½ (12.7) ⅜ (9.5) ½ (12.7) ⅜ (9.5) ½ (12.7) ⅜ (9.5) ½ (12.7) ⅜ (9.5) ½ (12.7)

Number of Brick per 100 sq ft (per 10 m²) 675 (727) 563 (605) 450 (484) 300 (323) 225 (242) 600 (646) 450 (484) 375 (404) 300 (323) 375 (404) 300 (323) 300 (323) 338 (363) 225 (242) 113 (121) 225 (242) 225 (242) 113 (121)

Cubic Feet (Cubic Meters) of Mortar Per 100 sq ft Per 1000 (10 m²) Brick 5.5 (1.7) 8.1 (0.23) 6.9 (2.1) 10.3 (0.29) 4.8 (1.5) 8.5 (0.24) 6.1 (1.9) 10.8 (0.31) 4.1 (1.3) 9.1 (0.26) 5.2 (1.6) 11.6 (0.33) 3.2 (0.98) 10.7 (0.30) 4.1 (1.3) 13.7 (0.39) 2.8 (0.84) 12.3 (0.35) 3.5 (1.1) 15.7 (0.44) 6.4 (2.0) 10.7 (0.30) 8.2 (2.5) 13.7 (0.39) 5.1 (1.5) 11.2 (0.32) 6.5 (2.0) 14.3 (0.41) 4.4 (1.3) 11.7 (0.33) 5.6 (1.7) 14.9 (0.42) 3.7 (1.1) 12.3 (0.35) 4.7 (1.4) 15.7 (0.44) 6.8 (2.1) 18.1 (0.51) 8.8 (2.7) 23.4 (0.66) 5.7 (1.7) 19.1 (0.54) 7.4 (2.3) 24.7 (0.70) 7.8 (2.4) 25.9 (0.73) 10.1 (3.1) 33.6 (0.95) 4.9 (1.6) 14.5 (4.7) 6.5 (2.1) 19.2 (6.2) 3.5 (1.1) 15.4 (0.44) 4.4 (1.4) 19.7 (0.56) 2.1 (0.64) 18.6 (0.53) 2.7 (0.82) 23.8 (0.67) 5.4 (1.6) 24.0 (0.68) 7.0 (2.1) 31.0 (0.88) 7.3 (2.2) 32.5 (0.92) 9.5 (2.9) 42.3 (1.2) 4.4 (1.3) 39.1 (1.1) 5.7 (1.8) 51.0 (1.4)

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TABLE 4 (continued) Quantity Estimates for Brick Masonry NON-MODULAR BRICK SIZES Specified Dimensions, in. (mm)

Number of Brick per 100 sq ft (per 10 m²)

Cubic Feet (Cubic Meters) of Mortar Per 100 sq ft Per 1000 (10 m²) Brick

W

H

L

Joint Thickness, in. (mm)

Queen

2¾ (70) 3 (76)

2¾ (70)

7⅝ (194) 8 (203)

⅜ (9.5) ½ (12.7)

550 (592)

6.7 (2.1) 7.4 (2.3)

12.2 (0.35) 13.5 (0.38)

King

2¾ (70) 3 (76)

2⅝ (67) 2¾ (70)

9⅝ (244) 9¾ (248)

⅜ (9.5) ½ (12.7)

455 (490)

6.5 (2.0) 7.3 (2.2)

14.2 (0.40) 16.0 (0.45)

—

3 (76)

2⅝ (67) 2¾ (70)

8⅝ (219)

⅜ (9.5) ½ (12.7)

512 (551)

6.6 (2.0) 8.2 (2.5)

13.0 (0.37) 16.1 (0.46)

Standard

3⅝ (92) 3½ (89)

2¼ (57)

8 (203)

⅜ (9.5) ½ (12.7)

655 (705)

9.5 (2.9) 11.0 (3.3)

14.5 (0.41) 17.8 (0.50)

Engineer Standard

3⅝ (92) 3½ (89)

213⁄16 (71) 2¾ (70)

8 (203)

⅜ (9.5) ½ (12.7)

539 (581)

8.2 (2.5) 9.7 (3.0)

15.3 (0.43) 18.7 (0.53)

Closure Standard

3⅝ (92) 3½ (89)

3⅝ (92) 3½ (89)

8 (203)

⅜ (9.5) ½ (12.7)

430 (463)

7.0 (2.2) 8.5 (2.6)

16.4 (0.46) 20.0 (0.57)

Brick Designation

Collar Joints. For multi-wythe construction, where the vertical joint between wythes is designed to be mortared solid, the values in Table 5 can be used to estimate the quantity of mortar within the collar joint. TABLE 5 Mortar Quantities in Collar Joints Cubic Feet of Mortar per 100 sq ft (m² per 10 m²) of Wall ¼-in. (6.4 mm) joint

⅜-in. (9.5 mm) joint

½-in. (12.7 mm) joint

¾-in. (19.1 mm) joint

2.08 (0.064)

3.13 (0.095)

4.17 (0.13)

6.25 (0.19)

Correction Factors Hollow Brick. The mortar quantities in Table 4 are based on fully bedded, solid masonry units (coring up to 25 percent of the bedded area). In veneer applications, hollow brick should also be laid in full mortar beds. Field testing has demonstrated that a veneer constructed of hollow brick units with a nominal thickness of 3 to 4 in. (76 to 102 mm) and cores or cells between 25 and 35 percent of the bedded area and laid in a full mortar bed does not significantly increase mortar usage compared to the same veneer constructed of solid brick units. Care should be taken to avoid using excessively plastic mortar or placement methods that would force excessive amounts of mortar into the cells or cores of the brick below. If these steps are taken, the estimates of Table 4 are valid for most hollow brick veneer applications. For hollow units laid with face shell bedding (as typically done in structural applications), the estimated quantities can be reduced by a percentage equal to the percentage of voids in the brick. This reduction will typically be between 25 and 35 percent. Bond Pattern. The values in Table 4 are based on running or stack bond patterns. For patterns that incorporate headers, the correction factors in Table 6 can be applied. The factor is a net increase for the number of brick and the mortar quantity, not including waste. For definitions of the patterns cited, refer to Technical Note 30. For example, for a standard-size brick laid with a ⅜ in. (9.5 mm) joint thickness in a common bond with full headers every fifth course, the following estimates would apply: • •

Number of brick per 100 sq ft (9.30 m²) of brickwork: 655 + (1⁄5 × 655) = 786 brick Cubic feet (0.028 m³) of mortar per 1000 brick: 14.5 + (1⁄15 × 14.5) = 15.5

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TABLE 6 Estimate Correction Factors for Bond Patterns Bond

Brick Correction Factor1

Mortar Correction Factor2

Common Bond with full headers every fifth course only

1

Common Bond with full headers every sixth course only

1

Common Bond with full headers every seventh course only

1

English Bond (full headers every second course) Flemish Bond (alternate full headers and stretchers every course)

⅓

1

Cross Bond with Flemish headers every sixth course

1

⁄18

1

Flemish Cross Bond (Flemish headers every second course)

1

⁄6

1

Double-stretcher, garden wall bond

1

⁄5

1

Triple-stretcher, garden wall bond

1

⁄7

1

⁄5

1

⁄6

1

⁄15

⁄7

1

½

1

⁄18 ⁄21 ⁄6 ⁄9

⁄54 ⁄18 ⁄15 ⁄21

1. The net increase for brick units may be less than that given when multiple headers can be made from a single brick. 2. Correction factors are applicable only to brick with lengths equal to twice the depth and 2½ to three times the height.

Brick Breakage and Waste. In the estimating procedure, determine the net quantities of all brick, including all correction factors above, before adding any allowances for waste. Allowances for waste and breakage vary, but as a general rule, at least 5 percent is added to the net brick quantities delivered to the jobsite. Particular job conditions or experience may warrant using a higher percentage for waste. Mortar Waste. In the estimating procedure, determine the net quantities of all materials, including all correction factors above, before adding any allowances for waste. Allowances for waste vary, but as a general rule, add 15 to 25 percent to the net mortar quantities. Particular job conditions, or experience, may dictate different factors.

SUMMARY This Technical Note provides a discussion of brick sizes and modular masonry construction and a discussion of the basic layout of brick masonry walls. Methods are presented for estimating quantities of brick and mortar materials for a chosen brick size, mortar joint size and bond pattern. The information and suggestions contained in this Technical Note are based on the available data and the experience of the engineering staff and members of the Brick Industry Association. The information contained herein must be used in conjunction with good technical judgment and a basic understanding of the properties of brick masonry. Final decisions on the use of the information discussed in this Technical Note are not within the purview of the Brick Industry Association and must rest with the project architect, engineer and owner.

REFERENCES 1. Annual Volume of ASTM Standards, ASTM International, West Conshohoken, PA, 2008. Volume 04.05 C216 “Standard Specification for Facing Brick” C270 “Standard Specification for Mortar for Unit Masonry” C652 “Standard Specification for Hollow Brick” Volume 04.11 E835/ “Standard Guide for Modular Coordination of Clay and Concrete Masonry Units” E835M

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Technical Notes 11 - Guide Specifications for Brick Masonry, Part 1 Rev. [Dec. 1971] (Reissued August 2001) INTRODUCTION Numerous methods are being explored to reduce constantly rising building costs. One means in which many segments of the construction industry believe holds promise of lowering these costs is the use of specific, definitive and concise specifications. They must convey to the contractor the exact requirements of the project and be organized to facilitate take-off and estimating. Many general contractors have testified that the use of such specifications results in lower contract bids. During recent years, organizations, such as the American Institute of Architects (AIA), Producers' Council (PC), Associated General Contractors of America (AGC), and the Construction Specifications Institute (CSI), have made the improvement of construction specifications one of their major activities. In accordance with the work of these agencies, the guide specifications in this series of Technical Notes are written to follow the CSI format insofar as possible. Use of Standards. It is recommended that, where suitable standards exist, such as those developed by the American Society for Testing and Materials (ASTM), American National Standards Institute (ANSI), American Concrete Institute (ACI) and other similar nationally recognized organizations, they be used and included in the project specifications by reference. Use of Detailed Descriptive Requirements. While detailed descriptive requirements are generally necessary as a means of specifying installation or workmanship, it is recommended that they be used only as a last resort in specifying materials. Use of Performance Specifications. Performance specifications are not, in general, considered suitable for specifying architectural building products. It is recommended that, if performance specifications are used to specify building materials, they should state results desired or properties desired, but not both. Use of Trade Names. It is recommended that, if building products are specified by trade names, the "special conditions" contain a clause providing that substitutes will be considered on a quality and price basis, and that the phrase "or equal", frequently included in such specifications, be eliminated. The following paragraph is suggested for substitutions: Variation From Materials Specified: It is intended that materials or products specified by name of manufacturer, brand, trade name or by catalog reference shall be the basis of the bid and furnished under the contract, unless changed by mutual agreement. Where two or more materials are named, the choice of these shall be optional with the contractor. Should the contractor wish to use any materials or products other than those specified, he shall so state, naming the proposed substitutions and stating what difference, if any, will be made in the contract price for such substitution should it be accented. Use of Allowances. It is recommended that allowances be used only with discretion. In all cases of allowances, there should be sufficient description to indicate to the contractor the extent of labor required to install the items for which allowances are listed. Also, all allowances should be listed under special conditions or under a separate section with cross references to the individual trade sections involved. SPECIFICATIONS FOR STRUCTURAL CLAY PRODUCTS

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Standard specifications for the various types and grades of brick and tile have been developed by technical committees of the American Society for Testing and Materials. Membership of these committees is balanced among consumers, manufacturers and a general interest group made up of engineers, scientists, educators, testing experts and representatives of research organizations. Because of this balance of committee membership, ASTM specifications are widely accepted and it is recommended that the appropriate ASTM specifications be included by reference in all specifications for solid brick, hollow brick, structural facing tile (glazed or unglazed) and structural clay tile. ASTM standards are under continuous review by the stands committees having jurisdiction over them. From time to time these standards are revised as a result of new developments. The ASTM designation of a standard consists of a letter and a number permanently assigned to the standard, a dash and a number indicating the year the standard was approved: as for example, C 216-69 which designates the Standard Specifications for Facing Brick approved in 1969. If the letter T follows the year designation, it indicates a tentative standard. When ASTM specifications are included by reference in project specifications, the full designation, including the year of approval, should be given, since, obviously, after a contract has been awarded, a revision of specifications by ASTM does not alter the contract. Similarly, the dates of any other specifications or codes included by reference should be given. Solid Masonry Units. ASTM Specifications C 216, C 62, and C 126 cover solid building brick, facing brick and ceramic glazed units made from clay and/or shale. Under these specifications, a solid masonry unit may be cored not in excess of 25 per cent; consequently, the term "solid brick" is not confined to those units which have no cores, unless so stated in the project specifications. Hollow Masonry Units. ASTM Specification C 652 covers hollow building brick, facing brick or hollow masonry units made from clay, shale, fire clay or mixtures thereof, and fired. The term "hollow" in this specification is defined to mean any unit cored in excess of 25 per cent, but not more than 40 per cent, in every plane parallel to the bearing surface. Supplementary Requirements. ASTM specifications for brick and tile do not fix the size or color and texture of the units. They do, however, include requirements for several grades and types of products, and some of them contain optional requirements which are applicable to specific projects, if so specified. When ASTM specifications are included in project specifications by reference, it is essential that they be supplemented with project requirements covering size, color, grade, type, etc. Without these supplementary provisions, the specifications are incomplete and inadequate as a basis for estimating. Size. Size of units required should be included in the project specifications. Without this information, a contractor cannot accurately estimate quantity of materials or the labor required to construct the masonry. It is recommended that the specified size be the manufactured size. Individual unit dimensions may vary from the specified or manufactured size by the allowable tolerances included in the appropriate ASTM specifications for the particular type or grade. Specifying nominal sizes of clay masonry units is not recommended, due to the ambiguity of the term "nominal". In some fields, it is understood to mean approximate and actual dimensions may vary from the nominal only by permissible variations in dimensions included in the specifications. However, in modular design, the nominal dimension of a masonry unit is understood to mean the specified or manufactured dimension plus the thickness of the mortar joint with which the unit is designed to be laid; that is, modular brick, whose nominal length is 8 in., would have a specified (manufactured) length of 7 1/2 in. if designed to be laid with a 1/2 - in. joint, or 7 5/8 in. if designed to be laid with a 3/8 - in joint. Color and Texture. Generally, the color and texture of the brick or structural facing tile in a masonry wall vary slightly. These variations, which prevent monotony in the appearance of the finished wall, are one of the most attractive features of brick and tile. Because of these variations and of the wide variety of colors and textures produced by the industry, it is impossible to write descriptions of either color or texture which will accurately identify the products required. For this reason, ASTM specifications for brick and structural clay facing tile provide that texture and color shall

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conform to an approved sample showing the full range of color and texture that will be acceptable. The number of units required in the sample should be stated in the project specifications and will depend upon the range of color and texture. In general, it will be from three to five. Grade and Type. Most ASTM specifications for brick or structural clay tile cover two or more grades, and specifications for facing brick, hollow brick and ceramic glazed structural facing tile include requirements for two or more types. Specifications for structural clay facing tile cover two types and two classes. When these specifications are included in project specifications by reference, it is essential that the grade and type or type and class of product required be specified. Failure to do so makes it difficult for the contractor to estimate the project and frequently results in a demand for extras after the contract is awarded. Cell Arrangement. Structural clay tile are produced with either vertical cells or horizontal cells. Furring tile, nominal thickness 2 in., in ceramic glaze often referred to as "soaps", are produced with either solid backs or open (ribbed) backs. If either vertical-cell or horizontal-cell units are required for specific locations, this should be stated in the project specifications. Similarly, if solid-back soaps or furring are required, it should be so stated. Otherwise, product specifications make the selection optional with the supplier. Plaster Base Finish. Specifications for structural clay facing tile and structural clay tile contain requirements for the finish of surfaces suitable for the application of plaster. When such surfaces are required, they should be specified in the project specifications; otherwise, the finish of the unexposed (back) of the unit is optional with the supplier. Tests. Most ASTM specifications for structural clay products provide that the cost of tests of units furnished for any particular project "shall be borne by the purchaser", unless the tests indicate that the units do not conform to the requirements of the specifications, in which case "the cost shall be borne by the seller". Project specifications should state the number of tests that will be required and should indicate who is responsible for selecting the samples and who pays the cost of testing. PROJECT SPECIFICATIONS FOR STRUCTURAL CLAY PRODUCTS As previously indicated, it is recommended that ASTM specifications, supplemented to meet project requirements, be used in specifying brick and structural clay tile. These specifications are suitable for use in any of the following forms: Open Specifications. This type of specification, frequently required in public work, makes no reference to product trade names. In such a specification, ASTM specifications should be included by reference, supplemented with project requirements, and an "approved sample" of the required color and texture should be available for inspection by bidders prior to submission of bids. Trade Names. For private work, specifying facing brick and structural facing tile by trade or manufacturer's names gives the contractor definite information as to the product required and provides the architect with assurance that the quality desired will be furnished. In general, when this method is used, three or more acceptable products are named and the contractor is given the option of selecting among them. When trade names are used for specifying brick or tile, it is recommended that the units be required to comply with applicable ASTM specifications and that samples of acceptable units be available for inspection of bidders prior to bidding; also, that a provision for substitution, similar to that previously recommended, be included in the specifications. Allowances. The use of allowances for cost of facing brick and facing tile has been used successfully for many years and, in general, this method is recommended by the Structural Clay Products Institute. Allowances place all contractors on an equal basis and permit the owner to select products that he considers most desirable. However, when this method is employed, the specifications should state the size and texture of the units that will be selected, the tests that will be required and the responsibility for payment of tests. GUIDE SPECIFICATIONS

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The guide specifications in Technical Notes 11A Revised and 11B Revised are written for both reinforced and non-reinforced brick masonry, designed to comply with ANSI A41.1-1953 (R1970), "Building Code Requirements for Masonry", ANSI A41.2-1960 (R 1970), "Building Code Requirements for Reinforced Masonry", or equivalent sections in the Model Building Codes. The guide specifications in these Technical Notes can be used for engineered brick masonry designed to comply with Building Code Requirements for Engineered Brick Masonry, BIA, August 1969, or equivalent sections in the Model Building Codes, when additional quality assurance requirements are incorporated into the specification. See Technical Notes 11C Revised. The specifications do not cover requirements for structural clay tile, concrete masonry units, glass block or stone. Where these materials and design procedures are included in the masonry section, the specifications should be supplemented or revised. It will be found, however, that many of the requirements pertaining to brick masonry are also applicable to other types of masonry construction. "Guide Specifications for Masonry Mortar" will be included as a separate Technical Notes 11E to comply with CSI format. Metric numbers listed are conversions from the current customary system and are not industry agreed-upon standards; i.e., a typical modular 3 1/2 x 2 1/4 x 7 1/2 - in.. (actual size) brick may be produced at some dimensions other than 89 x 57 x 191 mm when metric dimensions are adopted within the industry. The cold weather protection requirements contained in paragraph 1.05.C are those recommended by the International Masonry Industry All-Weather Council, published December 1, 1970. In using these specifications, the specification writer should cheek each section to insure compliance with project requirements and modify the paragraphs or delete those not needed. REFERENCES 1.

Brick and Tile Engineering, Harry C. Plummer, Brick Institute of America (BIA), November 1967.

2.

Building Code Requirements for Engineered Brick Masonry, BIA, August 1969.

3. Recommended Practice for Engineered Brick Masonry, J. G. Gross, R. D. Dikkers and J. C. Grogan, BIA, November 1969. 4.

Specifications for Clay Masonry Construction, BIA, February 1962.

5.

Technical Notes on Brick Construction, BIA, published monthly.

6.

Building Code Requirements for Masonry, ANSI - A41.1-1953 (R 1970).

7.

Building Code Requirements for Reinforced Masonry, ANSI - A41.2-1960 (R 1970).

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Technical Notes 11A - Guide Specifications for Brick Masonry, Part 2 Rev [June 1978] (Reissued Sept. 1988) INTRODUCTION This Technical Notes contains the guide specifications in CSI format for Division 4, Section 04210, Part I - General, and Part II - Products. Part III - Execution is in Technical Notes 11B Revised. The specifications are applicable to ANSI A41.1 - 1953 (R1970), ''Building Code Requirements for Masonry,'' ANSI A41.2 - 1960 (R 1970), "Building Code Requirements for Reinforced Masonry,'' or equivalent sections in the Model Building Codes. The guide specifications in Technical Notes 11A Revised and 11B Revised can be used for engineered brick masonry designed to comply with Building Code Requirements for Engineered Brick Masonry, BIA, August 1969, or equivalent sections in the Model Building Codes, when additional quality assurance requirements are incorporated into the specifications. See Technical Notes 11C Revised. Guide Specification & Notes PART I - GENERAL 1.01 DESCRIPTION: A. Related Work Specified Elsewhere: 1. Concrete work: Section 03__________. 2. Rough carpentry: Section 06__________. 3. Structural steel and metals: Section 05__________. 4. Waterproofing: Section 07__________. B. Material Installed but Furnished by Others: 1. Bolts. 2. Anchors. 3. Nailing blocks. 4. Inserts. 5. Flashing. 6. Lintels. 7. Doors. 8. Window frames. 9. Vents. 10. Conduits.

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11. Expansion joints. 1.02 QUALITY ASSURANCE: A. Brick Tests: 1. Test in accordance with ASTM C 67-__________with the following additional requirements: a. If the coefficient of variation of the compression samples tested exceeds 12%, obtain compressive strength by multiplying average compressive strength of specimens by where v is the coefficient of variation of sample tested. b. Cost of tests of units after delivery shall be borne by the purchaser, unless tests indicate that units do not conform to the requirements of the specifications, in which case cost shall be borne by the seller. NOTE: 1.02.A This section can be deleted if Architect/Engineer has sufficient experience and confidence in the brick manufacturer to accept compliance with project specifications based on certification section 1.03.C. 1.02.A. 1.a. To be applied only for engineered brick masonry. 1.02.A. 1.b. To be used only in a case of dispute.

B. Furnish Sample Panel: 1. Approximately 4 ft. (1.2 m) long by 3 ft. (1 m) high, showing the proposed color range, texture, bond, mortar and workmanship. All brick shipped for the sample shall be included in the panel. 2. Erect panel in the presence of the Architect/Engineer before installation of materials. 3. When required, provide a separate panel for each type of brick or mortar. 4. Do not start work until Architect/Engineer has accepted sample panel. 5. Use panel as standard of comparison for all masonry work built of same material. 6. Do not destroy or move panel until work is completed and accepted by Owner. NOTE: 1.02. B. 1. The sample panel, when accepted, shall become the project standard for: bond, mortar, workmanship and appearance. 1.02.B.3. Brick for sample panels are usually furnished at no cost. If additional panels are needed, care must be exercised not to burden the supplier with excessive costs.

1.03 SUBMITTALS: A. Samples: Furnish not less than five individual brick as samples, showing extreme variations in color and texture. B. Test Reports: 1. Test reports for each type of building and facing brick are to be submitted to the Architect Engineer for approval. 2. Testing and reports are to be completed by an independent laboratory. 3. Test reports shall show: a. Compressive strength. b. 24 - hr. cold water absorption. c. 5 - hr. boil absorption.

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d. Saturation coefficient. e. Initial rate of absorption (suction). C. Certificates: Prior to delivery, submit to Architect/Engineer certificates attesting compliance with the applicable specifications for grades, types or classes included in these specifications. NOTE: 1.03.A and B Sections can be deleted if Architect/Engineer has sufficient experience and confidence in the brick manufacturer to accept compliance with project specifications based on certification section 1.03.C. 1.03.B.3. This section should be altered to meet the requirements of the project. Brick are not required to meet the 5-hr boil absorption and/or saturation coefficient requirements of ASTM C 216, ASTM C 62 and ASTM C 652 if they meet the physical property requirements of Sections 5.1 and 5.2 of ASTM C 216, Sections 3A, 3.5 and 3.6 of ASTM C 62 and Sections 5.1 and 5.2 of ASTM C 652. No limit is placed on initial rate of absorption (suction). Units having initial rates of absorption exceeding 30 g./min./30 sq. in. (194 cm 2) should be wetted prior to laying. For cold weather masonry construction, higher suctions may be tolerated (up to 30-40 g.) than for normal construction. Note Sections 1.05.C.2.a and 3.01.A. 1. 1.03.C. List materials for which certificates of compliance are required.

1.04 PRODUCT DELIVERY, STORAGE AND HANDLING: A. Store brick off ground to prevent contamination by mud, dust or materials likely to cause staining or other defects. B. Cover materials when necessary to protect from elements. C. Protect reinforcement from elements 1.05 JOB CONDITIONS: A. Protection of Work: 1. Wall covering: a. During erection, cover top of wall with strong waterproof membrane at end of each day or shutdown. b. Cover partially completed walls when work is not in progress. c. Extend cover minimum of 24 in. (610 mm) down both sides. d. Hold cover securely in place. 2. Load application: a. Do not apply uniform floor or roof loading for at least 12 hr. after building masonry columns or walls. b. Do not apply concentrated loads for at least 3 days after building masonry columns or walls. B. Staining: 1. Prevent grout or mortar from staining the face of masonry to be left exposed or painted: a. Remove immediately grout or mortar in contact with face of such masonry. b. Protect all sills, ledges and projections from droppings of mortar, protect door jambs and corners from damage during construction. Protection:

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1. Preparation: a. If ice or snow has formed on masonry bed, remove by carefully applying heat until top surface is dry to the touch. b. Remove all masonry deemed frozen or damaged. 2. Products: a. When brick suction exceeds recommendations of Section 1.03.B.3, sprinkle with heated water: o

o

o

o

o

o

(1) When units are above 32 F. (0 C.), heat water above 70 F. (21 C.). o

o

(2) When units are below 32 F. (0 C.), heat water above 130 F. (54 C.). b. Use dry masonry units. c. Do not use wet or frozen units. 3. Construction requirements while work is progressing: a. Air temperature 40o F. (4o C.) to 32o F. (0o C.): (1) Heat sand or mixing water to produce mortar temperatures between 40o F. (4o o o C.) and 120 F. (49 C.). o

o

o

o

b. Air temperature 32 F. (0 C.) to 25 F. (-4 C.): (1) Heat sand and mixing water to produce mortar temperatures between 40o F. (4o C.) and 120o F. (49o C.). (2) Maintain temperatures of mortar on boards above freezing. o

o

o

o

c. Air temperatures 25 F. (-4 C.) to 20 F. (-7 C.): o

(1) Heat sand and mixing water to produce mortar temperatures between 40 F. (4o C.) and 120o F. (49o C.). (2) Maintain mortar temperatures on boards above freezing. (3) Use salamanders or other heat sources on both sides of walls under construction. (4) Use windbreaks when wind is in excess of 15 mph. d. Air temperature 20o F. (-7o C.) and below: o

(1) Heat sand and mixing water to produce mortar temperatures between 40 F. o o o (4 C.) and 120 F. (49 C.). (2) Provide enclosures and auxiliary heat to maintain air temperature above 32o F. (0o C.). o

o

(3) Minimum temperature of units when laid: 20 F. (-7 C.).

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4. Protection requirements for completed masonry and masonry not being worked on: o

o

o

o

a. Mean daily air temperature 40 F. (4 C.) to 32 F. (0 C.): (1) Protect masonry from rain or snow for 24 hr. by covering with weatherresistive membrane. b. Mean daily air temperature 32o F. (0o C.) to 25o F. (-4o C.): (1) Completely cover masonry with weather-resistive membrane for 24 hr. c Mean daily air temperature 25o F. (-4o C.) to 20o F. (-7o C.): (1) Completely cover masonry with insulating blankets or equal protection for 24 hr. o

o

d. Mean daily air temperature 20 F. (-7 C.) and below: (1) Maintain masonry temperature above 32o F. (0o C.) for 24 hr. by: (a) Enclosure and supplementary heat. **OR** (a) Electric heating blankets. **OR** (a) Infrared lamps. **OR** (a) Other approved methods. NOTE: 1.05.C.3 Ideal mortar temperature is 70o F. ± 10o F. (21o C. ± 6o C.). The mixing temperature should be maintained within 10o F. (6o C.). 1.05.C.4 The following options may be used in cold weather construction: 1. Change to a higher type of mortar required in ASTM C 270. (Example: If ASTM type N mortar is specified for normal temperature, change to type S or type M.) 2. Increase the protection time where required in Section 1.05.C.4 to 48 hr. with no change being made in the type of mortar. 3. Without changing the mortar type and maintaining 24-hr. protection in Section 1.05.C.4, replace type I Portland cement in the mortar with type III, ASTM C 150. 1.05.C.4.d This section may be written to allow the contractor to select means of protection.

PART II-PRODUCTS 2.01 BRICK: A. Facing Brick: 1. ASTM C 216-__________, Grade__________, Type__________. 2. Dimensions:__________ x __________ x __________. (t) (h) (l ) 3. Minimum compressive strength: _____________. 4. Provide brick similar in texture and physical properties to those available for inspection at the

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Architect/Engineer's office. 5. Do not exceed variations in color and texture of samples accepted by the Architect/Engineer. NOTE: 2.01.A.1 Grade: SW for brick in contact with earth or where weathering index is greater than 50, MW elsewhere. Type: FBS, FBX, FBA. 2.01.A.2 Determine availability. Typical actual sizes for use with 3/8 - in. mortar joints: 3 5/8 x 2 5/16 x 7 5/8 or 11 5/8 in. (92 x 59 x 194 or 295 mm); 3 5/8 x 2 13/16 x 7 5/8 or 11 5/8 in. (92 x 74 x 194 or 295 mm): 3 5/8 x 3 5/8 x 7 5/8 or 11 5/8 in. (92 x 92 x 194 or 295 mm);3 5/8 x 5 x 7 5/8 or 11 5/8 - in (92x 127x 194 or 295 mm);3 5/8 x 1 5/8 x 11 5/8 in. (92 x 41 x 295 mm); 5 5/8 x 2 5/16 x 11 5/8 in. (143 x 59 x 295 mm); 5 5/8 x 2 13/16 x 11 5/8 in. (l43 x 74 x 295 mm); 5 5/8 x 3 5/8 x 11 5/8 in. (143 x 92 x 295 mm). 2.01.A.3 Required only for structural masonry. Range: 2000 psi to 14,000 psi (13.8 MPa to 96.5 MPa).

**OR** A. Facing Brick: Provide a cash allowance of__________per thousand. B. Glazed Brick: 1. ASTM C 126-__________, Grade__________, Type__________. 2. Dimensions:__________ x __________ x __________. (t) (h) (l ) 3. Minimum compressive strength:__________. NOTE: 2.01.B.1 Grade: S for narrow mortar joints; SS where face dimension variation must be very small. Type: I, II. 2.01.B.2 See 2.01.A.2. 2.01. B.3 See 2.01.A.3.

C. Building Brick: 1. ASTM C 62-__________, Grade__________. 2. Dimensions:__________ x __________ x __________. (t) (h) (l ) 3. Minimum compressive strength:__________. NOTE: 2.01.C.1 Grade: SW for brick in contact with earth or where weathering index is greater than 50, MW elsewhere, NW in interior and backup areas. 2.01.C.2 See 2.01.A.2. 2.01.C.3 See 2.01.A.3.

D. Hollow Brick: 1. ASTM C 652-__________, Grade__________, Type__________. 2. Dimensions:__________ x __________ x __________. (t) (h) (l ) 3. Minimum compressive strength:__________. 4. Provide brick similar in texture and physical properties to those available for inspection at the Architect/Engineer's office.

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5. Do not exceed variation in color and texture of samples accepted by the Architect/Engineer. NOTE: 2.01.D.1 Grade: SW for brick in contact with earth or where weathering index is greater than 50, MW elsewhere. Type: HBS, HBX, HBA, HBB. 2.01.D.2 See 2.01.A.2. 2.01.D.3 See 2.01.A.3.

2.02 REINFORCEMENT: A. Cold-drawn steel wire: ASTM A 82-__________. B. Welded steel wire fabric: ASTM A 185-__________. C. Billet steel deformed bars: ASTM A 615-_________, Grade__________. D. Rail steel deformed bars: ASTM A 616-__________, Grade_________. E. Axle steel deformed bars: ASTM A 617-__________, Grade__________. NOTE: 2.02.C Grade 40, 50, 60. 2.02.D Grade 50, 60. 2.02.E Grade 40, 60.

2.03 ANCHORS AND TIES: A. Coated or corrosion-resistant metal meeting or exceeding applicable standard: 1. Zinc-coating flat metal: ASTM A 153-__________, Class__________. 2. Zinc-coating of wire, ASTM A 116-__________, Class 3. 3. Copper-coated wire: ASTM B 227-__________ , Grade 30HS. 4. Stainless steel: ASTM A 167-__________, Type 304. NOTE: 2.03.A.1 Class B-1, B-2, B-3.

B. Types: 1. Wire mesh: a. Minimum gage: 20. b. Mesh: 1/2 in. (12.7 mm). c. Galvanized wire. d. Width: 1 in. (25 mm) less than width of masonry. 2. Corrugated veneer ties: a. Minimum gage: 22. b. Minimum width: 7/8 in. (22 mm). c. Length: 6 in. (152 mm) **OR**

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2. Wire ties: Use two 10-gage. 3. Cavity wall ties: a. Wire diameter: 3/16 in. (4.7 mm). b. Shape: Rectangular, at least 2 in. (51 mm) wide with ends overlapped or "Z" with 2 in. (51 mm) legs. c. Length: Select length to allow 1 - in. (25 mm) minimum mortar cover of ends or legs. 4. Multi-wythe wall ties: a. Prefabricated welded joint reinforcement. b. Longitudinal cross tie wire: (1) 9 gage. (2) Spaced 16 in. (406 mm) o.c. NOTE: 2.03.B.4 Cavity wall ties may be used.

5. Dovetail flat bar or wire anchors: a. Flat bar: (1) Minimum gage: 16. (2) Minimum width: 7/8 in. (22 mm). (3) Fabrication: Corrugated, turned up 1/4 in. (6.4 mm) at end or with 1/2-in. (12.7 mm) hole within 1/2 in. (12.7 mm) of end of bar. b. Wire: (1) Wire gage: 6. (2) Minimum width: 7/8 in. (22 mm). (3) Fabrication: Wire looped and closed. 6. Rigid anchors for intersecting bearing walls: a. Dimensions: 1 1/2 in. (38 mm) wide by 1/4 in. (6.4 mm) thick by minimum 24 in. (610 mm) long. b. Fabrication: Turn up ends minimum 2 in. (51 mm) or provide cross pins. 7. Wire ties for high-lift grout reinforced brick masonry: a. Minimum gage: 9. b. Fabrication: (1) Bend into stirrups 4 in. (102 mm) wide and 2 in. (51 mm) shorter than overall wall thickness. (2) Form so that tie ends meet in center of one embedded end of stirrup. 2.04 CLEANING AGENTS:

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A. Do not use cleaning agent other than water on brick, except with concurrence of Architect/Engineer. B. Acceptable cleaner for dark brick: _____________. C. Acceptable cleaner for light colored brick: _______________. NOTE: 2.04.B Specify cleaner recommended by brick manufacturer. 2.04.C Proper cleaning agent is more critical for light colored brick.

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Technical Notes 11B - Guide Specifications for Brick Masonry, Part 3 Rev [Feb. 1972] (Reissued Sept. 1988)

INTRODUCTION This Technical Notes contains the guide specifications in CSI format for Part III - Execution. Part I - General, and Part II - Products are in Technical Notes 11A Revised. Guide Specification and Notes PART III - EXECUTION 3.01 PREPARATION: A. Wetting Brick: 1. Wet brick with absorption rates in excess of 30 g./30 sq. in./min. (30 g./194 cm2/min.) determined by ASTM C 67-__________, so that rate of absorption when laid does not exceed this amount. 2. Recommended procedure to insure that brick are nearly saturated, surface dry when laid is to place a hose on the pile of brick until the water runs from the pile. This should be done one day before brick are to be used. In extremely warm weather, place hose on pile several hours before brick are to be used. B. Cleaning Reinforcement: Before being placed, remove loose rust, ice and other coatings from reinforcement. NOTE: 3.01.A.1 Note requirements for cold weather, section 1.05.C.2.a, and section 1.03.B.3 for testing requirements.

3.02 GENERAL ERECTION REQUIREMENTS: A. Pattern Bond: 1. Lay exposed masonry in running bond. 2. Bond unexposed masonry units in a wythe by lapping at least 2 in. ( 51 mm). NOTE: 3.02.A.1 Alter if other than running bond required.

B. Joining of Work: 1. Where fresh masonry joins partially set masonry: a. Remove loose brick and mortar. b. Clean and lightly wet exposed surface of set masonry. 2. Stop off horizontal run of masonry by racking back 1/2 length of unit in each course. 3. Toothing is not permitted except upon written acceptance of the Architect/Engineer.

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C. Tooling and Tuck Pointing: 1. Tooling: a. Tool exposed joints when "thumb-print" hard with a round jointer, slightly larger than width of joint. b. Trowel-point or concave-tool exterior joints below grade. c. Flush cut all joints not tooled. 2. Tuck pointing: a. Rake mortar joints to a depth of not less than 1/2 in.(12.7 mm) nor more than 3/4 in. (19 mm). b. Saturate joints with clean water. c. Fill solidly with ______________ pointing mortar. d. Tool joints. NOTE: 3.02.C Alter to allow other joints to meet architectural requirements. 3.02.C.2 Delete if not required. 3.02.C.2.c Specify proportions. Pointing mortar should be of same proportions as mortar in main part of wall, if known; if not, type N.

D. Flashing: 1. Clean surface of masonry smooth and free from projections which might puncture flashing material. a. Place through-wall flashing on bed of mortar. b. Cover flashing with mortar. E. Weep Holes: 1. Provide weep holes in head joints in first course immediately above all flashing by: (a) Leaving head joint free and clean of mortar **OR** (a) Placing and leaving sash cord in joint. ******** 2. Maximum spacing: 24 in. (610 mm) o.c. 3. Keep weep holes and area above flashing free of mortar droppings. F. Sealant Recesses: 1. Leave joints around outside perimeters of exterior doors, window frames and other wall openings: a. Depth: uniform 3/4 in. (19 mm). b. Width: 1/4 in. (6.4 mm) to 3/8 in. (9.5 mm). G. Movement Joints: 1. Keep clean from all mortar and debris. 2. Locate as shown on drawings. H. Cutting Brick: 1. Cut exposed brick with motor-driven saw. **OR** 1. By other methods which provide cuts that are straight and true.

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******** I. Mortar Joint Thickness: 1. Lay all brick with__________in. joint. NOTE: 3.02.I Coordinate joint thickness with brick specified in 2.01.A.2.

3.03 NON-REINFORCED BRICK MASONRY A. Brick Installation: 1. Lay brick plumb and true to lines. 2. Lay with completely filled mortar joints. 3. Do not furrow bed joints. 4. Butter ends of brick with sufficient mortar to fill head joints. 5. Rock closures into place with head joints thrown against two adjacent brick in place. 6. Fill vertical, longitudinal joints, except in cavity walls: a. By parging either face of backing or back of facing. **OR** a. By pouring the vertical joint full of grout. **OR** a. Shoving alone. 7. Do not pound corners and jambs to fit stretcher units after they are set in position. Where an adjustment must be made after mortar has started to harden, remove mortar and replace with fresh mortar. NOTE: 3.03.A If hollow units are specified, alter to conform to requirements of the units.

B. Cavity Walls: 1. Keep cavity in cavity walls clean by: a. Slightly beveling mortar bed to incline toward cavity. **OR** a. Placing wood strips with attached wire pulls on metal ties. b. Before placing next row of metal ties, remove and clean wood strips. ******** 2. As work progresses, trowel protruding mortar fins in cavity flat on to inner face of wythe. C. Non-Bearing Partitions: 1. Extend from top of structural floor to bottom surface of floor construction above. 2. Wedge with small pieces of tile, slate or metal. 3. Fill topmost joint with mortar. NOTE: 3.03.C Alter to local code requirements if suspended ceilings are used.

D. Structural Bonding: 1. Bond or anchor corners and intersections of loadbearing brick walls. 2. Structural bond multi-wythe non-reinforced brick walls with__________.

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a. Extend headers not less than 3 in. (76 mm) into backing. b. Maximum distance between adjacent headers: 24 in. (610 mm) either vertically or horizontally. c. When a single header does not extend through wall, overlap headers from opposite sides of wall at least 3 in. (76 mm). d. Minimum headers: 4%. **OR** a. Provide minimum of one cavity wall tie for each 4 1/2 sq. ft. (0.42 m2) of wall surface. b. Stagger ties in alternate courses. c. Maximum distance between adjacent ties: (1) Vertically: 24 in. (610 mm). (2) Horizontally: 36 in. (920 mm). d. Embed ties in horizontal joints of facing and backing. e. Provide additional ties at openings: (1) Maximum spacing around perimeter: 36 in. (920 mm). (2) Install within 12 in. (305 mm) of opening. **OR** a. Use continuous prefabricated joint reinforcement to bond multi-wythe walls; spaced not more than 16 in. (406 mm) vertically. ******** 3. Stack bond: a. Embed continuous No. 2 steel reinforcement or No. 9 gage wire in horizontal joints at vertical intervals not to exceed 16 in. (406 mm). b. Provide not less than one longitudinal bar or wire for each 6 in. (152 mm) of wall thickness or fraction thereof. NOTE: 3.03.D Note special bonding requirements for high-lift grout, section 3.05.B. 3.03.D.2 Masonry headers, metal ties or continuous joint reinforcement.

E. Anchoring:

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1. Anchor exterior brick walls facing or abutting concrete members with dovetail, flat-bar or wire anchors inserted in slots built into concrete. a. Maximum anchor spacing: (1) Vertically: 24 in. (610 mm). (2) Horizontally: 36 in. (920 mm). b. Maintain a space not less than 1/2 in. (12.7 mm) wide between masonry wall and concrete members. c. Keep space free of mortar or other rigid material to permit differential movement between concrete and masonry . 2. For intersecting bearing or shear walls carried up separately: a. Regularly block vertical joint with 8-in. (203 mm) maximum offsets. b. Provide joints with rigid steel anchors. c. Space anchors not more than 4 ft. (1.2 m) apart vertically. **OR** a. When acceptable to the Architect/Engineer, eliminate blocking and provide rigid steel anchors spaced not more than 24 in. (610 mm) apart vertically. ******** 3. Anchor non-bearing partitions abutting or intersecting other walls or partitions with: a. Cavity wall ties at vertical intervals of not more than 24 in. ( 610 mm). **OR** a. Masonry bonders in alternate courses ******** 4. Attach brick veneer to backing with metal veneer ties: a. Use one tie for each 4 sq. ft. (0.37 m2 ) of wall area. b. Maximum space between adjacent ties: (1) Vertically and horizontally: 24 in. (610 mm). c. Embed ties at least 2 in. (51 mm) in horizontal joint of facing. d. Provide additional ties at openings: (1) Maximum spacing around perimeter: 36 in. (914 mm). (2) Install within 12 in. (305 mm) of opening. NOTE: 3.03.E 4 Tie spacing is based on a design wind pressure of 20 psf (958 N/m 2). Maximum spacing should be decreased for higher wind pressures. Recommended spacing for: 30 psf (1436 N/m2): Vertically: 24 in. (610 mm) Horizontally: 16 in. (406 mm) 40 psf (1913 N/m2): Vertically: 18 in. (457 mm) Horizontally: 16 in. (406 mm)

3.04 REINFORCED BRICK MASONRY: A. Brick Installation: 1. Lay brick plumb and true to lines.

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2. Lay with completely filled mortar joints. 3. Do not furrow bed joints. 4. Butter ends of brick with sufficient mortar to fill head joints. 5. Slightly bevel mortar bed to incline towards cavity. 6. Rock closures into place with head joints thrown against two adjacent brick in place. 7. Do not pound corners and jambs to fit stretcher units after they are set in position. Where an adjustment must be made after mortar has started to harden, remove mortar and replace with fresh mortar. NOTE: 3.04.A If hollow units are specified, alter to conform to requirements of the units.

B. Forms and Shores: 1. Provide substantial and tight forms. 2. Leakage of mortar or grout is not permitted. 3. Brace or tie forms to maintain position and shape. 4. Do not remove forms and shores until masonry has hardened sufficiently to carry its own weight and other temporary loads that may be placed on it during construction: a. For girders and beams: Minimum 10 days. b. Under brick slabs: Minimum 7 days. C. Placing Reinforcement: 1. Position metal reinforcement accurately. 2. Secure against displacement: a. Hold vertical reinforcement firmly in place by means of frames or other suitable devices. b. Horizontal reinforcement may be placed as brickwork progresses. 3. Spacing: a. Minimum clear distance between longitudinal bars, except in columns: Nominal diameter of bar or 1 in. (25 mm). b. Minimum clear distance between bars in columns: Not less than 1/2 times bar diameter or 1/2 in. (38 mm). 4 4. Minimum thickness of mortar or grout between brick and reinforcement: 1/4 in. (6.4 mm), except: a. 1/4 - in. (6.4 mm) bars may be laid in 1/2-in.(12.7 mm) horizontal mortar joints. b. No. 6 gage or smaller wires may be laid in 3/8-in. (9.5 mm) mortar joints. 5. Minimum width of collar Joints containing both horizontal and vertical reinforcement: 1/2 in. (12.7 mm) larger than sum of diameters of horizontal and vertical reinforcement. 6. Splice reinforcement or attach reinforcement to dowels by placing in contact and wiring.

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7. Do not splice reinforcement at points other than shown on drawings, unless approved by the structural engineer. 8. Shape and dimension reinforcement as shown on drawings: a. Cold bend all bars. b. Do not straighten or repair in a manner that will injure material. c. Do not use bars with kinks or bends not shown on drawings. d. Reinforcement can be heated when entire operation is approved by structural engineer. 3.05 GROUTING: A. Low-Lift Grouting: 1. Keep grout core clean from mortar and drippings. 2. Grout spaces less than 2 in. (51 mm) in width at intervals of not more than 24 in. (610 mm) in lifts of 6 to 8 in. (152 to 203 mm) as the wall is built. 3. In grout spaces more than 2 brick in thickness: a. Place or float brick in grout. b. Minimum grout between brick: 3/8 in. (9.5 mm). 4. Agitate or puddle grout during and after placement to insure complete filling. 5. Stop grout 1/2 in. (38 mm) below top of masonry: a. If grouting is stopped for 1 hr. or more. b. Except when completing grouting of finished wall. 6. If brick headers are used for ties in low-lift grouting space: a. Maximum: 8% of wall area. NOTE: 3.05.A.6 Using headers for tying wythes is not recommended; however, if selected, construction should conform to the requirements of this section.

B. High-Lift Grouting: 1. For running bond, provide one metal tie for each 3 sq. ft. (0.28 ma) of wall with maximum spacing: a. Vertically: 16 in. (406 mm). b. Horizontally: 24 in. (610 mm). 2. For stack bond, provide one metal tie for each 2 sq. ft. (0.19 m2) of wall with maximum spacing: a. Vertically: 12 in. (305 mm). b. Horizontally: 24 in. (610 mm). 3. Keep grout core clean from mortar and droppings. 4. Provide cleanout holes by omitting every other brick in bottom course on one side of wall.

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5. Prior to closing cleanout holes and pouring grout, use high-pressure jet stream of water or high-pressure air to remove excess mortar from grout space and to clean reinforcement. 6. Do not plug cleanout holes until condition of area to be grouted has been approved. 7. Before pouring grout, plug cleanout holes with masonry units and brace against grout pressure. 8. Grout spaces 2 in. (51 mm) or more in width in lifts not exceeding 4 ft. (1.2 m) at intervals: a. Coarse grout: Not more than 48 times the least clear dimension of grout space. **OR** a. Fine grout: Not more than 64 times the least clear dimension of grout space. ******** b. Not to exceed height of 12 ft. (3.7 m). 9. Do not place grout until the entire wall has been in place 3 days. 10. Vibrate or agitate grout during, and after placement to insure complete filling of grout space. 11. Stop grout 1 1/2 in. (38 mm) below top of masonry: a. If grouting is stopped for 1 hr. or more. b. Except when completing grouting of finished wall. 12. Provide grout blocks at convenient intervals to meet project requirements. 3.06 CLEANING: A. Cut out any defective joints and holes in exposed masonry and repoint with mortar. B. Clean all exposed unglazed masonry: 1. Apply cleaning agent to sample wall area of 20 sq. ft. (2 m2 ) in location acceptable to the Architect/Engineer. 2. Do not proceed with cleaning until sample area is approved by Architect/Engineer. 3. Clean initially with stiff brushes and water. 4. When cleaning agent is required: a. Follow brick manufacturer's recommendations. b. Thoroughly wet surface of masonry on which no green efflorescence appears. c. Scrub with acceptable cleaning agent. d. Immediately rinse with clear water. e. Do small sections at a time. f. Work from top to bottom. g. Protect all sash, metal lintels and other corrodible parts when masonry is cleaned with acid solution. h. Remove green efflorescence in accordance with brick manufacturer's recommendations. NOTE:

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3.06 If care is taken during laying and the wall is acceptable, the requirements of this section can be deleted.

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Technical Notes 11C - Guide Specifications for Brick Masonry, Part 4 Rev. [July 1972] (Reissued May 1998)

INTRODUCTION This issue of Technical Notes and the following issue, Technical Notes 11D, contain the required additional sections and statements to be incorporated into the "Guide Specifications for Brick Masonry", Technical Notes 11A Revised and 11B Revised. This will make the guide specifications in those Technical Notes suitable for Engineered Brick Masonry. The sections contained in these Technical Notes deal primarily with the quality assurance, selection of units, strength and construction tolerances to provide masonry that meets the minimum design requirements for Engineered Brick Masonry. In the construction of Engineered Brick Masonry, quality control may be maintained in either of two ways: (1) by testing the brick and controlling the mortar which can be done by laboratory tests or by mixing proportions, or (2) by periodic testing of masonry prisms. This Technical Notes covers quality control by method (1), testing brick and control of mortar. Technical Notes 11D covers quality control by method (2), testing masonry prisms. When quality control by materials testing (brick and mortar) is to be used, the design compressive strength (f'm) can be assumed, using Table 2 of the BIA Standard, "Building Code Requirements for Engineered Brick Masonry", and the quality control requirements of this Technical Notes should be incorporated into the guide specifications in Technical Notes 11A Revised and 11B Revised. All other sections of the Guide Specifications for Brick Masonry (Technical Notes 11A Revised and 11B Revised) are appropriate for Engineered Brick Masonry. QUALITY ASSURANCE BASED ON BRICK AND MORTAR TESTS Guide Specifications and Notes PART I - GENERAL 1.02 QUALITY ASSURANCE Delete section and notes for 1.02.A in Technical Notes 11A Revised, and substitute the following quality control requirements based on brick tests. A. Brick Tests: 1. Preconstruction Tests: a. Test five brick for compressive strength to determine acceptability of units for compliance with specifications. b. Use brick similar to those selected for use, matching color, texture, raw material, moisture content and coring. c. Cost of tests shall be borne by the General Contractor.

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2. Site Control Tests: a. Test units selected at random from units delivered to the project. b. Cost of tests of units after delivery shall be borne by the General Contractor, unless tests indicate that units do not conform to the requirements of the specifications, in which case cost shall be borne by the seller. 3. Test in accordance with ASTM C 67-__________, with the following additional requirements: a. If the coefficient of variation of the compression samples tested exceeds 12%, obtain compressive strength by multiplying average compressive strength of specimens by 1 - 1.5 ( V - 0.12 ) 100 where v is the coefficient of variation of sample tested. Add the following to Section 1.02 in Technical Notes 11A Revised. C. Preconstruction Requirements: 1. Prebid conference: a. A prebid conference, directed by the Architect/Engineer, will be held one week prior to the bid opening to discuss: (1) Structural concept. (2) Method and sequence of masonry construction. (3) Special masonry details. (4) Quality control requirements. (5) Material requirements. (6) Job organization. (7) Workmanship. b. Attendance is mandatory for all prospective: (1) General contractors. (2) Masonry subcontractors. (3) Brick suppliers. NOTE: 1.02.C This requirement may be deleted if not necessary for the project due to bidders being knowledgeable with engineered brick masonry. 1.02.C.1.b Invitation to attend should be extended to others, such as the inspectors (local building department and other government agencies) and Owner.

2. Preconstruction Testing and Certification: a. After award of the contract, the General Contractor shall: (1) Within 14 days, submit to the Architect/Engineer for approval the name of the independent laboratory which will perform the site control tests and provide the certificates and test reports required in Section 1.03.

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(2) Upon approval of the laboratory, certificates and test reports, and prior to any masonry construction, make arrangements for the following tests: (a) Brick tests in accordance with preconstruction requirements, Section 1.02.A (b) Mortar tests in accordance with mortar section. b. Masonry work can begin only after approval of testing. c. Testing is acceptable if test results indicate that materials meet the minimum requirements of Part II - Products. d. Cost of preconstruction testing shall be borne by the General Contractor, unless tests indicate that units do not conform to the requirements of the specifications, in which case cost shall be borne by the seller. NOTE: 1.02.C.2 Inspection, laboratory and testing for quality control can be a responsibility of the Structural Engineer. If so, revise section.

3. Preconstruction Conference: a. A preconstruction conference, directed by the Architect/Engineer, will be held after the award of the General Contract, but prior to beginning of masonry work to discuss: (1) Structural concept. (2) Method and sequence of masonry construction. (3) Special masonry details. (4) Standard of workmanship. (5) Quality control requirements. (6) Job organization. b. Attendance is mandatory for: (1) General contractor job superintendent. (2) Masonry subcontractor job superintendent. (3) Masonry subcontractor foreman. (4) At least two masons. (5) Authorized representative of the brick supplier. (6) Mortar material suppliers. NOTE: 1.02.C.3.b Invitations to attend should be extended to others, such as inspectors (local building department and other government agencies) and Owner.

D. Job Site Quality Control: 1. Site control brick and mortar tests: a. Use compressive strength of brick units and compressive strength of mortar cubes to control quality.

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b. Test brick in accordance with site control requirements, Section 1.02.A. c. Test mortar cubes in accordance with mortar section. d. Test five brick and three mortar cubes for each 100,000 brick or fraction thereof. e. Brick and mortar to be selected at random by the Architect/ Engineer. f. Site control data shall be acceptable if material exceeds specified strength. g. Cost of tests shall be borne by the General Contractor. NOTE: 1.02.D.1.c Type M, S or N as specified in the mortar section. More than one mortar type may be specified. If so, provide sections to cover all requirements. Mortar design compressive strengths should be based on laboratory tests of mortar made from materials mixed to the proportion specification as required by the mortar section. 1.02.D.1.e As calculated by the Structural Engineer. May vary for different parts of the building. If so, provide sections to cover all design strengths.

**OR** 1. Site control brick and mortar batching: a. Use compressive strength of brick units and control on material proportions used in batching mortar to control quality. b. Test brick in accordance with site control requirements, Section 1.02.A. c. Control mortar batches to conform to proportion specification specified in mortar section. d. Test five brick for each 100,000 brick or fraction thereof. e. Site control data shall be acceptable if brick compressive strengths meet the requirements of Part II and mortar is batched to proportion specification. f. Cost of tests shall be borne by the General Contractor. PART II - PRODUCTS 2.01 BRICK A. Facing Brick: 1. Delete Note and replace with: NOTE: 2.01.A.1 Grades and Types. Brick subject to the action of weather or soil, but not subject to frost action when permeated with water, shall be of grade MW or grade SW, and where subject to temperature below freezing while in contact with soil shall be grade SW. Brick used in loadbearing or shear wall construction shall comply with the dimensional and distortion tolerances specified for type FBS of ASTM C 216-__________. Where such brick do not comply with these tolerance requirements, the compressive strength of brick masonry shall be determined by prism tests.

PART Ill - EXECUTION 3.02 GENERAL ERECTION REQUIREMENTS Delete Section 3.02.I in Technical Notes 11B Revised, and replace with the following Section 3. 02.I and add Section 3. 02.J. I. Mortar Joint Thickness 1. Lay brick with __________-in. mortar joints, not to exceed 1/2 in. (12.7 mm). NOTE:

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3.02.I Coordinate joint thickness with brick specified in 2.01.A.2.

J. Construction Tolerances: 1. Maximum variation from plumb in vertical lines and surfaces of columns, walls and arrises: a. 1/4 in. (6.4 mm) in 10 ft. (3 m). b. 3/8 in. (9.6 mm) in a story height not to exceed 20 ft. (6 m). c. 1/2 in. (12.7 mm) in 40 ft. (12 m) or more. 2. Maximum variation from plumb for external corners, expansion joints and other conspicuous lines: a. 1/4 in. (6.4 mm) in any story or 20 ft. (6 m) maximum. b. 1/2 in. (12.7 mm) in 40 ft. (12 m) or more. 3. Maximum variation from level of grades for exposed lintels, sills, parapets, horizontal grooves and other conspicuous lines: a. 1/4 in. (6.4 mm) in any bay or 20 ft. (6 m). b. 1/2 in. (12.7 mm) in 40 ft. (12 m) or more. 4. Maximum variation from plan location of related portions of columns, walls and partitions: a. 1/2 in. (12.7 mm) in any bay or 20 ft. (6 m). b. 3/4 in. (19 mm) in 40 ft. (12 m) or more. 5. Maximum variation in cross-sectional dimensions of columns and thicknesses of walls from dimensions shown on drawings: a. Minus 1/4 in. (6.4 mm). b. Plus 1/2 in. (12.7 mm). NOTE: 3.02.J These construction tolerances are for engineered brick masonry only, and are based on actual dimensions. They are intended for the sole purpose of protecting the structural integrity of engineered brick masonry elements and may not be adequate for establishing construction tolerances associated with esthetics or visual requirements.

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Technical Notes 11D - Guide Specifications for Brick Masonry, Part 4 Continued [Aug. 1972] (Reissued Sept. 1988)

INTRODUCTION This issue of Technical Notes is a continuation of Technical Notes 11C Revised and contains additional sections and statements to be incorporated into the "Guide Specifications for Brick Masonry", Technical Notes 11A Revised and 11B Revised. This will make the guide specifications in those Technical Notes suitable for Engineered Brick Masonry. The sections contained in these Technical Notes deal primarily with the quality assurance, selection of units, strength and construction tolerances to provide masonry that meets the minimum design requirements for Engineered Brick Masonry. In the construction of Engineered Brick Masonry, quality control may be maintained in either of two ways: (1) by testing the brick and controlling the mortar which can be done by laboratory tests or by mixing proportions, or (2) by periodic testing of masonry prisms. This Technical Notes covers quality control by method (2), prism testing. Technical Notes 11C covers quality control by method (1), testing brick and control of mortar. When quality control is maintained by prism tests, the brick masonry strength is determined in accordance with paragraph 4.2.2.1 of the BIA Standard, "Building Code Requirements for Engineered Brick Masonry". Test prisms are built as the walls are constructed and tested in compression at 7 days or 28 days. If prism tests are used, the quality control requirements of this Technical Notes should be incorporated into the guide specifications in Technical Notes 11A Revised and 11B Revised. All other sections of the Guide Specifications for Brick Masonry (Technical Notes 11A Revised and 11B Revised) are appropriate for Engineered Brick Masonry. QUALITY ASSURANCE BASED ON PRISM TESTS Guide Specification and Notes PART I - GENERAL 1.02 QUALITY ASSURANCE Delete sections and notes for 1.02 in Technical Notes 11A Revised, and substitute the following quality control requirements based on prism tests. A. Prism Tests: 1. Preconstruction Prisms: a. Build ten prisms: (1) Of site materials insofar as possible. (2) Use brick units similar as to color, texture, raw materials, moisture content and coring.

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(3) Under same conditions, insofar as possible, as the structure. (4) With same bonding, insofar as possible, as for structure. (5) With same mortar as for the structure. (6) With same joint thickness. (7) With same workmanship. 2. Site Control Prisms: a. Build prisms as required by Section 1.02.D.1 at the direction of the Architect/Engineer. (1) Of site materials. (2) Of brick units selected at random from units delivered to the project. (3) At the project site. (4) With same bonding, insofar as possible, as the structure. (5) With site mortar. (6) With same joint thickness as for the structure. (7) With same workmanship. 3. Dimensions a. Minimum height: 12 in. (305 mm). b. Height-to-thickness ratio (h/t) range: (1) Minimum: 2 (2) Maximum: 5 4. Mark each specimen for identification. 5. Store prisms: a. Preconstruction prisms: o

o

(1) In air at temperatures not less than 65 ; F. (18.3 C.). b. Site control prisms: (1) At site for not less than 24 hr. o

o

(2) Thereafter, in air at temperatures not less than 65 F.(18. C.). 6. Test prisms: a. Preconstruction prisms: (1) Five after aging 7 days. (2) Five after aging 28 days.

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b. Site control prisms: (1) After aging 7 days. c. Cap each prism with suitable material to provide bearing surfaces on each end: (1) Plane within 0.003 in. (0.076 mm). (2) Approximately perpendicular to the axis of the prism. NOTE: 1.02.A.6.c It is suggested that calcined gypsum be used for the capping material.

7. Test in accordance with relevant provisions of ASTM E 447-__________, with the following provisions: a. For h/t less than 5, reduce specimen compressive strength by correction factors as follows:

alnterpolate to obtain intermediate values.

b. If the coefficient of variation of the sample tested exceeds 10%, obtain the compressive strength by multiplying the average compressive strength of the specimens by 1 - 1.5 ( V - 0.10 ) 100 where v is the coefficient of variation of the sample tested. B. Brick Tests: 1. Preconstruction Tests: a. Test five brick for compressive strength to determine acceptability of units for compliance with specifications. b. Use brick similar to those selected for use, matching color, texture, raw material, moisture content and coring. c. Cost of tests shall be borne by the General Contractor. 2. Test in accordance with ASTM C 67-__________, with the following additional requirements: a. If the coefficient of variation of the compression samples tested exceeds 12%, obtain compressive strength by multiplying average compressive strength of specimens by 1 - 1.5 ( V - 0.12 ) 100 where v is the coefficient of variation of sample tested. C. Preconstruction Requirements: 1. Prebid conference:

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a. A prebid conference, directed by the Architect/ Engineer, will be held one week prior to the bid opening to discuss: (1) Structural concept. (2) Method and sequence of masonry construction. (3) Special masonry details. (4) Quality control requirements. (5) Material requirements. (6) Job organization. (7) Workmanship. b. Attendance is mandatory for all prospective: (1) General contractors. (2) Masonry subcontractors. (3) Brick suppliers. NOTE: 1.02.C This requirement may be deleted if not necessary for the project due to bidders being knowledgeable with engineered brick masonry. 1.02.C.1.b Invitation to attend should be extended to others, such as the inspectors (local building department and other government agencies) and Owner.

2. Preconstruction Testing and Certification: a. After award of the contract, the General Contractor shall: (1) Within 14 days, submit to the Architect/Engineer for approval the name of the independent laboratory which will perform the site control tests and provide the certificates and test reports required in Section 1.03. (2) Upon approval of the laboratory, certificates and test reports, and prior to any masonry construction, make arrangements for the following tests for each combination of brick and mortar: (a) Tests of ten prisms in accordance with preconstruction requirements, Section 1.02.A. (b) Test five brick in accordance with Section 1.02.B. b. Masonry work can begin only after approval of testing. c. Testing is acceptable if test results indicate that materials meet the minimum requirements of Part II - Products, or Section 3.02.K. d. Cost of preconstruction testing shall be borne by the General Contractor. NOTE: 1.02.C.2 Inspection, laboratory and testing for quality control can be a responsibility of the Structural Engineer. If so, revise section.

3. Preconstruction Conference:

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a. A preconstruction conference, directed by the Architect/Engineer, will be held after the award of the General Contract, but prior to beginning of masonry work to discuss: (1) Structural concept. (2) Method and sequence of masonry construction. (3) Special masonry details. (4) Standard of workmanship. (5) Quality control requirements. (6) Job organization. b. Attendance is mandatory for: (1) General contractor job superintendent. (2) Masonry subcontractor job superintendent. (3) Masonry subcontractor foreman. (4) At least two masons. (5) Authorized representative of the brick supplier. (6) Mortar material suppliers. NOTE: 1.02.C.3.b Invitations to attend should be extended to others, such as inspectors (local building department and other government agencies) and Owner.

D. Job Site Quality Control: 1. Site control prism tests: a. Use 7-day compressive strength of brick prisms to control quality. b. Build, store and test prisms in accordance with site control requirements, Section 1.02.A. c. Build three prisms for each 5000 sq. ft. (465 m2) of wall area as directed by the Architect/Engineer. **OR** c. Provide three prisms for each story height. d. Site control test data shall be acceptable if the 7-day prism strength indicates that the 28-day strength will be equal to or greater than the required minimum ultimate compressive strength. See Section 3.02.K. e. Cost of control prisms to be borne by the General Contractor NOTE: 1.02.D.1.c Select, depending upon whichever is more frequent.

E. Furnish Sample Panel: 1. 4 ft. (1.2 m) long by 3 ft. (1 m) high, of the proposed color range, texture, bond, mortar and workmanship.

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2. Erect panel in the presence of the Architect/Engineer before installation of materials. 3. Provide separate panels for each type of brick or mortar. 4. Do not start work until Architect/Engineer has accepted sample panel. 5. Use panel as standard of comparison for all masonry work built of same material. 6. Do not destroy or move panel until work is completed and accepted by Owner. 1.03 SUBMITTALS Add the following section to 1.03 in Technical Notes 11A Revised: D. Prism Test Reports: 1. Test reports are to be submitted to Architect/Engineer for approval. 2. Testing and reports are to be completed by an independent laboratory. 3. Test reports shall show: a. Age at test. b. Storage conditions. c. Dimensions (h/t). d. Compressive strength of individual prisms. e. Coefficient of variation (v). f. Ultimate compressive strength of masonry (f 'm ) which has been corrected for the coefficient of variation and the hit of the prisms tested. PART II -PRODUCTS 2.01 BRICK A. Facing Brick: 1. Delete Note and replace with: NOTE: 2.01.A.1 Grades and Types. Brick subject to the action of weather or soil, but not subject to frost action when permeated with water, shall be of grade MW or grade SW and where subject to temperature below freezing while in contact with soil shall be grade SW. Brick used in loadbearing or shear wall construction shall comply with the dimensional and distortion tolerances specified for type FBS of ASTM C 216-__________. Where such brick do not comply with these tolerance requirements, the compressive strength of brick masonry shall be determined by prism tests.

PART III -EXECUTION 3.02 GENERAL ERECTION REQUIREMENTS Delete Section 3.02.I in Technical Notes 11B Revised, and replace with the following Section 3.02.I and add Sections 3.02.J And 3.02.K I. Lay brick with __________-in. mortar joints, not to exceed 1/2 in. (12.7 mm). J. Construction Tolerances: 1. Maximum variation from plumb in vertical lines and surfaces of columns, walls and arrises: a. 1/4 in. (6.4 mm) in 10 ft. (3 m).

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b. 3/8 in. (9.6 mm) in a story height not to exceed 20 ft. (6 m) c. 1/2 in. (12.7 mm) in 40 ft. (12 m) or more. 2. Maximum variation from plumb for external corners, expansion joints and other conspicuous lines: a. 1/4 in. (6.4 mm) in any story or 20 ft. (6 m) maximum. b. 1/2 in. (12.7 mm) in 40 ft. (12 m) or more. 3. Maximum variation from level of grades for exposed lintels, sills, parapets, horizontal grooves and other conspicuous lines: a. 1/4 in. (6.4 mm) in any bay or 20 ft. (6 m). b. 1/2 in. (12.7 mm) in 40 ft. (12 m) or more. 4. Maximum variation from plan location of related portions of columns, walls and partitions: a. 1/2 in. (12.7 mm) in any bay or 20 ft. (6 m). b. 3/4 in. (19 mm) in 40 ft. (12 m) or more. 5. Maximum variation in cross-sectional dimensions of columns and thicknesses of walls from dimensions shown on drawings: a. Minus 1/4 in. (6.4 mm). b. Plus 1/2 in. (12.7 mm). K. Minimum Ultimate Compressive Strength of Masonry (f'm )__________psi ( __________kgf/cm2). NOTE: 3.02.K Ultimate compressive strength as determined by the Structural Engineer may vary for different parts and walls of the building. If so, provide sections to cover all design requirements.

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Technical Notes 11E - Guide Specifications for Brick Masonry, Part 5, Mortar and Grout September 1991 Abstract: This Technical Notes is a guide specification for mortar and grout used in brick masonry. Using this Technical Notes, a specifier can prepare a job specification for Section 04100. Notes are provided to help the specifier understand certain decisions that affect the project specifications. The guide specification is in accordance with the Construction Specifications Institute's (CSI) Masterformat. Key Words: brick masonry, grout, guide specification, mortar. INTRODUCTION This Technical Notes is a continuation of Technical Notes 11 Series on "Guide Specifications for Brick Masonry" and contains the requirements for mortar and grout for brick masonry. This Technical Notes is appropriate for both empirically designed and rationally designed brick masonry. The guide specification in this Technical Notes is in accordance with the Construction Specifications Institute's Masterformat and is based on the requirements of BIA M1 Standard Specification for Portland Cement-Lime Mortar for Brick Masonry contained in Technical Notes 8A and ASTM C 270 Mortar for Unit Masonry. Mortar conforming to the requirements of BIA M1 will meet all of the requirements of portland cement-lime mortars of ASTM C 270. A complete discussion of mortar properties is contained in Technical Notes 8.

GENERAL Mortar requirements differ from concrete requirements because the primary function of mortar is to bond masonry units into an integral element. The basic mortar ingredients include portland cement, hydrated lime, sand and water. Masonry cements, proprietary mortar mixes, are sometimes used to replace portland cement and hydrated lime or combined with portland cement to make mortar. BIA M1, ASTM C 270 and ASTM C 1142 Ready-Mixed Mortar for Unit Masonry are the recommended standards for mortar to be used with brick masonry. Grout is different from both concrete and mortar. Grout is a high slump mixture used to fill cells of masonry units or between wythes of masonry to resist stresses and develop bond with reinforcement. Grout can consist of portland cement, hydrated lime, fine or coarse aggregate and water. Grout should be specified by ASTM C 476 Grout for Masonry.

RECOMMENDED MORTAR USES Selection of a particular mortar type is usually a function of the needs of the finished structural element. For example, where high wind loads are expected, high lateral strength may be required and, hence, mortar with high flexural bond strength should be considered. For loadbearing walls and reinforced brick masonry, high compressive strength may be the governing factor. In some projects considerations of durability, color, flexibility, etc., may be of most concern. No single type of mortar is best for all purposes. Factors which improve one property of mortar may do so at the expense of others. For this reason, when selecting a mortar, evaluate properties of each mortar type and choose that type and materials which will best meet all requirements. Technical Notes 8B discusses the selection of mortar types in depth. The following sections

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briefly discuss selection of mortar.

Type N Mortar Type N mortar is suitable for general use in exposed masonry above grade. It is recommended for use in parapet walls, chimneys and exterior walls when subject to severe exposure.

Type S Mortar Type S mortar is recommended for use in reinforced and unreinforced masonry where higher flexural strengths than Type N are required.

Type M Mortar Type M mortar is recommended for use in masonry in contact with earth such as foundations, retaining walls, paving, sewers and manholes, and in reinforced masonry.

Type O Mortar Type O mortar is suitable for interior use in non-loadbearing applications.

SPECIFYING MORTAR Mortars are specified in one of two ways: proportions or properties, but not both. Mortar prepared by the proportion requirements should not be compared to mortar prepared by the property requirements. The proportion specification requires that mortar materials be mixed according to given volumetric proportions or weight. If mortar is specified by this method, no laboratory testing of the mortar is required. If mortar is specified by the property specifications, compressive strength, water retention and air content tests must be performed on mortar mixed in the laboratory. Field mortar is then mixed to the proportions selected from these laboratory tests. When neither proportion nor property is specified, the proportion specifications govern.

SPECIFYING GROUT Grout is specified by proportion using ASTM C 476. Either fine or fine and coarse aggregate can be used in grout. Experience has shown that grout mixed to the specified proportions performs well with brick masonry since the grout compressive strength closely matches the compressive strength of the brick masonry. Grout must have adequate compressive strength, bonding with reinforcement and for embedment of anchor bolts. There is usually no need to specify compressive strength of grout unless required by design. Grout strength can be verified by field testing using ASTM C 1019. Slump of the grout is usually specified to be between 8 and 11 in. (203.2 and 279.4 mm).

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CONCLUSION This Technical Notes is a guide specification for mortar and grout for brick masonry. Notes are provided to assist in editing the specification. The information and suggestions contained in this Technical Notes are based on the available data and the experience of the engineering staff of the Brick Institute of America. The information contained herein must be used in conjunction with good technical judgment and a basic understanding of the properties of masonry. Final decisions on the use of information contained in this Technical Notes are not within the purview of the Brick Institute of America and must rest with the project architect, engineer, owner or all.

04100 MORTAR AND GROUT

Guide Specification & Notes PART 1 GENERAL 1.01 SECTION INCLUDES A. Mortar for masonry. B. Grout for masonry. C. Repointing mortar. 1.02 RELATED SECTIONS A Concrete: Section 03__________. B. Masonry: Section 04__________. C. Masonry Cleaning: Section 04500. D. Structural Metal Framing: Section 05100. E. Rough Carpentry: Section 06100. F. Waterproofing: Section 07100.

NOTE: 1.02 Some of these broadscope sections may not be included. Other narrow scope sections under these broadscope sections may be added.

1.03 PRODUCTS INSTALLED BUT NOT FURNISHED UNDER THIS SECTION A. Reinforcing Steel: Section 03210. B. Metal Accessories: Section 04150. C. Masonry Units: Section O4200.

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D. Flashing and Sheet Metal: Section 07600. 1.04 REFERENCES A. ACI 530.1/ASCE 6-__________ - Specifications for Masonry Structures. B. ASTM C 91 - __________, [UBC Standard No. 24-16] - Masonry Cement. C. ASTM C 144 - __________ - Aggregate for Masonry Mortar. D. ASTM C 150 - __________, [UBC Standard No. 26-1] - Portland Cement. E. ASTM C 207-__________, [UBC Standard No. 24-18] - Hydrated Lime for Masonry Purposes. F. ASTM C 270-__________, [UBC Standard No. 24-20] - Mortar for Unit Masonry. G. ASTM C 404-__________ - Aggregates for Masonry Grout. H. ASTM C 476-__________, [UBC Standard No. 24-29] - Grout for Masonry. I. ASTM C 780-__________ - Preconstruction and Construction Evaluation of Mortars for Plain and Reinforced Unit Masonry. J. ASTM C 979-__________ - Pigments for Integrally Colored Concrete. K. ASTM C 1019-__________, [UBC Standard No. 24-28] - Sampling and Testing Grout. L. ASTM C 1142-__________ - Ready-Mixed Mortar for Unit Masonry. M. BIA Technical Notes 8A - "Specifications for Portland Cement-Lime Mortar for Brick Masonry" BIA M1-88).

NOTE: 1.04 The applicable date for each reference can be given here or in Section 01090-Reference Standards. Alternate standards are given for Uniform Building Code specifications.

1.05 SUBMITTALS A. Submit data indicating proportion or property specifications used for mortar. B. Submit test reports for mortar materials indicating conformance to ASTM C 270 [UBC Standard No. 24-20] property specifications. Report proportions resulting from laboratory testing used to select mortar mix. C. Submit test reports for field sampling and testing mortar in conformance to ASTM C 780. D. Submit test reports for grout materials indicating conformance to ASTM C 476 [UBC Standard No. 24-29]. E. Submit test reports for field sampling and testing grout in conformance to ASTM C 1019 [UBC Standard No. 24-28]. F. Samples: Submit two ribbons of mortar for conformance with color.

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NOTE: 1.05.A ASTM C 270 and UBC Standard No. 24-20 require that mortar be specified by proportion or property, not both. 1.05.B ASTM C 270 and UBC Standard No. 24-20 require comparison of laboratory prepared mortars to establish proportions for field-mixed mortar when the property specifications are used. 1.05.C ASTM C 780 allows preconstruction evaluation of mortar and comparison of field prepared mortars. Mortar prepared in the field should not be compared to values found in the property specifications of ASTM C 270 or UBC Standard No. 24-20. 1.05.E ASTM C 1019 or UBC Standard No. 24-28 is used to test uniformity of grout preparation during construction.

1.06 DELIVERY, STORAGE AND HANDLING A. Store materials in dry location and protected from dampness and freezing. B. Stockpile and handle aggregates to prevent contamination from foreign materials. 1.07 ENVIRONMENTAL REQUIREMENTS A. Follow requirements for cold and hot weather construction in ACI 530.1/ASCE 6 [Uniform Building Code]. PART 2 PRODUCTS 2.01 MORTAR MATERIALS A. Cementitious materials: 1. Portland Cement: ASTM C 150 [UBC Standard No. 26-1], Type__________. 2. Hydrated Lime: ASTM C 207 [UBC Standard No. 24-18], Type S__________. 3. Masonry Cements: ASTM C 91 [UBC Standard No. 24-16], Type__________. B. Sand: ASTM C 144. C. Admixtures: 1. No air-entraining admixtures or material containing air-entraining admixtures. 2. No antifreeze compounds shall be added to mortar. 3. No admixtures containing chlorides shall be added to mortar. D. Water: Clean and potable. E. Mortar pigment: 1. ASTM C 979: Pigment shall not exceed 10% of the weight of portland cement. 2. Carbon black shall not exceed 2% of the weight of portland cement.

NOTE: 2.01.A Allowable flexural tensile stresses for masonry built with air-entrained portland cement-lime mortars, or with

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masonry cement mortars are lower than those built with portland cement-lime mortars. 2.01.A.1 Only Types I, II or III. 2.01.A.3 Types M, S, or N. 2.01.B Sand not conforming to ASTM C 144 must have mortar meet the property specification requirements. 2.01.E Limits on amount of pigments should be halved when using masonry cement mortars.

2.02 GROUT MATERIALS A. Cementitious materials: 1. Portland Cement: ASTM C 150 [UBC Standard No. 26-1], Type__________. 2. Hydrated Lime: ASTM C 207 [UBC Standard No. 24-18], Type S__________. B. Aggregates: 1. Fine aggregate: ASTM C404. 2. Coarse aggregate: ASTM C 404. C. Water: Clean and potable. D. Admixtures.

NOTE: 2.02.A.1 Only Types 1, II or III. 2.02.D Grout admixtures are used to decrease grout shrinkage, aid in pumping grout, or for other reasons. The use of such admixtures should not adversely affect the performance of the grout.

2.03 MORTAR AND GROUT MIXES A. Mortar - ASTM C 270 [UBC Standard No. 24-20] or BIA M1: 1. Type based on proportion specifications. **OR** 1. Type__________based on property specifications to achieve __________ psi strength, __________% air content, __________% water retention.

NOTE: 2.03.A Mortar mixes can be specified separately by specifying ASTM C 270, UBC Standard No. 24-20 or BIA M1; or by specifying ASTM C 1142 alone. 2.03.A.1 Type M, S, N or O depending on design requirements.

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**OR** A. Mortar - ASTM C 1142: Type__________.

NOTE: 2.03.A Ready mixed mortar can be mixed on-site or off-site. Types RM, RS, RN or RO.

B. Grout: ASTM C 476 [UBC Standard No. 24-29] 1. Fine grout. 2. Coarse grout. 3. Slump: __________inches (__________mm).

NOTE: 2.03.B The use of fine or coarse grout is based on the size of the grout space and the height of the grout pour. 2.03.B.3 Specify desired slump between 8 and 11 inches (203.2 and 279.4 mm). Higher slump is necessary for smaller dimensioned grout spaces and with higher unit/grout volume ratios.

PART 3 EXECUTION 3.01 FIELD MORTAR MIXING A. All cementitious materials and aggregate shall be mixed between 3 and 5 min. in a mechanical batch mixer with the maximum amount of water to produce a workable consistency. B. Control batching procedure to ensure proper proportions by measuring materials by volume. Sand measurement by shovel count shall not be permitted. C. If water is lost by evaporation within 2 1/2 hours after initial mixing, retemper with water. D. Discard all mortar which is more than 2 1/2 hours old.

NOTE: 3.01 ASTM C 270 or BIA M1 can be referenced for field mortar mixing. 3.01.B Materials can be specified by weight if volume proportions are converted to weight proportions

3.02 FIELD GROUT MIXING A. Control batching procedure to ensure proper proportions by measuring materials by volume.

NOTE: 3.02 ASTM C 476 can be referenced for field grout mixing. 3.02.A Materials can be measured by weight if volume proportions are converted to weight proportions.

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3.03 INSTALLATION A. Install mortar and grout in accordance with ACI 530.1/ASCE 6. 3.04 REPOINTING MORTAR A. Use mortar materials listed in 2.01, Type N. B. Prehydrate the mortar by the following method. Mix dry ingredients together. Then add only enough water to make a damp, stiff mix which will retain its form when pressed in a ball. After 1 to 2 hours, add sufficient water to bring it to the proper consistency.

NOTE: 3.04.A If materials and proportions of existing mortar are known, use those instead of Type N mortar if the existing mortar provided sufficient durability.

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TECHNICAL NOTES on Brick Construction

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December 2005

Ceramic Glazed Brick Exterior Walls Abstract: Buildings and other structures employ glazed brick in a variety of uses, from decorative bands to entire wall systems. Due to the imperviousness of its ceramic glazed surface, a vented air space is recommended behind the glazed brick wythe. Proper wall design, detailing and material selection, along with quality construction will result in attractive glazed brick applications exhibiting durability, structural stability and virtually maintenance free aesthetics.

Key Words: ceramic, condensation, drainage, expansion joints, flashing, glaze, moisture, movement, vents, weeps.

SUMMARY OF RECOMMENDATIONS General: • Consult manufacturers for assistance with special shapes and to determine the property requirements of double-fired glazed units • Specify surfaces other than stretcher faces to be glazed

Wall System Design: • Use vented drainage walls to ensure the most rapid removal of moisture that enters the wall

• Specify concave, "V", or grapevine mortar joint profiles Air Space: • 2 in. (51 mm) minimum air space recommended, required to be no less than 1 in. (25.4 mm)

• When prescriptive anchor spacings are used, air space may not exceed 41/2 in. (114 mm)

Flashing: • Extend flashing to the face of the brickwork or beyond • Install at all horizontal interruptions to the air space • Turn flashing ends into head joint a minimum of 1 in. (25.4

Weeps: • Open head joint weeps spaced no more than 24 in. (610 mm) o.c. recommended • Most building codes permit weeps no less than 3/16 in. (4.8 mm) diameter and spaced no more than 33 in. (838 mm) o.c. • Wick and tube weep spacing recommended at no more than 16 in. (406 mm) o.c.

Vents: • Place vents at the tops of walls and below horizontal interruptions such as shelf angles and flashing locations • Use open head joint weeps as vents; If weeps are not open head joints, vents are needed one or two courses above weeps • Space vents 24 to 48 in. (610 mm to 1.22 m) o.c. • Stagger vents in relation to overlying weeps

mm) to form end dam

INTRODUCTION Glazed brick can be used in both interior and exterior applications, as accent brick or as the field brick covering the entire facade, as shown in Photos 1 and 2. Glazed units have been integral parts of buildings for decades and have performed well under all climatic conditions. Glazed brick are often selected for use because of the many characteristics that make them distinct among brick products. One of these is the wide variety of colors that are not available in standard brick production. These may be applied to special shapes or brick of different sizes to further enhance visual interest. It is even possible to apply multiple glazes to a single brick unit, as shown in Photo 3. Glazes may be clear, translucent or opaque, and are available in almost any color with a glossy, satin or matte finish. Glazed brick also provide an impervious surface that is extremely durable and resistant to staining which results in easy maintenance. Resistance to scratching and abrasion, as well as fire resistance of the glaze, also enhance the durability of glazed brick units. Successful performance of exterior glazed brick walls can

Photo 1 Glazed Brick Used for Entire Facade Page 1 of 6

be ensured through the use of vented drainage wall systems that allow water to evaporate from the unglazed back surface of the brick as well as through mortar joints. Other wall systems utilizing glazed brick exist and are serviceable, but are outside the scope of this Technical Note. Attention must be given to proper material selection, detailing and construction practices to ensure successful performance. Proper design and installation of exterior glazed brick walls allows water drainage and minimizes the possibility of water being trapped behind the glazed surface which may lead to efflorescence or spalling. As in all brick construction, stress concentrations due to restrained movement must also be minimized. This Technical Note addresses these concerns and offers recommendations to ensure proper performance. a) Glazed Brick at Top of Wall

WALL SYSTEM DESIGN Moisture Resistance It is recommended that exterior glazed brick walls be designed to drain water that enters the wall system and to allow moisture from wind-driven rain or condensation to evaporate from the behind the brickwork. Therefore, a vented drainage wall system is recommended. Drainage walls must be designed, detailed and constructed properly to accommodate the flow of water collected within the wall. Common examples of drainage walls include brick and block cavity walls, brick veneer, and rain screen walls. See Technical Note 7 for more information on water penetration resistance.

b) Glazed Brick at Shelf Angle

c) Glazed Brick at Foundation Figure 1 Glazed Brick Wall Sections

In drainage wall design, penetrant water is intended to drain down the back of the brick, which is separated from interior wall elements by an air space. While a minimum 1 in. (25.4 mm) air space is required, 2 in. (51 mm) is recommended. Flashing and weeps are needed at horizontal interruptions in the air space to collect water and direct it out of the wall system, refer to Figures 1a, 1b and 1c. They are typically provided above lintels and shelf angles, beneath sills, under copings and masonry or stone caps, and at the wall base. Discontinuous flashing, such as at window sills and loose lintels, should be constructed with end dams to ensure that collected water is directed out of the brickwork. End dams are also recommended where stepped flashings are used, such as at sloped grades, above arches, and above sloped roofs. Weeps must be provided in head joints directly above the flashing. Open head joint weeps are recommended with a spacing of no more than 24 in. (610 mm) on center. Spacing of wick and tube weeps is recommended at no more than 16 in. (406 mm) on center. Most building codes require weeps to have a minimum diameter of 3/16 in. and permit weeps to be spaced up to 33 inches (838 mm) on center. Mortar joints affect the moisture resistance of brickwork since they can account for up to twenty percent of the brickwork surface. Selecting mortar joint profiles that are

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most resistant to water penetration and cover the bed surface of the brick unit further minimize water intrusion and the possibility of water being trapped behind the glazed surface. Thus, concave, "V" and grapevine tooled mortar joints are recommended. Vents. Vents placed at the top of glazed brick wall segments, as shown in Figures 1a and 1b, encourage air circulation and help to dissipate moisture within the air space. These vents should be located a course or two below horizontal interruptions of the air space such as shelf angles and flashing locations and be spaced 24 to 48 inches (610 mm to 1.22 m) on center. The vent should be an open head joint and may include a weep vent or louvered insert to deter insect access. In multi-story construction, the horizontal placement of vents and weeps should be staggered, or louvered inserts may be utilized to prevent draining water from entering vents. When wick or tube weeps are used at the base of a wall, additional vents should be added no more than two courses above weeps to best assure air movement through the air space. Caps, Copings and Sills. Glazed brick should not be used in locations where they are likely to be saturated. Rowlock courses of brick used as caps, copings or sills are vulnerable to water penetration, especially when the slope is not sufficient to drain water away quickly. Therefore, glazed brick should be avoided in favor of concrete, stone, or metal elements that reduce the potential for water penetration at these locations. More information about caps and copings can be found in Technical Note 36A.

Movement Brick masonry walls expand or contract with changes in temperature and moisture content. Brick expansion and other building movements are typically accommodated by expansion joints, placed vertically and horizontally, which divide the wall into rectangular segments and limit cumulative movement. Segment lengths and heights will vary with the building and wall design; however, expansion joints must be placed beneath all shelf angles. Expansion joints are typically needed near corners, at changes in wall height, at offsets in the wall plane and at the ends of elements rigidly anchored to the backing or structure. The segments formed by expansion joints should be limited to a maximum length of approximately 25 feet (7.62 m). Segment lengths in building parapets should be limited to approximately 15 feet (4.57 m). The building geometry will also dictate locations for vertical expansion joints in glazed brick walls. Vertical expansion joints should extend full height from the foundation to the roof, or between locations of horizontal support. Brick masonry expansion joints must be formed with highly compressible materials and be free of mortar and obstructions. Expansion joints are typically 3/8 in. (9.5 mm) or 1/2 in. (12.7 mm) wide with a foam backer rod and elastic sealant at the wall face to prevent air and water penetration from the exterior. See the Technical Notes 18 Series for more discussion regarding building movements and expansion joints.

Structural Design Glazed brick can be used in loadbearing, cavity or veneer walls and should be designed in accordance with the appropriate chapter of ACI 530/ ASCE 5/ TMS 402, Building Code Requirements for Masonry Structures, also known as the Masonry Standards Joint Committee (MSJC) Code. [Ref. 11] Design can be based on either the requirements for veneer in Chapter 6, or the rational design approach of Chapters 2 or 3. In either case, the preferred design should be based on minimizing the potential for cracking of the glazed brick wythe under applied loading. More detailed information on structural design of veneer walls and cavity walls are included in the Technical Notes 28 Series and Technical Notes 21 Series, respectively.

Photo 2 Glazed Brick Used as Accents

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The MSJC Code and Specification also contain material, size and spacing requirements for wall ties in cavity walls and anchors in veneer walls. Anchor and wall tie spacing in the MSJC Code depends on the wall design method and anchor type. See the Technical Notes 28 Series for anchor spacing in veneer walls and the Technical Notes 21 Series for spacing of wall ties in cavity walls.

MATERIALS Glazed Brick Two methods are used to apply glazes to brick bodies: a single-firing process and a double-firing process. In the single-firing process, the glaze is applied to the unfired brick body and is fused to the body when fired. In the double-firing process, brick that have been fired previously have a glaze applied and are fired again to fuse the glaze onto the brick. For some glazes with certain compositions or color pigments, double-firing is necessary to ensure the proper firing of the brick body at a higher temperature and the proper color and finish of the glaze at a lower temperature. Both methods result in quality glazed brick. ASTM standards for glazed brick include requirements for both brick body and the glazes.

Photo 3 Multiple Glazes, Shapes and Sizes Add Variety

Body Properties. The physical properties of brick vary depending on raw material, method of forming, and the degree of firing. ASTM standards establish indicators of durability based only upon physical property requirements that correlate with freeze thaw testing.

Single-fired glazed brick must meet the requirements of ASTM C 1405, Standard Specification for Glazed Brick (Single Fired, Brick Units). This standard establishes minimum criteria for the glaze as well as for solid and hollow brick bodies. Single-fired glazed brick intended for exterior exposure should meet the property requirements for Class Exterior. These include prescriptive requirements for minimum compressive strength, maximum cold water absorption and maximum saturation coefficient as shown in Table 1. The saturation coefficient requirement does not apply provided the average compressive strength of a random sample of five brick equals or exceeds 8000 psi (55.2 MPa) with no individual strength less than 7500 psi (51.8 MPa) and the 24 hr cold water absorption of each unit does not exceed 6.0%. The saturation coefficient and water absorption requirements do not apply if a sample of five brick pass the freezing and thawing test in ASTM C 67. Currently, proper specification of double-fired brick units requires the designer to adopt two separate ASTM standards: ASTM C 126, Standard Specification for Ceramic Glazed Structural Clay Facing Tile, Facing Brick, and Solid Masonry Units to cover applicable properties of the ceramic glaze finish, and ASTM C 216, Standard Specification for Facing Brick (Solid Masonry Units Made from Clay or Shale); ASTM C 652, Standard Specification for Hollow Brick (Hollow Masonry Units Made from Clay or Shale) or ASTM C 1088, Standard Specification for Thin Veneer Brick Units Made From Clay or Shale to cover requirements for the brick body. TABLE 1 ASTM C 1405 Physical Requirements of Clay Bodies for Glazed Units Designation

Class Exterior Class Interior

Minimum Compressive Strength, psi (MPa), Gross Area Average of 5 Brick 6000 (41.4) 3000 (20.7)

Individual 5000 (34.8) 2500 (17.2)

Maximum Water Absorption by 24-hr Cold1, % Individual 7.0

Maximum Saturation Coefficient 1,2 Average of 5 Brick 0.78

Individual 0.80

1. The saturation coefficient and/or cold water absorption requirement(s) may not apply when other criteria are met. See Body Properties text for more information. 2. The saturation coefficient is the ratio of absorption by 24 hr submersion in cold water to that after 5 hr submersion in boiling water.

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Specifying glazed brick in this manner addresses material concerns necessary for exterior use. Conformity to the requirements of the appropriate standard is an indication of the ability of the brick to withstand internal stresses caused by freezing of moisture within its body. Glaze Properties. Ceramic glazes produce a durable, aesthetically pleasing surface feature on brick. ASTM standards C 126 and C 1405 set minimum property requirements for glaze finishes. Both standards cover finish requirements for glazes applied to the body before the brick unit is fired (single-firing). ASTM C 126 also covers double-fired glazed brick when the glaze is fused to the brick unit at temperatures over 1500 °F (816 °C). The ASTM C 126 and C 1405 property requirements for glaze finishes are listed below. One or more of the properties listed may not be applicable to some special decorative and textured glazes. Manufacturers should be consulted for the property requirements of these.

•

Imperviousness - A wet cloth and water must be able to remove permanent blue black ink that has been allowed to dwell on the finish for five minutes, with no stain remaining on or beneath the surface.

•

Hardness and Abrasion Resistance - Glazes must be rated above five on the Mohs hardness scale and resist scratching from ordinary glass or steel in addition to being subjected to an abrasion test.

•

Resistance to Crazing - Glazes may not craze, spall or crack when subjected to one cycle of autoclaving.

•

Fire Resistance - The brick body and glaze are rated "noncombustible" and must withstand temperatures up to 1900 °F (878 °C) without melting, distorting or releasing toxic fumes. They must also measure "0" flame spread, fuel contribution and smoke density when tested in accordance ASTM E 84.

•

Resistance to Fading/Chemical Resistance - Glaze colors must not change from the approved sample after a 3 hr submersion in prescribed acidic and basic solutions.

•

Opacity - When specified, ink applied to the brick body must not be visible through the glaze.

Appearance. Aesthetic characteristics of glazed brick are specified by grade and type in ASTM C 126 and ASTM C 1405. The two grades, S and SS, limit dimensional variations, distortion and set squareness criteria of the exposed face. The requirements of Grade S are utilized in most glazed brick projects. Where a higher degree of precision is necessary the more precise Grade SS units should be specified. The type of a glazed brick indicates the number of glazed faces on the brick. Type I units have one glazed face, and Type II units are glazed on two opposite faces. Unless specified otherwise, the stretcher face (or exposed face of shapes) is coated with the glaze finish. When glazed surfaces other than those identified by Type I or Type II are required, the additional surface(s) should be specified. Brick which will be exposed on their ends, or on their bed surfaces as in recessed courses or quoins, should also be explicitly specified. Consultation with the brick manufacturer is advised to determine if the proposed glazed brick can be made.

Mortar Mortar should conform to ASTM C 270 Standard Specification for Mortar for Unit Masonry. Type N mortar is typically recommended for exterior walls above grade. Type S may provide better flexural bond strength to brick having initial rates of absorption (IRA) under 5 g/min•30 in.2 (5 g/min•194 cm2). Use of admixtures and additives is not usually recommended unless their effect on the masonry, masonry units and items embedded in the brickwork is known, and they do not detrimentally affect plastic or hardened mortar. ASTM C 1384, Standard Specification for Admixtures for Masonry Mortars provides methods to evaluate the effect of admixtures on mortar properties. See Technical Note 8B for more information on mortar selection.

Anchors and Wall Ties Acceptable connectors for anchored masonry veneer and cavity wall applications include adjustable ties, unit ties, and ladder-type or tab-type joint reinforcement. Connectors may be of stainless steel conforming to ASTM A 580, carbon steel protected from corrosion by hot-dipped galvanizing conforming to ASTM A 153 or epoxy coatings conforming to ASTM A 884, Class A, Type 1, minimum 7 mils (175 µm) for joint reinforcement and ASTM A 899, Class C - 20 mils (508 µm) for wire items. For more information on selection of anchors and ties see Technical Note 44B.

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Flashing Flashing materials should be sufficiently tough and flexible to resist puncture and cracking. In addition, flashing should not degrade when exposed to ultraviolet light or when placed in contact with metal, mortar or sealants. Flashing materials are generally formed from sheet metals, bituminous-coated membranes, rubber, or combinations thereof. The selection is largely determined by cost and suitability. Asphalt-impregnated felt is not acceptable as a flashing material. The cost of flashing materials varies widely. It is suggested, however, that only superior materials be selected, since replacement in the event of failure is difficult. See Technical Note 7A for a more detailed discussion of flashing materials.

SUMMARY As with any brick masonry wall system, performance is the result of successful material selection, design detailing and construction practices. While the recommendations contained in this Technical Note are similar to those for non-glazed brick, it is important to consider the imperviousness of the glazed brick surface. Consequently, attention to each aspect of design and construction is essential to obtain the intended service life of the structure. Therefore, some glazed brick designs may entail more thorough detailing, as they may be less forgiving of detailing and construction deficiencies than non-glazed brick. Ceramic glazed brick can present a bright, bold, colorful statement with a durable brick surface. The information and suggestions contained in this Technical Note are based on the available data and the combined experience of engineering staff and members of the Brick Industry Association. The information contained herein must be used in conjunction with good technical judgment and a basic understanding of the properties of brick masonry. Final decisions on the use of the information contained in this Technical Note are not within the purview of the Brick Industry Association and must rest with the project architect, engineer and owner.

REFERENCES 1. Annual Book of ASTM Standards, ASTM International, West Conshohocken, PA, 2005: Volume 1.03 - A 580/A 580M, Standard Specification for Stainless Steel Wire A 899, Standard Specification for Steel Wire, Epoxy-Coated Volume 1.04 - A 884/A 884M, Standard Specification for Epoxy-Coated Steel Wire and Welded Wire Reinforcement Volume 1.06 - A 153/A 153M, Standard Specification for Zinc Coating (Hot-Dip) on Iron and Steel Hardware Volume 4.05 - C 126, Standard Specification for Ceramic Glazed Structural Clay Facing Tile, Facing Brick, and Solid Masonry Units C 216, Standard Specification for Facing Brick (Solid Masonry Units Made from Clay or Shale) C 652, Standard Specification for Hollow Brick (Hollow Masonry Units Made From Clay or Shale) C 1088, Standard Specification for Thin Veneer Brick Units Made From Clay or Shale C 1384, Standard Specification for Admixtures for Masonry Mortars C 1405, Standard Specification for Glazed Brick (Single Fired, Brick Units) 2. Building Code Requirements for Masonry Structures (ACI 530-05/ASCE 5-05/TMS 402-05), The Masonry Society, Boulder, CO, 2005. 3. Specification for Masonry Structures (ACI 530.1-05/ASCE 6-05/TMS 602-05), The Masonry Society, Boulder, CO, 2005.

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TECHNICAL NOTES on Brick Construction 14 1850 Centennial Park Drive, Reston, Virginia 20191 | www.gobrick.com | 703-620-0010

March 2007

Paving Systems Using Clay Pavers Abstract: This Technical Note presents an overview of paving systems made with clay pavers used in pedestrian and vehicular, residential and nonresidential projects. Commonly used systems that include clay pavers are discussed, and guidance is given in selecting the appropriate clay paver, setting bed and base. Site conditions and project requirements that may affect choice are discussed, including subgrade soil, pedestrian and vehicular traffic, accessibility requirements, drainage, and appearance.

Key Words: base, design, flexible, mortared paving, mortarless paving, paving, permeable paving, rigid, subbase.

SUMMARY OF RECOMMENDATIONS: Select Paving System • Use Table 1 to determine paving system based on application • Use Table 2 to evaluate clay paving systems based on their general advantages and disadvantages • Use Table 3 to verify choice of the clay paving system for specific site conditions and project requirements

Design Paving System • Use Technical Note 14 for design considerations and

general specification of clay pavers, base and subbase • Use appropriate Technical Note in this series to provide design and construction information specific to the setting bed of the paving system selected as follows: - Sand Setting Bed – Technical Note 14A - Bituminous Setting Bed – Technical Note 14B - Mortar Setting Bed – Technical Note 14C • Use a design professional as necessary to verify suitability of a paving system design

INTRODUCTION Technical Note 14 is the first in a series discussing the use of clay pavers for pedestrian and vehicular, residential and nonresidential applications (see Photo 1). It provides guidance in selecting a paving system (see Figure 1) and the appropriate clay paver, setting bed and base. Once these are determined, other Technical Notes in this series provide additional information specific to the setting bed chosen, including common construction for particular applications, typical details, installation practices and maintenance. Paving systems exposed to more than 251 daily equivalent single axle loads (ESAL) from trucks or combination vehicles having three or more loaded axles are considered heavy duty vehicular applications. Such paving

Clay Pavers Setting Bed Joint with Sand or Mortar Wearing Course Specified Edge Restraint

Compacted Base Compacted Subgrade Geotextile (If Required) Photo 1 Pedestrian Plaza with Clay Pavers © 2007 Brick Industry Association, Reston, Virginia

Figure 1 Typical Pavement Section Page 1 of 19

systems are beyond the scope of this Technical Note series. For more information on paving systems for heavy duty vehicular use, refer to Flexible Vehicular Brick Paving – A Heavy Duty Applications Guide [Ref. 14]. Table 1 lists acceptable paving systems for typical paving applications. Table 2 is a comparison of paving systems listing the general advantages and disadvantages for each system. Table 3 indicates which paving systems are appropriate for specific site conditions and project requirements. TABLE 1 Acceptable Paving Systems Bituminous Setting Bed

Sand Setting Bed Application

Typical Examples

Mortar Setting Bed Bonded

Unbonded

Aggregate Base

Asphalt Base1

CementTreated Aggregate Base

Patios and walks on property of a one- or twofamily house or townhouse

A

A

A

A

A

A

A

A

Driveways on property of a one- or twofamily house or townhouse

A

A

A

A

A

A

A

NA

Commercial/ Pedestrian

Public plazas, courtyards or sidewalks

A

A

A

A

A

A

A

A

Light Duty Vehicular3

Paving with low volume2 of heavy vehicles such as streets, parking areas, turnarounds or passenger drop-offs

A

A

A

A

A

A

A

NA

Heavy Duty Vehicular3

Paving with a high volume2 of heavy vehicles such as streets, commercial driveways or crosswalks across them

Residential

Concrete Base1

Asphalt Base1

Concrete Base1

Concrete Base1

Concrete Base1

Refer to Flexible Vehicular Brick Paving - A Heavy Duty Applications Guide

NOTES:

KEY:

1. For a paving system that uses existing asphalt or concrete as base, verify that the condition of the base is acceptable. 2. For a definition of high volume of heavy vehicles, see Introduction. 3. For these applications, a design professional should design the paving system.

A = Acceptable NA = Not Acceptable

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TABLE 2 Comparison of Pavements Made with Clay Pavers Clay Pavers On: Sand Setting Bed on Aggregate Base

Advantages

Disadvantages

• Most durable

• Intensive cleaning may erode joint sand

• Cost-effective

• May require a thicker base

• Easy access to repair underground utilities • Good as overlay to existing asphalt or concrete pavement • Allows use of semi-skilled labor • Can be designed as a permeable pavement Sand Setting Bed on Asphalt Base

• Good as overlay to existing asphalt pavement

• Intensive cleaning may erode joint sand

Sand Setting Bed on Cement-Treated Aggregate Base

• Good over poor soils or in small, confined areas

• Intensive cleaning may erode joint sand

Sand Setting Bed on Concrete Base

• Good over poor soils or in small, confined areas

• Intensive cleaning may erode joint sand

• Good as overlay to existing concrete pavement

• Requires good drainage above base

• Good as overlay to existing concrete pavement

• Susceptible to greater offset with subgrade movement Bituminous Setting Bed on Asphalt Base

• Reduced horizontal movement and uplift

• Repairs are more difficult and expensive

• Enhanced water penetration resistance

• Little tolerance for paver thickness variations or inaccurate base elevations

Bituminous Setting Bed on Concrete Base

• Reduced horizontal movement and uplift

• Repairs are more difficult and expensive

• Enhanced water penetration resistance

• Little tolerance for paver thickness variations or inaccurate base elevations

• Good over poor soils or in small, confined areas

Mortar Setting Bed Bonded to Concrete Base

Mortar Setting Bed Unbonded to Concrete Base

• Greater tolerance for paver thickness variations or inaccurate base elevations

• Movement joints must align through entire paving system

• Can be used on steeper slopes and greater vehicle speeds

• Least cost-effective

• Drainage occurs on the surface

• Repairs are most difficult and expensive

• Greater tolerance for paver thickness variations or inaccurate base elevations

• Bond break must be used to avoid stresses caused by horizontal movement between layers

• Movement joints in setting bed and base are not required to align • Preferred when used over elevated structural slab

• Mortar joint maintenance required

• Least cost-effective • Mortar joint maintenance required • Repairs are most difficult and expensive

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TABLE 3 Selection of Setting Bed and Base Bituminous Setting Bed

Sand Setting Bed Site Condition or Project Requirement

Mortar Setting Bed Bonded

Unbonded

Aggregate Base

Asphalt Base

CementTreated Aggregate Base

Soft Soil in Subgrade

R

R

A

A

R

A

A

A

Tree Roots in/near Subgrade

R

A

NA

NA

A

NA

NA

NA

Expansive Soil in Subgrade

A1

R

A

NA

R

NA

NA

NA

Snow Melt System

A2

A2

A2

R2

A1

NA

R

R

Suspended Structural Slab

A1

NA

A1

R1

NA

R1

R

R

Good Surface Drainage

R

R

R

R

R

R

R

R

Poor Surface Drainage

R

R

R

R

R

R

NA

NA

Permeable Pavement

R

NA

NA

NA

NA

NA

NA

NA

Deep Frost Line

R1

R1

R1

R1

A1

A1

A

A

Freeze/Thaw

R1

R1

R1

R1

A1

A1

A

NA

Minimal Frosts

R

R

R

R

R

R

R

R

Pressure Washing

R1

R1

R1

R1

R1

R1

R

R

Vacuuming

R1

R1

R1

R1

R1

R1

R

R

Minimal Cleaning

R

R

R

R

R

R

R

R

ADA Compliance

R

R

R

R

R

R

A

A

Pedestrians Only

R

R

R

R

R

R

R

R

Light Vehicular Traffic

R3

R3

R3

R3

R3

R3

R

NA

NOTES: 1. Use stabilized joint sand 2. When snow melt system is in sand setting bed, use stabilized sand in setting bed. 3. Use Application PS or PX pavers

Concrete Base

Asphalt Base

Concrete Base

Concrete Base

Concrete Base

KEY: R = Recommended A = Acceptable NA = Not Acceptable

DESIGN CONSIDERATIONS Aesthetics The relatively small size of clay pavers creates a pavement surface with a human scale. As many pavers can be observed simultaneously, the nuances of different colors, textures and patterns can be clearly seen when standing on the pavement. Single colors can present a monolithic appearance. Multiple colors can break down the scale of the pavement (see Photo 2). Borders laid in a different color can add interest to the pavement. In larger areas, it may be desirable to introduce different colors in the form of bands or panels. Some highly decorative pavements have introduced patterns that flow, repeat and intertwine (see Figure 2). Color. Clay pavers are available in a wide range of colors. The most common are red and brown earth tones, but buff and gray colors also are produced

Photo 2 Multiple Colors Affect Pavement Scale

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Double Basket Weave

Herringbone

Running Bond

Single Basket Weave

Spanish Bond

Stack Bond

Figure 2 Brick Paving Bond Patterns (see Photo 3). Single colors as well as variegated pavers can also be mixed together to form blends that expand the palette of available colors. The color of clay pavers is typically consistent through the body of the paver and is highly resistant to weathering and fading because of its vitrified composition. Since clay pavers are made from natural materials, there may be some inherent color variations between different production runs from the same manufacturer. This is most evident in large paved areas of a single color. Using a field panel to establish acceptable color variations and laying pavers taken from different cubes of pavers helps avoid this issue. Texture. Clay pavers are available with a range of surface textures, such as wire cut and molded. Viewed at a flat angle from a distance, a variation in paver texture can be more obvious than a variation in color. Designers may find it advantageous to change the surface texture in different areas or bands to exaggerate the contrast. The texture also has an impact on slip and skid resistance.

Photo 3 Clay Paver Colors

Some pavers are manufactured with a more pronounced texture or surface pattern. Surface features — including a grid of dimples or domes — also can be imprinted into the surface of the paver before firing. Pavers also can be manufactured and installed to provide a tactile/detectable warning surface. In addition, patterns and words can be engraved or laser etched into the surface of fired pavers.

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Edge Treatment. Pavement texture is created not only by the character of the texture of each paver, but also by the treatment of the edges. Pavers can have square edges, rounded edges or beveled edges formed during the extrusion, molding or pressing processes. These can be uniform along the entire edge of the paver, which enhances the uniformity of the surface, or they can be made to be variable or irregular to create the feel of a historic pavement. Additionally, fired pavers can be tumbled to create distressed edges. Pavement use and maintenance should be considered when selecting the edge treatment of pavers, as they may affect the appearance or smoothness of the paving surface. When square-edge pavers are laid with sand joints, care should be taken to ensure that they do not make direct contact with or lip under adjacent pavers. A minimum of 1/16 in. sand-filled joint should separate each clay paver. Maintaining Photo 4 full sand joints and taking care not to distress paver Clay Paver Sidewalk in Basket Weave Pattern edges during snow removal procedures helps minimize potential chippage of a paver's edges. Using clay pavers with chamfers enhances drainage by channeling water away from the surface, which can improve skid resistance. Bond Patterns. Many installation patterns can be used when laying clay pavers. Some of the most popular are herringbone bond, running bond, stack bond and basket weave, as shown in Photo 4. When choosing a pattern, considerations should include the setting bed of the pavement and the horizontal loads. Vehicle loads typically generate the largest horizontal load on a pavement. Sand and bituminous setting beds are more prone to paver creep, or horizontal movement. A herringbone bond best distributes horizontal forces across a pavement, reducing the potential for creep. Running bond and other patterns with continuous joints do not distribute horizontal loads as well as herringbone bond. If these bond patterns are used, continuous joints should be oriented perpendicular to the direction of traffic. In some projects, different-colored pavers are arranged to create a pattern that aligns with adjacent features, such as building columns or trees. The size of different colored clay pavers may vary within permissible tolerances. Pavers supplied to a project may be slightly smaller or slightly larger than the specified sizes assumed in design. As such, the exact number of pavers that can be laid within a set dimension will vary unless the joint widths are slightly adjustable. Paving systems with sand or bituminous setting beds that are subject to vehicular applications can have their structural integrity reduced if joints are too wide. Therefore, the paver layout should be designed with a degree of flexibility to accommodate slight variations in the pattern. As necessary, cutting individual pavers also may be used to solve alignment and structural integrity issues.

Pedestrian Traffic Paving systems using clay pavers exposed to pedestrian traffic for residential and nonresidential applications are common. Many residential patios and walks can be constructed with only a base layer between the subgrade and the setting bed. For more public pedestrian applications such as sidewalks and plazas, a more substantial paving system may be required.

Vehicular Traffic Light vehicular traffic includes general access for cars and for trucks, but in smaller volumes. As stated in ASTM C 1272, high volumes of traffic are considered traffic with over 251 daily equivalent single loads (ESAL), a standard term used by pavement engineers. For further information about clay pavements subject to heavy vehicular traffic, refer to Flexible Vehicular Brick Paving – A Heavy Duty Applications Guide [Ref. 14].

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The load capacity of a clay paving system with a sand setting bed and aggregate base is dependent on the total pavement section rather than just the clay paver layer. Most individual clay pavers have a high compressive strength and, with sufficient thickness, can develop significant interlock with surrounding pavers to support light vehicular loads when properly constructed. Sufficient thickness and compaction of subbase, base and paver layers virtually eliminates pavement deformation under loading. For light duty vehicular paving systems, a maximum traffic speed of 30 mph (50 kph) is considered appropriate for pavers in a sand setting bed. As vehicle speeds increase, the horizontal loading caused by accelerating, braking and turning increases. Light duty vehicular clay paving systems with sand setting beds where a herringbone bond is used, where joint width is maintained between 1/16 to 3/16 in. (1.6 to 4.8 mm), where an appropriate jointing sand is properly installed and maintained and where sufficient edge restraint is provided can perform well and substantially reduce the potential for movement of the pavers from horizontal creep.

Slip Resistance, Skid Resistance and Hydroplaning Each of these issues relates to the slipperiness of the pavement surface. Slip resistance generally refers to the slipperiness of a pavement as experienced by pedestrians. Skid resistance and hydroplaning are related to the slipperiness of a pavement as experienced by vehicles. The slip resistance is determined as the static coefficient of friction of a surface. A number of test procedures are available for laboratory and field testing, but they may provide different values. Slip resistance can be measured in the laboratory and the field using ASTM C 1028, Test Method for Determining the Static Coefficient of Friction of Ceramic Tile and Other Like Surfaces by the Horizontal Dynamometer Pull-Meter Method [Ref. 4]. For surfaces in an accessible route, the United States Access Board historically recommended, but did not mandate, a value of 0.6 for level surfaces and 0.8 for ramps when measured by the portable NBS-Brungraber machine using a silastic sensor shoe. Most clay pavers exceed these values. Skid resistance is typically determined on the basis of a material’s dynamic coefficient of friction, which generally decreases as speed increases. Testing usually involves either a specialized test vehicle moving at more than 30 mph (50 kph) or a portable British Pendulum Tester used in accordance with ASTM E 303, Test Method for Measuring Surface Frictional Properties Using the British Pendulum Tester [Ref. 11]. For paving systems exposed to light duty application pavements covered in this Technical Note 14 series, skid resistance is not an issue. Hydroplaning also is associated with speed, but in conjunction with standing water on the pavement surface. Due to the speed restrictions imposed on clay pavements subject to light duty vehicle traffic, hydroplaning should not be a concern for clay pavements.

Slope Paving systems can be successfully used on slopes with up to a 10 percent gradient. For projects where site conditions involve slopes exceeding 10 percent, a design professional and local codes should be consulted.

Drainage Adequate drainage is important to the performance and durability of any clay paving system. Water should be drained from the paving system as quickly as possible. A minimum slope of 1/4 in. per ft of slope (2 percent grade) is recommended. Adequate drainage should be provided to ensure the integrity of all layers in a paving system. Three types of drainage potentially exist in clay paving systems: surface restricted, subsurface restricted and unrestricted. Surface restricted drainage occurs on the surface of the paving system. This type of drainage is typical of clay paving systems with a mortar setting bed. Subsurface restricted drainage occurs when water drains over the surface and immediately below the paving course. This type of drainage is typical of paving systems installed with a bituminous setting bed. Unrestricted drainage involves draining water from the surface, the subsurface and through the subgrade. This type of drainage requires a sand setting bed on an aggregate base. Drains should be selected and placed to adequately handle anticipated water flow. Drains serving paving systems should have openings not only on the surface but also on the sides. Such drains should be used for all paving systems to drain water from adjacent materials and to prevent capillary rise. Side openings should extend below the top of any impervious layer or membrane in the paving system. Drains placed in pavements with sand setting beds should have screens to prevent sand from entering the drain. Pavement edges that restrict water flow at the lowest point in the paving system where water is anticipated should have weeps at 16 in. (406 mm) on center. www.gobrick.com | Brick Industry Association | TN 14 | Paving Systems Using Clay Pavers | Page 7 of 19

Accessibility The Americans with Disabilities Act Accessibility Guidelines (ADAAG) [Ref. 1] establish minimum design requirements that cover access for people with disabilities to public and private buildings and facilities. The Public Rights-Of-Way Accessibility Guidelines (Draft PROWAG) [Ref. 13] in draft form cover disability access provisions for pedestrian areas along public rights-of-way. Research has documented that clay paving systems can comply with the accessible provisions within these guidelines [Ref. 12 and 15]. The ADAAG and Draft PROWAG mandate several surface profile requirements applicable to all pavement systems. The designer should be aware of maximum permissible gradients and other requirements that often are overlooked (see Photo 5). In addition to planning and designing in accordance with these guidelines, it is important to implement regular maintenance programs to maintain these routes in a safe and serviceable condition. Specific requirements especially pertinent to clay pavers include surface, changes in level, joints and detectable warning surfaces. Surface. The ADAAG and Draft PROWAG require an accessible surface to be firm, stable and slipresistant. Smoothness also may be an important criterion, because a pedestrian in a wheelchair may be more sensitive to vibration or trip hazards. Properly designed, installed and maintained clay paver surfaces achieve these properties. Besides inadequate design, installation or maintenance, all pavement systems may be subject to heaving and settlement of underlying soils that result in changes in level. Research has shown that the vibration on clay paver surfaces is comparable to or less than that of poured concrete and other common paving materials [Refs. 12 and 15]. Changes in Level. Both the ADAAG and Draft PROWAG allow a change in level (surface discontinuity) up to 1/4 in. (6.4 mm) (see Figure 3a). Both the ADAAG and Draft PROWAG allow a change in level between 1/4 in. (6.4 mm) minimum and 1/2 in. (12.7 mm) maximum. The ADAAG requires this change in level to be sloped (beveled) not steeper than 1:2 (see Figure 3b). The Draft PROWAG also requires a maximum slope (bevel) of 1:2 for this change in level, but further mandates that the slope (bevel) be applied across the entire change in level (see Figure 3c). With respect to pavers, sudden changes in level (differences in elevation of the top surfaces of adjacent pavers) should be kept to a minimum through careful

Photo 5 At Grade Street Crossing with ADA-Compliant Surface Texture Changes

Max. 1/4 in. (6.4 mm)

a) ADAAG & Draft PROWAG Change in Level up to 1/4 in. (6.4 mm)

Max. 1/4 in. (6.4 mm)

1

2

Max. 1/2 in. (12.7 mm) b) ADAAG Vertical Change between 1/4 and 1/2 in. (6.4 and 12.7 mm)

1

2

Max. 1/2 in. (12.7 mm) c) Draft PROWAG Vertical Change between 1/4 and 1/2 in. (6.4 and 12.7 mm)

For Vertical Changes Greater Than 1/2 in. (12.7 mm), Use Ramp Figure 3 Requirements for Making Changes in Elevation

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design and installation and should be maintained as part of a regular maintenance program. Changes in level can result from heaving or settling of the pavement; uneven joints or can occur at frames and manhole covers. Joints. The ADAAG does not specifically cover joints, but it does have requirements for openings in gratings, which could be considered as being similar. The Draft PROWAG ADAAG has requirements for horizontal openings in walkway joints and gratings. Both guidelines allow openings up to 1/2 in. (12.7 mm) wide, more than twice the typical width of joints between pavers in pavements with sand and bituminous setting beds that are typically 1/16 in. (1.6 mm) to 3/16 in. (4.7 mm) wide. Joints between pavers in a mortar setting bed are generally 3/8 in. (9.4 mm) to 1/2 in. (12.7 mm) wide, but would not be considered an opening. Detectable Warning Surfaces. Both the ADAAG and the Draft PROWAG require detectable warning surfaces consisting of truncated domes sized to have a base diameter of 0.9 in. (23 mm) minimum and 1.4 in. (36 mm) maximum, a top diameter of a minimum of 50 percent to a maximum of 65 percent of the base diameter, and a height of 0.2 in. (5.1 mm). Clay pavers can be made with truncated domes. The ADAAG requires truncated domes to be placed on a square grid with a center-to-center spacing of 1.6 in. (41 mm) minimum and 2.4 in. (61 mm) maximum, and a base-to-base spacing of 0.65 in. (17 mm) minimum, measured between the most adjacent domes. The Draft PROWAG requires truncated domes to be placed in either a square or a radial grid pattern meeting the same dimensional layout requirements as set forth in the ADAAG. Both guidelines require detectable warning surfaces to extend 24 in. (610 mm) from rail platform boarding edges. The Draft PROWAG also covers curb ramps and blended transitions that are not covered in the ADAAG. Curb ramps and blended transitions require detectable warning surfaces to extend 24 in. (610 mm) minimum in the direction of travel for their full width. Flares of curb ramps are not required to have a detectable warning surface.

CLAY PAVERS Manufacturing Clay pavers are manufactured in much the same way as face brick, as discussed in Technical Note 9. Extrusion (stiff-mud), molding (soft-mud) or drypressing processes are used to produce pavers (see Figure 4). Extruded clay pavers have a wire-cut texture or smooth die-skin wearing surface. Lugs (spacer bars) and chamfers may be formed on the sides and edges of the pavers during the extrusion or cutting process. Clay pavers produced by the molding or dry-pressing processes have a smooth or textured surface. Lugs and chamfers also may be formed by the sides and edges of the molds. Pavers from any of the production methods may have aesthetic features such as irregular or textured edges. Clay pavers made by the molding or dry-pressed process may have frogs or cavities on one bed surface, although they would not be exposed.

Paver with Square Edges

Paver with Textured Edges

Chamfer Lug Extruded or Re-Pressed Paver with Chamfer and Lugs

Molded Paver with Rounded Edges

Figure 4 Clay Pavers

Pavers generally are manufactured with their length equal to a module of their width. Two commonly specified clay paver sizes are 4 in. wide by 8 in. long (102 mm by 203 mm) and 3 5/8 in. wide by 7 5/8 in. (92 mm by 194 mm) long. Other similar sizes are available, such as 3¾ in. (95 mm) wide by 7½ in. (190 mm) long, and several manufacturers are able to provide custom sizes. Common specified thicknesses are 1½ in. (38 mm), 2¼ in. (57 mm) and 2 5/8 in. (67 mm).

Standards Clay pavers can be used as a wearing course in many exterior pavement and interior floors. Most pavers in the United States are manufactured to comply with consensus standards published by ASTM International (ASTM). Two ASTM standards define requirements for clay pavers for exterior use: ASTM C 902, Standard Specification for Pedestrian and Light Traffic Paving Brick [Ref. 3], and ASTM C 1272, Standard Specification for Heavy www.gobrick.com | Brick Industry Association | TN 14 | Paving Systems Using Clay Pavers | Page 9 of 19

Vehicular Paving Brick. [Ref. 5] For light duty applications addressed by the Technical Notes 14 series, clay pavers complying with ASTM C 902 are normally used. Clay pavers manufactured to meet ASTM C 1272 may be used in light duty or heavy vehicular applications and may provide longer pavement service life — especially where the pavement is subject to higher volumes of vehicular traffic. Only clay pavers meeting the requirements of ASTM C 1272 are suitable for heavy vehicular applications, which are covered in Flexible Vehicular Brick Paving – A Heavy Duty Applications Guide. ASTM C 902. This specification covers clay pavers suitable for patios, walkways, floors, plazas, residential driveways and commercial driveways (passenger drop-offs). It describes three Classes and three Types of clay pavers according to severity of their exposure to weather and to traffic, respectively. Three Applications also are defined, based upon the pavers’ intended use, and limit their dimensional tolerances, distortion and extent of chipping. Class - A paver’s Class relates to its resistance to damage from exposure to weather and is based on compressive strength and absorption properties. Class SX pavers are intended for use where the pavers may be frozen while saturated with water. Class MX pavers are intended for exterior use where the pavers will not be exposed to freezing conditions. Class NX pavers are not acceptable for exterior use but may be used for interior areas where the pavers are protected from freezing when wet. For most exterior residential or light duty applications, Class SX pavers are used. Type - A paver’s Type relates to its resistance to abrasion. Type I pavers are intended for use where the pavers are exposed to extensive abrasion, such as sidewalks and driveways in publicly occupied spaces. Type II pavers are intended for use where the pavers are exposed to intermediate pedestrian traffic, such as heavily traveled residential walkways and residential driveways. Type III pavers are intended for use in low pedestrian traffic, residential areas such as floors and patios of single-family homes. For most exterior residential or light duty applications, Type I or II pavers are used. Application - A paver’s Application relates to its aesthetics and use. Application PS pavers are intended for general use and can be installed in any bond pattern with mortar or with sand-filled joints when not exposed to vehicular traffic. When Application PS pavers are installed with sand-filled joints for light duty vehicular applications, they should be laid in running bond or other bonds not requiring extremely close dimensional tolerances. Any bond pattern can be used when Application PS pavers are installed with mortar joints. Application PX pavers have tighter dimensional tolerances that allow consistently narrow joints between pavers. Such uses include pavements without mortar joints between pavers where exceptionally close dimensional tolerances are required as a result of special bond patterns or unusual construction requirements. Application PA pavers are characterized by aesthetic effects such as variability in size, color and texture. Such pavers have performed successfully in many historic clay paving applications and are generally used where a distinctive architectural character is desired. Such applications are often installed with mortar joints between pavers, but can be successful in sand-filled joint applications that are laid by workers with experience installing Application PA pavers in this manner. Using stabilized joint sand or applying stabilizer to joint sand will help prevent sand loss from wider sand-filled joints. Pavers complying with ASTM C 902 are not required to have a minimum thickness. However, they are commonly manufactured to a specified thickness of 2¼ in. (57 mm) and 1½ in. (38 mm). Except for patios or walks for oneor two-family homes in southern climates with limited frost exposure, clay pavers 1½ in. (38 mm) thick are usually installed only over a rigid base. ASTM C 1272. This standard addresses heavy vehicular pavers generally used in streets, commercial driveways and industrial applications. ASTM C 1272 designates two Types of pavers depending on their method of installation. Three Applications limit dimensional tolerances, distortion and extent of chipping. The paver Type is based upon the compressive strength, breaking load and absorption properties of the pavers. Type F pavers are intended to be set in a sand setting bed with sand-filled joints. The minimum paver thickness is required to be 2 5/8 in. (67 mm). They also can be installed over flexible or rigid bases. Type R pavers are intended to be set in a mortar setting bed with mortar joints over a concrete base. Type R pavers also can be set on a bituminous setting bed with sand-filled joints and supported by an asphalt or concrete base. The minimum thickness for Type R pavers is required to be 2¼ in. (57 mm). Applications PS, PX and PA are common to both ASTM standards and denote similar requirements. Pavers complying with ASTM C 1272 may contain frogs but must be without cores or perforations. www.gobrick.com | Brick Industry Association | TN 14 | Paving Systems Using Clay Pavers | Page 10 of 19

ASTM Properties for Clay Pavers. The Class, Type and Application designations within ASTM clay paver standards are based upon physical properties and characteristics, including compressive strength, breaking load, absorption, abrasion, dimensional tolerances and extent of chipping. Pavers must be resistant to damage from the effects of traffic and the environment. In many regions of the United States, clay pavers will be exposed to severe environmental conditions. Pavers often are in a saturated condition and can experience numerous freeze/thaw cycles. Application of deicers can cause additional thermal shock to pavers. Compliance with property requirements of ASTM C 902 and C 1272 provides the required durability. Compressive Strength, Breaking Load and Absorption - The strength and absorption requirements of pavers from the ASTM standards are shown in Table 4. Some pavers are durable, but cannot be classified under the physical requirements shown in Table 4. Using alternatives in the specifications allows pavers that are known to perform well to meet the durability requirement. It does not signify that the pavers are of a lower quality. TABLE 4 Property Requirements ASTM Standard

C 902

Minimum Compressive Strength, psi (Mpa)

Maximum Cold Water Absorption, %

Maximum Saturation Coefficient

Minimum Breaking Load, lb/in. (kN/mm)

Avg of 5 Brick

Avg of 5 Brick

Avg of 5 Brick

Avg of 5 Brick

Individual

Individual

Individual

Individual

Class SX

8,000 (55.2)

7,000 (48.3)

8.0

11.0

0.78

0.80

----

----

Class SX (molded)

4,000 (27.6)

3,500 (24.1)

16.0

18.0

0.78

0.80

----

----

Class MX

3,000 (20.7)

2,500 (17.2)

14.0

17.0

No Limit

No Limit

----

----

Class NX

3,000 (20.7)

2,500 (17.2)

No Limit

No Limit

No Limit

No Limit

----

----

C 1272 Type R

8,000 (55.2)

7,000 (48.3)

6.0

7.0

----

----

----

----

Type F

10,000 (69.0)

8,800 (60.7)

6.0

7.0

----

----

475 (83)

333 (58)

For pavers complying with ASTM C 902 or C 1272, several alternatives are allowed. The freezing and thawing test alternative allows the cold water absorption and the saturation coefficient to be waived if a sample of five brick that meet all other requirements passes the freezing and thawing test of ASTM C 67 without breaking and with no greater than 0.5 percent loss in dry weight of any individual unit. The sulfate soundness alternative allows the cold water absorption and saturation coefficient to be waived if five brick survive 15 cycles of the sulfate soundness test with no visible damage. The performance alternative allows specifiers to waive all property requirements for pavers if they are satisfied with information furnished by the manufacturer on the performance of the pavers in a similar application subject to similar exposure and traffic. For pavers complying with ASTM C 902, the absorption alternative allows the saturation coefficient to be waived for pavers that absorb less than 6.0% after 24 hours of submersion in room-temperature water. Abrasion - The Abrasion Index is the ratio of the absorption divided by the compressive strength, multiplied by 100. The compressive specimen must be half pavers that are without core holes, frogs or other perforations, and the full height of the paver no less than 2¼ in. (57 mm). The volume abrasion loss is used if the height requirement cannot be met. The volume abrasion loss is determined by the loss of material created by sandblasting the surface of the paver. The abrasion requirements of pavers from the ASTM standards are shown in Table 5. TABLE 5 Maximum Abrasion Requirements ASTM Standard C 902

C 1272

Abrasion Index

Volume Abrasion Loss (cm3/cm2)

Type I

0.11

1.7

Type II

0.25

2.7

Type III

0.50

4.0

Type R & F

0.11

1.7

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Dimensional Tolerances - The dimensional tolerances for pavers are based upon the dimension — width, height or length — considered. The actual dimensions may vary from the specified dimension by no more than plus or minus the dimensional tolerance. The tolerances for both C 902 and C 1272 pavers are shown in Table 6. TABLE 6 Dimensional Tolerance Requirements Dimension, in. (mm)

ASTM C 902 and C 1272 Application PS,

Application PX,

in. (mm)

in. (mm)

Application PA

3 (76) and under

1/8 (3.2)

1/16 (1.6)

no limit

over 3 to 5 (76 to 127)

3/16 (4.7)

3/32 (2.4)

no limit

over 5 to 8 (127 to 203)

1/4 (6.4)

1/8 (3.2)

no limit

over 8 (203)

5/16 (7.9)

7/32 (5.6)

no limit

Chippage - Clay pavers may chip in transit or during construction. Table 7 shows the extent of chippage allowed by prescribing the maximum distance that chips may extend into the surface of a paver from an edge or a corner. The sum of the length of chips on a single paver must not exceed 10 percent of the perimeter of the exposed face of the paver. Cobbled or tumbled pavers that are intentionally distressed after production are classified as Application PA pavers. TABLE 7 Maximum Chippage Requirements ASTM Standard C 902

C 1272

Edge, in. (mm)

Corner, in. (mm)

Application PS

5/16 (7.9)

1/2 (12.7)

Application PX

1/4 (6.4)

3/8 (9.5)

Application PA

As specifed by purchaser

As specifed by purchaser

Application PS & PX

5/16 (7.9)

1/2 (12.7)

Application PA

No Limit

No Limit

Distortion - Both ASTM C 902 and C 1272 limit distortion and warpage of surfaces and edges intended to be exposed in use. The distortion must not exceed the maximum for the Application specified as noted in Table 8. TABLE 8 Tolerances on Distortion ASTM C 902 & C 12721

Specified Dimension, in. (mm)

Maximum Permissable Distortion, in. (mm) Application PX

Application PS

Application PA

8 (203) and under

1/16 (1.6)

3/32 (2.4)

no limit

Over 8 (203) to 12 (305)

3/32 (2.4)

1/8 (3.2)

no limit

Over 12 (305) to 16 (406)

1/8 (3.2)

5/32 (4.0)

no limit

1 ASTM

C 1272 Type F clay paver required to meet Application PX

SETTING BEDS Setting beds provide a means to adjust for dimensional variations in the height of a paver. They also support the clay pavers and transfer load to the base.

Sand Setting Bed Individual pavers in sand setting beds are held in position by the frictional interlock that is developed in each sandfilled joint between adjacent pavers. The joints transfer vertical and horizontal forces, but can absorb expansion

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and contraction of the individual pavers. If the pavement deflects slightly, the pavers will realign themselves to the new profile without significant loss in structural capacity. Interlock is developed by properly sized joints filled with consolidated joint sand. Sand setting beds may be installed directly on an aggregate base, asphalt base, cementtreated aggregate base or concrete base. For further information about pavements with sand setting beds, refer to Technical Note 14A.

Bituminous Setting Bed In pavements with a bituminous setting bed, less interlock is developed by the joint material than in a pavement with a sand setting bed. However, additional restraint is provided by the adhesive nature of the tack coat. Bituminous setting beds can be are set on an asphalt base or concrete base. For further information about pavements with bituminous setting beds, refer to Technical Note 14B.

Mortar Setting Bed Pavers in a mortar setting bed are bonded to the underlying mortar bed and transfer most of the vertical load through direct bearing. Mortar setting beds should be used only with a concrete base and may be bonded or unbonded to it. The joints between pavers are filled with mortar that transfers horizontal load. However, mortar will not absorb expansion and contraction of individual pavers. If the pavement deflects significantly, the pavement may crack along mortar lines or across pavers. For further information about pavements with mortar setting beds, refer to Technical Note 14C.

BASES The base layer in the pavement is the primary structural layer. It is subjected to the compressive, tensile and shearing stresses transmitted through the wearing course. Materials in the base layer need to be capable of resisting these stresses. Pedestrian loading is sufficiently light that a base thickness of only 4 in. (102 mm) is required when no specific site conditions dictate a thicker base. Vehicular loading requires a thicker base. Including a subbase often provides economic benefits when the subgrade is of low strength or is susceptible to frost. Because it is lower in the pavement section, the subbase is subjected to lower stresses than the base course (see Figure 1). A subbase also can serve as a working platform to prevent subgrade damage from construction equipment. Subbase material also may be added to increase the depth of the pavement section in frostsusceptible soils. A subbase is not usually required for light duty vehicular pavements. Pedestrian-only pavements generally do not include a subbase.

Aggregate Subbase and Base Aggregate subbase materials are typically medium-quality graded aggregates or clean sand-and-gravel mixtures. They should not be susceptible to deterioration from moisture or freezing. Subbase materials are covered by ASTM D 2940, Specification for Graded Aggregate Material for Bases or Sub-bases for Highways or Airports [Ref. 9]. Typical gradation envelopes are prescribed, along with other properties such as durability and plasticity. Aggregate subbase materials generally are graded from 1½ in. (38 mm) to No. 200 (0.075 mm) sizes. Aggregate subbase materials may be used directly over the subgrade soil or on top of a geotextile. Aggregate base materials are typically high-quality, crushed, dense-graded aggregates. They usually are specified in ASTM D 2940. Aggregate base materials generally are graded from 3/4 in. (19.1 mm) to No. 200 (0.075 mm) sizes. An aggregate base may be placed directly on the subgrade or over an aggregate subbase. A sand setting bed may be installed directly on an aggregate base. It is important to compact aggregate subbase and base layers. Each layer should be compacted in accordance with ASTM D 698 to 95 percent maximum density.

Asphalt Base Asphalt base materials consist of mixtures of aggregates and asphalt cement that are produced at a central hotmix plant. The materials are proportioned to comply with a mix design, and the materials usually are specified in state or local standards and in ASTM D 3515, Specification for Hot-Mixed, Hot-Laid Bituminous Paving Mixtures [Ref. 10]. Asphalt aggregates usually are blended to achieve a gradation from 1/2 in. (12.7 mm) or 3/8 in. (9.5 mm) to No. 200 (0.075 mm). An asphalt base may be placed directly on the subgrade but is more commonly laid over an aggregate subbase or base. It creates a relatively stiff and impermeable base layer. www.gobrick.com | Brick Industry Association | TN 14 | Paving Systems Using Clay Pavers | Page 13 of 19

Cement-Treated Aggregate Base A cement-treated aggregate base material is a relatively dry, lean mixture of aggregate and portland cement that creates a stiff and impermeable base layer. These materials should be mixed at a concrete plant and laid by machine. Cement contents vary between 5 and 12 percent with sufficient water added to achieve required compaction and full hydration of cement. Compressive strengths typically are around 750 psi (5.17 MPa). A cement-treated aggregate base may be placed directly on the subgrade but is more commonly laid over an aggregate subbase. This type of base does not include reinforcement, and because of the low water and cement content, can be laid without movement joints.

Concrete Base The compressive strength of a concrete base should be at least 4,000 psi (27.6 MPa). Concrete bases may be plain or reinforced, incorporating a grid of movement joints with load transfer devices, such as dowels. Layouts of movement joints require careful consideration of the overlying pavement system. Movement joints placed more than 12 ft ( 3.66 m) apart should extend through the entire pavement to prevent damage to the pavers unless using an unbonded system. A concrete base should be placed over an aggregate subbase or base.

SUBGRADE The subgrade is classified by the existing soil conditions, the environment and drainage. For vehicular applications, the existing soil conditions for the project should be determined by a geotechnical engineer before design of the paving system. For pedestrian and residential applications, a geotechnical engineer should be used as necessary to verify suitability of existing soil for the proposed paving system. Environmental conditions and the quality of drainage can affect the support provided by the subgrade. In wet climates, poorly drained areas or those that experience freezing conditions, the support from the subgrade is likely to be reduced during certain periods of the paving system’s life. Conversely, in arid climates or well-drained areas, it is likely that a higher degree of subgrade support will be experienced during part of the paving system’s life. Where water can penetrate the subgrade, it is important to drain water quickly to alleviate any potential fluctuations in soil moisture content. Soils are typically classified into different groups to represent their engineering properties. In general, soils consisting primarily of gravel and sand can be used to support most paving systems. In general, soil consisting of clay can usually be used to support a paving system as long as it is located in a dry environment or is drained. Soils classified as organic are not suitable for subgrade and should be removed and replaced. For further guidance regarding soil capacities, refer to Flexible Vehicular Brick Paving – A Heavy Duty Applications Guide [Ref. 14].

GEOTEXTILE Geotextiles are formed from plastic yarns or filaments such as polypropylene and polyester. They may be woven or nonwoven fabrics supplied in rolls. A geotextile may be used between fine-grained subgrade materials and base or subbase layers, particularly where moist conditions are anticipated. This separates the two layers, preventing the intrusion of fine soil particles into the overlying granular layer and preventing larger aggregates from punching down into the subgrade. This enables the base to retain its strength over a longer period. Geotextiles also can provide limited reinforcement to the overlying pavement layer. As the subgrade begins to deform, the geotextile is put into tension, which reduces the loading on the subgrade, slowing rut development. The geotextile manufacturer’s recommendations should be sought during selection of the appropriate geotextile for particular soil conditions.

PAVEMENT LAYER CONSTRUCTION Subgrade Preparation The subgrade should be excavated to achieve a uniform pavement thickness, and any substandard or soft materials should be undercut and replaced with acceptable backfill. A subsurface drainage system may be installed as perforated pipes or fin drains if necessary. All utility trenches should be properly backfilled and each layer thoroughly compacted to prevent settlement. The subgrade should be scarified and moisture conditioned

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to within 2 percent of optimum moisture content as determined by ASTM D 698, Test Methods for Laboratory Compaction Characteristics of Soil Using Standard Effort (12,400 ft-lbf/ft3 (600 kN-m/m3)) [Ref. 7], to a depth of 6 in. (152 mm). Moisture conditioning clay subgrades can be more complicated, because the clay absorbs water more slowly. It should then be graded to the appropriate profile and compacted by rolling with appropriate static or vibratory rollers. The subgrade should be compacted in accordance with ASTM D 698 to 95 percent maximum dry density for clay and 100 percent maximum dry density for sand/gravel.

Geotextile When a geotextile is used, it should be placed immediately before spreading the aggregate subbase or aggregate base. Geotextiles are not used when other base types are constructed directly on the subgrade. Care should be taken to stretch the material as it is unrolled to remove any wrinkles. A minimum lap of 12 in. (305 mm) should be provided at the sides and ends of rolls. Construction equipment should not be allowed to operate directly on the geotextile.

Aggregate Subbase and Base Aggregate subbase and base courses are spread in layers of up to 6 in. (152 mm) in compacted thickness, dependent upon the proposed compaction process. Material may be end-dumped from the delivery trucks and spread by grader spreaders or by hand with care to avoid segregation. The material should be moisture conditioned to within 2 percent of the optimum moisture content from ASTM D 698. It should then be compacted by rolling with appropriate static or vibratory rollers, or with a plate vibrator. When using a plate vibrator, the layer thickness must be 3 in. (76 mm) or less, and more than one layer may be required. The subbase and base layers should be compacted according to ASTM D 698 to 95 percent maximum dry density. Limited regrading is permissible to achieve correct surface profile and elevations. The maximum variation under the setting bed should be +/- 3/16 in. (4.8 mm) when tested with a 10 ft (3.05 m) straightedge laid on the surface. The minimum slope of the aggregate base should be 1 in. (25.4 mm) in 4 ft (1.22 m) to allow for drainage.

Asphalt Base Asphalt materials are produced at a hot-mix plant. They are mixed at temperatures up to 300 ºF (149 ºC) and should be installed before they cool to temperatures below 200 ºF (93 ºC). Asphalt base layers can be spread by machine or by hand. Asphalt can be laid in lifts from 1½ to 3 in. (38 to 76 mm) in thickness depending on the aggregate size and compaction equipment. Hand spreading requires adequate compaction of the base. Machine installation using a paving machine provides initial compaction, enabling more accurate placement and elevations to be achieved. Compaction of the asphalt is accomplished by an initial “breakdown” rolling and then by a finish rolling with steel- or rubber-tired rollers. Compaction is continued until the required density is achieved. This normally is a minimum of 96 percent of the density of samples of the same material compacted in a laboratory. Once materials have cooled to the ambient temperature, the layer can receive traffic, although the asphalt continues to stiffen over several months. The maximum variation under the setting bed should be +/- 3/16 in. (4.8 mm) when a 10 ft (3.05 m) straightedge is laid on the surface. The minimum slope of the asphalt base surface should be 1 in. (25.4 mm) in 4 ft (1.22 m) to allow for drainage.

Cement-Treated Aggregate Base Plant-mixed cement-treated aggregate bases are transported to the site for spreading by machine or by hand. When spread by a paving machine, the base should be compacted to the appropriate thickness. When spread by a grader or by hand, adequate compaction is required. A cement-treated aggregate base also can be mixed in place using special equipment. A granular subgrade or imported aggregate is thoroughly mixed with cement and water to achieve the required thickness. Materials should be placed and compacted within two hours of adding water and before initial set of the cement. The base should be compacted according to ASTM D 1557, Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort (56,000 ft-lbf/ft3 (2,700 kNm/m3)) [Ref. 8] to at least 95 percent of the maximum dry density. The cement-treated layer should be cured by water misting or by applying an asphalt emulsion cure coat. Traffic should not be allowed on the base for at least seven days, but paver installation may commence after three days. The maximum variation under the setting bed should be +/- 3/16 in. (4.7 mm) when a 10 ft (3.05 m) straightedge is laid on the surface. The minimum slope of the base surface should be 1 in. (25.4 mm) in 4 ft (1.22 m) to allow for drainage.

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Concrete Base Concrete usually is plant-mixed and delivered to the site in ready-mix trucks. It is discharged between forms, where it is spread and consolidated. The formwork is set to the correct elevations, and a vibrating screed is drawn between the forms to achieve the appropriate surface elevations. Movement joints containing load-transfer devices may be formed at the edges of each pour, or the devices can be cast into the concrete between forms. Saw cutting may be undertaken to induce cracking at the desired locations. A concrete base may be finished with a broom, brush or wood float. A polished surface finish should be avoided. Care should be taken to follow proper curing procedures for at least 14 days. Vehicular loads should not be permitted for at least 7 days, but paver installation may commence after 3 days. The maximum variation under the setting bed should be +/- 3/16 in. (4.7 mm) when a 10 ft (3.05 m) straightedge is laid on the surface. The minimum slope of the concrete base surface should be 1 in. (25.4 mm) in 4 ft (1.22 m) to allow for drainage.

CLEANING AND MAINTENANCE Clay pavers are highly resistant to absorption of stains and can be kept clean in most environments by regular sweeping. Otherwise, cleaning of brick pavements essentially is the same as cleaning vertical brickwork, as discussed in Technical Note 20. Mortar-filled joints generally are more resistant to aggressive cleaning methods (i.e. pressure washers). Sand-filled joints subjected to aggressive cleaning methods should contain stabilized joint sand or should be treated with a joint sand stabilizer.

Efflorescence Efflorescence is a white, powdery substance that may occasionally appear on the surface of pavers. It is the product of soluble compounds normally found in other pavement components or underlying soils, which are deposited on the surface of the paver as absorbed water evaporates from the pavement surface. Soluble compounds absorbed by the pavement from deicing chemicals also may cause efflorescence. Efflorescence often can be vacuumed or brushed off the surface and removed from dry pavers. Washing downhill with water may temporarily dissipate soluble compounds by dissolving them. However, care must be taken to ensure that the contaminated water drains away from and does not re-enter the paving system. In many cases, efflorescence will be minimal and will wear away naturally with traffic and weathering during the early life of the pavement. If the salts are the result of groundwater or other more persistent water ingress, proprietary cleaners are available to assist in their removal. Proper surface and subsurface drainage are critical in these situations. For further information on efflorescence, refer to Technical Notes 23 and 23A.

Ice Removal Several proprietary chemical products are available for preventing and removing ice from paved surfaces that perform well and reduce potential staining of pavers. Among these are calcium magnesium acetate and urea. The former is preferred because it is more effective at lower temperatures. Deicing of pavements has been undertaken for many years using rock salt. This material contains calcium chloride and can cause efflorescence. Sand or grit used to provide traction on ice should be swept up after the freezing cycle to minimize grinding of the pavers.

Snow Removal Clearing snow from clay pavements can be undertaken using plows, snow blowers, shovels and brushes as used for other pavements. Care must be taken to ensure that the blades of the equipment do not scrape the pavement surface in a manner that might cause chipping. Rubber or urethane blade edges can be used, or proper blade height can be maintained above the pavement surface using guide wheels. Any residual snow can be cleared with brushes. Some snow-clearing procedures use heavy equipment to stockpile and subsequently remove the snow from the property. If such equipment is used, the load capacity of the pavement should be adequately designed.

SPECIAL APPLICATIONS AND CONDITIONS Clay pavers can be used in a number of special applications that require consideration of additional aspects. The following sections cover the design of clay paver wearing surfaces for suspended decks, permeable paving systems and hydronic snowmelt systems.

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Clay Pavers Setting Bed Base Rigid Insulation Drainage Mat

Waterproof Membrane Topping Slab Suspended Structural Deck

Figure 5 Typical Suspended Deck Paving Section

Photo 6 Permeable Clay Pavement

Suspended Structural Slabs The design of pavement surfaces on suspended decks presents a special series of challenges, particularly when constructed over habitable space (see Figure 5). These include prevention of water penetration into the structure, reduction in heat loss/gain and dealing with elastic deflections. Waterproofing. A pavement constructed over a structural concrete slab often requires a waterproof membrane. Several sheet and liquid-applied membranes are available. In most applications, a protection board is required over the waterproof membrane. Drainage. Water inevitably will penetrate the paver system, and drainage is required to prevent it from collecting on top of the waterproof membrane. Horizontal drainage mats consisting of a dimpled three-dimensional plastic core covered with filter fabric frequently are used. A 2 percent slope should be provided toward drains to assist drainage of water. Although the core material has a high compressive strength, the filter fabric can be compressed. Consequently, horizontal drainage mats in pavements subject to vehicular traffic should not be positioned immediately below the setting bed. Insulation. When a paved surface is located over a habitable space, it may be necessary to incorporate insulation into the section. The most common type of insulation is extruded polystyrene, available in boards of various compressive strengths and thicknesses. However, compressive strength values are measured when the insulation thickness is compressed 5 percent. As such, the material is resilient under load and should not be placed immediately under the setting bed when vehicular traffic will use the pavement. An alternative insulating material that can be used in pavement systems on suspended structural slabs subject to vehicular traffic is foamed concrete. It is more rigid than extruded polystyrene but is less thermally efficient. This material also is available in a range of compressive strengths and insulation values. Loading. Pavers and setting bed materials can be considered to apply a dead load of 10 lb/sq ft per inch (190 Pa per cm) of thickness. Deflections. A maximum deflection of 1/360 of the span is recommended for flexible pavement systems installed over a suspended structural slab. If vehicular loads are anticipated, flexible pavement deflection should be limited to 1/480. When rigid paving systems are installed, the deflections should be limited to 1/600.

Permeable Pavements Many urban development regulations require that the surface-water runoff from a new project should not exceed the original values. This may be expressed as a peak flow rate or as a total quantity of water. Permeable pavements (see Photo 6) can be used to reduce or delay entry of runoff from a pavement surface into stormwater systems or environmentally sensitive areas. In pavements with clay pavers, this can be achieved by creating wide www.gobrick.com | Brick Industry Association | TN 14 | Paving Systems Using Clay Pavers | Page 17 of 19

joints that are filled with a permeable aggregate rather than sand. The pavers are also laid on a permeable setting bed. This allows the water that falls on a pavement to filter through the surface into a permeable base. The water will be temporarily stored in the base, or it may soak into the subgrade if this is also permeable (see Figure 6). Subgrades. If the subgrade is permeable, water that infiltrates the pavement through the surface voids can drain away over time, after a rain event. Good practice usually requires that water completely drains within three days of entering the pavement. However, compaction in preparation for placing the base material may result in significant reduction in subgrade permeability. As such, there are few permeable pavements that can rely completely on exfiltration through the subgrade. If the water will not drain, provision should be made to release the water stored in the base material through drainage pipes.

Wide Joints with Permeable Filling Permeable Setting Bed Geotextile Clay Pavers Infiltration

Outflow Permeable Base

Exfiltration

Permeable Subgrade Perforated Drainage Pipe to Outfall As Necessary for Impermeable Subgrade Figure 6 Typical Permeable Pavement Section

Bases. Permeable bases are constructed using single size or open graded aggregate materials. These materials typically have a void content of 15 percent to 40 percent to accommodate the water that needs to be detained. Typical single-number aggregate sizes No. 4, No. 5 and No. 6 from ASTM C 33, Specification for Concrete Aggregate [Ref. 2] or ASTM D 448, Classification for Sizes of Aggregate for Road and Bridge Construction [Ref. 6] have a high void content and are frequently used. There are several double-number size options such as No. 57 and No. 67. For these aggregate materials, the void content is less because a broader grading envelope is used, but the material may be more readily available. Setting Bed and Joints. Similar aggregate is commonly used for the setting bed and joints. Size No. 8, No. 9 or No. 89 aggregates complying with ASTM C 33 or ASTM D 448 are most frequently used. Joints ranging from 1/4 to 3/8 in. (6.4 to 9.5 mm) are typical. There also are several systems that use plastic spacers to create consistent width joints of 1/2 to 3/4 in. (12.7 to 19.1 mm). However, the interlock between pavers is greatly reduced when joint sizes are greater than 1/4 in. (6.4 mm) or when plastic spacers are used.

Hydronic Snow Melt Systems Hydronic snow melt systems consist of a network of plastic tubing incorporated into the pavement system, typically at 6 to 8 in. (150 to 200 mm) centers. Heated liquid is pumped around the system during near- and subfreezing conditions so that the pavement temperature is maintained slightly above freezing, thus preventing the accumulation of snow or the development of ice on the pavement surface. Continuous loops of 3/4 to 1 in. (19.1 to 25.4 mm) diameter tubing are made from cross-linked polyethylene. Tubing usually is secured to welded wire fabric during construction to establish and maintain the designed layout. There are two common approaches to positioning the tubing in the pavement. The first is to cast the tubing into a concrete subslab, where it will be protected by the concrete. The second is to incorporate it within the bedding material under the pavers. The latter option is not recommended for pavements with frequent vehicular traffic but can be used for pavements under pedestrian loading. Adequate cover is required over the tubing, typically a minimum of 1/2 in. (12.7 mm) after compaction. Bituminous bedding materials are not appropriate for this approach, in part because of the installation temperature, but also because of the layer thickness. When a sand setting bed is used, pre-compaction of the sand before screeding is recommended to minimize the occurrence of hard spots under the pavers. This is achieved by providing approximately 1/2 in. (12.7 mm) additional cover when spreading the sand, followed by several passes of the plate vibrator to compact the sand. The top surface then is loosened slightly with a hoe or rake and screeded to the appropriate level, leaving a smaller surcharge than normal.

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SUMMARY Pedestrian and light duty vehicular pavements made with clay pavers can serve in a wide variety of applications, including plazas, sidewalks and residential driveways and commercial driveways (passenger drop-offs). Many paver sizes and colors are available, as are special shapes. Proper design and construction of a pavement’s base, setting bed and pavers ensure a structurally stable, durable pavement able to meet site and project requirements. Lending intrinsic character and sophistication to any space, clay pavers can be a structurally stable, economically viable pavement option. The information and suggestions contained in this Technical Note are based on the available data and the combined experience of engineering staff and members of the Brick Industry Association. The information contained herein must be used in conjunction with good technical judgment and a basic understanding of the properties of brick masonry. Final decisions on the use of the information contained in this Technical Note are not within the purview of the Brick Industry Association and must rest with the project architect, engineer and owner.

REFERENCES 1. Americans with Disabilities Act Accessibility Guidelines, United States Access Board, Washington, D.C., July 2004. 2. ASTM C 33, Standard Specification for Concrete Aggregate, Annual Book of Standards, Vol. 04.02, ASTM International, West Conshohocken, PA, 2006. 3. ASTM C 902, Standard Specification for Pedestrian and Light Traffic Paving Brick, Annual Book of Standards, Vol. 04.05, ASTM International, West Conshohocken, PA, 2006. 4. ASTM C 1028, Standard Test Method for Determining the Static Coefficient of Friction of Ceramic Tile and Other Like Surfaces by the Horizontal Dynamometer Pull-Meter Method, Annual Book of Standards, Vol. 04.03, ASTM International, West Conshohocken, PA, 2006. 5. ASTM C1272, Standard Specification for Heavy Vehicular Paving Brick, Annual Book of Standards, Vol. 04.05, ASTM International, West Conshohocken, PA, 2006. 6. ASTM D 448, Standard Classification for Sizes of Aggregate for Road and Bridge Construction, Annual Book of Standards, Vol. 04.03, ASTM International, West Conshohocken, PA, 2006. 7. ASTM D 698, Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Standard Effort (12,400 ft-lbf/ft3 (600 kN-m/m3)), Annual Book of Standards, Vol. 04.08, ASTM International, West Conshohocken, PA, 2006. 8. ASTM D 1557, Standard Test Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort (56,000 ft-lbf/ft3(2,700 kN-m/m3)), Annual Book of Standards, Vol. 04.08, ASTM International, West Conshohocken, PA, 2006. 9. ASTM D 2940, Standard Specification for Graded Aggregate Material for Bases or Sub-bases for Highways or Airports, Annual Book of Standards, Vol. 04.03, ASTM International, West Conshohocken, PA, 2006. 10. ASTM D 3515, Standard Specification for Hot-Mixed, Hot-Laid Bituminous Paving Mixtures, Annual Book of Standards, Vol. 04.03, ASTM International, West Conshohocken, PA, 2006. 11. ASTM E 303, Standard Test Method for Measuring Surface Frictional Properties Using the British Pendulum Tester, Annual Book of Standards, Vol. 04.03, ASTM International, West Conshohocken, PA, 2006. 12. Cooper, R.A., Wolf, E., Fitzgerald, S.G., Dobson, A., and Ammer, W., “Interaction of Wheelchairs and Segmental Pavement Surfaces,” Proceedings of the Seventh International Conference on Concrete Block Paving, Cape Town, South Africa, Concrete Manufacturers Association of South Africa, October 2003. 13. Draft Public Right-of-Way Accessibility Guidelines, United States Access Board, Washington, D.C., 2005. 14. Flexible Vehicular Brick Paving – A Heavy Duty Applications Guide, Brick Industry Association, Reston, VA, 2004. 15. Wolf, E., Pearlman, J., Cooper, R.A., Fitzgerald, S.G., Kelleher, A., Collins, D.M., Boninger, M.L., Cooper, R., Smith, D.R., “Vibration Exposure of Individuals using Wheelchairs over Concrete Paver Surfaces,” Proceedings of the Eighth International Conference on Concrete Block Paving, San Francisco, CA, International Concrete Pavement Institute, November 2006. www.gobrick.com | Brick Industry Association | TN 14 | Paving Systems Using Clay Pavers | Page 19 of 19

TECHNICAL NOTES on Brick Construction 14A 1850 Centennial Park Drive, Reston, Virginia 20191 | www.gobrick.com | 703-620-0010

October 2007

Paving Systems Using Clay Pavers on a Sand Setting Bed Abstract: This Technical Note describes the proper design and construction of pavements made with clay pavers on a sand setting bed in pedestrian and vehicular, residential and nonresidential projects.

Key Words: flexible, mortarless paving, paving, rigid, sand setting bed.

SUMMARY OF RECOMMENDATIONS: General

Clay Pavers

• Determine if application is pedestrian, light duty vehicular or heavy duty vehicular • Implement regular maintenance program to maintain pavers in a safe and serviceable condition

• For most residential, pedestrian and light duty vehicular applications, such as driveways, entranceways and passenger drop-offs, use clay pavers complying with ASTM C 902 • For heavy duty vehicular applications, such as streets, commercial driveways and industrial applications, use clay pavers complying with ASTM C 1272. • Refer to Technical Note 14 for additional recommendations

Patterns • Use herringbone pattern for pavements subject to vehicular traffic • Design flexibility into layout to accommodate field conditions

Drainage • Provide a minimum slope of 1/4 in. per foot (2 percent grade) • For concrete and impermeable bases, provide weeps through base

Edge Restraints • For pavements subject to vehicular traffic, use concrete or stone curbs or steel angles anchored to a concrete base or foundation or a proprietary system rated for traffic • For all other pavements, use any of the above or clay pavers in a concrete foundation, proprietary plastic or metal edge restraint systems spiked into aggregate • Use edge restraint with vertical face at paver interface

Joint and Setting Bed Sand • Use concrete sand complying with ASTM C 33

Stabilized Joint Sand • Use where potential sand loss or high water permeability is anticipated and not desired • Follow paver manufacturer’s recommendation regarding the use of stabilized joint sand or joint sand stabilizer • Use performance history as a basis for selection

Concrete Base

• For concrete base on ground, provide control joints spaced a maximum of 12 ft (3.66 m) o.c. • For elevated concrete slab, provide control joints through concrete slab and expansion joints through pavement above aligned with control joints • Provide weeps through base for drainage

Base, Subbase and Subgrade • Refer to Technical Note 14

INTRODUCTION

Edge Restraint

This Technical Note covers the design, detailing and specification of clay pavers when laid on a sand setting bed (see Figure 1). Refer to Technical Note 14 for clay paver design considerations, including traffic, site conditions, drainage and appearance. Sand-set pavers are the most cost-effective method of constructing a pavement made with clay pavers. The system relies upon developing interlock in the paving course, which is generated by friction between the pavers and the jointing sand. This enables the pavers to function as part of the structural pavement system.

Clay Pavers Setting Bed

Compacted Base Compacted Subgrade or Subbase

Figure 1 Typical Brick Pavement © 2007 Brick Industry Association, Reston, Virginia

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Clay Pavers

Applications

Min. 1/16 in. (1.6 mm) to Max. 3/16 in. (4.8 mm) Sand Filled Joints

Clay pavers set on a sand setting bed are appropriate for virtually any paver application, ranging from pedestrian to heavy duty vehicular traffic. At a minimum, the system requires clay brick pavers and a sand setting bed, compacted after paver placement. Depending on subgrade conditions, additional layers, base and subbase may be required.

Min. 1 to Max. 1 1/ 2 in. (25 to 38 mm) Sand Setting Bed Min. 4 in. (102mm) Compacted Aggregate Base Geotextile (If Required) Compacted Subgrade Figure 2 Typical Residential Patio or Walkway

Clay Pavers Min. 1/16 in. (1.6 mm) to Max. 3/16 in. (4.8 mm) Sand Filled Joints Min. 1 to Max. 1 1/ 2 in. (25 to 38 mm) Sand Setting Bed Min. 4 in. (102 mm) Concrete, Compacted Aggregate or Asphalt Base Min. 4 in. (102 mm) Compacted Aggregate Subbase

Geotextile (If Required) Compacted Subgrade Figure 3 Typical Residential Driveway

Clay Pavers Min. 1/16 in. (1.6 mm) to Max. 3/16 in. (4.8 mm) Sand Filled Joints Min. 1 to Max. 1 1/ 2 in. (25 to 38 mm) Sand Setting Bed Min. 4 in. (102 mm) Compacted Aggregate Base Min. 4 in. (102 mm) Compacted Aggregate Subbase

Geotextile (If Required) Compacted Subgrade

Residential Patios and Walkways. These applications are the most common and handle the lightest loads. The sand setting bed thickness should be 1 to 1½ in. (25 to 38 mm). The sand setting bed should be separated from the subgrade by a compacted aggregate base (see Figure 2). This base typically consists of coarse aggregate (gravel) of varying gradation, compacted to a minimum thickness of 4 in. (102 mm) using mechanical tamping or vibration. Residential Driveways. The heavier and more localized loads of vehicles on driveways serving oneor two-family houses result in a thicker paving system requiring a minimum 4 in. (102 mm) compacted aggregate subbase. The base should consist of a minimum 4 in. (102 mm) layer of coarse aggregate, cast-in-place concrete or asphalt (see Figure 3). The sand setting bed thickness should be 1 to 1½ in. (25 to 38 mm). The base typically consists of coarse aggregate (gravel) of varying gradation, compacted to a minimum thickness of 4 in. (102 mm) using mechanical tamping or vibration. Commercial/Public Plazas and Walkways. With increased pedestrian traffic and increased risk of injury from any localized differential displacements, these types of applications require a firm pavement, similar to that of residential driveways. For plazas, however, a minimum 4 in. (102 mm) compacted aggregate base and subbase typically are used (see Figure 4). Note that for these applications on sites consisting of silty or clayey soils, geotextile should be placed on the compacted subgrade, below the subbase. The sand setting bed thickness should be 1 to 1½ in. (25 to 38 mm). The base typically consists of coarse aggregate (gravel) of varying gradation, compacted to a minimum thickness of 4 in. (102 mm) using mechanical tamping or vibration.

Figure 4 Typical Commercial/Pedestrian Public Plaza/Sidewalk

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Clay Pavers Min. 1/16 in. (1.6 mm) to Max. 3/16 in. (4.8 mm) Sand Filled Joints Min. 1 to Max. 1 1/ 2 in. (25 to 38 mm) Sand Setting Bed Min. 4 in. (102 mm) Concrete or 8 in. (204 mm) Compacted Aggregate Base Min. 4 in. (102 mm) Compacted Aggregate Subbase

Compacted Subgrade Figure 5 Typical Light Duty Vehicular

Light Duty Vehicular. For parking areas and neighborhood streets serving light duty vehicles, the brick pavement section should be similar to that of a residential driveway, but with a more substantial base. A pavement with a concrete base as depicted in Figure 5 or a thicker aggregate or asphalt base is required. Heavy Duty Vehicular. Paving systems exposed to more than 251 daily equivalent single axle loads (ESAL) from trucks or combination vehicles having three or more loaded axles are considered heavy duty vehicular applications. Such paving systems are beyond the scope of this Technical Note series. For further information about heavy vehicular applications, refer to Flexible Vehicular Brick Paving – A Heavy Duty Applications Guide [Ref. 6].

GENERAL DESIGN AND DETAILING CONSIDERATIONS Interlock Sand-set pavers interlock with one another by generating friction across the joints. This is the result of tightly packing sand into the joints during the vibration process. The interlock improves as the pavement is subjected to traffic. There are three types of interlock present in a sand-set paver pavement when properly constructed: vertical, horizontal and rotational interlock. Interlocked pavers cannot be readily extracted from the pavement. Vertical interlock allows load transfer across joints between pavers. When a load is applied to one paver, a portion is transferred through sand in the joints to adjacent pavers, as shown in Figure 6, distributing the load to a greater area and reducing the stress on the sand bed and the underlying layers. Vertical interlock allows a paving layer to act as a structural layer. Without vertical interlock, the pavers do not act as a structural layer, and localized stress on the setting bed directly under a loaded paver is increased. Pavers installed on a sand setting bed should not be laid with 1/4 in. (6.4 mm) joints, because this is too wide to achieve interlock, making the pavers unable to transfer load to adjacent pavers. The proper joint width is 1/16 to 3/16 in. (1.6 to 4.8 mm). Rotational interlock is the result of lateral resistance from adjacent pavers and adequate edge restraints, as shown in Figure 7. It is improved with full joints that support the top of the paver. Without adequate restraint, the pavers can roll in the direction of lateral loading, which may result in an irregular surface profile.

Load

Narrow Joints Vertical Interlock Load

Load

Rotational Interlock

Load

Wide Joints No Vertical Interlock

No Rotational Interlock

Figure 6 Vertical Interlock of Pavers

Figure 7 Rotational Interlock of Pavers

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The extent of horizontal interlock depends upon the laying (bond) pattern of the pavers and the edge restraint. Patterns that have staggered joint lines allow the load to be distributed to a larger number of pavers, as shown in Figure 8. This reduces joint compressive stress and potential for horizontal creep of pavers. Continuous joints result in minimal load distribution and increased joint compressive stress, which may produce horizontal movement.

Load

Pavement Section Clay pavers over a sand setting bed can be installed over a flexible or rigid base, including aggregate, asphalt, cement-treated aggregate or concrete bases. For further information on bases, refer to Technical Note 14. The design of the base is beyond the scope of this Technical Note, and the advice of a qualified and experienced pavement designer should be sought. For preliminary design, it is reasonable to assume that a minimum of 4 in. (102 mm) of concrete, cement-treated aggregate, asphalt or aggregate base will be needed for sand and gravel subgrades. For residential driveway, commercial/pedestrian and light duty vehicular applications with clay or silt subgrades, an additional 4 in. (102 mm) of aggregate subbase or base should be added to each option. Additional thickness may be required when the subgrade is susceptible to frost heave or when the pavement must support heavy axle loads from trucks. Concrete bases should be reinforced with welded wire fabric or reinforcement bars and should have control joints spaced at 12 ft (3.66 m) intervals to control expansion and contraction. To minimize movement of slabs, detail movement joints as shown in Figure 9. Control joints in suspended structural slabs should extend through the entire slab and align with an expansion joint through the pavement above. Control joints should have dowels or a keyway to limit vertical separation across the joint.

Horizontal Interlock Load

No Horizontal Interlock Figure 8 Horizontal Interlock of Pavers

Clay Pavers Sand Setting Bed Concrete Base Control Joint with Dowels

Vehicular Traffic For light duty vehicular paving systems, a maximum traffic speed of 30 mph (50 kph) is considered appropriate for pavers in a sand setting bed. When frequent vehicular traffic is anticipated, additional attention is required to ensure that joints between pavers remain filled with sand. Higher speed applications require more vigilance, as the interlock between pavers is reduced with sand loss. Paving systems for vehicular traffic applications usually will include a compacted subbase to distribute loads (see Figure 5).

Compacted Subbase Compacted Subgrade Figure 9 Control Joints

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Field Pattern Brick Cut as Necessary to Ensure Good Fit Edge of Band Aligned with Building Column +/- 1/ 2 in. (12.7 mm) to Ensure Good Fit

6 to 8 in. (152 to 204 mm) Header Course Cut as Necessary to Ensure Good Fit

Figure 10 Pattern Options to Maintain Specified Joint Widths The designer should consider the bond pattern for vehicular traffic applications. Any pattern may be used under foot traffic. When vehicles operate on a pavement, patterns that distribute horizontal loads (i.e., loads from turning, accelerating or braking vehicles) across multiple pavers, such as herringbone, are recommended. Patterns with continuous joints, such as stack bond or running bond, are more susceptible to creep from horizontal loading. Where such patterns are used in vehicular pavements, continuous joint lines should be oriented perpendicular to the direction of vehicle travel.

Bond Patterns/Layout The size of pavers may influence the selection of a suitable bond pattern. Pavers for use on a sand setting bed typically are manufactured in sizes that accommodate a joint width of approximately 1/8 in. (3.2 mm) to encourage optimal interlock. Bond patterns such as herringbone, basket weave and others make use of the 1:2 or 1:3 ratios between the pavers’ length and width to maintain the pattern and joint alignment. Pavers sized to accommodate joint widths of approximately 3/8 in. (9.5 mm) do not achieve these ratios. Such pavers typically are used in pavements with mortar joints. When they are laid on a sand setting bed, only a running bond, stack bond or chevron pattern should be used, since these patterns do not depend on these ratios. An individual clay paver’s dimensions may be slightly different from the dimensions of another clay paver from the same run. The inherent variability of their dimensions is a result of their manufacturing process. Pavers may be larger or smaller within allowable tolerances of their specified size. This variability may not be consistent, because actual dimensions may be greater or smaller than the specified dimensions. As such, the pavers may not be able to be placed in a standard modular pattern. Blending of pavers from multiple cubes during installation can overcome this issue. The installer should constantly monitor paver size during installation to ensure that the bond pattern and joint size are maintained. When designing an installation pattern with changes in bond and color, incorporating some tolerance in the placement of certain paver features is recommended. This can be achieved by using saw cut pavers at junctions of colored areas or by allowing approximate dimensions and realistic tolerances when placing certain paver features. Two examples are depicted in Figure 10.

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Heavy Plastic or Metal Edging Secured with Spikes Clay Pavers on Sand Setting Bed

Compacted Aggregate Base

Compacted Subgrade

(a) Proprietary Edge Restraint System

Clay Pavers on Sand Setting Bed Clay Paver, Precast Concrete or Cut Stone

Edge Restraints Edge restraints are critical in a pavement with a sand setting bed to enable consistent interlock and resist horizontal loads transferred from pavers. Selection of edge restraint will depend on pavement section and use. Figure 11 (pages 6 and 7) presents various options, in increasing order of load capacity. Concrete curbs or steel angles attached to a concrete foundation or concrete base layer are the most robust edge restraints. They are recommended for all pavements subject to regular vehicular traffic. Edge restraints for other applications may include pavers bonded to a concrete foundation, and a range of proprietary plastic and metal edge restraint systems that are typically spiked into aggregate bases. Timber edging and concrete backing poured to restrain edge pavers may not be effective over the long term. It is important that all edge restraints have a vertical rather than inclined face for the pavers to butt against.

Poured Concrete, Precast, or Cut Stone Curb

Clay Pavers on Sand Setting Bed

Compacted Aggregate Base

Compacted Subgrade Concrete or Mortar as Required Extend Base Beyond Restraint

Base as Selected Compacted Subgrade

(b) Clay Paver, Precast Concrete or Cut Stone Edge Restraint

(d) Curb Edge

Clay Pavers on Sand Setting Bed

Clay Pavers on Sand Setting Bed Clay Paver Bonded to Concrete

Concrete Base

Base as Selected

Compacted Subgrade Galvanized Steel or Aluminum Angle

Compacted Subgrade

(e) Steel Angle Edge Restraint

Concrete Foundation (c) Bonded Clay Paver Edge Restraint Figure 11 Edge Restraints

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Clay Pavers on Sand Setting Bed Clay Paver, Precast Concrete or Cut Stone

Min. 1 in. (25.4 mm) dia. Weep @ 24 in. (610 mm) o.c. Screen as Necessary

Concrete Curb & Gutter

Concrete or Asphalt Base Compacted Aggregate Subbase (If Required)

Pavers Set 1/ 8 in. (3.2 mm) Higher than Concrete After Vibration of Pavers

Base as Selected Compacted Subgrade

Compacted Subgrade Concrete Foundation (f) Clay Paver, Precast Concrete or Stone Edge Restraint

(g) Poured Concrete Curb and Gutter Edge Restraint

Figure 11 (continued) Edge Restraints

Drainage Adequate drainage is important to the performance and durability of any clay paving system. Water should be drained from the paving system as quickly as possible. A minimum slope of 1/4 in. per foot (2 percent grade) is recommended. Adequate drainage should be provided to ensure the integrity of all layers in a paving system. A sand setting bed will continue to consolidate slightly after construction is complete. Pavers should be finished slightly higher than drainage inlets and other low edges of a pavement. This will minimize water puddling at these locations. Typically 1/8 in. (3.2 mm) will be adequate and will not present a short-term tripping hazard. Over time, small amounts of water will migrate through sand joints. Consequently, a sand-set paving system with an impermeable base will require weep openings at low points in the pavement. Weep openings permit moisture to seep out of the pavement rather than saturating the setting bed. Even a well-compacted aggregate base may benefit from installing weep openings. Sand is less durable in a saturated state than when dry or slightly damp. Several weep opening options are available. A small-diameter (1½ to 2 in. [38 to 51 mm]) pipe with ends wrapped in geotextile may be placed through the side wall of drain inlets or through edge restraints. Such weeps should be installed at spacings of 2 to 6 ft (0.60 to 1.83 m) depending on pavement geometry and profiles, environmental conditions and pavement use. As an alternative, a drainage mat may be placed vertically through the base. This may be used in conjunction with small pipes at drain inlets. For a concrete base, holes may be drilled or formed through the slab to weep water to the subbase. Locating holes away from the impact of wheel loads is necessary since subbase materials may be moisture-sensitive.

Penetrations Large and small features that penetrate through the paver layer should be properly detailed. These features include utility covers, tree pits, light pole bases, signposts and street furniture. Features may either penetrate the entire pavement section to an independent structure or foundation, or be anchored to a concrete subslab. Such features can present some issues in cutting the pavers to form a uniform joint around them. Some utility covers and other frames are relatively shallow, or have buttresses, inclined faces, anchor bolts or other features that may interfere with the bottom of a paver. Where possible, features should be specified,

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Cover Plate

Sand Setting Bed Clay Pavers Set 1/ 8 in. (3.2 mm) Higher than Thinset Pavers After Vibration

Pole with Base Plate

Soldier Course in Thinset Mortar

Clay Pavers Sand Setting Bed

Compacted Base Compacted Subgrade

Base as Selected

Concrete Surround

Anchor Bolts

Manhole Wall Frame with Inclined Outer Face Figure 12 Large Penetration

Compacted Subgrade

Concrete Plinth on Foundation

Figure 13 Small Penetration

designed and installed deeper than the setting bed. Where this is not possible, casting a concrete collar around the frame and thin-setting a header course of pavers on the concrete may clear obstructions to the sand setting bed interface, as shown in Figure 12. Accurately cutting and placing pavers against small features may prove difficult. An alternative is to construct a concrete plinth up to the pavement surface and to install a cover plate to conceal the anchorage of the feature, as shown in Figure 13. This also allows easy access for repairs, without removing pavers.

MATERIALS Subgrade For design purposes, the subgrade is considered to be either sand/gravel or clay/silt. The latter are more sensitive to moisture and frost and may require the use of subbase layers and proper drainage to protect against shrinkage, swelling and frost heave. The advice of a properly qualified and experienced pavement designer should be sought in regard to the preparation of the subgrade.

Base and Subbase Base materials for pavers laid in a sand setting bed may be of aggregate, cement-treated aggregate, asphalt or concrete. When a subbase is required, aggregate generally is used. Aggregate materials should comply with ASTM D 2940 and be compacted in accordance with ASTM D 698 to 95 percent maximum density. Asphalt should meet ASTM D 3515. Concrete should have a minimum compressive strength of 4,000 psi (27.6 MPa) and should have control joints spaced a maximum of every 12 feet (3.66 m). For a more detailed discussion of base and subbase materials, refer to Technical Note 14.

Geotextiles Geotextiles are used on top of silt or clay soils to help stabilize subgrades and under sand setting beds to prevent loss of sand through weep openings and other gaps in the pavement base or at edge restraints or penetrations. The preferred type of geotextile is a woven, polypropylene fabric complying with ASTM D 4751, Test Method for Determining Apparent Opening Size of a Geotextile [Ref. 5], with an approximate opening size from a No. 70 to No. 100 sieve size opening. Nonwoven geotextiles can be used for light-traffic applications. Geotextiles should be lapped at the sides and ends of rolls a minimum of 12 in. (305 mm). Care should be taken to not locate laps directly under anticipated wheel paths. Geotextiles should extend 6 in. (152 mm) beyond potential areas of sand

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loss. These may be adhered in place, but generally will stay in position once covered by the sand setting bed. Geotextiles should not be allowed to span over unfilled holes or pits in the surface of the base that are greater than 1 in. (25.4 mm).

Setting Bed Sand A sand setting bed provides a strong support layer under pavers and accommodates variations in paver thickness to produce a smooth surface profile. A portion of setting bed sand penetrates the joints during vibration and initializes the development of interlock between the pavers. Sand for the setting bed should be clean, naturally occurring material with angular and subangular shaped particles, with a maximum size of about 3/16 in. (4.8 mm). Concrete sand conforming to the requirements of ASTM C 33, Specification for Concrete Aggregate [Ref. 1], or local department of transportation standards is recommended for use as setting bed material. This provides a more stable and durable setting bed than mason sand or screenings, which have a more rounded shape and should not be used. Sand rich in silica-based minerals is desirable, because carbonate-based minerals are softer and can break down when saturated. Manufactured limestone sand usually causes efflorescence and should be avoided unless it has a proven track record on similar projects.

Clay Pavers A wide selection of colors and textures is available in clay pavers. Further information on clay pavers can be found in Technical Note 14. Pavers generally are manufactured with their length equal to a module of their width. Two commonly specified clay paver sizes are 4 in. wide by 8 in. long (102 by 203 mm) and 3¾ in. wide by 7½ in. long (95 by 190 mm). Other similar sizes are available, such as 3⅝ in. wide by 7⅝ in. long (92 by 194 mm), and several manufacturers are able to provide custom sizes. Common specified thicknesses are 1½ in. (38 mm), 2¼ in. (57 mm) and 2¾ in. (70 mm) [2⅝ in. (67 mm) excluding chamfered edge]. All clay pavers covered by ASTM C 902, Specification for Pedestrian and Light Traffic Paving Brick [Ref. 3], and ASTM C 1272, Specification for Heavy Vehicular Paving Brick [Ref. 4], can be installed on a sand setting bed. The designer should select the appropriate Application, Type and Class of the paver for the project based on aesthetics, use, abrasion resistance and the required resistance to damage from weather exposure. For more detailed information on specifying clay pavers, refer to Technical Note 14. When square-edged pavers or pavers without lugs are laid with sand joints, care should be taken to ensure that they do not make direct contact with or lip under adjacent pavers. A minimum 1/16 in. (1.6 mm) wide sand-filled joint should separate each clay paver to minimize potential chipping. However, the maximum joint width should be no more than 3/16 in. (4.8 mm) to minimize the potential for horizontal movement under vehicular traffic. If pavers with spacers and/or a rounded or chamfered edge are installed, there is less potential for direct paver contact. When lugs are used, the potential for creep is reduced.

Jointing Sand Sand within pavement joints creates interlock between pavers by generating friction across the joint. Larger particles present in joints reduce the potential for lateral movement. Finer particles act to reduce contact stresses around the larger particles, reducing the potential of the particles breaking down. The sand also accommodates the variations in paver size and reduces the potential for contact between pavers that can lead to chipping. ASTM C 33 concrete sand should be placed in joints before vibration to maximize interlock at the bottom portion of joints. However, coarse particles that do not fall into joints should be brushed off the pavement surface rather than worked in. After vibration, finer jointing sand may be placed so that it penetrates to the bottom of the joints and achieves better filling. When the typical joint dimension exceeds 3/16 in. (4.8 mm), stabilized sand or joint sand stabilizer should be used.

Joint Sand Stabilizers In conditions where potential sand loss or high joint permeability may not be desirable, a joint sand stabilizer is recommended. These conditions include intensive cleaning practices, high surface water flows and flat areas with moisture-sensitive subgrades. There are several different types of joint sand stabilizers. These include breathable polymeric liquids that can be sprayed onto the pavement surface and squeezed into the joints with a squeegee, as www.gobrick.com | Brick Industry Association | TN 14A | Paving Systems Using Clay Pavers on a Sand Setting Bed | Page 9 of 13

well as dry products that can be mixed with the joint sand before installation. Pretreated sands also are available for joint filling. Strict adherence to the stabilizer manufacturer’s recommendations is required to achieve successful installations. When selecting a stabilizer, it is important to choose one with a proven history that does not discolor the surface or peel over time. The paver manufacturer's recommendation regarding joint sand stabilizers should be followed. Joint sand stabilizers should be applied to the completed paver surface. Stabilizers should be applied to the pavement surface before the application of other coatings to enhance the appearance of the pavers or to protect against staining. For further guidance on selecting coatings for use on brick pavements, refer to Technical Note 6A.

INSTALLATION AND WORKMANSHIP Subgrade The subgrade should be brought to the proper level and cleared of organic material. Compaction should comply with ASTM D 698 to 95 percent maximum dry density for clay and 100 percent maximum dry density for sand/gravel. For a more detailed discussion of subgrade preparation, refer to Technical Note 14.

Base and Subbase Base and subbase materials should be placed per the design. Aggregate should be compacted in accordance with ASTM D 698 to 95 percent maximum density. The maximum variation under the setting bed should be +/- 3/16 in. (4.8 mm) when a 10 ft (3.05 m) straightedge is laid on the surface. The minimum slope of the concrete base surface should be 1 in. (25.4 mm) in 4 ft (1.22 m) to allow for drainage. For a more detailed discussion on the installation of base and subbase materials, refer to Technical Note 14.

Setting Bed Whenever possible, the direction of installation should be planned to protect the paving against premature use or damage by rain or other construction activities. The surface of the underlying base material should be thoroughly clean and dry before installation of the bedding sand. Elevations should be verified to ensure that the sand setting bed will be a consistent thickness after compaction. The setting bed should not be used to bring the pavement to the correct grade. Isolated high and low spots should be corrected before sand placement to avoid an uneven pavement surface resulting from variable sand setting bed thicknesses. Lines should be established for setting out the pattern. The contractor should become aware of size variations in the pavers to maintain the pattern without localized opening or closing of joints to meet a fixed edge. All areas of potential sand loss should be covered with geotextile. Screed rails should be set on the surface of the base to proper line and level. They are typically placed 8 to 12 ft (2.44 to 3.66 m) apart, or closer when working on a grade. An allowance should be made in the thickness of the setting bed for compaction of bedding sand as pavers are installed, as well as additional consolidation in service. An experienced contractor will be aware of the proper thickness for different conditions to achieve the correct longterm surface profiles. The bed thickness should be established so that when the pavers are compacted, their top surface will be 1/8 in. (3.2 mm) above the required grades to allow for limited settling in service. To prevent disturbance, setting bed sand should not be spread too far ahead of the paver laying face. Voids left after removing the screed rails should be filled. The screeded bedding sand may be affected by wind or rain as well as by wayward construction operations. If sand is disturbed, it should be loosened and rescreeded. Extensive areas of screeded sand should not be left overnight unless they are properly protected from disturbance and moisture. Moisture content of setting bed sand should be kept as uniform as possible to minimize undulations in the pavement surface. The sand should be kept in a damp condition conducive to packing. Water should not be applied except by very light misting. Stockpiled sand should be covered to protect it from wind and rain.

Paver Installation The pavers are laid on the setting bed working away from an edge restraint or the existing laying face while following the pattern lines that have been established. Full pavers should be laid to the required pattern with 1/16 to 3/16 in. (1.6 to 4.8 mm) wide joints. The optimum joint width for vehicular traffic is between 1/16 and 1/8 in. (1.6 and 3.2 mm), but some wider joints may be required with Application PS pavers, and particularly with

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Application PA pavers. Lugs enable the correct joint width to be achieved when the pavers are placed in contact with one another. Pavers should not be forced together, resulting in excessive contact, because this may cause the pavers to chip during installation or compaction. At least two cubes of each color of pavers should be drawn from at one time, and the manufacturer’s recommendations on color blending should be followed. The pavers should be adjusted to form straight pattern lines while maintaining the correct joint widths. Several feet of pavers should be installed before beginning to add cut pavers as infill against edge conditions. Bench-mounted masonry saws are the best means of cutting the pavers to achieve a neat edge and a vertical cut face. Use of a wet saw or dust collection system is recommended to control dust. Guillotine cutters also may be used, but their cuts typically are not as straight and neat. Convex curves can be formed using multiple cuts, but this requires a skilled craftsman to meet allowable joint tolerances. Concave curves are very difficult to form and should be avoided when possible. Pavers should be compacted at the end of each day to prevent any damage while left unattended. The pavement surface should be compacted using a plate compactor. These typically have a plate area of 2½ to 3 sq ft (0.23 to 0.28 sq m) and operate at a frequency of 80 to 100 Hz. To prevent pavers from chipping during vibration, a little bedding sand material can be swept into the joints, or the underside of the plate compactor can be fitted with a rubber mat. Pavers also can be covered with a sheet of geotextile or sheets of plywood during vibration For molded pavers, vibration is especially important since irregularities and dimensional variations on the underside could lead to air gaps or improper support if not properly compacted into the sand setting bed. Compaction should not be carried out within 4 ft (1.2 m) of unfinished edges. The vibrated surface should be slightly above adjacent pavement surfaces, drainage inlets and channels to allow for secondary compaction of the bedding layer under traffic. The maximum variation in surface profile should be less than 3/16 in. (4.8 mm) in 10 ft (3.05 m). Water should drain freely from the surface and not form puddles. Lipping between adjacent pavers should not be greater than 1/8 in. (3.2 mm) if the pavers have chamfers, or 1/16 in. (1.59 mm) if they have square edges. After vibration of the pavers to finished elevations, dry fine-grained jointing sand is brushed over the surface of the pavement and additional vibration is undertaken until all of the joints are completely filled with sand. Surplus jointing sand should be maintained on the surface to enhance the process of joint filling. Typically the sand should be level with the bottom of the chamfer or approximately 1/8 in. (3.2 mm) below the top of square edge pavers.

Joint Sand Stabilizers The paver manufacturer's recommendation regarding joint sand stabilizers should be followed. Jointing sand that is pretreated with a stabilizer product should be brushed or blown off the pavement surface as soon as possible and not be allowed to become stuck in the surface texture of the pavers. If pretreated sand or a joint sand additive is used, the stabilizer should be activated by lightly misting the surface with water. If a liquid joint sand stabilizer is used, it should be sprayed onto the pavement surface and forced into the joints with squeegees. It may be necessary to fill the tops of the joints with the liquid several times before it sets to achieve adequate penetration. The stabilizer manufacturer’s instructions should be followed closely, because each stabilizer is slightly different. Probing several joints to verify that the sand is stabilized to an adequate depth of approximately two times the joint width — rather than just forming a crust — is recommended.

MAINTENANCE Cleaning Sand-set pavers can be kept clean in most environments by regular sweeping. In situations that lead to a greater degree of buildup of grease, tire marks or other stains, the pavers can be cleaned by pressure-washing. The sandfilled joints generally are resistant to this treatment if the nozzle surface is clear and the water jet is not directed along the joints. Aggressive pressure-washing can cause localized removal of the joint filling material and can even undermine the pavers. More stubborn stains, including paint and gum, can be cleaned by scraping off the hard residue and then scrubbing with a stiff-bristled brush and a proprietary cleaner or scouring powder. In damp or shady areas where moss and lichen have grown in the joints, these can be killed with a bleach-water mixture or with proprietary treatments.

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Snow Removal Snow prevention and removal can be carried out by hand, by machine or by chemicals. Hand methods include shovels and brooms. Mechanical methods include snow blowers, snowplows, and buckets or brushes attached to tractors. Shovel and machine removal methods can chip the edges of the pavers, particularly if excessive lipping is present. This equipment should be properly adjusted so that it does not damage the pavement surface. Skid-steer snow removal equipment also may move pavers, causing distortion of pattern lines and some chipping of the pavers if the equipment is driven aggressively. When tractor and particularly skid-steer mounted equipment is used, the pavement must be able to support the wheel loads without damage. A range of anti-icing and deicing chemicals are used for pavements. Deicing chemicals can cause thermal shock in a pavement by “supercooling” the pavement surface. This can lead to spalling or surface damage on pavers of Class NX or MX pavers. Deicing agents should be used with care, as chemical residue left on the surface can penetrate into the joints and result in staining and efflorescence. Class NX should not be used where subject to freezing.

Resanding Over time, due to wind, rain and other means, the sand within the top portions of joints can be eroded. Therefore, the joints should be periodically resanded using the same methods described above for applying jointing sand after vibration of the pavers.

Repairs Underground utilities frequently pass beneath paved areas on congested sites. Access to these utilities frequently is required for repair or to install new lines. Sand set pavers readily accommodate such work, as they can be removed and reinstated with little evidence of the work having been carried out. Repairs to the paving also can be made if they are overloaded or otherwise damaged. Removal can be undertaken by prying or breaking out the initial paver so that it can be removed without damaging adjacent units. It is then possible to work the adjacent pavers loose using a hammer and chisel or pry bars in the joints and under the paver. Some chipping of the pavers should be expected, and a few spare pavers will be required for reinstatement. The bedding sand can be removed as necessary. Traffic should be kept at least 4 ft (1.2 m) from the unrestrained edge. If a trench is open for a significant amount of time, the adjacent pavers should be temporarily restrained to stop them from moving laterally. Trenches should be filled with proper care paid to compaction of the backfill. The base should be replaced to match the original section. To reinstall the pavers, the bedding sand should be replaced with an adequate pressure to allow for compaction. The pavers should be replaced in the appropriate pattern and fresh sand spread into the joints. The repair area should be leveled by hammering on a wooden pack if the area is small or with a plate vibrator if it is large enough. The joints should be refilled with sand and new stabilizer applied if necessary.

SUMMARY Pedestrian and light duty vehicular pavements of clay pavers laid on a sand setting bed provide the most costeffective system for pedestrian and light duty vehicular pavement. When properly constructed, the interlock of the pavers provides the necessary stability for the desired service life of the pavement. This Technical Note provides the basic information required to properly select materials, design, detail and construct brick pavements over sand setting beds. Further information about the properties of other brick pavements and concepts not unique to sand setting beds is discussed in the Technical Note 14 series. The information and suggestions contained in this Technical Note are based on the available data and the combined experience of engineering staff and members of the Brick Industry Association. The information contained herein must be used in conjunction with good technical judgment and a basic understanding of the properties of brick masonry. Final decisions on the use of the information contained in this Technical Note are not within the purview of the Brick Industry Association and must rest with the project architect, engineer and owner.

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REFERENCES 1. ASTM C 33, Standard Specification for Concrete Aggregate, Annual Book of Standards, Vol. 04.02, ASTM International, West Conshohocken, PA, 2006. 2. ASTM C 144, Standard Specification for Aggregate for Masonry Mortar, Annual Book of Standards, Vol. 04.05, ASTM International, West Conshohocken, PA, 2007. 3. ASTM C 902, Standard Specification for Pedestrian and Light Traffic Paving Brick, Annual Book of Standards, Vol. 04.05, ASTM International, West Conshohocken, PA, 2007. 4. ASTM C 1272, Standard Specification for Heavy Vehicular Paving Brick, Annual Book of Standards, Vol. 04.05, ASTM International, West Conshohocken, PA, 2007. 5. ASTM D 4751, Standard Test Method for Determining Apparent Opening Size of a Geotextile, Annual Book of Standards, Vol. 04.13, ASTM International, West Conshohocken, PA, 2007. 6. Flexible Vehicular Brick Paving – A Heavy Duty Applications Guide, Brick Industry Association, Reston, VA, 2004.

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Technical Notes 15 - Salvaged Brick May 1988

Abstract: The use of salvaged brick in new building construction is discussed. Factors affecting the selection include altered physical properties (durability), esthetics, economics, building code requirements and experimental testing. Key Words: brick, masonry, mortar bond, salmon brick, salvaged brick. INTRODUCTION Selecting building material requires the consideration of four factors: esthetics, design properties, economics and required level of performance. Salvaged brick are occasionally selected for their "rugged appearance" and sometimes for their low initial cost. Rare is the case when salvaged brick are chosen for their design properties. In general, walls using salvaged brick are weaker and less durable than walls constructed of new brick masonry units. Most salvaged brick are obtained from demolished buildings which stood 40 to 50 yr, or more. In fact, it may be next to impossible to salvage brick from modern structures which use brick set in portland cement mortars. When brick are initially placed in contact with mortar, they absorb some particles of the cementitious materials. It is virtually impossible to completely clean these absorbed particles from the surfaces of the brick units. This may greatly affect the bond between brick and mortar when reused. MANUFACTURING METHODS In the early 1900's, manufacturing methods were markedly different from those of today. De-aired brick were unknown; coal- and wood-fired periodic and scove kilns were commonplace. The modern solid, liquid or gas-fired tunnel kilns with accurate temperature controls throughout were also unknown. Manufacturing conditions years ago were generally such that large volumes of brick were fired under greater kiln-temperature variations than could be tolerated today. These conditions resulted in a wide variance in finished products. Brick from the high-temperature zones were hard-burned, high-strength, durable products; those from low-temperature zones were under-burned, low-strength products of low durability. These temperature variations also resulted in a wide range in absorption properties and color. The under-burned brick were more porous, slightly larger, and lighter colored than the harderburned brick. (It is the nature of ceramic products to shrink during firing. Generally, for a given raw clay, the greater the firing temperature, the greater the shrinkage and the darker the color.) Their usual pinkish-orange color resulted in the name salmon brick. During these bygone years, prevalent methods of construction made production of both hard-burned and salmon brick economically feasible. Most masonry buildings had loadbearing brick walls which were a minimum of 12 in. in thickness. The hardest, most durable units were used in exterior wythes; the salmons (and others) were used for the interior wythes and were not exposed to the exterior elements. Much sorting and grading of brick was performed at the construction site by the mason, although the brick manufacturers eventually assumed this responsibility. The advent of skeleton frames marked the beginning of high-rise construction and the gradual demise of thick loadbearing masonry wall construction. (Despite the reduction in its use, loadbearing remains a very economical method for constructing low- and mid-rise buildings). Architects and engineers began to design non-loadbearing walls, and gradually decreased wall thicknesses. This evolution in design and construction techniques necessitated a change in brick manufacturing procedures. Slowly but surely, the demand for salmon brick dwindled. After the use of hollow backup units became prevalent, the need for salmon brick became practically non-existent. At the same time, having invented the thinner, lighter weight panel wall, designers focused their attention on wall strength which they equated to compressive strength of the individual brick. Because the principal demand was for high compressive strength and durability, manufacturers had to produce a

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high proportion of well-burned brick. This demand necessitated a change in manufacturing methods. Thus, an evolution in design and construction techniques brought on a significant and beneficial evolution in the production of brick. (For a synopsis of present day manufacturing methods, see Technical Notes 9 Revised, "Manufacturing, Classification and Selection of Brick; Manufacturing - Part 1"). MATERIAL SELECTION Physical Properties. Several arguments are often advanced in favor of the use of salvaged brick. Among these are: 1. Because brick are extremely durable, they can be salvaged and used again. 2. If the brick were satisfactory at the time they were first used, they are satisfactory at present. Both arguments are fallacious. When brick are initially placed in contact with mortar, they absorb some water and some particles of cementitious materials. The initial rate of absorption (suction) is an important factor which greatly affects the bond between brick and mortar. Brick with extremely high or extremely low suctions do not develop good bond. (For discussion of bond strength between mortar and new clay masonry units, see Technical Notes 8 Revised, "Mortars for Brick Masonry"). With salvaged brick, more factors influence bond. Pores in brick are filled with particles of lime, dirt and other deleterious matter. Many bedding surfaces of salvaged brick will not be thoroughly clean, but will instead be covered with mortar. The bond between new mortar and old mortar is not very strong. If the original mortar bond was weak, the new bond will be adversely affected. The bond to salvaged brick is considerably less than to similar new brick and has been demonstrated many times by comparative tests (see Experimental Tests Section in this Technical Notes). Most authorities agree that water penetration through masonry results from incompletely filled joints and incomplete bond between brick and mortar. That is, water penetrates through flaws at joints rather than directly through the brick and mortar. Thus, masonry walls of salvaged brick, with their inferior mortar bond, are likely to be more susceptible to water penetration and weaker under lateral loading than similar masonry of walls constructed of new units. The ultimate compressive strength of the walls will also be lower if salmon brick are present. The durability of masonry depends upon the quality of materials and mortar bond. Generally, salmon brick do not provide the same durability as new brick when exposed to weathering. With the thinner masonry walls of today, brick are used primarily as a facing material to provide a weather resistant barrier of protection. Thus, many salmon brick are eventually placed in exposed faces of walls constructed of salvaged brick. Even where solid brick walls are used, many salmons are likely to be exposed to weathering, because it is impossible to accurately sort and grade salvaged brick. With soft, highly absorptive salmon brick exposed to the weather, and with poor mortar bond permitting excessive water penetration, it is quite likely that masonry of salvaged brick will spall, flake, pit, and crack due to freezing and thawing in the presence of excessive moisture. One common characteristic of most manufactured building materials is a reasonable degree of uniformity within a particular grade or within a given manufactured lot. Salvaged brick lack this distinction. Hard-burned and soft-burned brick, hopelessly mixed during wrecking operations, effectively create a material stockpile of two widely differing grades of materials (see Figure 1). A sample of the material will contain specimens of each grade. If tested for absorption or compression strength properties, the sample will show widely diversified characteristics. The average absorption or strength will not approximate the true values for either grade, but will lie somewhere between. In effect, it is difficult to determine whether salvaged brick will meet present day material specifications or building code requirements.

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When existing walls are demolished, hard-burned brick and salmons are hopelessly mixed. It is virtually impossible to distinguish between durable and non-durable units. FIG. 1

Esthetics. Salvaged brick may satisfy the desire for a rugged, colorful masonry surface. Architects often desire the extreme range of colors from dark-red to the whites and grays of units still partially covered with mortar. But most frequently the light pink color of the salmon creates the desired effect. Unfortunately, the pink in salmons results from under-burning which produces units that must not be exposed to weathering. Excessive disintegration due to weathering can soon drastically alter the appearance originally desired (See Figs. 2 - 4).

A chimney of salvaged brick which has spalled considerably within a relatively short time after construction (Knoxville, Tennessee). FIG. 2

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A close-up of a wall indicating the excessive spalling that is likely to occur where salvaged brick are exposed to weathering. FIG. 3

Because of the greater likelihood that moisture will be present, salvaged brick should not be used for exterior patios, walks, pavements, etc. FIG. 4

All pink brick are not necessarily under-burned. During recent years the architectural demand for a variety in colors has led to the extensive use of raw clays which burn other than dark red when fired to maturity. Today, among other colors, many hard-burned, pink brick are available. These units may conform to the requirements for highest quality under applicable ASTM specifications. (Many pink brick conform to Grades SW or MW (severe or moderate weathering) under ASTM C 216 or C 62. Many manufacturers blend different colored brick to provide a rustic appearance similar to salvaged brick. There are advantages to using new brick: the architect may specify any desired color blending and may specify the desired grade under ASTM specifications. Thus, he can obtain the desired esthetic effect without sacrificing durability or strength, a feat which is nearly impossible to accomplish when using salvaged brick. Economics. Although in many instances salvaged brick have sold for more money than new brick, a principal reason for their use is their low prevailing initial cost. But initial economy often proves to be false economy. For example,

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labor costs are usually higher for salvaged brick due to the required sorting and cleaning of the units. Maintenance costs for salvaged-brick masonry are very likely to exceed this initial cost considering: 1) cutting out and replacing disintegrated units; 2) tuck pointing mortar joints to reduce leaks and repair cracks; and 3) repeated attempts at waterproofing. (The dangers of coating masonry of under-burned units are discussed in Technical Notes 6A, "Colorless Coatings For Brick Masonry". Under-burned units may undergo accelerated disintegration if impermeable coatings are applied to the exterior wall face). In many cases, the initial economics of salvaged brick prove false and result in higher total expenditures. BUILDING CODE REQUIREMENTS (See references) American Standard Building Code Requirements for Masonry, ANSI A41.1, Section 2.1.1 (appendix commentary): "Irrespective of the original grading of masonry units, compliance with code requirements of material which has been exposed to weather for a term of years cannot be assumed in the absence of test. Much salvaged brick comes from the demolition of old buildings constructed of solid brick masonry in which hard-burned bricks were used on the exterior and salmon brick as back-up, and, since the color differences which guided the original brick masons in their sorting and selecting of bricks become obscured with exposure and contact with mortar, there is a definite danger that these salmon bricks may be used for exterior exposure with consequent rapid and excessive disintegration. Before permitting their use, the building official should satisfy himself that second-hand materials are suitable for the proposed location and conditions of use. The use of masonry units salvaged from chimneys is not recommended, since such units may be impregnated with oils or tarry material." National Building Code, Section 1401.2: "Second-hand units: Brick and other second-hand masonry units which are to be reused, shall be approved as to quality, condition and compliance with the requirements for new masonry units. The unit shall be of whole, sound material, free from cracks and other defects that would interfere with its proper laying or use, and shall be cleaned free from old mortar before reuse." Standard Building Code, Section 1401.2: "1401.2.1 Masonry units may be reused when clean, whole and conforming to the other requirements of this chapter, except that the allowable working stresses shall be 50% of those permitted for new masonry units. 1401.2.2 Masonry units to be reused as structural units in areas subject to the action of the weather or soil shall not be permitted unless representative samples are tested for compliance with the applicable requirements of 1402." Uniform Building Code, Section 2406 (k): "Reuse of Masonry Units. Masonry units may be reused when clean, whole and conforming to the other requirements of this section. All structural properties of masonry of reclaimed units, especially adhesion bond, shall be determined by approved test. The allowable working stresses shall not exceed 50 percent of that permitted for new masonry units of the same properties." EXPERIMENTAL TESTS At various times interested parties have conducted tests to compare salvaged-brick masonry to masonry of similar new brick. One of the more comprehensive series of tests was conducted many years ago by the Engineering Experiment Station, University of New Hampshire. The following statements are from this test report: (Project No. 98, "Relative Adhesion of Mortars to New and Used Brick", for Star Brick Yard, Epping, NY (1934-1935)). "The object of this study was to determine by laboratory methods the relative adhesion of different standard mortars to new and used or reclaimed brick . . . (using only) those materials . . . that would generally be employed . . . ". . . as far as materials are concerned . . . a wall laid up with used or reclaimed bricks . . . differ(s) from one laid up with new bricks . . . (only) in the adhesion of the mortar to the brick surfaces. It is this quality with which this study is concerned."

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Four types of used brick were tested and compared to the same four types of new brick (a total of eight types). (The report describes the eight brick types tested as including hard and soft, water-struck and sand-struck, new and old brick). Seven different standard mortars were employed. In describing the testing procedures, the report states, in part: "The brick to be tested were selected and were cleaned of all loose particles of mortar which could be removed by means of a hammer and wire brush. No attempt, however, was made to remove any particle of mortar, etc. which adhered so firmly to the brick surface that pounding and wire brushing would not release it." The bulk of the report is too large to reproduce in its entirety. However, the following excerpts from the conclusions to the tests are of interest: " . . . The adhesion of mortar to new (hard) bricks was materially greater than to second hand bricks." "With but few exceptions the adhesion of mortar to hard bricks was far greater than . . . to soft bricks of the same type." "Without exception . . . failure of the mortar to adhere to the surface of used brick far exceeded the failures of the joint between mortars and new brick. In other words, it appears that the capillary pores of the second hand brick were so plugged . . . that the new mortar could not gain any appreciable hold on the surface of the brick." " . . . (The tests indicate) that the adhesive strength of mortar to the hard brick exceeded its cohesive strength..." "With (all) used brick . . . cohesive strength of the mortars exceeded many times the adhesive strength of the same mortars to the surfaces of the brick." " . . . within the limits of the test . . . relative adhesion of mortars to . . . reclaimed brick . . . (is) less than half what can be expected if the same mortars are used with new brick of the same type and degree of hardness." SUMMARY This Technical Notes has discussed the use of salvaged brick in new brick masonry wall construction. The considerations are based on existing knowledge and experience. No effort is made or implied that this is a total discussion of the subject matter, since conditions vary widely throughout the country. However, it is a basis from which the designer can decide on the use of salvaged brick in new masonry structures. Final decisions on the use of the information and suggestions discussed in this Technical Notes are not within the purview of the Brick Institute of America and must rest with the project designer, owner or both. REFERENCES (Building codes undergo continual revision. The editions listed are those current as the publication date of this Technical Notes). 1. American Standard Building Code Requirements for Masonry; ANSI A41.1; National Bureau of Standards (Miscellaneous Publications 211); Washington, D.C.; July 15, 1954 (Reaffirmed 1970). 2. National Building Code, 1987 Edition; Building Officials and Code Administrators International; 4051 W. Flossmoor Road, Country Club Hills, Illinois. 3. Standard Building Code, 1985 Edition; Southern Building Code Congress International; 900 Montclair Road, Birmingham, Alabama. 4. Uniform Building Code, 1985 Edition; International Conference of Building Officials; 5360 South Workman Mill Road, Wittier, California.

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TECHNICAL NOTES on Brick Construction 16 1850 Centennial Park Drive, Reston, Virginia 20191 | www.gobrick.com | 703-620-0010

March 2008

Fire Resistance of Brick Masonry Abstract: This Technical Note presents information about the fire resistance of brick masonry assemblies in loadbearing and veneer applications. Fire resistance ratings of several brick masonry wall assemblies tested using ASTM E119 procedures are listed. For untested wall assemblies, procedures are presented for calculating a fire resistance rating.

Key Words: balanced design, building codes, equivalent thickness, fire, fire resistance period, fire resistance rating, fire test.

SUMMARY OF RECOMMENDATIONS: Fire Resistance Requirements

Assembly with Calculated Fire Resistance Rating

Assembly with Tested Fire Resistance Rating

Construction Details

• Use the building code to determine the fire resistance rating required for separations, corridors, exterior walls and other building features • Use fire control systems, compartmentalization of space or other “balanced design” approaches to lower required fire resistance ratings • Determine whether fire resistance is needed for one side or two sides of fire exposure • Use wall construction prescribed by the building code or testing agency to achieve fire resistance rating • For wall construction not prescribed by the building code, include reference for test results in design documents

• Determine minimum equivalent thickness required of brick unit from tables in the building code or ACI 216.1/ TMS 0216 [Ref. 5] • Specify brick standard, brick size and void area to meet the minimum equivalent thickness requirements • For multi-wythe masonry walls, determine contributions from other wall components such as concrete, concrete masonry, air spaces and plaster

• Where assemblies with a fire resistance rating are supported by other assemblies, specify that the support assembly have an equal or greater fire resistance rating • Seal penetrations through assemblies with a fire resistance rating with appropriate sealants or details to maintain fire resistance rating

INTRODUCTION Building codes and other local ordinances require critical building components to have a certain level of fire resistance to protect occupants and to allow a means of escape. Several factors contribute to the level of fire resistance required of a wall, floor or roof assembly, including whether combustible (wood) or noncombustible (steel, concrete and masonry) construction is used. Other factors include the building’s use, floor area and height, the location of the assembly, and whether a fire suppression system such as stand pipes or sprinklers is installed.

Definitions Fire Resistance. The property of a building element, component or assembly that prevents or retards the passage of excessive heat, hot gases or flames under conditions of use. Fire Resistance Period. A duration of time determined by a fire test or method based on a fire test that a building element, component or assembly maintains the ability to confine a fire, continues to perform a given structural function or both. Fire Resistance Rating. A duration of time not exceeding 4 hours (as established by the building code) that a building element, component or assembly maintains the ability to confine a fire, continues to perform a given structural function or both. A legal term defined in building codes for various types of construction and occupancies. A fire resistance rating is based on a fire resistance period and usually given in half-hour or hourly increments. As an example, a wall with a fire resistance period of 2 hours and 25 minutes may only attain a fire resistance rating of 2 hours. It is also referred to as a fire rating, fire resistance classification or hourly rating.

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Determining a Fire Resistance Rating Traditionally, a fire resistance rating has been established by testing. The most common test method used is ASTM E119, Standard Test Methods for Fire Tests of Building Construction and Materials [Ref. 3]. In this test, a sample of the wall must perform successfully during exposure to a controlled fire for the specified period of time, followed by the impact of a stream of water from a hose. This standard test, along with other ASTM fire test standards, is used to measure and describe the response of materials, products or assemblies to heat and flame under controlled conditions, but does not by itself replicate actual fire conditions in a building. Rather, the intent of the test is to provide comparative performance to specific fire-test conditions during the period of exposure. Further, the test is valid only for the specific assembly tested. Fire testing is expensive because each specific assembly must be tested by constructing a large specimen, placing multiple monitoring devices on that specimen and subjecting the specimen to both a fire and a hose stream. As a result, a calculated fire resistance method developed jointly by The Masonry Society and the American Concrete Institute and based on past ASTM E119 tests has largely replaced further fire resistance testing for masonry and concrete materials [Ref. 5].

FIRE RESISTANCE TESTING

2400

ASTM E119 Test Method

2000 1000 1600

800

1200

600

800

400

400

200

Temperature, Deg. C

Temperature, Deg. F

The test methods described in ASTM E119 are applicable to assemblies of masonry units and to composite assemblies of structural materials for buildings, including bearing and other walls and partitions, columns, girders, beams, slabs and composite slab and beam assemblies for floors and roofs.

1200

0

0 1

2

3 4 5 Time, hours

6

7

8

When fire testing a wall assembly according to ASTM Figure 1 E119, a sample of the wall is built using the materials Time-Temperature Curve for ASTM Standard E119 and details of the assembly to be used in construction. The specimen is then subjected to a controlled fire until a failure occurs (termination point is reached) or a designated extent of time passes. ASTM E119 requires that the air temperature at a distance of 6 in. (152 mm) from the exposed (fire) side of the specimen conform to the standard time-temperature curve, as shown in Figure 1. Wall Specimens. The area exposed to the fire must be at least 100 sq ft (9.3 m2) with no dimension less than 9 ft (2.7 m). Non-bearing walls and partitions are restrained at all four sides, but bearing walls and partitions are not restrained at the vertical edges. Nine thermocouples are placed on the side of the wall unexposed to the fire to measure temperature rise. Protected Steel Column Specimens. If the fire resistant material protecting the column is structural, the column specimen must be at least 9 ft (2.7 m) tall, and acceptance is based on its ability to carry an axial load for the duration of the fire test. If the fire resistant material is not structural, the minimum column height is 8 ft (2.4 m), and acceptance is based on temperature rise on the surface of the column. Temperature rise is measured by placing a minimum of three thermocouples on the column surface (behind the fire resistant material) at each of four levels. Hose Stream Test. For most fire resistance ratings ASTM E119 requires that walls be subjected to both a fire endurance test and a hose stream test. The hose stream test subjects a specimen to impact, erosion and cooling effects over the entire surface area that has been exposed to the fire. The procedure stipulates nozzle size, distance, duration of application and water pressure at the base of the nozzle. Some of these requirements vary with the fire resistance rating. The hose stream test may be performed on a duplicate wall specimen that has been subjected to a fire endurance test for one-half of the period determined by the fire test (but not more than 1 hour); or the hose stream test may be performed on the wall specimen immediately after the full duration of fire exposure. The latter option is typically used to test brick walls because the test termination point is almost always a temperature rise rather than a failure by passage of hot gases or collapse where there is a degradation of the brick wythe from the hose stream test. Some other materials rely on the duplicate specimen to meet certain fire ratings. www.gobrick.com | Brick Industry Association | TN 16 | Fire Resistance of Brick Masonry | Page 2 of 16

Loading. Throughout the fire endurance and hose stream tests, a superimposed load is applied to bearing specimens. The applied load is required to be the maximum load condition allowed by nationally recognized structural design criteria or by limited design criteria for a reduced load. Columns are loaded to simulate the maximum load condition allowed by nationally recognized structural design criteria or by limited design criteria for a reduced load. The column is then subjected to the standard fire on all sides. Where the fire protection is not designed to carry loads, an alternate test method in which the column is not loaded may be used.

Conditions of Acceptance The number of criteria considered as termination points for a fire test on an assembly depends on whether the assembly is loadbearing or not. Non-Bearing Walls and Partitions. The test is successful and a fire resistance rating is assigned to the construction if all of the following criteria are met: 1. The assembly withstands the fire endurance test without passage of flame or gases hot enough to ignite cotton waste for a period equal to that for which classification is desired. 2. The assembly withstands the fire endurance test without passage of flame and the hose stream test without passage of water from the hose stream. If an opening develops in the wall specimen that permits a projection of water beyond the surface of the unexposed side during the hose stream test, the assembly is considered to have failed the test. 3. The average rise in temperature of nine thermocouples on the unexposed surface is not more than 250 ºF (139 ºC) above their average initial temperature, and the temperature rise of a single thermocouple is not more than 325 ºF (181 ºC) above its initial temperature. Bearing Walls. The conditions of acceptance for bearing walls are the same as for non-bearing walls and partitions (above), with the following addition: 4. The specimen must also sustain the applied load during the fire endurance and hose stream tests. The first three criteria relate to providing a barrier against the spread of fire by penetration of the assembly; the fourth relates to structural integrity. The termination point for fire tests of brick masonry walls is almost invariably due to temperature rise (heat transmission) of the unexposed surface. Brick masonry walls successfully withstand the load during the fire endurance test and the hose stream test conducted immediately after the wall has been subjected to the fire exposure. This structural integrity of brick masonry walls is attested to in many fires where the masonry walls have remained standing when other parts of the building have been destroyed or consumed during the fire. Columns. Columns with integral structural fireproofing are assigned a fire resistance rating when they support the superimposed load during the fire endurance test. For columns with fireproofing not designed to carry loads, a fire resistance rating is assigned when the average temperature rise does not exceed 1000 ºF (556 ºC) or the maximum temperature rise does not exceed 1200 ºF (667 ºC) at any one point.

FIRE RESISTANCE RATINGS OF WALLS There are several sources of fire resistance ratings for brick masonry assemblies that will typically satisfy the requirements of the local building official. Model building codes contain results based on testing. Private laboratories report fire test results. Individual associations and companies sponsor fire tests and make the results available.

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Building Codes Table 1 presents fire resistance ratings for various masonry wall assemblies, as taken from the 2006 International Building Code Table 720.1(2) [Ref. 1]. Note that for item numbers 1.1-1 through 1.1-3, 1-2.1, and 2-1.1 through 2-1.2, the required thickness of clay brick masonry is the equivalent thickness, i.e. the thickness is the volume of clay in a unit divided by the face area. Table 2 presents fire resistance ratings for brick veneer/steel stud wall assemblies as taken from Table 721.4.1(2) of the same code. TABLE 1 Fire Resistance Ratings (Periods) for Various Walls and Partitions Material

Item Number

Construction

Minimum Finished Thickness, Face-to-Face, in. (mm) 4 hr

1. Brick of clay or shale2

2. Combination of clay brick and loadbearing hollow clay tile2

15. Exterior or interior walls4,5,6

3 hr

2 hr

1 hr

1-1.1

Solid brick of clay or shale1

6.0 4.9 (152) (124)

3.8 (97)

2.7 (69)

1-1.2

Hollow brick, not filled

5.0 4.3 (127) (109)

3.4 (86)

2.3 (58)

1-1.3

Hollow brick unit wall, grouted solid or filled with perlite vermiculite or expanded shale aggregate

6.6 5.5 4.4 (168) (140) (112)

3.0 (76)

1-2.1

4 in. (102 mm) nominal thick units at least 75 percent solid backed with hat-shaped metal furring channel ¾ in. (76 mm) thick formed from 0.021 in. (0.53 mm) sheet metal attached to the brick wall at 24 in. (610 mm) o.c. with approved fasteners, and ½ in. (12.7 mm) Type X gypsum wallboard attached to the metal furring strips with 1 in. (25.4 mm) long Type S screws spaced at 8 in. (203 mm) o.c.

—

—

53 (127)

—

2-1.1

4 in. (102 mm) solid brick and 4 in. (102 mm) tile (at least 40 percent solid)

—

8 (203)

—

—

2-1.2

4 in. (102 mm) solid brick and 8 in. (203 mm) tile (at least 40 percent solid)

12 (305)

—

—

—

—

—

10 (254)

—

15-1.57

2¼ × 3¾ in. (57 × 95 mm) clay face brick with cored holes over ½ in. (12.7 mm) gypsum sheathing on exterior surface of 2 × 4 in. (51 × 102 mm) wood studs at 16 in. (406 mm) o.c. and two layers ⅝ in. (15.9 mm) Type X gypsum wallboard on interior surface. Sheathing placed horizontally or vertically with vertical joints over studs nailed 6 in. (152 mm) on center with 1¾ in. (44 mm) by No. 11 gage by 7⁄16 in. (11.1 mm) head galvanized nails. Inner layer of wallboard placed horizontally or vertically and nailed 8 in. (203 mm) on center with 6d cooler or wallboard nails. Outer layer of wallboard placed horizontally or vertically and nailed 8 in. (203 mm) on center with 8d cooler or wallboard nails. All joints staggered with vertical joints over studs. Outer layer joints taped and finished with compound. Nail heads covered with joint compound. 0.035 in. (0.89 mm) (No. 20 galvanized sheet gage) corrugated galvanized steel wall ties ¾ × 6⅝ in. (19.1 × 168 mm) attached to each stud with two 8d cooler or wallboard nails every sixth course of bricks.

1. For units in which the net cross-sectional area of cored brick in any plane parallel to the surface containing the cores is at least 75 percent of the gross cross-sectional area measured in the same plane. 2. Thickness shown for brick and clay tile are nominal thicknesses unless plastered, in which case thicknesses are net. Thickness shown for clay masonry is equivalent thickness defined by Equation 3. Where all cells are solid grouted or filled with silicone-treated perlite loose-fill insulation; vermiculite loose-fill insulation; or expanded clay, shale or slate lightweight aggregate, the equivalent thickness shall be the thickness of the brick using specified dimensions. Equivalent thickness may also include the thickness of applied plaster and lath or gypsum wallboard, where specified. 3. Shall be used for non-bearing purposes only. 4. Staples with equivalent holding power and penetration shall be permitted to be used as alternate fasteners to nails for attachment to wood framing. 5. For all of the construction with gypsum wallboard described in this table, gypsum base for veneer plaster of the same size, thickness and core type shall be permitted to be substituted for gypsum wallboard, provided attachment is identical to that specified for the wallboard, and the joints on the face layer are reinforced and the entire surface is covered with a minimum of 1⁄16 in. (1.6 mm) gypsum veneer plaster. 6. For properties of cooler or wallboard nails, see ASTM C514, ASTM C547 or ASTM F1667. 7. The design stress of studs shall be reduced to 78 percent of allowable F′c with the maximum not greater than 78 percent of the calculated stress with studs having a slenderness ratio l/d of 33.

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TABLE 2 Fire Resistance Ratings for Brick Veneer/Steel Stud Assemblies Plaster Side Exposed (hours)

Brick Faced Side Exposed (hours)

Outside facing of steel studs: ½ in. (12.7 mm) wood fiberboard sheathing next to studs, ¾ in. (19.1 mm) air space formed with ¾ × 1⅝ in. (19.1 × 41 mm) wood strips placed over the fiberboard and secured to the studs; metal or wire lath nailed to such strips, 3¾ in. (95 mm) brick veneer held in place by filling ¾ in. (19.1 mm) air space between the brick and lath with mortar. Inside facing of studs: ¾ in. (19.1 mm) unsanded gypsum plaster on metal or wire lath attached to 5⁄16 in. (7.9 mm) wood strips secured to edges of the studs.

1.5

4

Outside facing of steel studs: 1 in. (25.4 mm) insulation board sheathing attached to studs, 1 in. (25.4 mm) air space, and 3¾ in. (95 mm) brick veneer attached to steel frame with metal ties every fifth course. Inside facing of studs: ⅞ in. (22.2 mm) sanded gypsum plaster (1:2 mix) applied on metal or wire lath attached directly to the studs.

1.5

4

Same as above except use ⅞ in. (22.2 mm) vermiculite — gypsum plaster — or 1 in. (25.4 mm) sanded gypsum plaster (1:2 mix) applied to metal or wire.

2

4

Outside facing of steel studs: ½ in. (12.7 mm) gypsum sheathing board, attached to studs, and 3¾ in. (95 mm) brick veneer attached to steel frame with metal ties every fifth course. Inside facing of studs: ½ in. (12.7 mm) sanded gypsum plaster (1:2 mix) applied to ½ in. (12.7 mm) perforated gypsum lath securely attached to studs and having strips of metal lath 3 in. (76 mm) wide applied to all horizontal joints of gypsum lath.

2

4

Wall or Partition Assembly

UL Listings Underwriters Laboratories is a resource recognized throughout the building industry that has thousands of published fire resistance rated designs and product certifications that appear in the UL Fire Resistance Directory [Ref. 7] and are typically accepted without modification by building officials. The UL certification is based on an assembly complying with the ASTM E119 test, as described previously. The directory lists several masonry wall assemblies with various potential alternates in materials as shown in Table 3. TABLE 3 UL Fire Resistance Ratings for Brick Masonry Walls Design Number

Rating1

Assembly Brick Veneer/Wood Stud, Loadbearing

U302

2 hr

• (2) layers ⅝ in. (15.9 mm) thick gypsum wallboard or nominal 3⁄32 in. (2.4 mm) thick gypsum veneer plaster on Classified veneer baseboard • (1) layer ½ in. (12.7 mm) thick exterior gypsum sheathing • 1 (25.4 mm) in. (51 × 102 mm) air space • nominal 2 × 4 in. wood studs spaced at 16 in. (406 mm) o.c. • nominal 4 in. (102 mm) clay facing brick laid in mortar with ¾ in. (19.1 mm) wide × 6⅝ in. 168 mm) long 20 MSG corrugated wall ties spaced at 16 in. (406 mm) o.c. each way

1. Unless noted otherwise, fire resistance rating applies to both sides of assembly.

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TABLE 3 (continued) UL Fire Resistance Ratings for Brick Masonry Walls Design Number

Rating1

Assembly Brick Veneer/Wood Stud, Loadbearing (continued)

U356

U371

1 hr

• (1) layer ⅝ in. (15.9 mm) thick gypsum board • nominal 2 × 4 in. (51 × 102 mm) wood studs spaced at 16 in. (406 mm) o.c., with 3½ in. (89 mm) thick glass fiber batt or spray applied cellulose insulation • 7⁄16 in. (11.1 mm) min. thick wood structural panels or min. ½ in. (12.7 mm) thick mineral and fiber boards • 1 in. (25.4 mm) air space • nominal 4 in. (102 mm) brick veneer with corrugated metal wall ties spaced not more than each sixth course of brick and max. 32 in. (813 mm) o.c. horizontally

1 hr

• (2) layer ⅝ in. (15.9 mm) thick gypsum board • nominal 2 × 4 in. (51 × 102 mm) wood studs spaced at 16 in. (406 mm) o.c. with min. 3 in. (76 mm) mineral wool batt insulation • (1) layer ⅝ in. (15.9 mm) thick gypsum board • 1 in. (25.4 mm) air space • nominal 4 in. (102 mm) brick veneer with corrugated metal wall ties attached with screws and spaced not more than each fourth course and a max. 24 in. (610 mm) o.c. horizontally Brick Veneer/Steel Stud, Loadbearing

U418

U424

U425

45 min 1 hr 2 hr

• (45 min): (1) layer ⅝ in. (15.9 mm) thick gypsum wallboard (1 hr): (2) layers ½ in. (12.7 mm) thick gypsum wallboard (2 hr): (3) layers ½ in. (12.7 mm) thick gypsum wallboard • 3½ or 5½ in., (89 or 140 mm) 18 gage, steel studs, spaced at 24 in. (610 mm) o.c., with 3½ in. (89 mm) thick glass fiber batt insulation • (1) layer ½ in. (12.7 mm) thick exterior gypsum sheathing • 1 in. (25.4 mm) air space • 4 in. (102 mm) nominal clay facing brick laid in mortar with metal ties at 24 in. (610 mm) o.c. horizontally and 16 in. (406 mm) o.c. vertically

45 min 1 hr 1½ hr 2 hr

• (45 min): (1) layer ⅝ in. (15.9 mm) thick gypsum wallboard (1 hr): (2) layers ½ in. (12.7 mm) thick gypsum wallboard (1½ hr): (2) layers ⅝ in. (15.9 mm) thick gypsum wallboard (2 hr): (3) layers ½ in. (12.7 mm) or (2) layers ¾ in. (19.1 mm) thick gypsum wallboard • 3½ in. (89 mm), 20 gage steel studs, spaced up to 24 in. (610 mm) o.c., with 3½ in. (89 mm) thick glass fiber or mineral wool batt or blanket insulation • (1) layer ½ or ⅝ in. (12.7 or 15.9 mm) thick exterior gypsum sheathing • Air space thickness not specified • 3¾ in. (95 mm) min. brick veneer with corrugated metal wall ties attached to each stud with steel screws, not more than each sixth course of brick

45 min 1 hr 1½ hr 2 hr

• (45 min): (1) layer ⅝ in. (15.9 mm) thick gypsum wallboard (1 hr): (2) layers ½ in. (12.7 mm) thick gypsum wallboard (1½ hr): (2) layers ⅝ in. (15.9 mm) thick gypsum wallboard (2 hr): (3) layers ½ in. (12.7 mm) or (2) layers ¾ in. (19.1 mm) thick gypsum wallboard • 3½ in. (89 mm), 20 gage steel studs, spaced up to 24 in. (610 mm) o.c., with 3½ in. (89 mm) thick glass fiber or mineral wool batt or blanket insulation • (1) layer ½ or ⅝ in. (12.7 or 15.9 mm) thick exterior gypsum sheathing • Air space thickness not specified • 3¾ in. (95 mm) brick veneer with corrugated metal wall ties attached to each stud with steel screws, not more than each sixth course of brick

1. Unless noted otherwise, fire resistance rating applies to both sides of assembly.

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TABLE 3 (continued) UL Fire Resistance Ratings for Brick Masonry Walls Design Number

Rating1

Assembly Brick Veneer/Steel Stud, Loadbearing (continued)

V434

V454

V458

1 hr

• (1) layer ⅝ in. (15.9 mm) thick gypsum wallboard • 3½ in. (89 mm), 20 gage, steel studs with max. spacing at 24 in. (610 mm) o.c., with 3½ in. (89 mm) thick glass fiber batt insulation • 2 in. (51 mm) max. thick foamed plastic • 1 in. (25.4 mm) min. air space • 4 in. (102 mm) nominal brick veneer with wall anchor ties attached to studs at max. 24 in. (610 mm) o.c.

1 hr

• (1) layer ⅝ in. (15.9 mm) thick gypsum wallboard • 3½ in. (89 mm), 20 gage, steel studs at max. spacing of 24 in. (610 mm) o.c. • (1) layer ⅝ in. (15.9 mm) thick gypsum wallboard • 4 in. (102 mm) max. thick rigid polystyrene insulation • 1 in. (25.4 mm) min. air space • 4 in. (102 mm) nominal brick veneer with wall anchor ties attached to studs at max. 24 in. (610 mm) o.c.

45 min

• (1) layer ⅝ in. (15.9 mm) thick gypsum wallboard bearing UL Classification Mark • 3⅝ in. (92 mm) 18 gage steel studs at max. spacing of 24 in. (610 mm) o.c. with nominal 3.5 pcf mineral wool batt • (1) layer ⅝ in. (15.9 mm) thick gypsum wallboard • 1 in. (25.4 mm) min. air space • 3¾ in. (95 mm) min. thick brick veneer with corrugated metal wall ties attached to each stud with steel screws, not more than each sixth course of brick Brick Veneer/Steel Stud, Non-Loadbearing

V414

3 hr, interior 1 hr, exterior

• (1) layer ⅝ in. (15.9 mm) thick gypsum wallboard • 3⅝ in. (92 mm) wide, 1⅝ in. (41 mm) legs, 20 gage steel studs, spaced 16 in. (406 mm) o.c., studs cut ¾ in. (19.1 mm) less than assembly height • 2 in. (51 mm) thick foamed plastic (rigid insulation) • 2 in. (51 mm) air space • 4 in. (102 mm) nominal clay facing brick laid in mortar with metal ties at 16 in. (406 mm) o.c. max. each way Brick/Concrete Masonry, Loadbearing

U902

4 hr

• 4 in. (102 mm) nominal loadbearing concrete masonry unit laid with full mortar beds and with 9 gage joint reinforcement at 16 in. (406 mm) o.c. vertically • min. 1 in. (25.4 mm) air space with up to 4 in. (102 mm) foamed plastic (rigid insulation) as option • ¾ in. (19.1 mm) wide, 7 in. (178 mm) long, 26 gage corrugated metal ties spaced at 8 in. (203 mm) o.c. horizontally and 16 in. (406 mm) o.c. vertically or truss or ladder type joint reinforcement of 9 gage wire for full width of wall assembly, cross wires at 16 in. (406 mm) o.c., spaced at 16 in. (406 mm) o.c. vertically • 4 in. (102 mm) nominal clay facing brick laid in mortar

1. Unless noted otherwise, fire resistance rating applies to both sides of assembly.

Other In addition to assemblies listed above, there are several other assemblies previously tested with results published in past building codes or other publications. A selection of these appears in Table 4.

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TABLE 4 Fire Resistance Ratings for Other Brick Masonry Wall Assemblies1 Test

Rating2

Assembly Brick Veneer/Wood Stud

1

2

3

1 hr

• (1) layer ½ in. (12.7 mm) thick gypsum wallboard • 2 × 4 in. (51 × 102 mm) wood studs spaced at 16 in. (406 mm) o.c. with 3½ in. (89 mm) glass fiber batt insulation between studs • (1) layer ½ in. (12.7 mm) thick wood fiberboard sheathing • (1) layer No. 15 asphalt felt paper • 1 in. (25.4 mm) air space • 3½ in. (89 mm) actual width hollow clay brick with void area of 34.5% (equivalent thickness of 2.3 in. (58 mm)), laid in mortar with ⅞ in. (22.2 mm) wide, 22 gage corrugated wall ties spaced at 24 in. (610 mm) o.c. horizontally and 16 in. (406 mm) o.c. vertically

1 hr

• (1) layer ½ in. (12.7 mm) thick gypsum wallboard • 2 × 4 in. (51 × 102 mm) wood studs spaced at 16 in. (406 mm) o.c. with 3½ in. (89 mm) glass fiber batt insulation between studs • (1) layer ½ in. (12.7 mm) thick wood fiberboard sheathing • (1) layer No. 15 asphalt felt paper • 1 in. (25.4 mm) air space • 2⅞ in. (73 mm) actual width hollow clay brick with void area of 36% (equivalent thickness of 1.8 in. (46 mm)), laid in mortar with ⅞ in. (22.2 mm) wide, 22 gage corrugated wall ties spaced at 24 in. (610 mm) o.c. horizontally and 16 in. (406 mm) o.c. vertically

1 hr

• (1) layer ½ in. (12.7 mm) thick gypsum wallboard • 2 × 4 in. (51 × 102 mm) wood studs spaced at 16 in. (406 mm) o.c. with 3½ in. (89 mm) glass fiber batt insulation between studs • (1) layer ½ in. (12.7 mm) thick wood fiberboard sheathing • (1) layer No. 15 asphalt felt paper • 1 in. (25.4 mm) air space • 1¾ in. (44 mm) actual width3 hollow clay brick with void area of 26.9% (equivalent thickness of 1.3 in. (32 mm)), laid in mortar with ⅞ in. (22.2 mm) wide, 22 gage corrugated wall ties spaced at 24 in. (610 mm) o.c. horizontally and 16 in. (406 mm) o.c. vertically

1. As tested by the Southwest Research Institute [Ref. 4]. 2. Fire resistance rating applies to brick (exterior) side only. Test stopped at 1 hour. 3. Width not in compliance with 2006 IBC veneer requirements; however, complies with 2006 IRC [Ref. 2] veneer requirements.

CALCULATED FIRE RESISTANCE Theory and Derivation The extent of fire resistance provided by a clay masonry wall is a function of the wall’s mass or thickness. This well-established fact is based on the results of many fire resistance tests conducted on walls of solid and hollow clay units. During the ASTM E119 fire test, the fire resistance period of clay masonry walls is usually established by the temperature rise on the unexposed side of the wall specimen. Few masonry walls have failed due to loading or thermal shock of the hose stream. The method for calculating a fire resistance period is described in NBS BMS 92, Fire-Resistance Classifications of Building Construction [Ref. 6]. The construction must be similar to others for which the fire resistance periods are known or of composite construction for which the fire resistance period of each component is known. The calculated fire resistance formulas are based on the temperature rise on the unexposed side of the wall. Heat transmission theory states that when a wall made of a given material is exposed to a heat source that maintains a constant temperature at the surface of the exposed side and the unexposed side is protected against heat loss, the unexposed side will attain a given temperature rise inversely proportional to the square of the wall’s thickness. In the standard fire test, the time required to attain a given temperature rise on the unexposed side will be different than when the temperature on the exposed side remains constant. This is because the fire in the standard fire test increases the temperature at the exposed surface of the wall as the test proceeds. Based on fire test data collected from many fire tests, the following formula has been derived to express the fire resistance period of a wall based on its thickness:

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R = (cV)n

Eq. 1

where: R = fire resistance period, hr c = coefficient depending on the material, design of the wall, and the units of measurement of R and V V = volume of solid material per unit area of wall surface, and n = exponent depending on the rate of increase of temperature at the exposed face of the wall For walls of a given material and design, an increase of 50 percent in volume of solid material per unit area of wall surface results in a 100 percent increase in the fire resistance period. This relationship results in a value of 1.7 for n. The lower value for n compared with 2 for the theoretical condition should be anticipated since a rising temperature at the exposed surface will shorten the fire resistance period of a wall. For a wall composed of layers of multiple materials, the fire resistance period may be expressed as follows: R = (c1V1 + c2V2 + c3V3)n = (R11/n + R21/n + R31/n)n Substituting 1.7 for n and 0.59 for 1/n, the general formula for calculating a fire resistance period becomes: R = (R10.59 + R20.59 + R30.59 … + Ri0.59)1.7

Eq. 2

where: R1, R2, R3, … Ri = known fire resistance period of each component layer, hr Where available, the fire resistance period (the full duration of the fire test before a termination point is reached) should be used. Where this period is not available (many brick wall tests are stopped after the desired rating time period elapses), the fire resistance rating (typically truncated to be the highest full hour of fire test duration) can be used. However, using the fire resistance rating for a component layer will generally result in a lower calculated fire resistance period for the overall assembly than using the fire resistance period for each component layer. The calculated fire resistance, calculated using either the fire resistance period or fire resistance rating of each layer, can then be used to verify that the wall assembly equals or exceeds the fire resistance rating required by the building code. The theory proposed and derived in NBS BMS 92 has been incorporated into Code Requirements for Determining Fire Resistance of Concrete and Masonry Assemblies (ACI 216.1/TMS-0216) [Ref. 5].

Calculations The 2006 International Building Code (IBC) [Ref. 1] permits the fire resistance of masonry assemblies to be calculated in accordance with TMS-0216. In addition, the IBC also includes methods for calculating the fire resistance of a masonry assembly that are based on and very similar to those in TMS-0216. The methods discussed below are taken from TMS-0216 unless noted otherwise. Equivalent Thickness of a Single Wythe. The average thickness of the solid material (i.e., minus cores or cells) in a masonry unit as placed in the wall is the equivalent thickness of the masonry unit. This is determined by measuring the total volume of the masonry unit, subtracting the volume of the core or cell spaces and dividing by the area of the exposed face of the masonry unit, which is expressed as follows: Te=Vn /LH

Eq. 3

where: Te = equivalent thickness of the masonry unit, in. Vn = net volume of the masonry unit, in.3 L = specified length of the masonry unit, in. H = specified height of the masonry unit, in. Equation 3 can be simplified as follows: Te = [WLH × (1 – Pv)] / LH = (1 – Pv) × W = Ps × W

Eq. 4 Eq. 5

where: W = specified width of the masonry unit, in. Pv = percent void of the masonry unit Ps = percent solid of the masonry unit www.gobrick.com | Brick Industry Association | TN 16 | Fire Resistance of Brick Masonry | Page 9 of 16

For ungrouted and partially grouted construction, the equivalent thickness should be determined according to Equation 3. The equivalent thickness should be taken as the actual thickness of the masonry unit for solid grouted construction or brickwork constructed of hollow brick units complying with ASTM C652 and filled with one of the following: • Sand, pea gravel, crushed stone or slag complying with ASTM C33 • Pumice, scoria, expanded shale, clay, slate, slag or fly ash; or cinders complying with ASTM C331 • Perlite complying with ASTM C549 • Vermiculite complying with ASTM C516 Fire Resistance of a Single Wythe. The minimum equivalent thickness required to achieve a given fire resistance rating with a clay masonry wythe is listed in Table 5. The table is organized by material type and hourly fire resistance ratings. For fire resistance periods that are between the hourly increments listed in the table, the minimum equivalent thickness may be determined by linear interpolation. Where combustible members such as wood floor joists are framed into the wall, the thickness of solid material between the end of each member and the opposite face of the wall, or between members set in from opposite sides is allowed to be no less than 93 percent of the thickness shown in Table 5. TABLE 5 Fire Resistance Ratings of Clay Masonry Walls Minimum Equivalent Thickness for Fire Resistance, in. (mm)1,2,3

Material Type

1 hr 4

2 hr

3 hr

4 hr

Solid brick of clay or shale

2.7 (69)

3.8 (97)

4.9 (124) 6.0 (152)

Hollow brick or tile of clay or shale, unfilled

2.3 (58)

3.4 (86)

4.3 (109) 5.0 (127)

Hollow brick or tile of clay or shale, grouted or filled with materials specified

3.0 (76)

4.4 (112) 5.5 (140) 6.6 (168)

1. Equivalent thickness as determined from Equations 3, 4 or 5. 2. Calculated fire resistance between the hourly increments listed shall be determined by linear interpolation. 3. Where combustible members are framed into the wall, the thickness of solid material between the end of each member and the opposite face of the wall, or between members set in from opposite sides, shall not be less than 93% percent of the thickness shown. 4. Units in which the net cross-sectional area of cored or deep frogged brick in any plane parallel to the surface containing the cores or deep frogs is at least 75 percent of the gross cross-sectional area measured in the same plane.

Multiple Wythe Walls. For walls with multiple wythes of brick, concrete masonry or concrete, the calculated fire resistance formula is: R = (R10.59 + R20.59 + … Rn0.59 + A1 + A2 +… An)1.7 Eq. 6 where: R = calculated fire resistance period of the assembly, hr R1, R2 … Rn = fire resistance periods of the individual wythes, hr A1, A2 … An = 0.30; the air factor for each continuous air space having a distance of ½ to 3½ in. (12.7 to 89 mm) between wythes The fire resistance period used in Equation 6 for each individual wythe or layer is determined from Table 5 for a wythe made of clay units, from Table 6 for a wythe made of concrete masonry units and from Table 7 and Figure 2 for a concrete layer. TABLE 6 Fire Resistance Periods of Concrete Masonry Walls Aggregate Type

Minimum Equivalent Thickness for Fire Resistance Rating in. (mm)1,2 ½ hr

¾ hr

1 hr

1½ hr

2 hr

3 hr

4 hr

Calcareous or siliceous gravel (other than limestone)

2.0 (51)

2.4 (61)

2.8 (71)

3.6 (91)

4.2 (107)

5.3 (135)

6.2 (157)

Limestone, cinders, or air-cooled slag

1.9 (48)

2.3 (58)

2.7 (69)

3.4 (86)

4.0 (102)

5.0 (127)

5.9 (150)

Expanded clay, expanded shale or expanded slate

1.8 (46)

2.2 (56)

2.6 (66)

3.3 (84)

3.6 (91)

4.4 (112)

5.1 (130)

Expanded slag or pumice

1.5 (38)

1.9 (48)

2.1 (53)

2.7 (69)

3.2 (81)

4.0 (102)

4.7 (119)

1. Fire resistance periods between the hourly fire resistance rating listed shall be determined by linear interpolation based on the equivalent thickness value of the concrete masonry assembly. 2. Minimum required equivalent thickness corresponding to the fire resistance rating for units made with a combination of aggregates shall be determined by linear interpolation based on the percent by dry-rodded volume of each aggregate used in manufacturing the units.

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Aggregate Type

Siliceous

Fire Resistance Period (Rn), hours

TABLE 7 Fire Resistance Periods of Normal-Weight Concrete Panels Minimum Equivalent Thickness for Fire Resistance Rating, in. (mm) 1 hr

1½ hr

2 hr

3 hr

4 hr

3.5 (89)

4.3 (109)

5.0 (127)

6.2 (157)

7.0 (178)

Carbonate

3.2 (81)

4.0 (102)

4.6 (117)

5.7 (145)

6.6 (168)

Semilightweight

2.7 (69)

3.3 (84)

3.8 (97)

4.6 (117)

5.4 137)

Lightweight

2.5 (64)

3.1 (79)

3.6 (91)

4.4 (112)

5.1 (130)

50 5

75

Panel Thickness, mm 100 125 150

175

Insulating Concrete 35 pcf (560 kg/m3)

4

Lightweight 100 pcf (1600 kg/m3)

3

Semi-Lightweight 115 pcf (1850 kg/m3)

2

Air-Cooled Blast Furnace Slag Carbonate Aggregate

1 0

Silicaceous Aggregate

2

3 4 5 6 Panel Thickness, inches

7

Figure 2 Fire Resistance Periods for Other Concrete Panels

Finish Materials. When drywall, stucco or plaster finishes are applied to a masonry wall, the fire resistance of the wall is increased. Where finish materials are used to attain a required fire resistance rating, the fire resistance provided by the masonry alone must be a minimum of half the required fire resistance rating to ensure the structural integrity of the wall. For finishes applied to the non-fire exposed side of a wall, the finish is converted to an equivalent thickness of brickwork. This adjusted thickness is then calculated by multiplying the thickness of the finish by the applicable factor from Table 8 established by the durability of the finish and the wall material. The adjusted finish thickness is then added to the base equivalent thickness of the wall used in Table 5. TABLE 8 Multiplying Factor for Finishes on Non-Fire Exposed Side of Masonry and Concrete Walls Type of Material Used in Slab or Wall

Type of Finish Applied to Slab or Wall Portland Cement-Sand Plaster1 or Terrazzo

Gypsum-Sand Plaster

GypsumVermiculite or Perlite Plaster

Gypsum Wallboard

Clay masonry – solid brick of clay or shale

1.00

1.25

1.75

3.00

Clay masonry – hollow brick or tile of clay or shale

0.75

1.00

1.50

2.25

Concrete masonry – siliceous, calcareous, limestone, cinders, sir-cooled blast-furnace slag

1.00

1.25

1.75

3.00

Concrete masonry – made with 80% of more by volume of expanded shale, slate or clay, expanded slag, or pumice

0.75

1.00

1.25

2.25

Concrete – siliceous, carbonate, air-cooled blastfurnace slag

1.00

1.25

1.75

3.00

Concrete – semi-lightweight

0.75

1.00

1.50

2.25

Concrete – lightweight, insulating concrete

0.75

1.00

1.25

2.25

1. For portland cement-sand plaster ⅝ in. (15.9 mm) or less in thickness and applied directly to clay masonry on the non-fire exposed side of the wall, the multiplying factor shall be 1.0.

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For finishes on the fire exposed side of the wall, a time is assigned to the finish according to Table 9, which is the length of time the finish will contribute toward the fire resistance rating of the fire exposed side of the wall. This time is added to the fire resistance rating determined for the base wall and non-fire exposed finish. TABLE 9 Time Assigned to Finish Materials on Fire Exposed Side of Wall Finish

Gypsum wallboard

Thickness

Time (minutes)

⅜ in. (9.5 mm)

10

½ in. (12.7 mm)

15

⅝ in. (15.9 mm)

20

Two layers of ⅜ in. (9.5 mm)

25

One layer of ⅜ in. (9.5 mm) and one layer of ½ in. (12.7 mm)

35

Two layers of ½ in. (12.7 mm)

40

½ in. (12.7 mm)

25

⅝ in. (15.9 mm)

40

Type X gypsum wallboard Direct-applied portland cement-sand plaster

See Note 1 ¾ in. (19.1 mm)

Portland cement-sand plaster on metal lath

Gypsum-sand plaster on ⅜ in. (9.5 mm) gypsum lath

Gypsum-sand plaster on metal lath

20

⅞ in. (22.2 mm)

25

1 in. (25.4 mm)

30

½ in. (12.7 mm)

35

⅝ in. (15.9 mm)

40

¾ in. (19.1 mm)

50

¾ in. (19.1 mm)

50

⅞ in. (22.2 mm)

60

1 in. (25.4 mm)

80

1. For purposes of determining the contribution of portland cement-sand plaster to the equivalent thickness of concrete or masonry for use in Tables 5, 6 or 7, it shall be permitted to use the actual thickness of the plaster or ⅝ in. (15.9 mm), whichever is smaller.

Examples Example 1, Cavity Wall with Air Space. A multi-wythe cavity wall consists of a wythe of 4 in. (102 mm) nominal solid brick units complying with ASTM C216 and cored at 25 percent, a 2 in. (51 mm) air space and a wythe of 8 in. (203 mm) nominal concrete masonry unit made of calcareous gravel. The concrete masonry unit has actual dimensions of 7⅝ × 7⅝ × 15⅞ inches (194 × 194 × 397 mm) and is 53 percent solid. The fire resistance rating is determined by Equation 6 as follows: a. From Equation 4, the equivalent thickness of the solid brick is: Te = (1 – 0.25) × 3.625 in. (92 mm) = 2.71 in. (69 mm) b. From Table 5, the fire resistance period for the clay unit is: R1 = 1.0 hr c.

For a 2 in. (51 mm) air space: A = 0.30

d. From Equation 5, the equivalent thickness of the concrete masonry unit is: Te = 0.53 × 7.625 in. (194 mm) = 4.0 in. (102 mm) e. Interpolating from Table 7, the fire resistance period of the concrete masonry is: R2 = 1.5 hr + 0.5 hr [(4.0 – 3.6) / (4.2 – 3.6)] = 1.5 hr + 0.5 hr (0.67) = 1.8 hr f.

From Equation 6, the fire resistance rating of the entire wall assembly is: R = [(1.0)0.59 + (1.8)0.59 + 0.3]1.7 = 5.5 hr → Fire Resistance Rating = 4 hr

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Example 2, Composite Wall. A multi-wythe composite wall consists of 4 in. (102 mm) nominal hollow brick complying with ASTM C652 with a mortared collar joint and 4 in. (102 mm) siliceous aggregate concrete wall. The gross volume of the hollow brick includes 36 percent void. The fire resistance rating is determined as follows: a. From Equation 4, the equivalent thickness of the hollow brick is: Te = (1 – 0.36) × 3.625 in. (92 mm) = 2.3 in. (58 mm) b. From Table 5, the fire resistance period for the hollow brick is: R1 = 1.0 hr c.

From Figure 2, the fire resistance period for the concrete wall with siliceous aggregate is: R2 = 1.3 hr

d. Using Equation 6, the fire resistance rating of the wall assembly is: R = [(1.0)0.59 + (1.3)0.59]1.7 = 3.7 hr → Fire Resistance Rating = 3 hr Example 3, Composite Wall with Gypsum Wallboard. Determine the fire resistance rating for the composite wall of Example 2 when ½ in. (12.7 mm) thick gypsum wallboard is applied to the interior side of the wall. The fire resistance rating will apply to only the exterior side of the wall. a. Using Table 8, the multiplying factor for a siliceous concrete wall and gypsum wallboard is 3.00. The equivalent thickness of concrete for the gypsum wallboard on the unexposed side is: Te (finish) = 3.00 × 0.5 (12.7 mm) in. = 1.5 in. (38 mm) b. The equivalent thickness of concrete for the gypsum wallboard finish and concrete is: Te (finish) + Te (concrete) = 1.5 in. (38 mm) + 4 in. (102 mm) = 5.5 in. (140 mm) c.

From Figure 2, the fire resistance period for a 5.5 in. (140 mm) thick concrete wall of siliceous aggregate is: R2 = 2.4 hr

d. Using Equation 6, the fire resistance rating of the wall assembly is: R = [(1.00)0.59 + (2.4)0.59]1.7 = 5.3 hr → Fire Resistance Rating = 4 hr Example 4, Composite Wall with Gypsum Wallboard. Determine the fire resistance rating for the composite wall of Example 3 when the fire resistance rating will apply to both sides of the wall. Since the fire resistance rating will be applied to both sides, a calculation for fire exposure on each side of the wall must be performed. Gypsum Board Side (Interior) Exposed to Fire a. Using Table 9, the contribution of the ½ in. (12.7 mm) thick gypsum wallboard to the fire resistance is: Rf = 15 min / 60 min/hr = 0.25 hr b. Using the fire resistance period determined in Example 2, the fire resistance period for the interior side of the wall assembly is: R (interior) = 3.7 hr + 0.25 hr = 3.9 hr Brick Side (Exterior) Exposed to Fire c.

The fire resistance period determined in Example 3 for exposing the exterior side of the wall assembly to fire is: R (exterior) = 5.3 hr

Wall Assembly d. The fire resistance rating for the wall assembly is the lower of the fire resistance periods calculated from the interior and the exterior: 3.9 hr < 5.3 hr → Fire Resistance Rating = 3 hr

DESIGN AND DETAILING Support of Brick Masonry Rated for Fire Resistance Walls with a fire resistance rating should be supported by assemblies with a similar or better fire resistance rating. This prevents collapse of a rated assembly by an unrated support that burns through long before the required fire resistance period. Thus for a second-story wall with a 2-hour fire resistance rating, the floor-ceiling assembly providing support for the wall must also have a 2-hour fire resistance rating. www.gobrick.com | Brick Industry Association | TN 16 | Fire Resistance of Brick Masonry | Page 13 of 16

Where steel columns provide the support, clay masonry can be used as fireproofing of those columns. Table 10, taken from TMS 0216, gives the equivalent thickness required to provide various levels of column protection, based on the steel shape used for the column. TABLE 10 Fire Resistance of Clay-Masonry-Protected Steel Columns1 W Shapes Column Size

W14 × 82 W14 × 68 W14 × 53 W14 × 43 W12 × 72 W12 × 58 W12 × 50 W12 × 40 W10 × 68 W10 × 54 W10 × 45 W10 × 33 W8 × 40 W8 × 31 W8 × 24 W8 × 18

Clay Masonry Density, lb/ft3 (kg/m3)

Minimum equivalent thickness for fire-resistance rating of clay masonry protection assembly, in. (mm) 1 hour

2 hours

3 hours

4 hours

120 (1926)

1.23 (31)

2.42 (61)

3.41 (87)

4.29 (109)

130 (2087)

1.40 (36)

2.70 (69)

3.78 (96)

4.74 (120)

120 (1926)

1.34 (34)

2.54 (65)

3.54 (90)

4.43 (113)

130 (2087)

1.51 (38)

2.82 (72)

3.91 (99)

4.87 (124)

120 (1926)

1.43 (36)

2.65 (67)

3.65 (93)

4.54 (115)

130 (2087)

1.61 (41)

2.93 (74)

4.02 (102)

4.98 (126)

120 (1926)

1.54 (39)

2.76 (70)

3.77 (96)

4.66 (118)

130 (2087)

1.72 (44)

3.04 (77)

4.13 (105)

5.09 (129)

120 (1926)

1.32 (34)

2.52 (64)

3.51 (89)

4.40 (112)

130 (2087)

1.50 (38)

2.80 (71)

3.88 (99)

4.84 (123)

120 (1926)

1.40 (36)

2.61 (66)

3.61 (92)

4.50 (114)

130 (2087)

1.57 (40)

2.89 (73)

3.98 (101)

4.94 (125)

120 (1926)

1.43 (36)

2.65 (67)

3.66 (93)

4.55 (116)

130 (2087)

1.61 (41)

2.93 (74)

4.02 (102)

4.99 (127)

120 (1926)

1.54 (39)

2.77 (70)

3.78 (96)

4.67 (119)

130 (2087)

1.72 (44)

3.05 (77)

4.14 (105)

5.10 (130)

120 (1926)

1.27 (32)

2.46 (62)

3.46 (88)

4.35 (110)

130 (2087)

1.44 (37)

2.75 (70)

3.83 (97)

4.80 (122)

120 (1926)

1.40 (36)

2.61 (66)

3.62 (92)

4.51 (115)

130 (2087)

1.58 (40)

2.89 (73)

3.98 (101)

4.95 (126)

120 (1926)

1.44 (37)

2.66 (68)

3.67 (93)

4.57 (116)

130 (2087)

1.62 (41)

2.95 (75)

4.04 (103)

5.01 (127)

120 (1926)

1.59 (40)

2.82 (72)

3.84 (98)

4.73 (120)

130 (2087)

1.77 (45)

3.10 (79)

4.20 (107)

5.13 (130)

120 (1926)

1.47 (37)

2.70 (69)

3.71 (94)

4.61 (117)

130 (2087)

1.65 (42)

2.98 (76)

4.08 (104)

5.04 (128)

120 (1926)

1.59 (40)

2.82 (72)

3.84 (98)

4.73 (120)

130 (2087)

1.77 (45)

3.10 (79)

4.20 (107)

5.17 (131)

120 (1926)

1.66 (42)

2.90 (74)

3.92 (100)

4.82 (122)

130 (2087)

1.84 (47)

3.18 (81)

4.82 (122)

5.25 (133)

120 (1926)

1.75 (44)

3.00 (76)

4.01 (102)

4.91 (125)

130 (2087)

1.93 (49)

3.27 (83)

4.37 (111)

5.34 (136)

1. Tabulated values assume a 1 in. (25.4 mm) air gap between masonry and steel section.

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TABLE 10 (continued) Fire Resistance of Clay-Masonry-Protected Steel Columns1 Square structural tubing Nominal tube size, in. (mm)

Clay masonry density, lb/ft3 (kg/m3)

Minimum equivalent thickness for fire-resistance rating of clay masonry protection assembly, in. (mm) 1 hour

2 hours

3 hours

4 hours 4.68 (119)

4×4×½ (102 × 102 × 12.7)

120 (1926)

1.44 (37)

2.72 (69)

3.76 (96)

130 (2087)

1.62 (41)

3.00 (76)

4.12 (105)

5.11 (130)

4×4×⅜ (102 × 102 × 9.5)

120 (1926)

1.56 (40)

2.84 (72)

3.88 (99)

4.78 (121)

130 (2087)

1.74 (44)

3.12 (79)

4.23 (107)

5.21 (132)

4×4×¼ (102 × 102 × 6.4)

120 (1926)

1.72 (44)

2.99 (76)

4.02 (102)

4.92 (125)

130 (2087)

1.89 (48)

3.26 (83)

4.37 (111)

5.34 (136)

6×6×½ (152 × 152 × 12.7)

120 (1926)

1.33 (34)

2.58 (66)

3.62 (92)

4.52 (115)

130 (2087)

1.50 (38)

2.86 (73)

3.98 (101)

4.96 (126)

6×6×⅜ (152 × 152 × 9.5)

120 (1926)

1.48 (38)

2.74 (70)

3.76 (96)

4.67 (119)

130 (2087)

1.65 (42)

3.01 (76)

4.13 (105)

5.10 (130)

6×6×¼ (152 × 152 × 6.4)

120 (1926)

1.66 (42)

2.91 (74)

3.94 (100)

4.84 (123)

130 (2087)

1.83 (46)

3.19 (81)

4.30 (109)

5.27 (134)

8×8×½ (203 × 203 × 12.7)

120 (1926)

1.27 (32)

2.50 (64)

3.52 (89)

4.42 (112)

130 (2087)

1.44 (37)

2.78 (71)

3.89 (99)

4.86 (123)

8×8×⅜ (203 × 203 × 9.5)

120 (1926)

1.43 (36)

2.67 (68)

3.69 (94)

4.59 (117)

130 (2087)

1.60 (41)

2.95 (75)

4.05 (103)

5.02 (128)

8×8×¼ (203 × 203 × 6.4)

120 (1926)

1.62 (41)

2.87 (73)

3.89 (99)

4.78 (121)

130 (2087)

1.79 (45)

3.14 (80)

4.24 (108)

5.21 (132)

Steel pipe Column size, diameter × thickness, in. (mm)

Clay masonry density, lb/ft3 (kg/m3)

Minimum equivalent thickness for fire-resistance rating of clay masonry protection assembly, in. (mm) 1 hour

2 hours

3 hours

4 hours

4 × 0.674 (102 × 17.1)

120 (1926)

1.26 (32)

2.55 (65)

3.60 (91)

4.52 (115)

130 (2087)

1.42 (36)

2.82 (72)

3.96 (101)

4.95 (126)

4 × 0.337 (102 × 8.6)

120 (1926)

1.60 (41)

2.89 (73)

3.92 (100)

4.83 (123)

130 (2087)

1.77 (45)

3.16 (80)

4.28 (109)

5.25 (133)

4 × 0.237 (102 × 6.0)

120 (1926)

1.74 (44)

3.02 (77)

4.05 (103)

4.95 (126)

130 (2087)

1.92 (49)

3.29 (84)

4.40 (112)

5.37 (136)

5 × 0.750 (127 × 19.1)

120 (1926)

1.17 (30)

2.44 (62)

3.48 (88)

4.40 (112)

130 (2087)

1.33 (34)

2.72 (69)

3.84 (98)

4.83 (123)

5 × 0.375 (127 × 9.5)

120 (1926)

1.55 (39)

2.82 (72)

3.85 (98)

4.76 (121)

130 (2087)

1.72 (44)

3.09 (78)

4.21 (107)

5.18 (132)

5 × 0.258 (127 × 6.6)

120 (1926)

1.71 (43)

2.97 (75)

4.00 (102)

4.90 (124)

130 (2087)

1.88 (48)

3.24 (82)

4.35 (110)

5.32 (135)

6 × 0.864 (152 × 21.9)

120 (1926)

1.04 (26)

2.28 (58)

3.32 (84)

4.23 (107)

130 (2087)

1.19 (30)

2.60 (66)

3.68 (93)

4.67 (119)

6 × 0.432 (152 × 11.0)

120 (1926)

1.45 (37)

2.71 (69)

3.75 (95)

4.67 (119)

130 (2087)

1.62 (41)

2.99 (76)

4.10 (104)

5.08 (129)

6 × 0.280 (152 × 7.1)

120 (1926)

1.65 (42)

2.91 (74)

3.94 (100)

4.84 (123)

130 (2087)

1.82 (46)

3.19 (81)

4.30 (109)

5.27 (134)

1. Tabulated values assume a 1 in. (25.4 mm) air gap between masonry and steel section.

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Penetrations All penetrations through an assembly with a fire resistance rating must conform to building code requirements for those penetrations. Codes typically require doors and windows to have a fire resistance rating, though depending on application, the fire resistance ratings of the doors and windows may be less than that of the surrounding wall construction. For mechanical ducts, fire dampers are typically required. For smaller penetrations, such as for drainage pipes and conduits, the space around the pipes is typically required to be filled with a fire resistant material and sealed to the surrounding masonry with a sealant rated for a specific fire resistance. In all cases, products used to seal penetrations should be carefully researched, selected and installed to ensure that the fire resistance rating of a wall is not compromised.

Other Details In fire resistant construction, the intent is to provide fire resistance that surrounds a three-dimensional, occupied space. Where a wall with a fire resistance rating meets an interior wall or floor/ceiling assembly, the integrity of the wall’s fire resistance rating should be maintained. In closely spaced buildings, a brick veneer wall assembly with a 1-hour fire resistance rating on the exterior side is typically unaffected by the intersection of interior partition walls. However, in a brick veneer wall assembly with a 2-hour fire resistance rating, the interior wallboard is a required component and may have to be installed prior to framing the interior partitions. Each project and circumstance may require specific details to maintain the fire resistance rating of the masonry assemblies described above.

SUMMARY Brick masonry has traditionally been used to provide superior fire resistance and safety for occupants. The fire resistance rating required by the building code for a wall will depend on many factors including the type of construction, the use of building, and the location of the wall within the building. Brick wall assemblies of varying styles have been tested to provide designers with standard wall sections and details that comply with the various fire resistance ratings. Alternatively, for non-standard assemblies, calculation methods presented herein can provide the fire resistance rating of the proposed wall sections based on the results of previously tested assemblies. The information and suggestions contained in this Technical Note are based on the available data and the experience of the engineering staff and members of the Brick Industry Association. The information contained herein must be used in conjunction with good technical judgment and a basic understanding of the properties of brick masonry. Final decisions on the use of the information discussed in this Technical Note are not within the purview of the Brick Industry Association and must rest with the project architect, engineer and owner.

REFERENCES 1. 2006 International Building Code, International Code Council, Inc., Country Club Hills, IL, 2006. 2

2006 International Residential Code, International Code Council, Inc. Country Club Hills, IL, 2006.

3. ASTM E119-07, Standard Test Methods for Fire Tests of Building Construction and Materials, Annual Book of Standards, Vol. 04.07, ASTM International, West Conshohocken, PA, 2007. 4. Borchelt, J.G., and Swink, J.E., “Fire Resistance Tests of Brick Veneer/Wood Frame Walls,” Proceedings of the 14th International Brick and Block Masonry Conference, University of Newcastle, Callaghan, Australia, 2008. 5. Code Requirements for Determining Fire Resistance of Concrete and Masonry Construction Assemblies, (ACI 216.1-07 / TMS-0216-07), The Masonry Society, Boulder, CO, 2007. 6. Fire-Resistance Classifications of Building Constructions, BMS92, National Bureau of Standards, Washington, D.C., 1942. 7. UL Fire Resistance Directory, Underwriters Laboratories, Northbrook, IL, 2007.

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Technical Notes 17 - Reinforced Brick Masonry - Introduction Reissued Oct. 1996 Abstract: The concept and use of reinforced brick masonry (RBM) has a long history. This Technical Notes documents the history of RBM. Recent and current code provisions are enumerated. Several applications of RBM show the variety of possible uses. Key Words: applications, brick, constructions, history, reinforced brick masonry, reinforcement, research. INTRODUCTION Reinforced brick masonry (RBM) consists of brick masonry which incorporates steel reinforcement embedded in mortar or grout. This masonry has greatly increased resistance to forces that produce tensile and shear stresses. The reinforcement provides additional tensile strength, allowing better use of brick masonry's inherent compressive strength. The two materials complement each other, resulting in an excellent structural material. The principles of reinforced brick masonry design are the same as those commonly accepted for reinforced concrete, and similar formulae are used. Brick masonry is one of the oldest forms of building construction, and reinforcement has been used to strengthen masonry since 1813. In the modern sense reinforced brick masonry in the United States is a relatively new type of construction, with specific design procedures and construction methods. These have been developed from experimental investigations beginning in the 1920's and with the experience of the performance of thousands of reinforced masonry buildings. These structures demonstrate the practicality and economy of the construction, and their performance confirms the soundness of the design principles. Figure 1 shows the Los Angeles Police Department, Devonshire Station, a reinforced brick structure, located 3 miles (4.8 km) from the epicenter of the Northridge earthquake. There was no structural damage and the building reportedly functioned as an emergency services coordination center following the 6.7 magnitude earthquake.

Los Angeles Police Department, Devonshire Station FIG. 1

This Technical Notes presents the history of reinforced brick masonry with a review of recent research and applications. Other Technical Notes in this series provide information on the design of reinforced brick masonry including applications such as beams, lintels, and retaining walls. HISTORY Marc Isambard Brunel is credited with the discovery of reinforcd masonry. He first proposed the use of reinforced brick masonry in 1813 as a means of strengthening a chimney then under construction. However, it was in connection with the building of the Thames Tunnel in 1825 that he made his first major application of reinforced brick masonry. As a part of the construction of this tunnel, two brick shafts were built, each 30 in.(760 mm) thick, 50 ft (15 m) in diameter and 70 ft (21m) deep. The shafts were reinforced vertically with wrought iron rods 1 in. (25 mm) in diameter, built into the brickwork. Iron hoops, 9 in. (230 mm) wide and 1/2 in.(13 mm) in thickness, were laid in the brickwork as building progressed. The first shaft was built to a height of 42 ft (13 m) and then sunk by excavating soil from the interior, using what is now commonly known as the open method of cassion construction. The remaining 28 ft (8.5 m) of its height was added to

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the top of the shaft as it settled and was stabilized by underpinning. In spite of unequal settlement of the shaft no cracks developed in the brick masonry. As a result, these cond shaft was built to its entire height of 70 ft (21 m) before it was lowered. Richard Beamish, in his Memoirs of the Life of Sir Marc Isambard Brunel [1], describes this construction and states that, after an unequal settlement of 7 in. (180 mm) on one side and 3 in. (76mm) on the other, "the surge was alarming, but so admirably was the structure bound together that no injury was sustained." Brunel continued the use of reinforced masonry and in 1836 constructed test structures in an effort to determine the additional strength imparted to the masonry by the reinforcement. Other engineers became interested in this type of construction and in 1837 Colonel Pasley of the Corps of Royal Engineers conducted a series of tests on reinforced brick masonry beams and reported results comparable to those obtained by Brunel. Pasley's tests were designed to settle the prevailing argument as to whether the flat hoop iron used as reinforcement really strenthened brick beams. Three beams were built, each 18 in. (460 mm) wide and 12 in (305 mm) (4 brick courses) deep, with a 10 ft (3 m) span. One beam was built without reinforcement, with the brick laid in neat cement. The second beam was also laid in neat cement, but this beam was reinforced with 5 pieces of hoop iron; two placed in the top mortar joint, one in the middle joint and two in the bottom mortar joint. The latter of these obviously carried most of the tensile stress. The third beam was reinforced in the same manner as the second beam, but the brick were laid in a mortar composed of 1 part lime and 3 parts sand. The first beam failed at a load of 498 lb (2.2 kN); the second beam carried 4723 lb (21.0 kN); and the third beam failed at between 400 and 500 lb (1.8 and 2.2 kN); thus settling the dispute. The results point out that bond between the brick, mortar and reinforcement develops when cement-based mortars are used. As indicated by the placement of the reinforcementin Pasley's beams, the manner in which steel and masonry act together to resist forces was not completely understood at the time. The empirical formulae dereved from such tests could not be used to determine dimensions and reinforcement of structural members varying in cross section or span from those tested. However, the interest in reinforced masonry construction continued and, with the increased use of cement in mortar, additional tests were conducted. One such test that received widespread publicity was a reinforced brick beam tested at the Great Exposition in London in 1851. The "new cement," comercially known as Portland Cement was used in the construction. This test was highly successful, and the publicity which it received resulted in the more widespread use of portland cement in several European countries and, to a lesser degree, in the United States. N. B. Corson published an article in the July 19, 1872 issue of Engineering [5] in which he reviewed the data obtained from the Exposition's test beam, Brunel's test structures, tests of unreinforced masonry beams and arches, and the performance of a large number of masonry structures. From these data, Corson computed tensile stresses of unreinforced masonry and recommended an allowable tensile stress for use in the design of masonry lintels. This appears to be the first recorded technical discussion of the relation of tensile strength of masonry to mortar strength. However, it did not recognize the full effect of the metal reinforcement in increasing the tensile strength of a member. The use of reinforced brick masonry continued to spread. The benefits of combining the tensile strength of iron or steel with the compressive strength of masonry was evident to those familiar with the potential damage of earthquakes. The Palace Hotel opened in San Francisco in 1875, covering a full city block, rising seven stories in height. The 3 ft (0.9 m) thick solid brick walls were reinforced by iron bands every few feet. These formed a "basket" that completely encircled the building. This is one of the few large structures that endured the 1906 San Francisco earthquake [2]. During the period 1880 to 1920, there was little recorded use of reinforced brick masonry and experimental investigations of this type of construction appear to have been practically discontinued. In 1923, the Public Works Department of the Government of India published Technical Paper No. 38 [3], a comprehensive report by Undersecretary A. Brebner of extensive tests of reinforced brick masonry structures extending over a period of about two years. A total of 282 specimens were tested, including reinforced brick masonry slabs of varying thickness, reinforced brick beams, both reinforced and unreinforced columns, and reinforced brick arches. The tests reported by Brebner appear to be the first organized research program on inforced brick masonry and the data obtained provided answers to questions raised regarding this type of construction. This research marks the initial stage of the modern development of reinforced masonry. Following Brebner's report and his statement of a rational design theory for reinforced brick masonry, its use increased, particularly in India and Japan. Both countries are subject to severe earthquakes, and buildings expected to withstand such shocks must be designed with relatively high resistance to lateral forces. Since structural steel and suitable lumber for concrete formwork were relatively expensive in these countries, engineers turned to reinforced brick masonry. It be-

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came standard construction for public and important private buildings, as well as for many types of engineering structures, such as retaining walls, bridges, storage bins and chimneys. Brebner wrote in 1923 of reinforced brick masonry, "In all, nearly 3,000,000 ft2 (279,000 m2) have been laid in the last three years." Skigeyuki Kanamori, Civil Engineer, Department of Home Affairs, Imperial Japanese Government, is reported in the July 15, 1930 issue of Brick and Clay Record [7] as stating, "There is no question that reinforced brickwork should be used instead of (unreinforced) brickwork when any tensile stress would be incurred in the structure. We can make them more safe and stronger, saving much cost. Further, I have found that reinforced brickwork is more convenient and economical in building than reinforced concrete and, what is still more important, there is always a very appreciable saving in time." Structures described by Kanamori include sea walls, culverts and railway retaining walls, as well as buildings. Research in the United States, sponsored by the Brick Manufacturers Association of America and continued by the Structural Clay Products Institute and the Structural Clay Products Research Foundation contributed much valuable material to the literature on reinforced brick masonry. Since 1924, numerous field and laboratory tests have been made on reinforced brick beams, slabs and columns, and on full size structures. Fig. 2 is an example of a 1936 test to demonstrate the structural capabilities of reinforced brick masonry elements.

Early Test of RBM Element FIG. 2

During this period, research was conducted on both reinforced and unreinforced brick masonry at the National Bureau of Standards, now the National Institute of Standards and Technology, and at practically all of the principal engineering colleges of the United States. As new data was developed through research, the er ratic performance of some of the earlier reinforced brick test specimens could be explained and, one by one, the principal variables affecting the strength of reinforced brick masonry have been identified and, to large degree, evaluated. In 1933 the Brick Manufacturers Association of America published Brick Engineering, Vol. 111, Reinforced Brick Masonry, by Hugo Filippi [6]. Regarding the uses of reinforced brick masonry, the author states, "Reinforced brick masonry is well adapted for use in the following types of structures, either wholly or in part: Buildings, Culverts and Bridges; Retaining Walls and Dams; Reservoirs; Sewers and Conduits; Tanks and Storage Bins; Chimneys and Circular Constructions; Abutments, Piers, Trestle Bents, etc. "In the United States alone, during the past year and one-half, more than 40 individual jobs of reinforced brick masonry have been built, consisting of such distinctive types of construction as highway bridges, storage bins, industry track trestle piers, floor and roof slabs, beams, girders and long lintels. At the present time approximately 50 additional jobs are either under construction or under consideration in various parts of the country." During the period referred to by Filippi, the development and use of reinforced brick masonry in the United States were in their early stages. A significant change in the use of RBM came after the 1933 Long Beach earthquake. It was realized that unreinforced structures were susceptible to major damage from earthquakes and that RBM could be used to save lives. Codes were developed that promoted the use of reinforced structures. Since that time thousands of such

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structures have been built and reinforced brick masonry construction has been adopted as standard practice for various types of structures in many areas. RECENT RESEARCH Research on reinforced brick masonry has continued. In 1984, the Technical Coordinating Committee for Masonry Research (TCCMAR) was formed for the purpose of defining and performing both experimental and analytical research and development necesary to improve structural masonry technology [9]. A unique aspect of this research was a phased step-by-step program of sepate, but coordinated research tasks. Initial research on materials was used in later tests on assemblies. These led to tests of building elements and then the combination of wall and floor elements. The research culminated in a full-scale, five story structure subjected to dynamic loading in 1993. Much of the research led to the development of a limit states design procedure for masonry. Interest in better utilization of brick masonry's high compressive strength has led to research in prestressed brick masonry. Knowledge about this form of reinforced brick masonry was increased by research in Great Britain. Research is currently underway in the United States, as is the development of design procedures. BUILDING CODE PROVISIONS Building codes first covered reinforced brick masonry in 1953 in the American National Standards Institute's A41.2 document [4]. Since that first code on RBM, other codes such as the Uniform Building Code and the Masonry Standards Joint Committee Code (ACI 530/ASCE5/TMS 402) have adopted provisions. Most code provisions on reinforced masonry arebased on allowable stress design (ASD). In ASD, the reinforcement in masonry is designed to resist all tensile forces. The reinforcement increases the masonry's shear resistance and may contribute to the compressive strength. The stress-strain relationship is linear at working loads and the strain is proportional to the distance from the neutral axis. Code requirements cover axial compression, flexure, and shear. The Uniform Building Code has provisions for slender wall design, which is loosely based on strength design. A more comprehensive design method, known as limit states design is in development. Limit states design considers the actual performance of the materials as they undergo load and deformation. Significant changes in the state of stress, such as cracking of the masonry and yielding of the steel, are identified. The capacity, or strength, of the element at these limit states is compared to that required to resist the applied load. These code provisions are expected to provide a complement to ASD.

BASIC CONSTRUCTION PROCEDURES The earliest method of placing reinforcement into brick masonry was simply to place iron or steel bars in mortar joints as the bricks were laid. Later the reinforcement was placed in collar joints between two masonry wythes and surrounded by mortar or fine grout. Eventually the space between wythes was increased in width and filled with grout. Horizontal reinforcement and grout were placed as the outer wythes were completed. The next development was the "High Lift Grouting System" in which the brick masonry wythes are built up around the reinforcement and allowed to set for a minimum period of three days. Then grout is pumped into the space containing the reinforcement. This method was developed in the San Francisco area during the late 1950s. This double wythe reinforced brick masonry is shown in Fig. 3.

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Double Wythe Reinforced Brick Masonry FIG. 3 The most recent means of constructing reinforced masonry incorporates hollow brick. These units are manufactured with large open cells which align vertically when the units are laid. Vertical reinforcement is placed in the cells by laying the brick over or around the bars, or by threading the bar in after the brick are laid. Horizontal reinforcement is placed in bed joints or in continuous bond beams made by removing portions of the webs that connect the face shells. Spaces containing reinforcement are grouted in lefts of up to 5 ft (1.5m) to make grout pours of up to 24 ft (7.3m). Construction of reinforced hollow brick masonry is shown in Fig. 4

Reinforced Hollow Brick Masonry FIG. 4 APPLICATIONS AND EXAMPLES During the past 60 years, reinforced brick masonry has been used for the construction of a variety of structures. In those countries where labor costs are low, one of its principal uses has been for the construction of floor and roof slabs. However, in the United States, its most extensive use has been in the construction of vertical members, such as walls and columns. Since no forms are required for these members, reinforced brick masonry is competitive with reinforced concrete, and walls of minimum thickness and light structural members can be constructed at substantially less cost in reinforced brick masonry than in reinforced concrete. Reinforced brick beams and lintels allow the designer to achieve exposed brick on the underside of these elements as in Fig. 5.

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Reinforced Brick Beams FIG. 5 This provides a hoizontal finished surface that matches the vertical surface. The idea of brick hanging upside down must be disconcerting. Some designers seem reluctant to use RBM construction for brick lintels or soffits. As demonstrated by tests since 1837, the bond of the mortar and grout to the brick holds the brick in place. Structures of all sizes, from single story residences to 23 story buildings have been constructed of reinforced brick masonry as shown in Figs. 6 and 7.

Reinforced Brick Masonry Single Family Residence, Ashbrun VA FIG. 6

Reinforced Brick Masonry High Rise, Cleveland, OH FIG. 7 The applications range from retaining walls to exterior cladding. The added tensile strength of the reinforcing steel opens the possibility for prefabricated brick panels. This method of design and construction is utilized frequently to achieve unusual shapes and bond patterns in brick masonry. See Fig. 8.

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Reinforced Brick Masonry Panels FIG. 8

SUMMARY The use of reinforced brick masonry has been recorded for over 175 years. RBM construction has been adapted to a wide variety of applications throughout its history. Beams, column, pilasters, arches, and other RBM elements have been used in buildings, culverts, retaining walls, silos, chimneys, pavements and bridges. Continuing research on RBM results in more economical structures able to withstand all types of loading. The information and suggestions contained in this Techical Notes are based on the available data and the experience of the engineering staff of the Brick Institute of America. The information contained herein must be used in conjunction with good technical judgment and a basic understanding of the properties of brick masonry. Final decisions on the use of the information contained in this Technical Notes are not within the purview of the Brick Institute of America and must rest with the project architect, engineer and owner. REFERENCES 1. Beamish, R., Memoirs of the Life of Sire Marc Isambard Brunel, Longmans, London, England, 1862. 2. Berger, Molly W., "The Old High-Tech Hotel," Invention and Technology, Fall 1995, pp. 46-52. 3. Brebner, A., Notes on Reinforced Brickwork, Technical Paper No. 38, Government of India, Public Works Deparment, India, 1923. 4. "Building Code Requirements for Reinforced Masonry," American Standards A 41.2-1960, American Standards Association, New York, NY, 1960. 5. Corson, N. B., "Article on Brick Masonry," Engineering, London, July 19, 1872. 6. Filippi, Hugo, Brick Engineering, Volume III, Reinforced Brick Masonry, Brick Manufacturers Association of America, Cleveland, OH, 1933. 7. Kanamori, S., "Reinforced Brickwork Opens Greater Possibilities," Brick and Clay Record, Chicago, IL, Vol. 77, #2, July 1930, pp.96-100. 8. Plummer, H. C. and Blume, J. A., "Reinforced Brick Masonry and Lateral Force Design," Structural Clay Products Institute, Washington, D.C., 1953. 9. "Status Report, U.S. Coordinated Program for Masonry Building Research," Technical Coordinating Committee for Masonry Research, Nov. 1988.

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Technical Notes 17A - Reinforced Brick Masonry - Materials and Construction Reissued Aug. 1997 Abstract: This Technical Notes provides a discussion of the proper methods of constructing reinforced brick masonry. Materials used in reinforced brick masonry are included Construction of brick masonry, placement of steel reinforcement and grouting are addressed. Recommendations are provided to ensure that the completed masonry will provide adequate performance. Particular empahasis is placed on those aspects of construction that are unique to reinforced brick masonry. Various quality assurance procedures and tests are also explained. Key Words: bracing, brick ,construction, grouting, inspection, reinforced brick masonry reinforcement, shoring. INTRODUCTION Reinforced brick masonry (RBM) is different from more conventional brick veneer in many ways. Key to those differences is the concept of grouting the brick masonry. Ground brick masonry is defined as construction made with clay or shale units in which cavities or pockets in elements of solid units, or cells of hollow units are filled with grout. Common examples of RBM elements are beams, columns, pilasters, multi-wythe brick walls with grouted collar joints and hollow brick walls. This Technical Notes reviews the materials and construction practices used to build RBM elements. The different techniques are discussed with particular emphasis on the concepts of grouting and the placement of reinforcement. Quality assurance and minimum standards of workmanship to ensure a high level of consistency and adequate masonry performance are addressed. The information in this Technical Notes should be carefully reviewed by the mason contractor prior to constructing reinforced brick masonry. It should also be studied by the masonry inspector. Other Technical Notes in this series provide design theories and design aids for RBM elements such as beams, walls, columns and pilasters. RBM MATERIALS The materials used to construct RBM elements should comply with applicable ASTM standards. Brick should meet the requirements of ASTM C 62 Specification for Building Brick, C 216 Specification for Facing Brick, or C 652 Specification for Hollow Brick. Mortar should comply with the requirements of ASTM C 270 Specification for Mortar for Unit Masonry. Grout should comply with ASTM C 476 Specification for Grout for Masonry. Metal wall ties, bar positioners, and reinforcing bars and wires should comply with the applicable ASTM standards as required by the Specification for Masonry Structures (ACI 530.1/ASCE 6/TMS 602)[2], also known as the MSJC Specification. All metal wall ties, positioners and joint reinforcement should be corrision resistant or protected from corrosion by appropriate coatings. Refer to Technical Notes 3A for a discussion of the material properties of brick, mortar, grout and reinforcement. The materials in both fine and coarse grout should comply with the requirements of ASTM C 476 Specification for Grout for Masonry. Both fine grout and coarse grout should comply with the volume proportions given in ASTM C 476. Specifying grout by proportions is preferred over specifying a minimum grout strength. Typically, the maximum aggregate size should be 3/8 in. (9.5 mm) for coarse grout. While larger size aggregate can be used when filling large grout spaces, it must be noted that such grout likely cannot be pumped and will require placement by pouring from a hopper. It must be remembered that grout is different from concrete. Concrete is placed with a minimum of water into nonporous forms. Grout is poured with considerably more water, as the brick masonry creates absorptive forms. Grout should be sufficiently fluid to flow into the space to be filled, and surround the steel reinforcement, leaving no voids. It should be wet enough to flow without separation of the constituents. Whereas good mortar should stick to a trowel, it should be impossible for grout to do so. The water cement ratio as mixed, highly important in concrete work, is less important for grout in brick masonry. Although excessive water is detrimental to the strength and durability of the grout, when introduced into the brick masonry the water cement ratio rapidly changes from a high to a low value. Grout is often mixed too dry and stiff for proper placement.

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One concern with the use of a very fluid grout mixture is excessive shrinkage. Shrinkage can create voids in the grout space, which are to be avoided. For this reason, plasticizers and shrinkage-compensating admixtures are recommended for grout in brick masonry. Such admixtures will provide the necessary fluidity while also providing a hardened grout mixture with minimal voids. There is a temptation to fill the grout space with the mortar that is used to lay up the brickwork, especially when simultaneously laying brick and grouting. This is not recommended, but may be permitted by local building codes. It is common to find excessive voids in the grout space with this practice. Proper placement and consolidaton of grout or grout mixture with a shrinkage-compensating admixture and poured in a continuous process is much more likely to form a solid grout fill. RBM CONSTRUCTION The construction of RBM elements can be separated into three parts: brick masonry construction, placement of the steel reinforcement and grouting. Each of these steps is critical to the end result. Following is a review of the three construction procedures in the order of their execution. There are two key points to remember when laying the brick. First, the brick masonry is the permanent formwork for the grout. This masonry formwork must be built in a manner that facilitates placement and positioning of the steel reinforcement and installation of grout. Second, the quality of workmanship will have a significant impact on the strength of the RBM. Unfilled mortar joints and elements that are out-of-plumb will not provide the performance assumed by the designer. All RBM elements constructed of solid brick should be laid with full head and bed joints. The ends of brick should be buttered with sufficient mortar to fill the head joints. Furrowing of bed joints should not be deep enough to result in voids. Years ago, it was believed by some that the head joints in solid brick masonry could be made only half full and that the grout would flow into the remainder of the head joint and fill the voids. It was felt that the grout would form a shear key and make the brick masonry bond more strongly to the grout core. This is not the case. In fact, creation of voids is more likely with this practice, which reduces the masonry's strength and can promote efflorescence due to entrapped water. Hollow brick are normally laid with face shell bedding. That is, the unit's face shells are filled solidly with mortar and head joints are filled with mortar to a depth equal to the face shell thickness. In some instances, bed joints of cross webs are covered with mortar to confine grout or to increase net area. Head joints may be filled solid for similar reasons. Cleanouts and Maintaining a Clear Grout Space Cleanouts are used to remove all mortar droppings and debris from the bottom of a grout space and also to ensure proper placement of reinforcement prior to grouting. Cleanouts should be provided in the bottom course of all spaces to be grouted when the grout pour exceeds 5 ft (1.5 m) in height. In partially grouted masonry, a cleanout is recommended at each vertical bar. In fully grouted masonry, the spacing of cleanouts should not exceed 32 in. (813 mm) on center according to the MSJC Specification. For reinforced brick masonry elements constructed with solid brick, cleanouts should be formed by omitting brick in the bottom course periodically along the base of the element. For hollow brick masonry, cleanouts should be provided in the bottom course of masonry by removing the face shell of the cells to be grouted. Examples of cleanouts in brick masonry walls are shown in Figure 1.

Example of Grout Space Cleanouts

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FIG. 1 The minimum cleanout opening dimension should be 3 in. (76 mm). However, smaller spaces can be used if it is shown with a demonstration panel that the spaces can be cleaned. The grout spaces should be cleaned prior to grouting. It is good practice to clean out grout spaces at the end of each work day so that mortar droppings can be easily removed. A high pressure water spray, compressed air or industrial vacuum cleaner should be used for this purpose. Many contractors have found that cleaning of the grout space is facilitated by placing a layer of sand or sheets of plastic film at the bottom of the cleanout to catch mortar droppings. After cleaning and prior to grouting, cleanouts should be closed with masonry units or sealed with a blocker to resist grout pressure. A minimum curing time of two days is recommended for the cleanout plugs or they should be adequately braced against the grout pressure. Bracing is discussed further in the section on Shoring and Bracing. For solid brick masonry, the top of the mortar bed joint should be beveled outward from the center of the grout space to minimize the amount of mortar extruded into the grout space when the brick are laid, as illustrated in Fig. 2.

Beveling Mortar Bed Joints FIG. 2 Mortar protruding from bed or head joints into the grout space should be struck flush with the surface or removed prior to grouting. The maximum protrusion of a mortar fin should be 1/2 in. (13 mm). The spaces to be grouted should also be kept free of mortar droppings. One method of keeping collar joints clear consists of laying wood strips on the metal ties as the two wythes of brick masonry are built. The strips catch mortar droppings during construction and are removed by means of attached heavy strings or wires as the wall is built. To keep the cells of hollow brick clear for grouting, sponges are typically used, as shown in Fig. 3.

Sponges to Keep Cell Clear of Mortar Droppings FIG. 3 Erection Tolerances All RBM elements should be laid within the permitted dimensional tolerances found in the MSJC Specifications. Masonry elements that are not constructed within these limits are not as strong in compression as those that are. The thickness of mortar joints will also influence the masonry's strength. Excessively thin or thick mortar joints will reduce brick masonry's tensile and compressive strength. The erection tolerances stated in the MSJC Specification are given in Table 1.

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This specification and its accompanying Building Code Requirements for Masonry Structures (ACI 530/ASCE 5/TMS 402) [1] [also known as the MSJC Code] stipulate minimum size of grout spaces that are dependent on the height of grout pour and the grout type. The limits given in Table 2 are to ensure adequate access of grout to the space.

Shoring and Bracing RBM elements typically require temporary support during construction provided by shoring and bracing. These supporting members are typically of wood or steel construction. Temporary support is required for two reasons. First, grout is very fluid when placed and exerts considerable pressure on the surrounding brick masonry. Second, RBM elements gain strength over time as the mortar and grout cure and harden. RBM walls, columns and pilasters are often braced along their height. RBM beams and arches may require both shoring for vertical support and bracing for lateral load resistance and grout pressure resistance. Shoring and bracing should be left in place until it is certain that the masonry has gained sufficient strength to carry its own weight and all other imposed loads including temporary loads that occur during construction. The most common problem related to temporary supports for masonry elements is inadequate lateral bracing to resist wind pressures during construction until the masonry has gained sufficient strength to resist these loads. This is especially true when the roof and floor diaphragms have not been installed and anchored to the top of the masonry wall. Without proper bracing, the wall is a free-standing cantilever element and is more vulnerable to collapse. Appropriate time for removal of shoring and bracing depends on many factors. For example, proper curing of the mortar and grout may take considerably longer under cold weather conditions. The results of suitable compression tests of prisms or grout may be necessary as evidence that the masonry has attained sufficient strength to permit removal of shoring or bracing. Rules-of-thumb for the minimum time which should elapse before removal of shoring or bracing that have been recommended for many years include the following:

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1. For RBM beams, 10 days after completion of the element 2. For RBM arches, 7 days after completion 3. Lateral bracing for walls, columns and pilasters, 7 days after placement of the grout. Longer time periods will be necessary with inadequate curing conditions. It is always a good idea to consult the project engineer for a recommended bracing scheme and the length of time required for bracing to remain in place. Curing Time Prior to Grouting. If grouting is performed too rapidly after construction the hydrostatic pressure of the grout can cause "blowout" of mortar joints or even entire sections of brickwork. This is especially true when the grout pour is high. Blowout of the grout can be avoided by a combination of proper curing time, adequate wall ties or joint reinforcement across the grout space and bracing. Recommended duration of curing prior to grouting depends upon the method of grouting and the extent of bracing to resist the grout pressure. If no bracing against grout pressure is provided, the masonry should be permitted to cure for at least 3 days to gain strength before placement of grout in lifts greater than 5 ft (1.5 m) in height. For shorter grout lift heights, grout may be poured relatively soon after the brick are laid. Since grout lift heights are very short, the mason contractor should adjust the speed of construction as needed to avoid blowout of the wall. Wall Ties Across Grout Spaces. Freshly placed grout exerts a hydrostatic pressure on the surrounding masonry formwork. This pressure increases with increasing pour height. To resist the grout pressure, wall ties are used across the grout space to tie the brick wythes together. For multi-wythe masonry walls, a minimum number of wall ties will already be provided to tie the wythes together in accordance with the building code. The wall ties resist the grout pressure by their tensile capacity. The ties provide the additional benefit of a positive mechanical anchorage between the grout core and the surrounding masonry. Ties may not be required across small grout spaces such as in columns or pilasters. Wall ties across grout spaces should be at least W 1.7 (9 gage) wire. For masonry elements laid in running bond, ties should be spaced not more than 24 in (610 mm) o.c. horizontally and not more than 16 in. (406 mm) o.c. vertically. If stack bond is used, the vertical spacing should be reduced to 12 in. (305 mm) o.c. All ties should be placed in the same line vertically to facilitate the grout consolidation process. Ties should be embedded at least one-half the thickness of the masonry wythe. Bracing Against Grout Pressure. For grout pour heights less than approximately 5 ft (1.5 m), bracing of the brick masonry may not be necessary. If the grout pour height is greater, consideration should be given to bracing the masonry. This is especially true when a longer curing time for the brick masonry prior to grouting is not feasible. Bracing members are typically externally applied wood construction. The bracing members should be designed by an engineer, based on the grout pour height.

PLACEMENT OF STEEL REINFORCEMENT Steel reinforcement should be placed in accordance with the size, type and location indicated on the project drawings, and as specified. Dissimilar metals should not be placed in contact with each other because this can promote corrosion of the reinforcement. Nonmetallic flashing should be used when the flashing will come in contact with the reinforcement. If it is possible, all vertical steel reinforcement should be placed after completion of the masonry surrounding the grout space. This keeps the reinforcement out of the mason's way during construction and makes cleaning of the grout space easier. It also prevents contamination of the reinforcement by mortar droppings or protrusions that can adversely affect grout bond to the reinforcement. Applicable building codes should be consulted regarding placement requirements for reinforcement in masonry elements. A summary of the placement requirements for reinforcement in masonry stated in the MSJC Code is given in Table 3.

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1 In Flexual members, the "d" dimension is the distance from the extreme compression face to the

centroid of the tensile reinforcement.

These requirements are to ensure proper bond to the grout, corrosion protection and fire resistance of the reinforcement. Table 3 also identifies the tolerance limits on positioning reinforcement in masonry elements. Reinforcement should only be spliced where indicated on the project drawings. Reinforcement should not be bent or disturbed after placement of the grout. Vertical reinforcement should be accurately placed and secured prior to the grouting process. Reinforcement can be secured by wire ties or other spacing devices. Some examples of common bar spacing devices are shown in Fig. 4.

Bar Spacing Devices FIG. 4 Vertical reinforcement should be braced at the top and bottom of the element. Additional positioners may be necessary to facilitate proper placement of the bars. When reinforcement is spliced in a grout space between wythes or within an individual cell of hollow brick masonry, the two bars should be placed in contact and wired together. Vertical reinforcement in hollow brick masonry may be spliced by placing the bars in adjacent cells, provided the distance between the bars does not exceed 8 in. (204 mm).

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Horizontal reinforcement is usually placed in the mortar joints as the work progresses or in bond beams at the completion of the bond beam course. In partially grouted walls, the bond beam should be grouted prior to further construction of brick masonry on top of the bond beam. For two-wythe, solid brick masonry walls, the horizontal reinforcement may be placed in the grouted collar joint. All horizontal bars should be on the same side of the vertical reinforcement to facilitate consolidation of the grout.

GROUTING The most crucial aspect of constructing RBM elements is the grouting process. While grouting may seem a simple matter of filling cavities or cells of masonry, it is the one aspect of RBM construction that can cause the most problems. The most common problem is the creation of voids in the grout space due to stiff grout, excessive pour height, grout shrinkage, or blocked grout spaces. To ensure proper grouting, four sequential steps should be properly executed: preparation of the grout space, grout batching, grout placement and consolidation, and curing and protection. Preparation of the Grout Space The configuration and condition of the grout space can vary considerably. Common grout spaces for RBM elements are the cells of hollow brick, the collar joint between multi-wythe brick walls, the core of columns or pilasters and the depth of a beam. For a multi-wythe brick wall with a grouted collar joint, vertical grout barriers, or dams, should be built across the grout space for the entire height of the wall at intervals of not more than 25 ft (7.6 m). Grout barriers control the horizontal flow of grout and reduce segregation. With hollow brick, mortar is placed on the cross webs to confine grout to certain vertical cells. Wire mesh is installed beneath a bond beam to prevent the flow of grout into the masonry below the bond beam. Examples of common grout barrier techniques are shown in Fig. 5.

Vertical Grout Barriers FIG. 5 Grout spaces should be checked to see that all foreign materials and debris have been removed prior to grouting. The reinforcement should be clean and properly positioned in the grout space. If cleanouts are used, they should be sealed and braced if needed. All grout barriers should be secured and braced, if necessary. The absorption rate of brick masonry will vary considerably with different units and weather conditions. To make the absorption more consistent, the grout space may be wetted prior to grouting. No free water should be on the units when the grout is placed. Grout Batching The quantities of solid materials in the grout mix should be determined by accurate volume measurement at the time of placing in the mixer. All materials for grout should be mixed in a mechanical mixer. Grout is most often supplied in bulk by ready-mix trucks and pumped into place because of the volume and speed of placement required. Batching

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on site is more common for smaller projects. When prepared on site, the grout mix should be batched in multiples of a bag of portland cement as a quality control measure. If less than a single bag of portland cement is used, extreme care should be used to accurately measure all parts.

Water, sand, aggregate and portland cement should be mixed for a minimum of 2 minutes, then the hydrated lime (if any) and additional water should be added and mixed for an additional 5 to 10 minutes. Make and maintain as high a flow as possible, consistent with good workability. This means that the grout should be wet enough to pour without segregation of the constituent materials or excessive bleeding. Grout should be a plastic mix that is suitable for pumping. The grout slump should be tested in accordance with ASTM C 143 Test Method for Slump of Hydraulic Cement Concrete and should be between 8 and 11 in. (203 and 279 mm).

Grout Placement and Consolidation Grout should be placed within 1 1/2 hours after the water is first added to the mix and prior to the initial set. Grout slump should be maintained during placement. The grout pour should be done in one or more lifts and the total height of each pour should be from the center of one course to the center of another course of brick masonry. When grouting is stopped for 1 hour or longer, the grout pour should be stopped approximately 1 1/2 in. (38 mm) below the top of the masonry to create a shear key. Whenever possible, grouting should be done from the unexposed face of the masonry element. Extreme care should be expanded to avoid grout staining on the exposed face or faces of the masonry. If grout does contact the face, it should be cleaned off immediately with water and a bristle brush. Waiting until after curing has occurred will make removal difficult. Grout in contact with brick solidifies more rapidly than that in the center of the grout space. It is, therefore, important to consolidate the grout immediately after pouring to completely fill all voids. The best procedure is to have two people performing the operation jointly; one to pour the grout and the other to consolidate it. A mechanical vibrator or pudding stick is used for this purpose, depending on the construction method used. There are two methods of RBM construction: simultaneous brick construction and grouting, and grouting after brick construction. These are sometimes referred to as "low lift" and "high lift" grouted masonry. In the first method, grout is placed in the masonry as the courses are laid. The grout is consolidated with a pudding stick or a mechanical vibrator. This method is typically used with narrow grout spaces. In the second method, the masonry is built to the story height or its full height, after which grout is poured from a hopper or pumped by mechanical means. The grout is consolidated with a low velocity vibrator with a 3/4 in. (19 mm) head. When grouting between wythes, the vibrator should be placed in the grout at points spaced 12 to 16 in. (305 to 406 mm) apart. The grout pour height restrictions given in Table 2 will limit the method of grout placement permitted in some instances. The mason contractor should give consideration to the advantages and disadvantages of each method. Simultaneous Brick Construction and Grouting. The main benefits of simultaneous construction and grouting are elimination of cleanouts, reduction of grout pressures, and simplicity of construction. With this method of grouting, the entire grout space can be kept entirely clear of blockage and can be easily inspected prior to grouting. Consolidation of the entire grout pour is also easier and bracing may be lessened or eliminated. For a multi-wythe brick wall with grouted collar joint, one wythe should be built up not more than 16 in. (406 mm) ahead of the other wythe. Typically, the grout pour height will not exceed 12 in. (305 mm) for such walls and a pudding stick may be used for consolidation purposes. If the grout is carried up too rapidly, there is a chance blowout will occur. If a wythe does move, even as little as 1/8 in. (3 mm) out-of-plumb, the work should be torn down rebuilt. This is because the bed joint bond has been broken and cannot be repaired merely by shoving the wall back into plumb. The grout should be placed to a uniform height between grout barriers and should be consolidated with a mechanical vibrator or pudding stick immediately after placement. Extreme care should be exercised during grout placement and consolidation to avoid displacement of the brick masonry. Grouting After Brick Construction. Grouting after construction of the masonry has become the industry standard due to its speed and the fact that grout is often supplied by ready-mix trucks. These trucks deliver large quantities of grout, but cannot remain on site indefinitely during construction. Grout delivery must be coordinated with brick

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construction and preparation of grout spaces. The grout spaces in RBM elements can be very small and become crowded with reinforcing bars and wall ties. In addition, some contractors have commented that the highly absorptive nature of some brick masonry causes the grout to dry out and not flow properly to the bottom of grout spaces if the lift height is too great. The first lift of grout should be placed to a uniform height between the grout barriers or the surrounding brick masonry, and should be mechanically vibrated to fill all voids. This first vibration should be done within 10 minutes after pouring the grout, while the grout is still plastic and before it has set. Grout pours in excess of 12 in. (305 mm) should be reconsolidated by mechanical vibration after initial water loss and settlement has occurred. The succeeding lift should be poured, vibrated and reconsolidated in a similar manner. In the first vibraton, the vibrator should extend 6 to 12 in. (152 to 305 mm) into the preceding lift. This further reconsolidates the first lift and closes any shrinkage cracks or separations that may have formed. The work should be planned for a single, continuous grout pour to the top of the wall in 5 ft (1.5 m) lifts. Under normal weather conditions, in the range of 40 to 90 degrees F of (4 to 32 degrees C), the waiting period between lifts should be between 30 and 60 minutes. Curing and Protection The masonry work, particularly the top of the grout pour, should be kept covered and damp to prevent excessive drying. The newly grouted masonry should be fog sprayed three times each day for a period of three days following construction when the ambient temperature exceeds 100 degrees F (38 degrees C) or 90 degrees F (32 degrees C) with a wind speed in excess of 8 mph (13 km/hr). The exposed faces of brickwork should be cleaned prior to the fog spraying. Cleaning will be much more difficult if it is postponed until after this curing. The water from cleaning will also aid in the curing process. Refer to the information in Technical Notes 1 Revised for proper construction and protection methods during excessive cold or hot weather conditions. For walls, columns and pilasters, at least 12 hours should elapse after construction before application of floor or roof members, except that 72 hours should elapse prior to application of heavy, concentrated loads such as truss, girder or beam members. QUALITY ASSURANCE MEASURES Not all masonry projects wil involve testing or inspection. However, the MSJC Code states that, "A quality assurance program shall be used to ensure that the constructed masonry is in conformance with the Contract Documents." A quality assurance program typically includes inspection of the work by an owner's representative and periodic sampling and testing of masonry materials. Inspection The masonry inspector's job is to obtain good quality masonry construction and workmanship according to plans and specifications. The inspector should be able to explain the reasons for the specified procedures and know the important aspects of quality workmanship that will produce RBM elements with the properties assumed in the structural design. The inspector should verify clean grout spaces prior to grouting. Type and positioning of wall ties, bar positioners, joint reinforcement, and reinforcement should be verified against the project drawings and specifications. During the grouting process, the inspector should verify that: the grout is proportioned properly, the proper grouting technique is used, and all grout spaces are completely filled with grout. The inspector should look for darkening of the masonry due to water absorption from the grout as evidence of proper grout placement. Bracing and shoring should be inspected for proper installation. Protection measures such as covering the tops of uncompleted work, heated enclosures, and insulation blankets should be verified . Testing On some RBM projects, it may be necessary to conduct various quality control tests to ensure that the masonry has been constructed properly. The frequency of testing should be stated in the project specifications. Testing may be conducted prior to or during construction on the individual materials, e.g. brick, mortar, and grout. This is the most common form of quality control testing. Brick are typically tested for compressive strength prior to construction. Mortar may be tested in compression prior to construction in order to establish proportions of ingredients to be measured at the jobsite. The same is true for grout, which should also be tested to verify the slump. Prism compression tests are one example of such testing. The MSJC Specification stipulates the type, method and frequency of material and assemblage quality control tests required for masonry elements. This document states that prisms and grout will be tested for each 5000 sq.ft. (465 m2) of wall area or portion thereof when testing is

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required. Finally, tests of samples extracted from the constructed masonry may be necessary to verify the strength of elements when this is in question. A prism cut out of a masonry element to be used for compression testing is an example of such a test. For a review of the common quality control tests for brick masonry, refer to the Technical Notes 39 Series. Quality control tests can seem an onerous and unwanted expense, but they are provided for two very important reasons. First and foremost, tests can indicate consistency during construction. Dramatic changes in strength properties of elements as the work progresses can indicate a problem and should be explained. The second reason for testing is to monitor the strength gain of the masonry elements upon curing. The strength gain is monitored to indicate when shores or bracing can be removed, when loads can be applied to an element, and to verify that the strength assumed in the design has been achieved by the constructed masonry. SUMMARY Reinforced brick masonry is constructed in a manner that is different in many ways from conventional brick veneer construction. Proper materials and construction practices as dicussed in this Technical Notes should be followed to ensure that RBM elements achieve adequate strength and meet the applicable building code requirements. The information and suggestions contained in this Technical Notes are based on the available data and the experience of the engineering staff of the Brick Institute of America. The information contained herein must be used in conjunction with good technical judgment and a basic understanding of the properties of brick masonry. Final decisions on the use of the information contained in this Technical Notes are not within the purview of the Brick Institute of America and must rest with the project architect, engineer and owner. REFERENCES 1. Building Code Requirements for Masonry Structures (ACI 530/ASCE 5/TMS 402-95), American Society of Civil Engineers, New York, NY, 1996 2. Specification for Masonry Structures (ACI 530.1/ASCE 6/TMS 602-95), American Society of Civil Engineers, New York, NY, 1996

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Technical Note 17

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Technical Notes 17B -REINFORCED BRICK MASONRY - BEAMS March 1999 Abstract: Reinforced brick masonry (RBM) beams are an efficient and attractive means of spanning building openings. The addition of steel reinforcement and grout permits brick masonry to span considerable distances while maintaining continuity of the building facade. Attractive brick soffits and elimination of steel support members are two of the advantages of reinforced brick masonry beams. This Technical Notes addresses the design of reinforced brick masonry beams. Building code requirements are reviewed and design aids are provided to simplify the design process. Illustrations indicate the proper detailing and typical construction of reinforced brick masonry beams. Key Words: beam, deflection, girder, lintel, reinforced brick masonry, reinforcement. INTRODUCTION Reinforced brick masonry (RBM) beams are widely used as flexural members. Common applications of RBM beams include girders supporting floor and roof systems, and arches and lintels spanning openings for windows and doors. Girder is the term applied to a large beam with a long span that usually supports smaller framing members. A lintel is a beam over a wall opening, typically simply supported with no framing members. The main advantage of RBM beams is that the structural element and the architectural finish are one and the same. In some cases, however, they provide economical solutions without considering the savings due to a built-in finish. They are often built as an integral part of a masonry wall as illustrated in Figure 1. RBM beams are designed to carry all superimposed loads, including that portion of the wall weight above supported by the beam. While steel lintels are more common, RBM beams provide distinct advantages over steel lintels. Among the advantages are: 1. More efficient use of materials. The masonry serves as a structural element with a relatively small amount of steel reinforcement added. 2.Elimination of differential movement. This movement is often the cause of cracks in masonry. 3. Inherent fire resistance. 4. Reduced maintenance. Periodic painting of exposed steel is eliminated. 5. Lower cost. This Technical Notes provides a review of the design of RBM beams. Factors influencing design and performance are reviewed. Design recommendations and aids are provided and their use illustrated with an example. For additional information about RBM beams and design calculations, refer to the Masonry Designers' Guide (MDG) [2]. The MDG also provides an extensive review of the requirements of the Building Code Requirements for Masonry Structures (ACI 530/ASCE 5/TMS 402-95)[1], hereafter termed the MSJC Code. Other Technical Notes in this series provide the history of RBM, material and construction requirements, and design of other RBM elements. This Technical Notes does not address the design of deep beams (wall beams) or bond beams. A deep beam is one with a depth-to-span ratio exceeding 0.8. Assumptions made in this Technical Notes regarding the distribution of stress in beams under flexure and the loading conditions do not apply to deep beams. Bond beams are formed by placing horizontal reinforcement in a wall without an opening underneath.

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Technical Note 17

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NOTATION Following are notations used in the text, figures, and table in this Technical Notes. 2 2 Av = Area of shear reinforcement, in. (mm ) b = Length of bearing plate, ft (m) d = Effective depth of beam, in. (mm) db = Nominal diameter of reinforcement, in. (mm) Fs = Allowable steel stress, psi (MPa) f'm = Specified compressive strength of masonry, psi (MPa) H = Height of beam, in. (mm) ld = Embedment length of reinforcement, in. (mm) MG = Design moment due to gravity loads, in.-lb (N-m) Ms = Design moment due to in-plane shear, in.-lb (N-m) Mw = Design moment due to out-of-plane wind or seismic load, in.-lb (N-m) P = Design concentrated load, lb (kg) s = Spacing of shear reinforcement, in. (mm) V = Design shear force, lb (kg) W = Width of beam, in. (mm) wp = Design uniform distributed load, lb/ft (kg/m) y = Distance from top of beam to bearing plate, ft (m) DETERMINATION OF LOADING The basic concept of a beam is as a pure flexural member. A flexural member spans an opening and transfers vertical gravity loads to its supports, as illustrated in Fig. 2(a). RBM beams act in this manner to support their own weight and other applied gravity loads. However, it is also common for RBM beams to be part of a masonry wall. As such, RBM beams are often subjected to out-of-plane wind and seismic forces, as depicted in Fig. 2(b). This causes bending of the RBM beam in the out-of-plane direction, which is often about the weak axis of the beam. In addition, reinforced masonry walls may be shearresisting members, or "shear walls", which are part of the lateral load-resisting system of a building. In such a structural system, RBM beams may be used as connections between shear walls or piers, as illustrated in Fig. 2(c). Such beams are called coupling beams because they "couple" the shear walls or piers. If the relative sizes of the two piers being coupled are similar, the RBM beam is subject to considerable load when an in-plane shear force is applied to the wall. This is why damage to masonry shear walls is often concentrated at coupling beams following an earthquake or high-wind event. The designer should consider all aspects of loading for an RBM beam. It is difficult to predict the loading condition that will produce the critical design condition. For example, a RBM beam that is part of a wall will be subject to a combination of gravity loads and out-of-plane wind or seismic loads. Many factors influence the loading conditions for RBM beams.

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Arching Action Arching action is a property of all masonry walls which are laid in an overlapping bond pattern. Brick masonry will span, in a step-like manner similar to a corbel, over a wall opening when laid in running bond pattern. Vertical gravity loads above the openings are transferred to the wall elements on each side.

This is the reason why sizable holes can be created in masonry walls without causing collapse. Arching action will occur provided that the following conditions are met: 1.An overlapping bond pattern is used in the masonry surrounding the opening. 2.The masonry above the apex of a 45 degree isosceles triangle above the beam exceeds 12 in. (300 mm). 3.There are no movement joints or adjacent wall openings that hinder the load path of arching action. 4.The abutments are sufficiently strong and rigid to resist the horizontal thrust due to arching action. These concepts are illustrated in Fig. 3. Provided arching action occurs, the self weight of masonry wall carried by the beam may be safely assumed as the weight within a triangular area above the beam formed by 45 degree angles, as shown in Fig. 3. The self weight of the wall must be added to the live and dead loads of floors and roofs which bear on the wall above the opening. If a stack bond pattern is used, the full area of brick masonry above the wall opening should be considered in the RBM beam design with no assumption of arching action.

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Conditions for Arching Action FIG. 3 Concentrated Loads Loads from beams, girders, trusses and other concentrated loads that frame into the wall must be applied to the RBM beam in the appropriate manner. Concentrated loads may be assumed to be distributed over a wall length equal to the base of a trapezoid whose top is at the point of load application and whose sides make an angle of 60 degrees with the horizontal. In FIG. 4, the portion of the concentrated load carried by the beam is distributed over the length indicated as a uniform load. The distributed load, wp, on the RBM beam is computed by the following equation: wp = P/(b + 2ytan 30) Eq. 1 where: wp= design uniform distributed load, 1b/ft (kg/m) P= design concentrated load, 1b (kg) b= length of bearing plate, ft (m) y= distance from top of beam to bearing plate, ft (m) This is approximately 0.866 times P divided by y. Because the apex of the 45 degree triangle is above the top of the wall in this example, the RBM beam should be designed assuming no arching action occurs. The designer should check the stress condition at bearing points for RBM beams. This applies to loads on the beam and to the beam's reaction on the wall. The MSJC Code limits the bearing stress to 0.25 f'm, where f'm is the specified compressive strength of masonry. A rule-of-thumb recommended for many years is to provide a minimum of 4 in. (100 mm) of bearing length for masonry beams. The masonry directly beneath a bearing point should be constructed with solid brick or with solidly grouted hollow brick. Concentrated loads should not bear directly on ungrouted hollow brick masonry because of the potential for localized cracking or crushing of the face shells.

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Loads on RBM Beam FIG. 4

Construction Loads When designing a RBM beam that is prefabricated or built on the ground and lifted into place, it is important to consider the loads during transport and handling. To address these loads, the beam may require reinforcement at both the top and bottom of the beam. Beams built in place are constructed on shores. These must be designed for the dead weight of the beam plus any superimposed load prior to adequate curing of the reinforced brickwork. Movement Joints Movement joints are a necessity in masonry walls to accommodate differential movement and avoid cracking. It is common to place vertical expansion joints at or near the jamb of wall openings. In RBM buildings there is a reduced need for expansion joints and such joints may be spaced farther apart. Refer to Technical Notes 18 Series for a discussion of the placement of movement joints. The presence of a movement joint near a RBM beam will influence the loads and support conditions for the beam. For example, a simple support condition should be assumed since arching action will not occur if a movement joint is at or near the jamb of the opening. Furthermore, the beam will not act as a coupling beam between shear walls. This is, in fact, one means of simplifying the design and function of a RBM beam by eliminating loads due to in-plane shear. DESIGN OF RBM BEAMS RBM beam design should not be relegated to "rule-of-thumb" methods or arbitrary selection of beam configuration and steel reinforcement. In any beam design, a careful analysis of the loads to be carried and a calculation of the resultant stresses should be incorporated to provide adequate strength and to prevent excessive cracking and deflection. In addition to adequate strength, it is preferred that beams exhibit ductile behavior when overloaded. If the beam is overloaded, it should deform (deflect) a considerable amount prior to collapse. Deformation allows redistribution of loads to other members and provides visual indication that the beam is overloaded. Some building codes stipulate a maximum reinforcement ratio for RBM beams for this purpose. Another aspect is the relation between the RBM beam's strength and its cracking moment. Failure of unreinforced masonry in flexure is brittle, exhibiting sudden cracking and often collapse. Consequently, a reinforced beam should provide a moment strength in excess of its cracking moment. The amount of this overstrength is somewhat arbitrary, but a factor of 1.3 is required by the Uniform Building Code[3]. This means that the moment strength of a cracked-section, RBM beam should exceed 1.3 times the cracking moment of the beam. This is not a requirement of the MSJC Code, but is considered good engineering practice.

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Beam Sizing In the design of an RBM beam, the required cross-sectional area of masonry is based primarily on the maximum bending moment. However, there are other factors to consider when sizing an RBM beam. For example, it is often desirable to have the width of the RBM beam coincide with the specified wall thickness. RBM beams are sometimes formed with special U-shaped, hollow brick for this reason. These brick may be manufactured specially for this purpose or they may be cut from full-size units at the site. Manufactured special shapes may not be readily available in many localities, so it is best to contact the brick manufacturer as early as possible before proceeding with a design based on their use. The beam's depth will be determined by the appropriate number of courses of masonry units present. The beam's depth should be taken as only those courses of solid brick or that are solidly grouted. The beam's depth may be limited by the height of the wall above an opening. In such cases, compression steel may be necessary when sufficient masonry area is not provided. Lateral Bracing With short spans and relatively deep beams, there is little likelihood of excessive cracking, deflection or rotation. This may not be the case, however, for beams that are relatively long span, shallow or highly loaded. Such beams may be vulnerable to lateral torsional buckling. The designer should consider the lateral bracing conditions to ensure that the beam is laterally braced. The MSJC Code requires that the compression face of beams be laterally supported at a maximum spacing of 32 times the beam thickness. A brick veneer wall is laterally braced by wall ties to the backup system. A RBM beam that is part of a load-bearing wall system may not be laterally braced along its span length. In addition, movement joints at the jambs of a wall opening may result in a lack of lateral bracing for the beam at its supports. In such cases, attachment of the wall to the floor or roof diaphragm is the common means of providing lateral bracing for the beam. RBM Arches Design of RBM arches should begin with an analysis assuming the arch is unreinforced, in accordance with Technical Notes 31A or the ARCH computer program available from the Brick Industry Association. Such an analysis will indicate the locations of highest moment and shear, and the horizontal thrust at the abutments. Should the analysis so indicate, the arch should be designed as a reinforced beam. Further, if the conditions shown in Fig. 3 are not met, or if movement joints are provided at the abutments so that the arch may spread under load, the arch should be designed as if it were a straight, simply supported beam as a conservative measure. Alternately, a finite element analysis of the arch may be conducted to determine design moment, shear, and thrust values. RBM arches cause both a vertical bearing stress and a horizontal thrust on their abutments. The designer has the option of resisting the horizontal thrust of the arch by the abutments or providing room for movement as the RBM arch deforms under load. Judicious placement of vertical expansion joints and flashing will permit horizontal movement and simplify the arch design. This is recommended for longer span arches because providing adequate thrust resistance is difficult and movement joint spacing is limited. In this case, it is very important to provide adequate bearing at the abutments. STEEL REINFORCEMENT AND TIES The quantity of reinforcement required for an RBM beam is typically determined by the applied loads. However, the applicable building code may prescribe a minimum amount of reinforcement and this may dictate the amount of reinforcement required in a RBM beam. For example, all building codes now stipulate a minimum amount of reinforcement for masonry members in areas prone to earthquakes. Some building codes require that reinforcement in masonry coupling beams be uniformly distributed throughout the beam's height. This may require additional reinforcement and grouting of the masonry above wall

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openings in RBM beams. Bond and Hooks Typically, reinforcement is inserted in masonry beams to resist tension. The tension must be transferred from the masonry to the reinforcement. This is achieved through adequate bond between the steel reinforcement and the masonry. The bond stress along the length of the reinforcement should not exceed an allowable bond stress of 160 psi (1.1 MPa), according to the MSJC Code Commentary. A minimum embedment length must be provided in order to not exceed this bond stress. Consequently, the MSJC Code stipulates a required bond length for reinforcement in tension, called the minimum embedment length. The minimum embedment length is computed by the following equation: ld = 0.0015dbFs Eq. 2 where: ld= embedment length of reinforcement, in. (mm) db= nominal diameter of reinforcement, in. (mm) Fs= allowable steel stress, psi (MPa) Table 1 provides the minimum development lengths for various bar and wire sizes, based on Grade 60 ksi (414 MPa) reinforcing bars and 70 ksi (483 MPa) steel wire. The ends of reinforcing bars and wires may require a standard hook to properly secure the reinforcement and to achieve its strength. In simply-supported beams, the peak moment is often at midspan. For this case, the reinforcement in RBM beams can likely be developed by the bond between the bar or wire and the surrounding masonry with no need for hooks at the ends of the beam. However, a cantilever RBM beam may require a hook at the support end. In addition, shear reinforcement should always be terminated with a hook. Standard hooks for principal reinforcement may be either a 90 degree or 180 degree turn. Often, the designated space for grout and reinforcement in RBM beams is very small. It can be difficult for a contractor to execute a reinforcement detail properly. Consider that a 180 degree hook doubles the number of bars at a given cross section. The designer should always consider the reinforcement placement, tolerances, and cover restrictions stated in the building codes. Technical Notes 17A Revised provides further information on bar sizes, placement requirements and construction tolerances. Shear Reinforcement Where shear reinforcement is required, it should be spaced so that every potential crack is crossed by shear reinforcement. Shear cracks are assumed to be oriented at a 45 degree angle to the longitudinal axis of the RBM beam. This restricts the spacing of shear reinforcement to one-half the beam's effective depth, d. The spacing of shear reinforcement may be computed by the following equation: s = AvFsd/V Eq. 3 where: s= spacing of shear reinforcement, in. (mm) 2 2 Av= area of shear reinforcement, in. (mm ) Fs= allowable stress for shear reinforcement, psi (MPa) d= effective depth of beam, in. (mm) V= design shear force, 1b (kg) When shear reinforcement is required, it should be designed to resist the entire shear force. Shear reinforcement should always be placed parallel to the shear force. For RBM beams the shear reinforcement should be placed vertically. It can be difficult to provide shear reinforcement in RBM beams due to the limited size of grout spaces. This is especially the case with hollow brick units 6 in. (150 mm) or less in thickness and grout spaces between wythes less than approximately 2 in. (50 mm) in width. Consequently, it may be advantageous to increase the beam's depth so that shear reinforcement is not necessary. In fact, this is often the method used by designers to determine the minimum depth of a RBM beam required for a given loading. Ties

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There are two instances when it may be necessary to include ties in reinforced brick beams. These instances occur only when the beam is formed by grouting between wythes. If the beam has sufficient depth, ties may be required between the wythes. The grout exerts a hydrostatic pressure that must be resisted during construction. The MSJC requires wall ties between wythes as follows: 2 2 Wire size W1.7 (3.8 mm), one tie per 2 2/3 ft (0.25 m ) 2 Wire size W2.8 (4.8 mm), one tie per 4 1/2 ft (0.42 m2 ) Maximum spacing of 36 in. (914 mm) horizontally and 24 in. (610 mm) vertically Rectangular or Z ties may be used. In beams that form deep soffits (large beam widths) it may be advisable to tie the soffit brickwork to the grout. Although the grout does bond to the brick, the metal ties should provide additional capacity and safety. Such ties are placed in the mortar joint and extend into the grout. DEFLECTION Deflection of RBM beams is considered a serviceability issue. Excessive deflection might cause damage to interior finishes, functional problems with doors or windows, and cracking of masonry supported by the beam. The MSJC Code requires that the deflection of RBM beams that support unreinforced or empirically-designed masonry should not exceed the lesser of 0.3 in. (7.6 mm) or span length divided by 600. Deflection of RBM beams may be computed based on uncracked or cracked section properties. Use of uncracked sections results in underestimating the deflection. Deflection based on cracked sections only are over-estimated and are more difficult to calculate. Use of uncracked section is recommended. Creep is a time-dependent property of brick masonry that will cause the deflection of RBM beams to increase over time. An accurate formula for the estimation of long-term deflections of RBM beams due to creep, that is applicable for all cases and easy to use, does not currently exist. A rule-of-thumb is that the long-term deflection of RBM beams due to creep will be approximately 50 percent greater than their instantaneous deflection. This means that a beam that deflects 1.0 in. (25 mm) when it is fully loaded will creep over time such that its final deflection will be approximately 1.5 in. (38 mm). DESIGN CURVES Maximum efficiency and safety dictate the need for a rational design of all RBM beams according to the applicable building code. However, it is often helpful for the designer to have design aids that can be used to quickly develop a preliminary beam design. The design curves in Figs. 5-9 are provided for that purpose. The size and configuration of masonry and quantity of reinforcement can be quickly determined from these curves based on the span of the beam and the uniform gravity load supported by the beam, including the beam's self-weight. The curves are based on the following assumptions: 1.Compressive strength of masonry is not less than 2000 psi (14 MPa). For most brick masonry, this value will be exceeded. This value was chosen so that beam capacity was not limited by the masonry's compressive strength. 2.Elastic modulus of masonry is not less than 1600 ksi (11030 MPa). 3.The beam is simply supported and subject to uniform gravity loads only. 4.No compression or shear reinforcement is provided. 5.Deflection is calculated on uncracked section properties. The deflection limit of span length divided by 600 does not govern for span lengths less than 14 ft. (4.3 m). The effective depth, d, reflected in the design curves is based on the beam height, H, minus a value for masonry cover. The cover value is based on a reasonable approximation of brick, mortar and grout cover on the underside of reinforcement for the beams shown. The actual effective depth should always be checked for each particular RBM beam configuration.

DESIGN EXAMPLE

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To illustrate the use of the Design Curves, consider the following example. A RBM beam is to span over a garage door with a clear span of 9 ft (2.7 m). The beam supports its own weight and the weight of the brick masonry wall above the beam, so that the uniform load on the beam is 250 lbs/ft (372 kg/m) of span. The RBM beam and the wall above the beam are nominal 6 in. (150 mm) wide and constructed with hollow brick. Determine the beam depth and reinforcement required for these conditions. From Figs. 5(b) and 5(e), one concludes that a 4 in. (100 mm) or 8 in. (200 mm) high by 6 in. (150 mm) wide RBM beam is not adequate for the given span and loading. Therefore, the applicable Design Curve is Fig. 6(b), which is for a full unit depth, RBM beam. For the given conditions, a minimum depth of 12 in. (300 mm) and one No. 4 bar are required. At this point, any deflection criteria should be considered and may require a greater beam depth. SUMMARY RBM beams are an attractive and efficient means of spanning openings. Attention to detailing of reinforcement and proper design are the key aspects addressed in this Technical Notes. The most common RBM beam configurations are shown with consideration of the inter-connection of beam and wall elements. Design curves provided in this Technical Notes can be used to develop preliminary beam designs for many different applications and loading conditions. The information and suggestions contained in this Technical Notes are based on the available data and the experience of the engineering staff of the Brick Industry Association. The information contained herein must be used in conjunction with good technical judgment and a basic understanding of the properties of brick masonry. Final decisions on the use of the information contained in this Technical Notes are not within the purview of the Brick Industry Association and must rest with the project architect, engineer and owner. REFERENCES 1.Building Code Requirements for Masonry Structures (ACI 530/ASCE 5/TMS 402-95), American Society of Civil Engineers, Reston, VA, 1996. 2.Masonry Designers' Guide, John Matthys, ed., The Masonry Society, Boulder, CO, 1993. 3.Uniform Building Code, 1997 Edition, International Conference of Building Officials, Whittier, CA, 1997.


0.29 but < 0.50 can be considered as an equivalent semicircular arch as shown in Fig. 3. Twice the radius is the equivalent L for use with the tables.

FIG. 3

ILLUSTRATIVE EXAMPLE Design an arch to meet the requirements as shown in Fig. 4. The arch is semicircular; the horizontal axis is 6 ft above the base; the span, L, is 10 ft; the arch ring depth, d, is 12 in. (11 1/2 in. actual); and the nominal wall thickness, t, is 8 in. (7 1/2 in. actual). A beam reaction of 5000 lb is located at the center line of the span and 17 ft above the base. The uniform load consists of 1000 lb per ft dead load and 500 lb per ft live load occurring 14 ft above the base. Assume fm = 400 psi and the brick masonry weighs 10 psf per 1-in. thickness.

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FIG. 4

Uniform Load

All the following calculations will be with 1 in. of wall thickness; actual t = 7.5 in., fm = 400 psi, d = 11.5 in. and L= 10 ft.

Uniform Load

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Use Table 2, since 0.7L < 0.8L < 0.9L From Table 2, W = 724 lb per ft and H = 2993 lb

Concentrated Load

Use Table 5 since 0.75L < 1.1 L < 1.2L From Table 5, P = 88 lb and H = 84 lb

However, since there is combined loading, advantage can be taken of the increased capacity due to the uniform load.

667 < 688 O.K.

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From Table 6, P'= 1060 lb 667 < 1060 O.K.

Horizontal Thrust H(total) =970 + 636 = 1606 < 2993 O.K. At this point the wall shear caused by the horizontal thrust at the spring line should be checked. Assume Vm = 40 psi and n = 2

The overturning moment of the support due to horizontal thrust should be checked next (see Technical Notes 31A). In this example, the horizontal thrust is 1606 (7.5) (8.5) = 102,000 ft-lb. The resistance to overturning is a function of the overall axial load, wall shape, and reinforcement, if any. This is a separate analysis that should be performed after considering the total loading conditions on the entire structure.

CONCLUSION

This issue of Technical Notes has presented a simplified but conservative approach to a complex structural design problem. To provide an analysis for all possible assumptions and loading conditions is beyond the scope of this publication. Most loading conditions encountered will be similar to those in Fig. 1 and Fig. 2. To load an arch unsymmetrically defeats its use as a natural load-carrying structure and induces bending stresses that may cause failure. If arches are to be loaded unsymmetrically or do not comply with the assumptions and limitations given in this Technical Notes, consideration should be given to reinforced brick masonry. (See Technical Notes 17A Revised, "Reinforced Brick Masonry - Flexural Design", and 17M, "Reinforced Brick Masonry Girders - Examples".) If conditions exist other than those covered in the tables, special analysis should be made by the designer. The Brick Institute of America can not assume responsibility for the results obtained when using this Technical Notes Issue. It is beyond the scope of the Institute to anticipate every design situation that may arise. However, so long as the design criteria agree with the assumptions and limitations, satisfactory results can be obtained which will save countless hours of calculation time.

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Technical Notes 36 - Brick Masonry Details, Sills, and Soffits Rev [July/Aug. 1981] (Reissued Jan. 1988) Abstract: Detailing of brick masonry is both an art and a science. Recommendations are provided for the development of successful details using brick masonry and other materials. Detailing of sills and soffits is specifically addressed. Performance, esthetic value and economics are the principal considerations in the development of successful details. Key Words: brick, connections, construction, design, detailing, economics, esthetic value, function, performance, prefabrication, sills, soffits, structural stability. INTRODUCTION Successful detailing of brick masonry is both an art and a science. Proper details should result in a structure which is pleasing to the eye, but more importantly, performs well over its lifetime. Good detailing is not accidental, it requires proper planning. This planning may involve close cooperation between the architectural, engineering and construction disciplines in the early stages of the design process. There are three items which should be considered in the development of a successful detail. These are: 1. Performance considerations; 2. Esthetic value considerations; and 3. Economic considerations. The last two of these items may be traded off against each other. But, the first is mandatory and if it is not the primary concern, the detail may, and probably will, be doomed to failure. This failure can manifest itself in several ways: cracking, structural failure, moisture penetration to the interior, or efflorescence, to mention a few. It is possible to have a successful detail while compromising either the esthetic value or the economic considerations. But, it is impossible to have a successful detail if the performance considerations are compromised. A successful detail can be developed with excellent esthetic value while completely ignoring the economic considerations or vice versa, but to ignore the performance considerations is to invite trouble. APPROACH TO DETAILING General Proper planning in the development of brick details is essential to the successful execution of that detail in the field. The designer must be familiar not only with the properties of the various materials involved, but also how they go together in the construction process and how they will perform, both individually and together in service. The most esthetically pleasing detail is of no benefit if it can't be built, or does not perform its intended function. The designer should always keep in mind that different materials react to temperature and moisture changes in different ways. While in some cases these differences may be minor, in others they may be significant. If they are not properly addressed, the result can be facade failures, such as leaking, bowing, cracking, etc. For a discussion of differential movement, see Technical Notes 18 Series. Performance Considerations Performance is all-important if the detail is to be successful. There are three items which must be considered in the development of a detail which will provide satisfactory performance. They are: 1. Functional considerations; 2. Structural stability; and 3. Construction considerations. In the development of the detail, it is imperative that all of these items be given proper consideration. Functional Considerations. One of the first steps in the development of a successful detail is to determine the function of the element. The designer must determine the purpose of the element, and how the element will affect the overall performance of the building. Typical questions which should be addressed are: 1. Is the element to serve

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as a weather-tight enclosure? 2. Will stresses, axial, flexural or shear, be developed in the member? 3. Should it channel and direct the flow of moisture? 4. Is it to seal the top of a vertical element? 5. Is its purpose merely for esthetic value? Only after the designer has determined the required functions of the element can he begin to consider the other factors which will dictate the final design. Structural Stability. The designer must develop a detail which ensures that all applied loads can be adequately resisted by the element or that they are transferred to other elements of the structure which can resist them. These applied loads may be axial, transverse, shear or in the case of prefabricated elements, loads due to transportation and erection. One area of concern is the manner and adequacy of the connection of the element to the structure. It is imperative that these connections be structurally sound, to ensure structural stability of the element. Construction Considerations. The designer should take great care to ensure that the details can be easily executed in the field. This requires that the designer be knowledgeable in current construction practices. While some innovation may be necessary and beneficial, the detail should not require radical deviation from conventional construction practices. Typically, the more simple and straightforward the detail is, the easier it is to construct and thus, the better its performance. In some instances, the construction can be simplified by prefabrication of the element. Care should be taken by the designer to ensure, to the greatest extent possible, that the detail does not require several crafts to be working in the same location at the same time. Esthetic Value Considerations The designer must also determine how best to fulfill the functional requirements and yet provide the desired esthetic value. This involves decisions on materials, colors and textures, and other esthetic considerations. The configuration of the element is also an important esthetic consideration. The designer may decide to project or recess parts of the element to provide shadow lines or to use a different bond pattern to call attention to the detail. The esthetic value of the detail is limited only by its function, its ease of construction, the designer's imagination and possibly its economic feasibility. Economic Considerations A detail, to be successful, should have the capability of being constructed economically. Economics involves both materials and labor. A successful detail requires that both the quantity and quality of materials be closely controlled. The use of excess materials to achieve the function of the detail should be avoided. Details which require very specialized skills by the crafts involved should be avoided. If very specialized skills are required, there is usually a reduction in productivity of the craftsmen and an increase in cost. SILLS General The prime function of a sill is to channel water away from the building. The sill may consist of a single unit or multiple units; it may be built in place or prefabricated; and it may be constructed of various materials. Esthetic Value The desired esthetic effect may be achieved through the use of special shaped units, either manufactured or cut to the desired shape. A word of caution concerning manufactured special shapes-while most manufacturers are capable of making special shapes to match the color and texture of the units selected for the project, there will be an added cost for each special-shaped unit. The added cost for the special shapes is dependent upon the complexity of the configuration of the shape and the number of units of each special shape required. Some manufacturers carry certain special shapes in stock. It may be advantageous to slightly alter the detail so that these stock special shapes may be used in lieu of one with a slightly different configuration. The appearance of the sill and the overall esthetic appeal of the structure may also be achieved by the use of a contrasting color or texture or by use of materials other than brick for the sill. Esthetics may also be affected by the use of a different bond pattern than that used in the adjacent wall. See Figs. 1 and 2.

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General Studies/Classroom/Instructional Resources Center State University Agricultural and Technical College - Delhi, New York FIG. 1

Westgate Corporation Building - McLean, Virginia FIG. 2 Materials Sills for use in brick masonry construction are typically brick, concrete, stone or metal. The selection of material is primarily dependent upon the required esthetic effect. But it is also important to note that metal, concrete and stone sills normally require fewer joints than do brick sills, and therefore provide fewer potential avenues for water penetration. Once the decision of which material to use is made, then decisions concerning the quality of that material can be made. Whichever material is selected, it should be of high quality. A discussion of brick and mortar properties is found in Technical Notes 7B Revised. Flashings for use in sills can be of a number of materials, such as copper, lead or plastics, see Technical Notes 7A Revised for additional information. Aluminum and asphaltic-impregnated felt are not recommended for use as flashing materials. Aluminum is not recommended since alkalies in the cement of the mortar may attack it and cause corrosion. Asphaltic-impregnated felt is not recommended because it is easily punctured during construction. For the same reason, plastic films of less than 20 mil thickness should also be avoided. Once the flashing has been punctured, it ceases to fulfill its function, thus in place flashing should be inspected for punctures and tears, and appropriately repaired prior to laying brick masonry on the flashing. Also, some plastics are subject to continued degradation after having been exposed to sunlight for an extended period of time. Details General. Since the primary function of sills is to divert water away from the building, the top surface should slope downward and away from the building. In the case of brick sills, see Figures 3 and 4, the slope should be at least 15

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deg from horizontal. This may vary somewhat according to the sill configuration of the window unit, particularly in the case of wood windows. The sill should extend a minimum of 1 in. (25 mm) beyond the face of the wall at its closest point to the wall, see Fig. 3. In some instances, it may be necessary that the brick units at the ends of the sills be uncored units so that no cores are exposed to view.

Sill in Frame/Brick Veneer Construction FIG. 3

Sill in Cavity Wall Construction FIG. 4 When concrete or stone sills are used, they should be sloped away from the building, and also sloped from the ends toward the center, see Figs. 5 and 6. The slope away from the building should be at least 15 deg from horizontal, the slope from the ends should be 1/8 in. (3 mm) to 12 in. (300 mm) toward the center of the sill. For sills longer than 4 ft ( 1.2 m), the slope should extend for at least a distance of 2 ft (600 mm) from the ends, see Fig. 6.

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Concrete or Stone Sill FIG. 5

Concrete or Stone Sill FIG. 6

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Flashing and Weepholes. In general, when a collar joint, cavity or air space is interrupted, such as at sills, at the base of the walls, at lintels over openings and at shelf angle supports, flashing should be provided in the wall. The function of flashing is to serve as a collector for any moisture penetrating the wall or the sill. It is important that the flashing extend through the brick to the exterior face of the wall at the lower end of the flashing and be turned down at least to in. (6 mm) to form a drip. The flashing at the sill should extend beyond the ends of the sill to the first head joint outside of the jamb of the opening, and should be turned up and outward for a distance of at least 1 in. (25 mm) at each end, see Fig. 5. If the ends are not turned up and out, the moisture collected on the flashing will have a path into the adjacent wall and there is no way to predict where it may go. The purpose of turning the flashing up and out is to assure that the moisture stays on the flashing until it drains from the wall. See Technical Notes 7A Revised for a discussion of materials to be used as flashing. Once moisture penetrating the wall or sill has been collected on the flashing, it must be removed from the wall. This is the function of weepholes. Weepholes may be installed in several ways, see Technical Notes 21C. Weepholes should be placed on top of the flashing, not one course up. If wick-type materials are employed, or if hidden flashing is used, the weepholes should have a maximum horizontal spacing of 16 in. (400 mm). If open weepholes with no wicks are used, the horizontal spacing may be increased to 24 in. (600 mm) maximum. Drips. Every sill should be provided with a drip. The function of the drip is to prevent water from returning to the exterior face of the wall. The drip of a properly sloped brick sill is the lower corner of the brickwork. A drip in a concrete or stone sill is usually formed, or cut into the bottom face of the sill, as shown in Figs. 5 and 6. The drip on a concrete or stone sill can be cut in several shapes, Vee-shape, rectangular, semi-circular, or a combination of these. The shape of the drip is not important, but its presence and location are important. The inner lip of the drip should be located a minimum of 1 in. (25 mm) from the exterior face of the wall, , as shown in Fig. 5. Connections. In brick masonry sills of short length, 4 ft. (1.2 m) or less, no special anchorage is necessary. However, sills of brick, concrete, metal and stone having long runs should be anchored to the masonry below or behind the sill, see Figs. 3 and 5. This will require penetration of the flashing below or behind the sill. Care must be taken to ensure that these penetrations are adequately sealed so that the flashing functions as intended. Attachment of the sill to the window will vary with window type and manufacturer. It is most important that the joint where the sill and window make contact be sealed with a high-quality sealant, see Technical Notes 28 Revised and 28B Revised. Expansion Joints. When expansion joints are necessary, it may be desirable to install them in vertical alignment with window jamb lines. If this is done, the expansion joint should also be installed through the sill. This will enable the expansion joint to perform as intended. If the sill extends beyond the jamb of the opening and an expansion joint is required at the jamb, then the expansion joint should be continuous around the entire sill extension, as should the flashing, see Fig. 6. Construction In the past, sills for use in brick masonry construction have generally been built in place, using conventional construction practices. A trend during recent years has been to use prefabricated sills, particularly when combined with a spandrel and soffit, see Technical Notes 40 Series. This type of construction will be further discussed in the Soffits portion of this Technical Notes. When prefabricated brick, pre-cast concrete, or stone sills are used, they should have section lengths as long as is practical. The lengths will be determined by ease of handling and erection and the sills' ability to resist erection stresses. The length of sill sections should be limited to a length that can easily be handled by equipment already on the jobsite. The joints between long sill sections should be constructed using a soft joint. It may also be necessary, in very long runs of sill, to provide expansion joints at the ends where the sill abuts the jamb. SOFFITS General Detailing of soffits for brick masonry requires special considerations. The primary function of a brick masonry soffit is to enclose the building while providing an esthetically pleasing appearance. There are two primary considerations in

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addition to esthetic value in the detailing of soffits: the structural stability of the system and whether it can be easily and economically constructed using conventional methods. Though prefabrication has not been widely used for total projects, it has been successfully used in many specialized applications and is considered a conventional construction method. Prefabrication has been widely used in the construction of soffits and may provide the most economical approach on certain projects. Construction of soffits in place often requires expensive forming and shoring. However, if there is only a small area of soffits involved on a given project, this may be the most efficient method. Materials Soffits generally are reinforced and grouted in some manner, whether built in place or prefabricated. Several projects have been constructed using reinforced and grouted hollow units, conforming to ASTM C 652. See Technical Notes 17 for information on reinforcement and grout. Properties for brick and mortar are discussed in Technical Notes 7B Revised. There are several high bond mortar additives available which may allow the designer to eliminate the reinforcement and grout. However, it should be noted that the high bond mortars do not work well with all brick units. The instructions of the additive manufacturer must be strictly followed, and a pre-design testing program should be carried out, see Technical Notes 39A. Design There are several questions which must be answered when designing soffits. Some deal with esthetic value, some with structural stability and some with construction. The primary esthetic concern is configuration. Should the soffit be horizontal, or sloped, should it be integral with the spandrel or separate? The primary design concern is structural. How should it be detailed to assure structural soundness, under all loading conditions, including any loads imparted during erection? This may require detailing and construction practices unfamiliar to the designer and contractor since this is not like a wall and demands careful consideration. One of the earliest decisions to be made about the construction of the soffit is whether it will be best to construct it in place, or to prefabricate it. The configuration, structural and economic considerations may dictate the method of construction to be used. See Figs. 7 and 8.

BIA Headquarters Building - McLean, Virginia FIG. 7

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Evans Library, Texas A&M University - College Station, Texas FIG. 8 Details General. Each soffit entails its own unique detailing problems. These may include: configuration, support available from the surrounding structure, space restriction on built in place soffits and construction sequencing. The manner in which these problems are solved will determine how successfully the soffit will perform. Flashing and Weepholes. Normally, soffits do not require flashing or weepholes. However, in some applications, both may be required, see Fig. 9. In other applications, only weepholes may be required, since the inclusion of flashing in some cases may impair the structural stability of the soffit. It can only be stressed that the detailer should always keep in mind the primary function of flashing and weepholes in determining whether they are needed in any particular application. Their primary functions are: Flashing - collect and divert to the weepholes any moisture which might penetrate the element. Weepholes - convey all collected and diverted water to the exterior.

Built-in-Place Brick Soffit FIG. 9 Connections. Whether the soffit is prefabricated or built in place, its connection to the structure is the most demanding detail for the designer to develop. Previously developed details may be totally inappropriate in the present situation. Connection details are critical in providing structural stability to the soffit. In detailing connections, it is important to keep one principal always in mind. That principle is: Keep It Simple. The simplest connection details are in most cases the most successful.

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Expansion Joints. The installation of expansion joints, in most cases, should be avoided in soffits; however, it may be necessary to provide expansion joints when soffits are to be installed over large areas. The installation of expansion joints may cause problems in providing structural stability of the element and require additional connections to the structure. If it is necessary that expansion joints be installed in soffits, it is important to remember that the function is expansion control. This is provided by resilient joints which can be compressed to provide for the movement of brick masonry, especially during hot weather, due to thermal expansion of the brick masonry and return to its original shape when the temperature is cooler. Reinforced and grouted brick masonry does not usually require expansion joints. Construction Structural and economic considerations normally determine the construction methods to be used. While the detailer does not normally specify the manner in which the detail is to be executed during construction, the method of support and economic aspects determined by the detail will affect the method of construction chosen. The method of supporting the soffit, both its permanent support and support during construction, has a direct bearing on the method of construction selected. The economics of constructing the element can be affected by configuration, structural support and materials selection. Economics in turn may well be the final determining factor in the selection of the construction methods employed. When a soffit is constructed in place, it sometimes requires a complicated system of centering and falsework which must be left in place for a number of days. Normal practice is to provide spacer strips on the forms which locate each unit within the form and provide a joint on the exposed face suitable for tuckpointing once the form is removed, see Fig. 10. These strips should be the width of the joint and a minimum of 1/2 in. (13 mm) in height. After the units have been placed on the form, the upper side is grouted and ties are placed in the joints for anchorage to the structure. After several days of curing, the forms are stripped and the joints can then be tuckpointed. The number of days required for curing is dependent upon conditions at the site during the curing period and the materials used. See Technical Notes 7 for tuckpointing recommendations.

Built-in-Place Brick Soffit Forming FIG. 10 In some cases, the use of built in place soffits may be precluded. Then, prefabrication may be the most logical and economical approach, see Technical Notes 40 Series. This method of construction has been used very satisfactorily on many projects. On most of the projects where it has been used, the soffit is built integral with a spandrel cover and a sloped sill, see Figs 11 and 12.

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Prefabricated Brick Sill, Spandrel and Soffit FIG. 11

Prefabricated Brick Sill, Spandrel and Soffit FIG. 12

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SUMMARY The designer, when developing details for sills and soffits, should keep in mind the function of the element being detailed, the esthetic value he wishes to achieve, the structural stability of the element, and the economics of construction. It is essential to provide details which allow the elements to perform their primary functions as well as possible. In order to do this, the designer must select the proper materials, locate them in the proper place, and provide sufficient information so that the element can be properly constructed. Several decisions and assumptions must be made by the designer because each project and each element on the project must be satisfactorily addressed. This Technical Notes addresses the major considerations necessary to successfully detail sills and soffits of brick masonry. In some cases, other considerations may be necessary due to unusual or unique conditions. It is beyond the scope of this Technical Notes to address all conditions and combinations of conditions which may occur, therefore the designer or owner, or both, must make the final decision on the details, the materials selected and the construction procedures used. The recommendations made in this Technical Notes are merely that-recommendations. The final configuration of the detail must in the long run be based on the designer's application of some or all of the principles set forth here.

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Technical Notes 36A - Brick Masonry Details, Caps and Copings, Corbels and Racking Rev [Sept./Oct. 1981] (Reissued February 2001) Abstract: Recommendations are provided for the development of successful details using brick masonry. Detailing of caps, copings, corbels and racking is specifically addressed. Performance, esthetic value and economics are the principal considerations in the develops meant of successful details. Key Words: brick, caps, connections, construction, copings, corbels, design, detailing, economics, esthetic values, function, performance, racking, structural stability. INTRODUCTION This Technical Notes is the second in a series that discusses brick masonry details. This Technical Notes will address the detailing of caps, copings, corbels and racking. Technical Notes 36 Revised addresses the detailing of sills and soffits. The recommended approach to detailing is covered in Technical Notes 36 Revised. While that Technical Notes is primarily for sills and soffits, it does provide the general approach applicable to all detailing. The following items should be considered in the development of a successful detail: 1. Functional considerations; 2. Esthetic value; 3. Construction considerations; 4. Economic considerations. DEFINITIONS Caps and Copings The definitions for cap and coping are entirely dependent upon which dictionary or glossary is used as a reference. In addition, there are other terms which are used interchangeably with them, such as water table, canting strip, and offset. For the purpose of this Technical Notes, the word "coping" applies to the covering at the top of a wall, and the term "cap" refers to a covering within the height of the wall, normally where there is a change in wall thickness. The other terms cited will not be used. Corbels and Racking A corbel is defined as a shelf or ledge formed by projecting successive courses of masonry out from the face of the wall. Racking is defined as masonry in which successive courses are stepped back from the face of the wall. CAPS AND COPINGS General The primary function of caps and copings is to channel water away from the building. The cap or coping may be a single unit or multiple units. They may be of several different materials. The tops may slope in one direction or both directions. Additionally, where caps are discontinuous, a minimum slope from the ends of 1/8 in. (3 mm) in 12 in. (300 mm) should be provided, as shown in Figures 4 and 6 in Technical Notes 36 Revised. The esthetic value the designer wishes to achieve may come from the configuration of the element, its color, or its texture. Caps and copings normally do not serve any structural function, and do not present any major problems in their construction. Materials Caps and copings can be constructed of several materials: brick, pre-cast or cast-in-place concrete, stone, terra cotta, or metal. It should be pointed out that because of their location in the structure, caps and copings are exposed

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to climatic extremes. This severe exposure must be of prime concern to the designer. Because caps and copings are subjected to extreme exposure, brick masonry may not be the best choice of materials. This is because caps and copings of brick require more joints than do those made of other materials. This provides more avenues for possible water penetration into the wall. If brick is the material selected, great care must be taken to provide for the movement to which the element will be subjected and also to make sure all joints are properly filled with mortar. Concrete, stone and metal caps and copings can be installed in relatively long pieces, thus requiring less joints than do those made from brick. Concrete, stone and terra cotta all have thermal expansion properties similar to those of brick masonry and normally present no extreme problems with differential movement when applied as caps and copings, if properly detailed. Metal has very different thermal expansion properties than brick masonry. Depending upon the metal used, its thermal expansion coefficient may be 3 to 4 times that of brick masonry. The designer should be aware of this and provide for this differential movement in the development of the details. Consideration must also be given to the drying shrinkage of the element if cast-in-place concrete is the material selected. If brick is the material chosen for the coping, it may be desirable in some applications to use a special shape to get a positive slope in two directions. In most applications, the slope should be only in one direction, with drainage onto the roof and not down the wall face. In such case, the coping can be built using regular shapes. Design The prime consideration in the design of caps and copings is the performance of the element in service. The designer must take into consideration the movement of the element, differential movement between the element and the wall, joint configuration and material, connection of the element to the wall, and type and location of flashings. The esthetic value of the detail should be evaluated. As with details of other elements, selection of material, color, texture and configuration will effect the esthetic value of the detail. The designer has a wide range from which to choose, but he must keep in mind that the performance should not be compromised to achieve esthetic value. The economic considerations are seldom a major consideration in the development of details for caps and copings. The material selected may have a minor effect on the economics of the detail. It affects the economics not only by its own costs, but also by the economics of installation. The economic considerations should not have a deleterious effect on the performance of the details in service. Details General. The function of caps and copings is to prevent the entry of water into the wall where the wall becomes partially or totally discontinuous vertically. Caps should have the top surface sloping downward, away from the face of the wall above. Copings may slope in one or both directions. In all cases, the slope should be a minimum of 15 degrees from horizontal. The caps should overhang the wall face on the exposed side. Copings should overhang the wall on both sides. The overhang should be of sufficient dimension so that the inner lip of the drip is at least 1 in. (25 mm) from the face of the wall. Since the function of caps and copings is to prevent moisture penetration, the fewer the number of joints, the more assurance that the detail will perform its function. Flashing and Weepholes. Flashings for caps and copings generally serve a different function from flashings used elsewhere in the structure. Flashing used with caps and copings has as its prime function the prevention of the entry of moisture into the wall. The collection and diversion of the water from the wall becomes a secondary, although important function. In order to properly anchor caps and copings to the wall, it may become necessary to penetrate the flashing with the anchor, see Figs. 1, 3, and 4. To prevent moisture from entering the wall, at these points, it is absolutely necessary that the penetrations be adequately sealed, or the flashing will fail to function as intended.

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Precast Concrete or Stone Coping on Cavity Wall Parapet FIG. 1

Coping for Cavity Wall Parapet FIG. 2

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Coping for Solid Masonry Parapet FIG. 3

Rowlock Coping on Solid Masonry Parapet FIG. 4 Flashings should be extended beyond the face of the wall and bent downward 1/4 in. (6 mm) to form a drip, as shown in Figs. 2, 5, and 6. Metal copings may also serve as flashings. It should be recognized that exterior flashings not contained within the wall serve the same functions as do interior flashing. Information on flashing materials is provided in Technical Notes 7A Revised. While the flashing for caps and copings may have a different prime function from normal usage, it is still necessary to provide weepholes immediately above the flashings to convey the water collected on the flashing out of the wall, unless exterior flashing is used. Weepholes should be spaced at a maximum of 24 in. (600 mm) o.c., unless wicks or hidden flashing are used. Then the spacing should be reduced to 16 in. (400 mm) o.c. maximum. Drips. Regardless of the material selected for caps or copings, drips should be provided. When brick caps and copings are used, the drip is the lowest point on the element, as shown in Figs. 4 and 7. When metal caps and copings are used, the drips can be formed by bending the material outward from the face of the wall, see Figs. 2, 5 and 6. With heavy gauge metals, stone concrete or terra cotta caps and copings, the drip is either cut or formed in the bottom of the projection beyond the face of the wall, as shown in Figs. 1, 3, and 7. This drip can be in several configurations, and still perform. The important thing is that a drip be provided and that the inner lip be at least 1 in. (25 mm) from the face of the wall as shown in Figs. 1, 3, and 7.

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Masonry Bearing Wall Coping FIG. 5

Masonry Cavity Wall Coping FIG. 6

Brick and Precast Concrete or Stone Caps FIG. 7 Connections. Elements other than caps and copings require careful consideration of their connection to the structure for the structural stability of the element. In the case of caps and copings, the structural stability becomes secondary to the climatic considerations, such as moisture and temperature. Connections which are usually provided

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for structural purposes are generally rigid. Because of the diversity of materials used for caps and copings in conjunction with brick masonry walls, the connection in some cases should be of a flexible nature. Brick masonry, concrete, stone and terra cotta, respond to climatic conditions in much the same manner, and rigid connections can be used with little consideration of differential movement. Because of the dissimilarity of metal and brick masonry in their reaction to climatic conditions, the connections require some flexibility. Light gauge metal copings as shown in Figs. 5 and 6 should be nailed to the wall, and horizontal slots should be provided at nailing locations to prevent buckling of the coping due to thermal expansion. Metal caps and copings require an extension down the face of the wall, 4 in. (100 mm) min., and a sealant between the metal and the wall to prevent wind uplift and water penetration. Care should be taken to seal each penetration of the metal cap or coping where it is exposed to the exterior environment. Expansion Joints. It is necessary to provide expansion joints in long walls to provide for movement of the wall due to thermal and moisture expansion. This is particularly true in parapet walls and other masonry walls which are exposed to the exterior climatic conditions on both sides. Expansion joints are discussed in Technical Notes 18 Series. When expansion joints are required in the wall, the expansion joints should also be provided through any caps or copings in the same locations. It may be necessary to provide additional joints in metal copings. Metal copings should be so detailed and constructed that they function independently of the movement of the wall below. Expansion joints should be of a compressible material, but should also be extensible. One method of providing expansion joints is to leave the mortar from the head joints in a vertical line and insert a synthetic backer rod to the desired depth and fill the remainder of the joint with a high-quality sealant. Construction. Caps and copings require no special construction skills. If brick masonry is used as the cap or coping material, great care should be taken to ensure that all head and bed joints are completely filled. If cast-in-place concrete is used, some provision must be made to allow for the initial drying shrinkage of the concrete. If precast concrete or stone are used for caps or copings, non-compressible shims should be placed on the top of the wall at the exterior face of the wall. The shims are used because the weight of this type of cap or coping would compress the plastic mortar and a smaller joint would result. Then the mortar for the bed joint is spread and the cap or coping installed. The shims which should have a thickness equal to the bed joints should be left in place until the mortar has set. Once the mortar has set, the shims should be removed and the joint tuckpointed. CORBELS AND RACKING General Corbeling of brick masonry may be done to achieve the desired esthetics, or to provide structural support. There are empirical requirements provided by most codes and standards for unreinforced corbels, as shown in Fig. 8. If these requirements are to be exceeded, then the element will require a rational design as a reinforced element.

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Limitations on Corbeling FIG. 8 Corbels. The empirical approach requires that the total horizontal projection not exceed one-half the thickness of a solid wall, or one-half the thickness of the veneer of a veneered wall. It is also required that the projection of a single course not exceed one-half of the unit height or one-third of the unit bed depth, whichever is less. From these limitations, the minimum slope of the corbeling can be established (angle measured from the horizontal to the face of the corbeled surface is 63 deg 26 min. see Fig. 8). The required slope could be increased by the requirements that the unit projection not exceed one-third of the bed depth if they are more restrictive. It should be pointed out that the eccentricity induced into the wall by the corbeling must be considered in the wall design. If these limitations are exceeded, the wall should be reinforced to resist the stresses developed by the corbeling. Fig. 9 illustrates graphically the pattern of stresses within two corbels of different configurations under identical loading conditions. The corbel on the left is 45 degrees from horizontal, which is not in accordance with building code requirements. The corbeled wall on the right has an angle of corbel 60 degrees from horizontal and is very close to the building code requirement of 63 degree 26 min discussed above. The 60 degree corbel shows a stress pattern with axial and shear stresses with the only concentration of stresses directly below the applied load, P. The shear stresses are well distributed within the wall section. The 45 degree corbel, on the other hand, has bending stresses in addition to the axial and shear stresses, and the pattern of the stresses has been drastically altered. In addition to the concentration of compressive stresses immediately beneath the load, P. there is another concentration of compressive stress at the toe of the corbel. The bending stresses require that a corbel of this configuration be rationally designed and reinforced. Those corbels having an angle from horizontal of 60 degree or greater do not require reinforcement unless they exceed the other requirements given above.

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Corbeling Stress Distribution FIG. 9 Racking. When racking back to achieve the desired dimensions, care must be exercised to insure that, since there is no limitation on the distance each unit may be racked, the cores of the units are not exposed. Preferred construction consists of a setting bed over the racked face with the uncored brick or paving brick set to provide a weather-resistant surface. Mortar washes may also be used. They may not, however, be as durable. When using a mortar wash, it should not bridge over the rack, but should fill each step individually. SUMMARY The designer, when developing details for caps, copings, corbels and racking should keep in mind the function of the element being detailed, the esthetic value he wishes to achieve, the structural stability of the element, and the economics of construction. It is essential to provide details which allow the elements to perform their primary functions as well as possible. In order to do this, the designer must select the proper materials, locate them in the proper place and provide sufficient information so that the element can be properly constructed. Several decisions and assumptions must be made by the designer because each project and each element on the project must be satisfactorily addressed. The information and suggestions contained in this Technical Notes are based on the available data and the experience of the technical staff of the Brick Industry Association. The information and recommendations contained herein if followed with the use of good technical judgment, will avoid many of the problems discussed here. Final decisions on the use of details and materials as discussed are not within the purview of the Brick Industry Association, and must rest with the project designer, owner, or both.

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Technical Notes 39 - Testing for Engineered Brick Masonry- Brick and Mortar November 2001 Abstract: Testing of brick, mortar and grout is often required prior to and during construction of engineered brick masonry projects. The tests involve a combination of laboratory and field procedures which are described in various ASTM standards. The extent of testing is a decision made by the engineering or architectural firm responsible for the masonry design, and may consist of only a few laboratory tests to determine the properties of the brick units, or may involve extensive laboratory and field sampling and testing. This Technical Notes describes the testing of materials; other issues in this series describe testing of brick masonry assemblages. Key Words: brick, engineered brick masonry, grout, mortar, quality control, testing.

INTRODUCTION The use of engineered brick masonry in the construction of loadbearing structures requires that the standard methods for determining the physical properties of both the materials and the masonry assemblages be strictly followed. The standards and specifications for engineered brick masonry are based, for the most part, on the results of American Society for Testing and Materials (ASTM) methods of testing. It is not the intent of this Technical Notes to supersede the various applicable ASTM standards, but to supplement them. The ASTM standards have been carefully developed by balanced technical committees composed of people experienced and knowledgeable in their chosen fields. Therefore, if the prescribed methods of tests are not adhered to, inaccurate and inconsistent test data and erroneous conclusions can result. This can be quite serious when the design of a masonry bearing wall structure is based on such tests, or when such tests are used as quality controls during construction. This Technical Notes covers testing of masonry materials for obtaining information needed to determine design properties for engineered brick masonry. Additional testing required for assessment of material compliance to various ASTM specifications is not included. In addition, field testing of brick, mortar and grout for quality control is discussed. This Technical Notes is the first in a series on testing. Other Technical Notes in this series discuss the construction, preparation and testing of masonry assemblages (in the laboratory); and the sampling, preparation and handling of jobsite test specimens for the purpose of quality control of the construction.

ENGINEERED BRICK MASONRY STANDARDS There are several standards used in the United States for the design of brick masonry structures, all of which contain some requirements for testing of masonry materials or assemblages. Likewise, other standards and building codes require testing in order to establish various design parameters. In addition to predesign and preconstruction testing, testing for the purpose of quality control is often implemented. Building Code Requirements for Masonry Structures (ACI 530 / ASCE 5 / TMS 402-99) and Specification for Masonry Structures (ACI 530.1/ ASCE 6 / TMS 602-99) [3], known as the MSJC Code and Specifications, contain several quality assurance requirements. For example, the MSJC Code and Specification require that the initial rate of absorption (IRA) of brick at the time of laying not exceed 1 gram per sq in. per min. ASTM C 62, ASTM C 216 and ASTM C 652 also 2

recommend that the limit on IRA be 30 g/30 in. /min. The determination of this property may be made in the laboratory on oven-dry brick, or at the construction site as a field test. The tests outlined within this Technical Notes are those which are most commonly performed to satisfy the requirements of the MSJC Code and Specification.

TESTING STANDARDS The ASTM standards which are most frequently utilized when testing brick masonry materials should be readily available to all laboratory personnel, and to individuals involved in field testing. The applicable standards are as follows:

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-ASTM C 67, Standard Test Methods of Sampling and Testing Brick and Structural Clay Tile -ASTM C 270, Standard Specification for Mortar for Unit Masonry -ASTM C 91, Standard Specification for Masonry Cement -ASTM C 109, Standard Test Method for Compressive Strength of Hydraulic Cement Mortars (Using 2-in. or 50-mm Cube Specimens) -ASTM C 780, Standard Test Method for Preconstruction and Construction Evaluation of Mortars for Plain and Reinforced Unit Masonry -ASTM C 476, Standard Specification for Grout for Masonry -ASTM C 1019, Standard Test Method for Sampling and Testing Grout

For the most part, these standards provide clear and concise explanations of the procedures for sampling and testing masonry materials; however, for the novice, some areas may present some confusion. The following sections will explain some of the procedures required by the various ASTM standards.

BRICK TESTING FOR ENGINEERED BRICK MASONRY The strength of brick varies considerably, depending on raw material, method of manufacture and degree of firing. The range in compressive strength is on the order of 2000 psi to in excess of 20,000 psi. The MSJC Code does not dictate minimum compressive strength requirements for brick, but since the allowable stresses and elastic moduli of masonry are a function of compressive strength of brick, testing to determine compressive strength is required. For the determination of unit compressive strength, f'b, the procedures given in ASTM C 67 [1] should be followed. The initial rate of absorption (IRA) is another important property. If the IRA of brick exceeds an acceptable upper limit, problems with excessive shrinkage of mortar and grout, and poor bond, are apt to occur. The procedures for determining the IRA, in the laboratory and in the field, are contained in ASTM C 67. Compressive Strength Specimen Size. ASTM C 67 requires that the specimen be full height and width, and approximately one-half of a brick in length, plus or minus 1 in. (25 mm). For example, an 8-in. (200 mm) long brick may be tested using a piece of brick with a length between 3 and 5 in. (75 and 125 mm). However, if the testing machine being used is not capable of providing sufficient force to crush the approximate half-brick, a piece of brick having a length of one-quarter of the original full brick 2

2

length may be used, so long as the total cross-sectional area is not less than 14 in. (90 cm ), see Figure 1.

Compressive Strength Specimens FIG. 1

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Although ASTM C 67 does not specifically state the method in which the samples are to be obtained, it has been common practice to use pieces of brick which are left over from modulus of rupture tests. If modulus of rupture tests are not being performed, then sawing the units to the desired size is acceptable. A minimum of five specimens is required. The compressive strength test specimens should be oven-dried. The amount of moisture in the brick can affect its compressive strength - the higher the moisture content, the lower the apparent strength. Therefore, by drying the specimens before testing, one variable that can affect the results is eliminated. If they are wet-cut with a masonry saw, the drying should follow the cutting. If a wet capping material, such as high-strength gypsum, is used, it is generally agreed that the small amount of moisture absorbed by the specimens will not make additional oven drying necessary. The 24-hr curing period in laboratory air will suffice. Capping Specimens. The importance of careful capping procedures cannot be over-emphasized. Brick units, by their inherent nature, are not perfectly formed and their bearing surfaces may not be parallel and free from surface irregularities. The purpose of capping the bearing surfaces is to assure reasonably parallel and smooth opposite bearing surfaces; thus reducing the likelihood of uneven bearing and stress concentrations, and the resulting premature failure of the test specimen. Laboratory technicians responsible for capping compressive test specimens should be thoroughly familiar with the capping procedures prescribed in ASTM C 67. Poor caps, resulting from careless capping techniques, can result in erratic test results and a lowering of the apparent compressive strengths of the specimens. Placing Specimens in Testing Machine. The requirement in ASTM C 67 that the specimen be centered under the spherical upper bearing block within 1/16 in. (1.6 mm) is not a capricious one. The introduction of an eccentric load, if the specimen is not carefully centered, can result in a lower apparent compressive strength for the test specimen. It should be understood, however, that this requirement assumes that the specimen is symmetrical about both horizontal axes or its center of gravity. For symmetrical specimens, the center of gravity will be the geometrical center of the unit. Such is not the case with unsymmetrical test specimens. Therefore, the centers of gravity of unsymmetrical specimens should be determined and marked, and it is those marks that should be aligned with the center of the upper bearing block. To determine the center of gravity for an unsymmetrical test specimen, a small steel rod, 1/8 in. to 1/4 in. (3 to 8 mm) in diameter, may be used. The location of the center of gravity is determined by finding the balance point of the brick specimen. To place the specimen over the rod in the exact position such that it balances perfectly is difficult, but a very good estimate of this location is not hard to achieve. Speed of Testing. The speed of testing specified in ASTM C 67 should be adhered to, primarily for the purpose of obtaining consistent results. Past experience on the effect of the rate of loading on the compressive strength of specimens has shown that, as the rate increases, there can be significant increases in the apparent compressive strengths of the specimens. The requirements of ASTM C 67, while not particularly specific, do provide a moderate rate of loading which, if followed, will produce consistent results that will represent more accurately the true compressive strengths of the specimens. ASTM C 67 specifies that the specimen should be loaded to one-half of the expected maximum load, and then the rate should be adjusted such that the test is completed in not less than one minute and not more than two minutes. For this reason, it is a good idea to do one or two preliminary tests to get an estimate of the maximum strength. Figure 2 illustrates the time vs. loading criteria of ASTM C 67.

Compressive Test Loading Rate FIG. 2 Determination of Minimum Net Area (Percent Voids). There are two reasons for determining the void area of brick:

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the first reason is to obtain the percentage of voids (percentage coring) in order to assess whether the brick will be classified as solid or hollow brick; the second reason is to obtain the average net cross-sectional area for determination of net area compressive strength of the units. ASTM C 216 and C 62 for solid brick, and ASTM C 652 for hollow brick require calculation of gross area compressive strength. If the net area compressive strength is required, the section "Measurement of Void Area in Cored Units" in ASTM C 67 should be followed. To perform these measurements, a sample of ten brick is specified by ASTM C 67. Following the procedure in this section, the cores are filled with sand. The sand is then placed in a graduated cylinder to determine the volume. Using the equation given in ASTM C 67 for percent void area, the void area can be determined. The net area can be determined by subtracting the void area from the gross area. Calculation and Report. The compressive strength is determined by dividing the maximum compressive load by the gross cross-sectional area of the specimen. If the net area compressive strength is required, the net area, as determined in the previous section, must be used to obtain the desired results. Since five specimens are used, the arithmetic average should be determined. Initial Rate of Absorption The initial rate of absorption (IRA) is an important property of brick because it affects mortar and grout bond. Brick IRA and mortar retentivity should be considered when selecting brick and mortar type. If the initial rate of absorption is over 2

1 gram per minute per in , brick will absorb moisture from the mortar or grout at a rapid rate, and may impair the strength and extent of the bond. Thus, determining the IRA is important. In the laboratory, the IRA is measured using brick which are oven-dried to equilibrium. The IRA of a dry brick is apt to be higher than one which contains some moisture. The field test for initial rate of absorption is performed on brick in their field condition, i.e., no attempt is made to dry the units. The laboratory test will give an idea of the order of magnitude of the IRA and the field test can be used to determine if additional wetting is necessary. Laboratory Procedure. As previously mentioned, the laboratory procedure is performed on oven-dried specimens. Five full-size specimens are required. The technician performing the test should be aware that the larger the tray size, the less effect the absorption has on the water level. ASTM C 67 requires a tray with a cross-sectional area of at least 300 2

2

2

in. (1935.5 cm ). For a brick with an IRA of 40 g/min/30 in. , the water level would drop less than 1/100 in., which is hardly measurable. Nevertheless, ASTM C 67 provides recommendations on maintaining the water level. Figure 3 illustrates the tray with a brick positioned for testing. The method is relatively straightforward and easy to perform. The results are reported in grams of water gained per 30 sq in. when the brick are immersed in 1/8 in. (3 mm) of water for 1 min. The calculation of IRA is as follows:

where:

IRA

=

30 W / LB

(Eq. 5)

W

=

actual gain in weight of specimen in grams,

L

=

length of specimen, in in. and

B

=

width of specimen, in in.

What some laboratory technicians fail to realize, however, is that the above equation is for specimens that are not cored. If the test specimens are cored brick, or are non-prismatic, the net area must be substituted for LB in Eq. 5.

Determination of IRA FIG. 3 Field Procedures. Brick units on the jobsite may have a different rate of absorption than that of the same units tested for IRA in the laboratory. The IRA may be lower due to moisture which brick absorb after leaving the manufacturing

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plant. Two tests are available for field determination of brick absorption. One is an ASTM procedure, described in ASTM C 67, which measures quantitatively the absorption rate. The other is an approximate, but effective, test which is not covered by an ASTM standard, and yields a qualitative indication of the bricks' absorption rate and necessity for wetting prior to use. ASTM Field Method for IRA - This method is described in detail in ASTM C 67, and is accomplished through volumetric means rather than by weight measurements. Using this method, the brick are placed in a pan of water for 1 min. removed and the quantity of water remaining in the pan is measured using a pycnometer (Fig. 4). The pycnometer is used to measure the initial quantity of water to be placed in the pan. The difference in the original amount of water and the quantity remaining after placement of the brick into the pan for 1 min is the amount absorbed by the brick. It is very important to use the correct size pan and to wet and drain the pan prior to testing.

Pycnometer FIG. 4 Test for Wetting Brick - The following test is useful for determining the necessity of wetting brick prior to use: A circle, approximately 1 in. (25 mm) in diameter, is drawn on the bed surface of the brick, using a wax pencil and a twenty-five-cent coin as a guide. Twenty drops of water are placed into the circle using an eyedropper. If, after 90 seconds, all of the water has been absorbed, wetting the brick prior to placement is recommended.

MORTAR TESTING FOR ENGINEERED BRICK MASONRY Technical Notes 8 Series discusses the various types of mortar, properties and mix designs. Also, ASTM C 270, Specification for Mortar for Unit Masonry, gives both prescriptive and performance requirements for mortar. Another standard specification for mortar, BIA M1-88, provides recommendations on selection proportions and test requirements of portland cement-lime mortars. This section will outline the various mortar tests which are important when designing and building engineered brick masonry elements. Laboratory Testing of Mortar Laboratory testing of mortar is performed in accordance with ASTM C 270 [2]and other standards referenced in ASTM C 270. The tests are performed on mortar samples which are prepared in the laboratory. ASTM C 270 is not a specification to determine mortar strength and properties through field testing. The amount of testing required by ASTM C 270 depends on the method in which the mortar is specified, i.e., proportion or property specification. If the mortar is specified by the proportion specifications, there are no testing requirements for mortar. For mortars specified by the property specifications, water retention, compressive strength and air content tests must be performed. The following sections describe the methods of tests for mortar which are specified by the property specifications. Water Retention. ASTM C 270 refers to the procedures of ASTM C 91 for water retention determination, except that the laboratory-mixed mortar shall be of the same materials and proportions to be used in the construction. Since the water content of mortar used on the jobsite varies somewhat, and is not a specified quantity, the laboratory technician should proportion the cementitious materials and sand in accordance with the job specification and add sufficient water to bring the flow up to 110 +/- 5%.

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To perform the water retention tests, the technician should review ASTM C 91 on Water Retention, ASTM C 305 on Mechanical Mixing, and ASTM C 109 on Performing Flow Tests. The flow test apparatus must meet the specifications of ASTM C 230. The chart in Fig. 5 indicates the ASTM standards relative to water retention testing of mortar specified by the property specifications.

Related ASTM Standards for Property Specifications FIG. 5

Compressive Strength. Compressive strength testing of laboratory-prepared mortar is required under the ASTM C 270 property specifications. To determine compressive strength, samples are to have the same proportions as in the actual construction. As with the water retention test, the amount of water to be used is not clearly stated; therefore, it is recommended that sufficient water be used to bring the flow to 110 +/- 5%. As shown in Fig. 5, other associated ASTM standards which must be used are ASTM C 109, C 305 and C 230. The technician should become familiar with the procedures of ASTM C 109 for specimen molding and load application since these procedures must be followed closely in order to obtain reliable results. Air Content. Air content determination is the third and last property which must be assessed for mortars specified under the property specifications. The air content is determined using a weight-volume relationship to determine the absolute volume of solids and water. ASTM C 91 and ASTM C 185 are used to determine air content, except that the equation for percent air content is given in ASTM C 270. The equation for air-free mortar density is:

(Eq. 2) and the volume of air in percent is

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(Eq. 3) where:

W1

=

weight of portland cement, g,

W2

=

weight of hydrated lime, g,

W3

=

weight of masonry cement (if used), g,

W4

=

weight of sand, g,

Vw

=

volume of water used, mL,

P1

=

unit weight of air-free portland cement, g/cm ,

P2

=

unit weight of air-free hydrated lime, g/cm ,

P3

=

unit weight of air-free masonry cement (if used), g/cm3,

P4

=

unit weight of air-free sand, g/cm ,

Wm

=

weight of 400 mL of mortar, g.

3

3

3

The air-free unit weights of the various materials in Eq. 2 are equal to the specific gravity of the material times the unit weight of water (which is unity); thus, the unit weight is numerically equal to the specific gravity. The specific gravity for the various materials should be obtained from the manufacturers or determined by testing. Table 1 gives the approximate specific gravities for several mortar materials

In performing the air-content tests, it is very important to weigh and measure the quantities accurately, since errors in weights and volumes would have significant impact upon the calculated air content. Field Testing of Mortar For purposes of quality control, field testing of mortar is sometimes required. Field testing should not be confused with laboratory testing, or be performed using the standards and procedures for laboratory testing of mortar. The appropriate standard for this type of testing is ASTM C 780 "Standard Test Method for Preconstruction and Construction Evaluation of Mortars for Plain and Reinforced Unit Masonry". The main purposes of field testing is to ensure that mortar is proportioned properly by the mixer operator, and to obtain an indication of variability or change in constituent materials, quality and performance. There are several tests which are covered in ASTM C 780, not all of which are required. Eight tests are outlined in the Annexes of ASTM C 780 which are: A1) Consistency by Cone Penetration Test Method, A2) Consistency Retention of Mortars for Unit Masonry, A3) Initial Consistency and Consistency Retention or Board Life of Masonry Mortars Using a Modified Concrete Penetrometer, A4) Mortar Aggregate Ratio Test Method, A5) Water Content Test Method, A6) Mortar Air Content Test Method, A7) Compressive Strength of Molded Masonry Mortar Cylinders and Cubes and A8) Splitting Tensile Strength of Molded Masonry Mortar Cylinders. The testing agency and the specifier should be aware that the compressive strength of mortar, as determined by field testing, does not have to meet the minimum compressive strength requirements of ASTM C 270. The specifier must decide which of the eight tests is to be performed, then preconstruction testing of the materials can be performed in order to establish requirements for construction site-sampled mortar. A complete discussion of the test procedures of ASTM C 780 is not within the scope of this Technical Notes; therefore, the technician in charge of performing the tests should become thoroughly knowledgeable with ASTM C 780 and its

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referenced documents.

GROUT TESTING FOR ENGINEERED BRICK MASONRY The specification for grout for engineered brick masonry, ASTM C 476, does not require any laboratory testing. Experience with grout mixed in accordance with the provisions of ASTM C 476 has been extremely favorable, and grout, therefore, does not require extensive testing if mixed with the materials and in the proportions stipulated by the standard. There is a relatively new standard for both field and laboratory sampling and compressive testing of grout used in masonry construction, entitled ASTM C 1019, "Standard Test Method for Sampling and Testing Grout". Sampling and Testing Grout for Engineered Brick Masonry According to ASTM C 1019, the use of the standard may be to select grout proportions by comparing test values or as a quality control test for uniformity of grout preparation during construction. The standard specification for grout, ASTM C 476, does not contain provisions for mixing grout to property specifications; therefore, the use of ASTM C 1019, at this time, for grout mix design is not advised. For purposes of quality assurance, the grout testing standard may be useful. The specimens are prepared by using masonry units as forms (Fig. 6). The masonry units are those which are to be used in the project under construction or to be constructed. The laboratory technician may find it strange to use the brick units as forms, but the reason is to simulate the conditions of the grout after placement into the brick masonry element. Grout is placed with a high water/cement ratio, slump of 10 to 11 in. (250 mm to 275 mm), in order to facilitate consolidation and eliminate voids. Due to the absorptive nature of the masonry, the water content of the grout is reduced after placement. The methods of sampling and testing, as described in ASTM C 1019, are easily accomplished; therefore, additional description and explanation will not be given in this Technical Notes.

Grout Mold Using 2 ¼ in. (152.4 mm) High Standard Size Brick FIG. 6

SUMMARY This Technical Notes has discussed testing of brick, mortar and grout used in engineered brick masonry. Most laboratory and field tests are covered by ASTM standards. Testing agencies using these tests should be fully aware of the procedures and limitations, so that improper application and erroneous results are avoided.

The information and suggestions contained in this Technical Notes are based on the available data and the experience of the engineering staff of the Brick Industry Association. The information contained herein must be used in conjunction with good technical judgment and a basic understanding of the properties of brick masonry. Final decisions on the use of the information contained in this Technical Notes are not within the purview of the Brick Industry Association and must rest with the project architect, engineer and owner.

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Technical Notes 39A - Testing for Engineered Brick Masonry - Determination of Allowable Design Stresses [July/Aug. 1981] (Reissued December 1987) INTRODUCTION

Prior to the development of a rational design procedure for brick masonry, it was sufficient to know that brick masonry units and mortar used were in compliance with the standards outlined in Technical Notes 39 Revised, "Testing for Engineered Brick Masonry - Brick, Mortar and Grout." These quality control tests provided assurance that the same quality of materials were being used throughout the building project. This did not give any assurance or knowledge as to the actual performance of the masonry in the wall. With the development of a rational design method, it became important that the architect and/or engineer have knowledge of the expected performance of the brick and mortar, not as individual parts of the wall, but as the total wall system. With this need in mind, this Technical Notes outlines several ASTM Standard Methods of Tests for Masonry Assemblages which will give the architect and/or engineer the ability to predict in-the-wall performance of masonry and determine allowable design stresses. It is essential in all of the tests described in this Technical Notes that the units, mortar and construction of the assemblage be nearly identical with the materials and methods to be used in the actual construction process. Only in this way can the actual performance of the masonry be accurately predicted. This Technical Notes will cover ASTM standards for the determination of all necessary design stresses for brick masonry as specified in the design standard, Building Code Requirements for Engineered Brick Masonry, BIA, August 1969, and the model building codes in present-day usage. It will also stipulate the revisions necessary to determine the same properties for hollow brick units. Subsequent issues of Technical Notes will discuss miscellaneous tests for masonry not to be used for design stress determinations. These tests will be used primarily for quality control, material comparability and in-the-wall performance predictions for properties other than strength.

STANDARD METHODS OF TESTS

The ASTM test standards with which this Technical Notes is concerned are contained in the Annual Book of ASTM Standards. The methods of tests described in the ASTM standards and listed below should be strictly adhered to; otherwise, the test performed is no longer a standard test and erroneous or misleading results may be obtained. The applicable ASTM standards for masonry are as follows: Compressive Strength and Modulus of Elasticity: Test Methods for Compressive Strength of Masonry Prisms, ASTM Designation E 447. Diagonal Tension (Shear) and Modulus of Rigidity: Test Method for Diagonal Tension (Shears in Masonry Assemblages, ASTM Designation E 519. Method for Conducting Strength Tests of Panels for Building Construction, ASTM Designation E 72.

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Flexural Tensile Strength: Method for Conducting Strength Tests of Panels for Building Construction, ASTM Designation E 72. In addition to the above listed standards, the brick and mortar used should conform to the standards listed in Technical Notes 39 Revised.

PURPOSE AND APPLICATION OF TESTS General. If a rational design approach for masonry is employed, it is essential to establish allowable design stresses early in the design process. Present design standard requirements provide two methods to establish these values. Under these requirements, the ultimate compressive strength (f'm) may be determined by (a) prism test, or (b) an approximation based upon brick strength and mortar properties. The prism test method is the preferred method as it provides the designer with more exact information; whereas the approximation method, of necessity, provides more conservative values.

Allowable design stresses may be determined under the design standard, once an ultimate compressive strength of masonry has been determined. However, in some cases, it may be desirable, or necessary, to establish tensile or shear strength to closer tolerances than is obtained by design standard values usually given as a function of ultimate compressive strength or of brick strengths and mortar types. Such conditions may occur when masonry is to be used in prefabricated panels, is to be subjected to unusual loading conditions or when high, early strengths are desirable. All masonry specimens for establishing design stresses should be built using "inspected workmanship;'' that is to say, all head, bed and collar joints should be completely filled (see Technical Notes 7B Revised for proper procedures). Once strength tests have been performed and masonry properties established, it is necessary to decide if, indeed, inspected workmanship can be achieved at the jobsite. If inspected, workmanship will be achieved, the ultimate stress, f'm , need not be reduced. If, however, uninspected workmanship is expected, the ultimate strength for "uninspected workmanship" must be used. This value is based upon inspected workmanship in which the ultimate strength is reduced by 33 1/3, percent in the design standard.

Test methods for determining strengths and other properties of masonry necessary to establish allowable design stresses are outlined below.

DETERMINATION OF f'm AND Em The ultimate compressive strength (f'm) of masonry may be approximated if the brick to be used have been tested in accordance with ASTM C 67 (see Technical Notes 39 Revised) and mortar type has been established. These values of f'm are given in tabular format in the design standard for both types of workmanship. Values from this table for a known brick strength, mortar type and workmanship classification may be used directly in determination of f'm, and thus the allowable design stresses.

The ultimate compression strength of masonry is best determined by testing of compressive prisms in accordance with ASTM Standard Test Methods for Compressive Strength of Masonry Prisms, E 447. There are two methods of performing this test. Method A, which is used primarily for strength comparisons of different brick and mortars, could be used in the selection process to determine what unit or mortar to use. For determination of ultimate compressive strength of a specific brick and mortar for a specific project, Method B of E 447 should be used. This Technical Notes will concern itself only with Test Method B.

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The test specimens for Method B shall be built to conform as nearly as possible with the actual wall they represent. They should have the same thickness as the wall represented; that is, if the wall is to be a solid wall of two wythes with filled collar joint, the specimens should be the same. Use the same joint dimensions and bonding pattern as the wall. The length of the specimen should be equal to, or greater than, the thickness. It has been general practice to construct specimen lengths equal to 1 1/2 times the thickness. The specimen height should be at least twice the thickness of the specimen or a minimum of 15 in. (3.81 cm). The height generally should not exceed five times the thickness. See Fig. 1 for prisms with h/t from two to five. The height of specimens may be controlled by the testing facilities available. Not all laboratories have testing machines of dimensions which will permit specimens of heightto-thickness of five to be placed in the machine for test. Prior to construction of specimens, a check of facilities available should be made and the specimens constructed with the greatest height-to-thickness ratio which the available machine can accommodate. Correction factors for different height-to-thickness ratios and reasons for them are discussed elsewhere in this Technical Notes. A minimum of three specimens representing each wall type should be constructed and tested. Less than three tests will not give a representative sample. Five specimens of each type of wall are desirable and will give the designer a more accurate ultimate compressive strength value on which he can base allowable stresses.

Compressive Prisms - Slenderness Ratios Two Through Five FIG. 1

All compressive strength specimens on which design stresses are to be based shall be tested at 28 days. The use of 7-day tests for quality control during construction will be discussed in a subsequent Technical Notes. Seven-day tests should not be used for determination of design stresses. However, if for some reason only 7-day test results are available, an approximation of the 28-day strength may be made. The estimated 28-day strength can be obtained by dividing the 7-day strength by 0.90. When prisms with height-to-thickness ratios of less than five are used for design determinations, a reduction factor must be used to determine the ultimate compressive strength of the masonry. Research experience indicates that the mode of failure of masonry walls under compressive loading is by vertical tensile splitting. Therefore, to accurately predict wall strength, the prism failures should be similar. Laboratory studies also show that masonry specimens having slenderness ratios (h/t) of five or greater consistently fail in compression by the mode of vertical tensile splitting and shorter prisms do not. Therefore, a slenderness ratio of five was selected as unity, and lesser slenderness ratio results must be corrected by the factors shown in Table 1. Research has shown a definite relationship between ultimate compressive strengths of prisms ranging from a slenderness ratio of two up to five. Table 1 is based upon this relationship.

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a

Height to thickness.

b

Interpolate to obtain intermediate values.

Solid Brick Compressive Prism - Tensile Splitting Failure FIG. 2

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Hollow Brick Compressive Prism - Tensile Splitting Failure FIG. 3

The h/t of the specimens shall be determined by dividing the actual measured height of the specimen by the actual measured thickness of the specimen. These specimen dimensions shall be determined in accordance with paragraph 6.2 of ASTM E 447. The cross-sectional area shall also be determined based upon actual dimensions of the specimen in accordance with paragraph 6.2 of ASTM E 447. The cross-sectional area to be used for determination of ultimate compressive strength shall be the specimen thickness times the specimen length. For masonry units in accordance with ASTM C 62 and C 216, the gross cross-sectional area shall be used (t x l). If units are hollow brick (ASTM C 652), the net cross-sectional area must be used for determination of ultimate compressive strength. The net cross-sectional area shall be determined as follows: the actual gross cross-sectional area (t x l), using measured dimensions, less the area of voids in the total cross section as measured or determined as outlined in Technical Notes 39 Revised. If the coefficient of variation (v) of the test results on the specimens exceeds 10 percent, the ultimate compressive strength to be used must be modified. This should not be confused with the 12 percent coefficient of variation requirement for the test samples of individual units as covered in Technical Notes 39 Revised. If less than 10 percent, the average of the specimen tests should be used for (f'm ) ultimate compressive strength. When the coefficient of variation exceeds 10 percent, modify the average compressive strength of the specimens by the following equation to obtain f'm:

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where: f'm = ultimate design compressive strength, psi (Mpa)

v = coefficient of variation of the specimen samples tested, percent _

X = average compressive strength of all specimens, psi (Mpa)

The test report should include the average compressive strength, the standard deviation and the coefficient of variation. If this information is not included, they may be calculated as follows:

where:

X = compressive strength of individual specimen, psi (Mpa) Xt = total of all individual specimen compressive strengths, psi (Mpa)

n = number of specimens s = standard deviation, psi (Mpa) v = coefficient of variation, percent In many instances, it is desirable or necessary to know the modulus of elasticity, Em, of the masonry being used. The modulus of elasticity of the masonry can be determined by instrumentation of the specimens to be tested for the determination of ultimate compressive strength. General practice for obtaining the strain of masonry in compression requires the installation of strain gages on compressive prisms. These strain gages, having equal gage lengths, are installed on each end of the prism along the neutral axis of the section (see Fig. 4). It is necessary in the case of multiple wythe wall constructions and/or multiple wythes of dissimilar materials to determine the neutral axis prior to loading as the load should also be applied at the neutral axis. The gage lengths should be as long as practicable.

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Dial strain gages during test should be read at predetermined load levels up to approximately 75 to 80 percent of the anticipated ultimate load and then removed to prevent damage to the gages at specimen failure. The strain in the masonry is determined by averaging the strain gage readings and dividing by the gage lengths as given by the formula:

where:

g = strain, average over entire section, in./in. (mm/mm) D V1 = dial reading gage No. 1, in. (mm) D V2 = dial reading gage No. 2, in. (mm)

g = vertical gage length in. (mm)

Compressive Prism Instrumentation for Modulus of Elasticity FIG. 4

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Once the strains at the various load levels, determined by formula (5) are obtained and stresses are calculated, a stress-strain curve for the specimen should be plotted (see Fig. 5). There are several methods of determining the modulus of elasticity from the stress-strain curve. The most common for masonry are the initial tangent modulus and secant modulus methods. The modulus of elasticity is the slope of the tangent or the secant of the curve. The secant modulus is most commonly used for masonry and is easier to determine. The two points selected on the stressstrain curve are generally at 0 psi (Mpa) and 250 psi (1.72 Mpa) stress levels and the modulus is calculated as follows:

where: Em = secant modulus of elasticity, psi (Mpa) fm0 = 0 psi (Mpa) stress fm250 = 250 psi (1.72 Mpa) stress

g0 = strain at 0 psi stress, in./in. (mm/mm) g250 = strain at 250 psi stress, in./in. (mm/mm) In addition to the determination of the modulus of elasticity by actual tests, the modulus may be based upon f'm of the compressive prism tests stated as a function of f'm. (See Tables 3 and 4 of the design standard. )

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Idealized Stress Strain Curve FIG. 5

DETERMINATION OF f'V AND EV (Vm AND G)

There are two methods of test provided in ASTM standards for the determination of the shear strength of masonry. Shear or diagonal tensile strength is of considerable concern to structural designers, especially in geographical areas where seismic design is required. Until recently, ASTM standards provided only one method of test for determining shear strength. The method of test is described in ASTM E 72, Method for Conducting Strength Tests of Panels for Building Construction. This method of test, referred to as the racking load test in the standard, has been supplemented for masonry by ASTM E 519, Standard Test Method for Diagonal Tension (Shear) in Masonry Assemblages. The E 72 racking load test provides for testing materials and constructions of all types, while E 519 applies only to masonry. It has long been recognized that the method of test provided for in E 72 introduces compressive stresses into the test specimen at the tie down which cannot be measured. See Figs. 6 and 7 for the testing apparatus used for this

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test and method of failure. The tie down is required to prevent rotation of the specimen when load is applied. In addition to the uncertainty of the tie-down stresses, this method of test requires a specimen 8 ft by 8 ft (2.438 m x 2.438 m) in size. This method of test generally is available only in large laboratories active in masonry research. On the other hand, E 519 provides a method of test which is easier to perform and provides very reliable data. The smaller specimens, 4 ft by 4 ft (1.219 m x 1.219 m), plus more simplified equipment place this method of test within the capabilities of many private testing facilities. See Figs. 8 and 9 for test setup and loading shoes required for this test. The specimens for both E 72 and E 519 should be constructed using the brick, mortar, bonding pattern and wall thickness that will be utilized in the construction. These specimens should be constructed using "inspected workmanship" as previously described. Specimens for both tests should be cured for 28 days prior to testing.

Racking Test Frame and Specimen FIG. 6

Racking Test Frame and Specimen After Testing

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FIG. 7

Diagonal Tension Test Instrumentation for Modulus of Rigidity FIG. 8

Diagonal Tension Loading Shoe FIG. 9

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The E 72 method of test calls for three 8-ft by 8-ft (2.438 m x 2.438 m) specimens. The panel can be instrumented as shown in the standard and the horizontal deflection plotted against the load applied in graph form as described in the standard. It has been common practice within the masonry industry to slightly modify this test. In lieu of the instrumentation shown in the standard, a series of strain gages are placed to measure horizontal displacement of the panel under load. These gages are placed along the vertical face of the panel where tie downs and load devices do not occur. The horizontal displacement or strain is then taken at various load levels. The strain is the calculated average of all dial readings at a particular load. The shear stress is calculated by dividing the horizontally applied load by the panel width times the panel thickness. From these data stress-strain curves may be plotted. The instrumentation should be removed at approximately 75 to 80 percent of the calculated load and the specimen tested to failure. Data pertinent to the determination of allowable design stresses are (f'v) ultimate shear stress, a plotted stress-strain curve and the modulus of rigidity at predetermined stress levels, usually 20 percent and 50 percent of ultimate shear stress.

The E 519 method of test also specifies three specimens. Instrumentation of the specimens is provided along the vertical and horizontal diagonals, as shown in Fig. 8. The vertical diagonal instrumentation measures the shortening along that diagonal. The horizontal instrumentation measures the lengthening along that diagonal. The calculations for shear stress for specimens constructed of solid units shall be based on gross area, while the shear stress for hollow unit specimens shall be based on net area. The shear stress shall be calculated as follows:

where: Ss = shear stress on gross or net area, psi (Mpa)

P = applied load, lb (N) A = average of the gross or net areas of the two contiguous upper sides of the specimen, sq in. (mm2)

Formula (8) shall be used when specimens are built of solid units and formula (8a) shall be used for specimens of hollow units.

where:

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(t x l)1 . . . (t x l)2 = thickness and length or gross area of the two upper contiguous sides of the specimen, sq in. (mm2) (t x l) = thickness and length or gross area of upper side of specimen built of hollow units, sq in. (mm2) Av = area of voids of the upper side of specimen built of hollow units, sq in. (mm2)

The shear strain shall be calculated as follows:

where:

g = shearing strain, in./in. (mm/mm) DV = vertical shortening, in. (mm) DH = horizontal lengthening, in. (mm)

g = vertical gage length, in. (mm)

DH must be based on the same gage length as DV.

The modulus of rigidity shall be calculated as follows:

where: Ev = G = modulus of rigidity, psi (Mpa)

The modulus of rigidity is calculated for predetermined stress levels, usually at approximately 20 percent and 50

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percent of ultimate load. The allowable shear stress should be determined by dividing the ultimate shear strength of the specimens by a safety factor selected by the designer, when E 72 or E 519 are used to determine allowable design values. The safety factor used should be based upon the designer's experience, type of workmanship expected, type of loading the masonry will be subjected to, or as recommended in the design standard or Recommended Practice for Engineered Brick Masonry.

DETERMINATION OF f't

At present, only one method of test is available in ASTM standards for determining the ultimate and design flexural tensile strengths for masonry. This method of test is covered in ASTM E 72. Recently ASTM adopted E 518, Standard Test Methods for Flexural Bond Strength of Masonry. This test, however, is to be used only as a compatibility test for brick and mortar or as a quality control test and should not be used for determination of flexural or transverse design stresses. ASTM E 518 will be more fully discussed in a subsequent issue of Technical Notes 39 series. ASTM E 72 provides four methods for testing the large scale panels. The specimen may be tested in either a horizontal (Fig. 10) or a vertical position (Fig. 11). In addition to these methods, the orientation of the masonry panel itself within the loading frame will have great effect on the results obtained. If the span is normal to the bed joints, simulating a wall supported by floor and roof framing in normal construction, the ultimate strengths obtained will be considerably less than those with spans parallel to the bed joints. The panel oriented with a span parallel to bed joints simulates a wall which in normal masonry construction is laterally supported by columns or pilasters.

Transverse Test - Horizontal Uniform Loading (Air Bag) FIG. 10

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Transverse Test - Vertical Uniform Loading (Air Bag) FIG. 11

The specimens for this method of test should be at least 4 ft by 8 ft (1.219 m x 2.438 m) and the same thickness as the proposed project walls. Three specimens are required for this method of test. The specimens should be built using the type of brick, mortar and bonding pattern proposed for the construction project. The specimens should be built using inspected workmanship as described earlier. The test procedure is as follows: The specimen once placed in the test frame, which usually has a span of 6 in. (152.5 mm) less than the specimen size, is instrumented only to measure the center of span deflection. The concentrated load method, whether the specimen is vertical or horizontal, applies two equal loads at a distance of one quarter of the span length from each support. The uniform loading is applied in either position, using an air bag. See Figs. 10 and 11. The loads should be applied in increments with deflection readings taken and recorded at each increment. Instrumentation should be removed at approximately 75 to 80 percent of anticipated ultimate load to prevent damage to the instrument at failure. The report of the test should provide a stress-deflection curve and ultimate transverse strength. The transverse stress at ultimate may be calculated as follows:

where: f't = ultimate transverse stress, psi (Mpa)

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M = bending moment for 1-ft (305 mm) wide strip in.-lb (N-m) S = section modulus of the specimen for 1-ft (305 mm) wide strip, in.3 (mm3)

The moment for uniformly loaded specimens is calculated as follows:

where: w = uniform load, psf (Mpa)

l = span length, ft (mm) The moment for the concentrated loading may be calculated as follows:

where: P = concentrated loads at the quarter points for 1-ft (305 mm) wide strip, lb (N) The section modulus for the specimen must take into account whether the masonry units are solid (up to 25 percent cored) or hollow (26 to 40 percent cored). Calculations for the section modulus of solid units would be as follows:

where: b = width of 1-ft (305 mm) wide strip, in. (mm) d = thickness of specimen, in. (mm) The calculation for the section modulus of hollow units becomes somewhat more complicated and is as follows:

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where: b1 . . . bn = width of cores, in. (mm), see Fig. 12 d1 . . . dn = depth of cores, in. (mm), see Fig. 12

The illustration for this calculation method, Fig. 12, is based on a 3-core unit with nominal length of 12 in. (305 mm). However, the formula can be adapted to fit other sizes of units and coring patterns. All dimensions shall be actual dimensions. Once the ultimate transverse strength has been determined by the test of three specimens, the designer should select a safety factor to apply to arrive at an allowable design stress. This safety factor should be based upon the designer's experience, type of workmanship expected, the in situ loadings expected or as recommended by the design standard.

Typical Hollow Brick Cross Section FIG. 12

CONCLUSION

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The methods of tests described in this Technical Notes provide the design professional with methods to determine allowable design stresses which may be used in the rational design of brick masonry. The values derived from tests will remain valid only so long as the brick properties, mortar properties and workmanship remain relatively close to that specified. The next issue of this Technical Notes series will detail the quality control tests available to insure the designer that he is obtaining masonry properties of sufficient quality to achieve the performance desired.

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Technical Notes 39B - Testing for Engineered Brick Masonry - Quality Control March 1988 Abstract: Testing prior to and during the construction of engineered brick masonry may be required to provide a means of quality assurance. Testing may cover materials, to determine compliance with the project requirements, assemblies, to determine the properties of the masonry as constructed or to establish the properties of masonry in existing structures. The extent of testing required must be determined by the engineering or architectural firm responsible for the project design and will depend upon the complexity and importance of the project. This Technical Notes describes quality assurance procedures applicable to brick masonry assemblies; other issues in this series address testing of component materials and testing to establish allowable design stresses. Key Words: brick, bond strength, diagonal tension, engineered brick masonry, grout, masonry testing, mortar, prism testing, quality assurance, shear, testing. INTRODUCTION Engineered brick masonry design is a rational design procedure based on material properties and fundamental engineering analysis principles. This type of approach, as opposed to an empirical approach, permits the designer to retain the aesthetic qualities of brick masonry and make efficient use of brick masonry's structural properties. Since engineered brick masonry design is dependent on material properties, minimum material strength requirements are determined in the preliminary design phase. Materials (brick, mortar and grout) are selected and may be tested to determine allowable design stresses for the combination of materials selected (see Technical Notes 39A). Quality assurance testing is then performed during construction to evaluate the properties of constructed masonry. The results of these tests are then used to determine if the constructed masonry is acceptable. This Technical Notes discusses standards developed by the American Society for Testing and Materials (ASTM) that may be used for quality assurance testing of engineered brick masonry. This Technical Notes is not intended to replace applicable ASTM standards, but to supplement them. The purpose of this Technical Notes is to serve as an aid in selecting, applying and interpreting tests. The engineer, architect or other responsible person must use judgment in selecting and applying these test methods, but it is hoped that this Technical Notes will aid in that process. PURPOSE OF QUALITY ASSURANCE TESTING Several standards are used in the United States for the design of brick masonry structures. These standards are referenced in most building codes and contain some type of requirement for testing of materials and assemblages to evaluate material properties, design parameters or as a means of quality assurance. Quality assurance testing is specifically performed to determine that the materials, construction and workmanship meet the project specifications. The BIA Standard (Building Code Requirements for Engineered Brick Masonry, Brick Institute of America, McLean, Virginia, August 1969), for example, requires inspection and testing in order for the designer to make use of higher allowable design stresses. Allowable stress values under the BIA Standard are divided into two categories: "With Inspection" and "Without Inspection". If no inspection is provided, the design allowables for "Without Inspection" are used and represent a thirty-three percent reduction in magnitude, as compared to the values permitted for "With Inspection". Therefore, it is advantageous to implement quality assurance measures in some cases to permit higher allowable stress values. The type of inspection required in the BIA Standard typically consists of an inspector (the engineer, architect or other

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responsible party) and some type of testing. The tests outlined in this Technical Notes are those that are most commonly performed to satisfy the requirements of the BIA Standard. TESTING METHODS The ASTM standards commonly used for quality assurance testing of brick masonry materials and assemblies are contained in the Annual Book of ASTM Standards. Current copies of applicable standards should be readily available to laboratory personnel, individuals involved in field sampling and testing, and individuals involved in interpreting test results. The applicable ASTM standards are: Component Materials Clay Masonry Units ASTM C 67, Standard Method of Sampling and Testing Brick and Structural Clay Tile. Mortar ASTM C 270, Standard Specification for Mortar for Unit Masonry. ASTM C 109, Standard Test Method for Compressive Strength of Hydraulic Cement Mortars (using 2-in. or 50-mm Cube Specimens). ASTM C 780, Standard Method for Preconstruction and Construction Evaluation of Mortars for Plain and Reinforced Unit Masonry. Grout ASTM C 476, Standard Specification for Grout for Masonry. ASTM C 1019, Standard Method for Sampling and Testing Grout. Assemblies Masonry Compressive ASTM E 447, Standard Test Methods Strength for Compressive Strength of Masonry Prisms. Flexural Bond Strength ASTM E 518, Standard Test Methods for Flexural Bond Strength of Masonry. ASTM C 1072, Standard Test Method for Measurement of Flexural Bond Strength. In addition to the preceding standards, other standards, while not generally used for quality assurance testing, may be performed in conjunction with compressive and/or flexural bond strength tests to establish a relationship between test methods for quality assurance purposes. These methods listed below are discussed in detail in Technical Notes 39A. Flexural Tensile Strength ASTM E 72, Standard Methods of Conducting Strength Test of Panels for Building Construction. Shear Strength Diagonal Tension (Shear) ASTM E 519, Standard Test Method for Diagonal Tension (Shear) in Masonry Assemblages. Typically, ASTM standards provide clear and concise explanations of the procedures involved in sampling and testing; however, for the novice, some areas may be confusing. Technical Notes 39 Revised presents a complete

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discussion of the preceding standards for testing component materials. The standards are listed here for the sake of completeness only. The remaining standards relating to the testing of masonry assemblages are the subject of this Technical Notes. LABORATORY SELECTION A laboratory selected to perform masonry testing should be properly staffed and be experienced in masonry testing. The equipment available at a laboratory will directly affect the types of tests that can be performed, and the specimens that can be tested. As a minimum, a laboratory will require a curing room with controlled temperature and humidity, and a compression testing machine with a minimum capacity of 300,000 lb and a 15-in. stroke to perform prism tests. Other test methods described in this Technical Notes require more specialized equipment that may not be available at some laboratories. EVALUATION OF MASONRY STRENGTH Compressive Strength General. Masonry assembly compressive strength should be determined by prism tests in accordance with ASTM E 447, Method B (see Figure 1).

Prism Test Schematic FIG. 1 Specimens. A minimum of three prisms should be constructed, using the same materials and workmanship as used in the project. The mortar bedding, joint thickness, joint tooling, bonding arrangement and grouting pattern should be the same as that in the project. No structural reinforcement should be included; however, metal wall ties may be included if used in the project. Prisms should not be grouted unless all hollow cells and spaces in the actual construction are to be grouted. The prism thickness should be the same as that of the actual construction. The prism length should be equal to or greater than the prism thickness. The height of the prism should be at least twice the prism thickness or a minimum of 15 in. (375 mm).

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Handling and Curing. Prisms should be constructed on the jobsite in an area where they will not be disturbed or damaged. Prisms should be subjected to atmospheric conditions similar to those of the masonry they represent for a period of 48 hr prior to being prepared for transportation to the testing laboratory. Prisms should be secured and transported in such a manner so as not to damage them. After prisms are delivered to the laboratory, they should be cured in laboratory air, free of drafts, at 75 deg F +/- 15 deg F (24 deg C +/- 8 deg C), with a relative humidity between 30 and 70% for a period of 26 additional days. Capping. Proper capping of prisms cannot be over-emphasized. Brick units are not perfectly formed and their bearing surfaces may not be parallel and free from surface irregularities. The purpose of capping the bearing surfaces is to assure reasonably parallel and smooth bearing planes. This reduces the likelihood of uneven bearing and stress concentrations that can result in premature prism failure. The capping material itself should have a compressive strength in excess of that expected of the prism to insure that the capping material does not fail before the prism. Laboratory personnel responsible for capping prisms should be knowledgeable of the capping procedures prescribed in ASTM C 67 and C 140. Poor capping techniques and inappropriate capping materials can result in erratic test results and lower apparent prism compressive strengths. Testing. Prisms should be centered under the spherical upper bearing block of the testing machine so that the resulting load will be applied through the center of gravity of each specimen. This is extremely important since the introduction of an eccentric load, if the specimen is not properly centered, can result in lower apparent prism compressive strength. The speed of testing specified in ASTM E 447 should be followed to obtain consistent results. Past experience on the effect of the loading rate on compressive strength has shown that, as the loading rate increases, there may be a significant increase in apparent compressive strength. The prescribed loading rate provides a moderate rate of loading that produces more consistent results and more accurately represents the true prism compressive strength. Calculation and Report. The ultimate compressive strength of a prism is calculated by dividing the maximum compressive load by the cross-sectional area of the prism. For prisms constructed with solid units (ASTM C 216 or ASTM C 62), or units grouted solid, the gross cross-sectional area is used to calculate compressive strength. For prisms constructed with ungrouted hollow units (ASTM C 652), the net cross-sectional area (determined by the procedure described in ASTM C 67) is used in the calculation. When brick masonry prisms with height-to-thickness ratios (h/t) of less than 5 are tested, the ultimate compressive strength, as calculated above, must be multiplied by the factors given in Table 1 to correct for slenderness effects. The report should contain the prism dimensions, prism age, description of materials, maximum compressive load for each prism, cross-sectional area of each prism, compressive strength of each prism, average compressive strength of the specimens, standard deviation and coefficient of variation.

aThese values are different from those now given in the August 1969 BIA Building Code Requirements for

Engineered Brick Masonry. They are based on subsequent research and more nearly reflect the masonry behavior in prisms with h/t less than 5. bHeight to thickness (h/t). cInterpolate to obtain intermediate values.

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Recommendations and Evaluation. When prism tests are used as a means of quality assurance for the BIA Standard, not less than 3 prisms should be constructed for each 5000 sq ft of wall area or each story height, whichever is more frequent. Additional test prisms may be constructed at the discretion of the engineer or architect. Often it is desirable to establish strength relationships for prisms cured less than 28 days to prisms cured for 28 days. This may be established by testing one set of 3 prisms (5 prisms preferred), constructed for each curing period. The prisms should be cured at the site for 24 hr and transported to the laboratory and stored with an ambient temperature and humidity as prescribed in ASTM E 447 for the remainder of the curing period. One set of prisms should be tested at 28 days and the other set tested at the desired age level, typically, 3 or 7 days. From this data, strength relationships between shorter curing periods and 28-day curing periods may be developed. It is desirable to establish the relationship between early prism strengths to 28-day strengths by testing. However, if this relationship is not or cannot be established, an approximate method may be used to predict the 28-day prism compressive strengths. The work represented by the quality assurance specimens may be deemed acceptable if the average 28-day compressive strengths or the projected average 28-day compressive strengths are not less than the specified design compressive strength. Diagonal Tension (Shear) Strength General. Under certain circumstance, it is sometimes necessary to directly establish design shear stresses more accurately than values established as a function of compressive strength (see allowable shear stresses in the BIA Standard). When this is the case, the methods outlined in ASTM E 519 or ASTM E 72 are used to establish design values (see Technical Notes 39A). These test methods require large masonry specimens and cannot be used practically as quality assurance tests. However, these tests may be performed with companion compressive test specimens to develop a relationship between shear and compressive test results. This permits testing of smaller compressive specimens as a means of quality assurance. Companion Specimens. Compressive test prisms should be constructed and tested as outlined in Technical Notes 39A. A minimum of 3 prisms (preferably 5 prisms) should be constructed and tested. The data collected from the compressive prism tests and diagonal tension tests can be used to establish a relationship between prism compressive strength and design shear strength. When this relationship is established, tests can then be conducted by ASTM E 447, in lieu of ASTM E 72 and E 519. FLEXURAL BOND STRENGTH General. ASTM E 518 or C 1072 may be used as quality assurance tests to measure the flexural bond strength between masonry units and mortar. These tests are not intended for use in establishing design stresses. Design stresses should be established through ASTM E 72, as described in Technical Notes 39A. Companion Specimens. A relationship between the flexural bond strength obtained by ASTM E 518 or ASTM C 1072 and the transverse strength of ASTM E 72 may be developed by testing companion specimens. This requires that ASTM E 72 transverse load tests be performed and that companion specimens, as prescribed in ASTM E 518 or ASTM C 1072 be constructed and tested using the same units, mortar and workmanship as the E 72 tests. The data from these tests can then be used to establish the relationship between the transverse flexural strength and the flexural bond strength. Once this relationship has been established, ASTM E 72 tests need not be conducted. Quality assurance tests can then be made by ASTM E 518 or ASTM C 1072. ASTM E 518 Test. E 518 provides two methods for performing tests on flexural beams. Method A uses concentrated loads at 1/3 points of the span (see Fig. 2). Method B uses a uniform loading over the entire span (see Fig. 3) applied by an air bag.

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E518 Method A Test FIG. 2

E518 Method B Test FIG. 3 Specimens - Prisms should be built at the jobsite with the same materials and workmanship as the actual construction. Prisms constructed in the field for quality assurance testing should be protected from damage, but exposed to the same atmospheric conditions as the constructed masonry. These prisms should be stored at the jobsite until the testing date. Testing - While ASTM E 518 does not specify the orientation of the specimens, specimens for both Method A and Method B (see Figs. 4 and 5) should be placed with the tooled joints downward; that is, loads should be applied to the unfinished face. This provides a more standardized test and allows a more accurate comparison of results.

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E518 Method A Setup FIG. 4

E518 Method B Setup FIG. 5 If Method A is used and failure of any specimen occurs outside of the middle third of the specimen, the test results for that specimen should be discarded. Calculation and Report - After testing is completed, the gross area modulus of rupture (tensile bond strength) can be calculated using one of the following formulae: Method A test: specimen made of solid masonry units.

where:

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R = gross area modulus of rupture, psi (Mpa) P = maximum machine-applied load, lb (N) Ps = weight of specimen, lb (N) l = span, in. (mm) b = average width of specimen, in. (mm) d = average depth of specimen, in. (mm) Method B test: specimen made of solid masonry units.

Method A test: specimen made of hollow masonry units.

where: S = section modulus of actual net bedded area, in.3 (mm3) Method B test: specimen made of hollow masonry units.

For calculation of the section modulus based on the net bedded areas of hollow units, the following formulae may be used: Fully bedded hollow units; (see Fig. 6).

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Cross Section-Full Bedded Hollow Unit FIG. 6

where: b1 = width of cores, in. (mm) d1 = depth of cores, in. (mm) Face shell bedded hollow units: (see Fig. 7)

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Cross Section-Face Shell Bedded Hollow Unit FIG. 7

ASTM C 1072 Test. ASTM C 1072, commonly known as the "bond wrench test", permits individual mortar joints to be tested for flexural bond strength by applying an eccentric load to a single joint in a prism (see Fig. 8). This method has several advantages over the ASTM E 518 test method in that: 1) More data is collected from each prism. 2) The data gathered is more representative since each joint in a specimen is tested instead of the weakest joint in the specimen. 3) It may be used to test specimens extracted from existing structures. 4) Joints remaining after testing by the ASTM E 518 method may be tested and the results of the two methods compared. Specimens- Prisms should be constructed at the jobsite with the same materials and workmanship used in the actual construction. Prisms should be constructed in a location where they will not be disturbed or damaged, but be subjected to atmospheric conditions similar to those of the actual masonry. Prisms should be a minimum of 2 units in height, with a minimum width of 4 in. (200 mm). It is recommended that the prisms be a full unit in width. Joints should be 3/8 in. ± 1/16 in. (9.4 mm ± 1.6 mm) in thickness. One face of each prism should be tooled to match the tooling of the project. Prisms should be stored at the jobsite until the testing date. As a minimum, 5 joints should be tested. Testing- Prisms should be placed in the support frame so that the tooled joints face the clamping bolts in the loading arm and are subjected to flexural tension (see Fig. 8). Prisms should be positioned vertically such that a single brick projects above the lower clamping bracket. A soft bearing material a minimum of 1/2 in. (13 mm) in thickness should be placed between the bottom of the prism and the adjustable prism support base. The loading arm clamping bolts should be tightened using a torque of not more than 20 lb-in. (2.3 N-m). Loading should be applied at a uniform rate such that the total load is applied in not less than 1 min. nor more than 3 min.

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Bond Wrench Test Apparatus FIG. 8 Calculation and Report- After testing is completed, the flexural bond strength can be calculated as: Specimens made of solid masonry units

where: Fg = gross area flexural tensile strength, psi (MPa), P = maximum machine applied load, lb (N), P1 = weight of loading arm, lb (N) (See Appendix X1 in ASTM C 1072) L = distance from center of prism to loading point, in. (mm), L1 = distance from center of prism to centroid of loading arm, in. (mm) (See Appendix X1 in ASTM C 1072) b = average width of the cross-section of failure surface, in. (mm), d = average thickness of cross-section of failure surface, in. (mm)

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Specimens made of hollow masonry units

where: Fn = net area flexural tensile strength, psi (MPa), S = section modulus of actual net bedded area, in.3 (mm3), A = net bedded area, in.2 (mm2).

For calculation of section modulus, see Eqs. 5 and 6 and Figs. 6 and 7. The net bedded area may be calculated as:

Fully bedded hollow units; (see Fig. 6)

Face shell bedded hollow units; (see Fig. 7)

EVALUATION OF TEST RESULTS General In most cases, strength levels are established by testing or by the selection of design values. Evaluation then becomes a simple matter of comparing the results of the quality assurance tests with the desired strength levels. Unsatisfactory Test Results Examination of Procedures. Several alternatives are available when test results fall below the required level. If backup specimens are not available for testing, then close examination should be made of the method of prism construction, the handling of the specimens during transportation and storage and of the laboratory facilities and test procedures. Actual stresses should be checked to determine if the lower strength will provide structural stability. After the above observations and calculations are completed, some judgments should then be made. They are: 1. Did mortar proportions or properties change? 2. Did brick properties change? 3. Were there unusual curing conditions? 4.Were specimens damaged during transit or storage?

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5. Were specimens properly constructed? 6. Were test procedures properly followed? 7. Were calculations correctly performed? As a result of these questions, the possible cause of low test results may be determined. Alternate Test Procedure. If no immediate solution is evident and reduced strengths result in safety factors below an acceptable level, prisms may be cut from the area in question and tested as described previously. After specimens are cut from the wall, they should be transported to the lab for testing. If specimens are cut by a water-cooled saw, they should be allowed to dry prior to testing. Exercise of Judgment. If the test results are still low, then a judgment is required. If the field-cut specimen tests result in strengths that lower the factor of safety below an acceptable level, then removal of the masonry in question must be considered. Obviously, this is the last resort after all other possibilities have been closely examined. SUMMARY This Technical Notes has discussed quality assurance testing based on procedures developed by ASTM. Testing agencies using these ASTM test methods should be fully aware of their procedures and limitations, so that improper application and erroneous results are avoided. While the testing procedures outlined in this Technical Notes are primarily for engineered brick masonry under the BIA Standard, they may also be used for non-structural masonry testing and quality assurance testing under other standards. Excessive testing can add unnecessary cost to the project. It is important that care be exercised to avoid excessive testing. It should also be pointed out that, while strengths are important properties of masonry, they are not the only desirable properties. Strengths should not become so important that other desirable properties of masonry are sacrificed. It is still important that masonry be resistant to water penetration, provide sound control and be properly detailed. Quality assurance testing is just one tool to provide assurance that all of the desirable properties of brick masonry are obtained. Testing procedures described in this Technical Notes may involve the use of hazardous materials, operations and/or equipment. This Technical Notes does not purport to address all of the safety practices associated with the use of these test methods. It is the responsibility of the user of this Technical Notes to establish appropriate safety and health practices and determine the applicability or regulatory limits prior to the use of the test methods described. The information contained in this Technical Notes is based on the available data and experience of the technical staff of the Brick Institute of America. The information should be recognized as recommendations which, if followed with judgment, should prove beneficial to the performance of masonry construction. Final decisions on the use of information, details and materials as discussed in this Technical Notes are not within the purview of the Brick Institute of America and must rest with the product designer, owner or both.

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RE

Technical Notes 40 - Prefabricated Brick Masonry - Introduction Revised August 2001 INTRODUCTION The desire of the construction industry to minimize on-site labor and reduce construction time has resulted in the prefabrication of building components. Methods for the prefabrication of masonry have been developed by several segments of the brick industry: mason contractors, brick manufacturers, equipment manufacturers and others closely associated with the industry. This Technical Notes covers the history, advantages, disadvantages, considerations for prefabrication, fabrication methods, materials, specifications and present applications of prefabricated brick masonry. There are several recent developments which make prefabrication of brick masonry possible. The most important is the development and acceptance of a rational design method for brick masonry. Other factors, such as research with new and improved brick units and mortars, have aided the rapid progress in the prefabrication process. This Technical Notes deals only with prefabricated brick masonry using full size brick units. Prefabricated elements of thin brick facing units, in conjunction with concrete, fiberboard or other backings, are discussed in Technical Notes 28C. HISTORY AND DEVELOPMENT Individual uses of prefabricated brick masonry have occurred for more than 100 years. Brick piers were laid on boards for use below sea level in Galveston, Texas prior to 1900. The prefabrication of brick masonry involving equipment rather than bricklayers had its early development during the 1950¹s in France, Switzerland and Denmark. At the same time, the Structural Clay Products Research Foundation, which was once a part of the Brick Industry Association¹s Engineering & Research Division, developed a prefabricated brick masonry system. This system, known as the ³SCR building panel² was used in the construction of several structures in the Chicago area. Most of the early methods of panelization were attempts to mechanize the bricklaying process to produce standard panels, using unskilled labor. Later trends, especially in the United States, have been toward the retention of skilled labor using conventional masonry construction practices and devising various means to increase mason productivity. (See FIG. 1) There are several different methods or systems of prefabrication being used in the U.S. today. Some systems employ proprietary mechanized equipment, while others are not patented but are merely methods of prefabrication developed by individual manufacturers or mason contractors. ADVANTAGES OF PREFABRICATION There are several advantages of prefabrication over conventional masonry construction. By using panelized construction, the need for on-site scaffolding is virtually eliminated. If an off-site plant is used, the work and storage area for masonry materials at the job site are kept to a minimum. When proper scheduling of delivery is maintained, the panels can be erected as they are delivered, eliminating any need for panel storage at the site. The use of panelization also makes possible the fabrication of complex shapes. These shapes can be accomplished without the need for expensive falsework and shoring necessary for laid in-place masonry. Complicated shapes with returns, soffits, arches, etc., are accomplished by using jigs and forms. Repetitive usage of these shapes can lower costs appreciably; the more re-uses, the lower the per panel cost. The designer is able to obtain more complex shapes and different bonding patterns when including brick masonry panels. (See FIG. 2) Fabricating a panel in

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running bond and rotating it results in soldier courses in running bond which are expensive and difficult to execute if conventionally laid. Sloped sills and soffits, along with other shapes and patterns, are easily achieved in this manner. One of the distinct advantages of prefabrication is the possibility of year round work and multi-shift workdays. Off-site construction permits the labor force to work under conditions not affected by weather. The use of prefabricated masonry may eliminate the need for cold weather construction practices. Prefabrication requires stringent quality control. Building panels on a standard form in a single location makes this easier to attain. Mortar batching systems can be tightly controlled by automation or sophisticated equipment. In a factory, the curing conditions are more consistent, since they are less affected by weather changes. Panelization on some projects may save construction time. In most cases it is possible to fabricate masonry panels prior to ground breaking, thus keeping far enough ahead of the in-place construction work to permit panel placement when needed. In the case of bearing wall structures, construction time could be shortened since panels have completely cured when erected. This allows the construction crew to immediately start erection of the next floor level and thus expedite construction. In some cases, the structure of the building, or the perimeter beams, may be downsized due to the ability of the prefabricated masonry panel to span column to column. This distributes the wall load directly to the columns thus lowering the floor load at the slab edge. The savings in construction and time can also provide economy to the building owner. Earlier completion allows earlier occupancy. In the case of rental or commercial properties, this allows the owner to have income production start sooner. DISADVANTAGES OF PREFABRICATION As with any construction method, prefabrication has inherent disadvantages as well as advantages. Prefabrication of masonry to date has not achieved the economy of construction originally desired on flat wall areas. Typically, prefabricated masonry costs are the same or higher than most conventionally laid-in-place masonry on a square foot (square meter) cost basis. The size of brick masonry panels is limited primarily by transportation and erection limitations. Architectural design may, in some cases, need modification to use prefabricated brick masonry. Another disadvantage of prefabricated brick masonry, as in other panel systems, is the limited adjustment capabilities during the construction process. In-place masonry construction allows the brick mason to build masonry to fit the other elements of the structure by adjusting mortar joint thickness over a large area so that it is not noticeable. With prefabricated elements, the adjustments must take place in the connections and the joints between panels. The use of prefabricated elements sometimes requires other crafts or trades to adopt more stringent construction tolerances for their work beyond the standard construction practices for their respected trades. CONSIDERATIONS OF PREFABRICATION The designer must evaluate each project to determine the feasibility and adaptability of prefabrication to that project. Basic questions that must be considered prior to a decision should include, but not necessarily be limited to, the following for each individual project: 1. 2. 3. 4. 5. 6. 7.

Is the building layout, plan and elevation suitable to prefabrication? Is there a location on-site suitable for panel fabrication and storage? Is it desirable to use off-site prefabrication due to the limited size of the building site? What is the completion schedule and what time of year is construction to take place? Are structural design solutions unrealistic when prefabrication is used? Can a reasonable level of quality control in all trades be achieved if prefabricated brick masonry is utilized? Is prefabrication, based on answers to questions 1 through 6, an economical answer?

Contacting a fabricator during the design development or construction document phase of a project may be advisable to determine whether particular elements can be constructed using prefabricated masonry. A fabricator can also advise how different panels can be supported from the building structure. FABRICATION METHODS

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There are two basic manufacturing methods being used in brick masonry prefabrication: hand-laying and casting. The equipment used in prefabrication as practiced today varies widely. It ranges from simple conventional masonry hand tools to highly sophisticated automated machinery. Hand-laying The hand-laying method of prefabrication is similar to conventional laid in-place masonry. That is, the brick are placed in mortar by a mason, except it is accomplished in an area removed from the final location of the masonry element. The bricklaying may be done using conventional bricklaying tools, automated equipment or both. Automated equipment typically has several components: 1. 2. 3. 4.

Devices (such as forms or jigs) for establishing the shape of the panel and locating courses. Scaffolding to keep the bricklayer at a comfortable position (See FIG. 3). Material delivery to the bricklayer. Mortar application.

The hand-laying method will usually employ the conventional mason¹s tools: trowel, jointing tool, etc. In addition, the hand-laying method may also utilize corner poles, jigs, and templates for special shapes. The hand-laying method will usually employ some type of adjustable scaffolding. Adjustable scaffolding can greatly increase mason productivity and reduce fabrication costs. Mechanized and pneumatic mortar spreaders may also be used in the hand-laying method to distribute mortar to the bed joints. This method is particularly adapted to a mason contractor serving as the prefabricator since the contractor¹s regular labor force can be employed. The fabrication operation can be performed either at an off-site plant or an on-site temporary production facility. Casting The casting method of fabrication involves the combining of masonry units, mortar and grout into a prefabricated element using unskilled labor. The casting method is performed with the element either in a horizontal or a non-vertical position. In general, the casting method lends itself to automated equipment that requires a form or an alignment device, some method of placing units and reinforcement, and a method for introducing mortar or grout. The usual practice is to place the units, either by hand or machine, and fill the form with a grout at atmospheric pressure or under moderate pressure. This method of prefabrication usually takes place in an off-site plant. There are specialized tools used in the casting method. Jigs and forms provide for the alignment of the brick and the spacing for the joints. The casting method may require that the face of the unit be protected from contamination by the mortar or grout. This is usually done by applying a contact surface to the exterior face of the brickwork. Pressure at the contact surface of the brick face is created by either an inflated form face or by applying a load to the brick and forcing it into a soft material. Some prefabrication has employed the casting method and automated unit placing machinery. This equipment places the unit with proper joint width by machine in lieu of hand placement of units in jigs or forms. Pressurized grouting systems have also been widely used in the casting method of prefabrication. MATERIALS Masonry Units Both solid brick and hollow brick have been used in prefabrication. Solid brick masonry units are those which have coring of less than 25 per cent of the bedding area. Hollow brick units are cored in excess of 25 per cent but no more than 60 per cent of the bedding area. The hollow units are suitable for and used in applications where reinforcement is required. Reinforcement is often required not only for in-place structural reasons but for loads and stresses included during panel handling. Unit face size is based on economy and appearance, just as in conventional masonry. Dimensional tolerances of the size and face of brick may be more stringent if the casting method is used to form the prefabricated masonry. Specially-shaped units are often employed in fabricated masonry panels. Special units made for returns other than at right angles allow continuity in bond. Channel-shaped units accommodate the placement of reinforcement. Single and multiple wythe panels of the units outlined above have been used in prefabricated work, but single wythe panels are most commonly used.

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Mortar and Grout Prefabrication may use either conventional mortar or mortar with additives to increase bond strength. If the panel is not reinforced, care must be taken to determine compatibility of the brick and mortar. Testing should be performed with the mortar and brick selected for construction to determine if the combination will indeed produce the required flexural strengths for the project. Most masonry panels utilize steel reinforcement to resist tensile and shear stresses due to handling and in-service loads. Fine grout is used to surround the reinforcement and create a homogeneous element. (See Technical Notes 17A for material requirements of reinforced brick masonry.) SPECIFICATION FOR PREFABRICATED PANELS The American Society for Testing and Materials (ASTM) has developed a standard specification for prefabricated masonry panels that includes many items that should be considered when using prefabricated brickwork. The ASTM C 901 Specification for Prefabricated Masonry Panels contain the following sections: Materials and Manufacturing; Structural Design; Dimensions and Permissible Variations; Workmanship, Finish and Appearance; Quality Control; Identification and Marking; Shop Drawings; and Handling, Storage and Transportation. Each section is discussed below. Materials and Manufacture The appropriate ASTM material standards for brick and structural clay tile for use in prefabricated masonry are referenced in this section of ASTM C 901. Brick must meet the requirements of one of the following standards: ASTM C 62 for building brick, ASTM C 216 for facing brick, ASTM C 652 for hollow brick, or ASTM C 126 for ceramic glazed units. Standards for brick that are not included in ASTM C 901, but which can be used to construct prefabricated brick masonry panels are ASTM C 1088 for thin brick veneer and ASTM C 1405 for single fired, glazed brick. Mortar and grout must meet the requirements specified in ASTM C 270 and ASTM C 476, respectively. All metal embedded in masonry panels, except structural reinforcement, must be coated with a corrosion-resistant material or be made of stainless steel Type 304 or 316. This includes all ties, fittings, anchors and lifting inserts. The corresponding specifications for zinc coatings, copper-coated wire, stainless steel, and all types of reinforcement are referenced in this section of ASTM C 901. Structural Design Structural design of prefabricated masonry panels must be performed in accordance with the local building code and ASTM C 901. Where there is no local building code, a national model code should be used. Panels must be designed for all loads and restraining conditions from fabrication to installation and in-service performance. Wind, seismic, and other dynamic loads must be considered as mandated by the building code. Differential movement between dissimilar materials within a panel and between panels and their supports must also be considered. Lifting devices and their connections must have an ultimate capacity of four times the dead weight of the appropriate portion of the panel. Inclination of the lifting forces must also be considered. Dimensions and Permissible Variations Panel sizes are based on multiples of the nominal sizes of the individual masonry units. The nominal thickness of panels shall be the sum of the nominal thickness of the masonry plus the nominal thickness of any cavities. Actual panel thickness must be determined for adequate strength, fire resistance, and other design criteria as required for the type of structure and occupancy. Specified dimensions of the panel can vary from the nominal size by the thickness of one mortar joint or ? in. (13 mm) maximum. Custom dimensions are permitted and should be shown on the drawings or specified, however modular dimensioning is recommended. (See Technical Notes 10A for more information on this subject.) Dimensional tolerances for panel size, thickness, and out-of-square are stated in this section of ASTM C 901.

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Workmanship, Finish and Appearance A sample panel should be used to establish acceptable workmanship and appearance for facing panels. Individual units and joints should be properly aligned. The location of anchors, inserts, and lifting and connection devices should not vary more than 3/8 in. (10 mm) from the specified location. Warpage is limited to a maximum of 1/8 in. (3 mm) for each 6 ft (1.8 m) of panel height or width. Quality Control Brick. The brick unit compressive strength and the initial rate of absorption of brick must be determined. A sample of at least ten units for each 50,000 units used in panel fabrication must be tested in accordance with ASTM C 67. Mortar and Grout. The proportions of mortar and grout must be determined as given in ASTM C 270 or C 476, respectively. Bond enhancing admixtures must be mixed in accordance with the manufacturer¹s specifications. Once the proportions are determined, the compressive strength of a sample of 12 specimens should be determined at intervals of 1, 3, 7, and 28 days to determine the relationship between early-age strengths and the 28-day strength for both mortar and grout. During production, at least one batch of mortar and grout should be sampled each day to determine 1, 3, or 7 day strengths. Completed Panels Masonry assemblies must also be tested. One sample of three compression specimens must be tested for every 5000 ft2 (465 m2) of panel production or every story height. Test one sample of three flexural specimens for each day¹s work. Specimens should be constructed and tested in accordance with ASTM Test Method C 1314 for compressive strength and ASTM Test Method E 518, horizontal beams with third-point loading, for flexure. Also, flexural bond strength may be evaluated by ASTM Test Method C 1072 or ASTM Test Method C 1357 in lieu of the method specified in ASTM C 901. Identification and Marking. Each prefabricated member must be marked to indicate its location on the structure, its top surface, and the date of fabrication. These marks shall correspond to those on the placing drawings. Shop Drawings Shop drawings consist of fabrication drawings and placing drawings. Fabrication drawings show details and locations of reinforcement, inserts, anchors, bearing seats, lifting inserts, coursing, size and shape of openings, and panel size and shape. Placing drawings show panel identification, location, reference dimensions, panel dimensions, dimension of joints between panels, and connection details. Handling, Storage and Transportation Care must be taken not to overstress, warp or otherwise damage the panels during manufacturing, curing, storage, and transportation. Damaged panels must be replaced, unless authorized by the architect or engineer. INSTALLATION OF PANELS Most panels are trucked to the job site and lifted into place by cranes. (See FIG. 4) Lifting devices are built into the panels for this purpose. These panels are usually attached to the structure by welding or bolting. (See FIG. 5) Connections between the panels and other structural elements of the building provide transfer of both vertical and horizontal loads. Typically per panel, there are only two connections located near the bottom that transfer the weight. These connections also transfer horizontal loads. The remaining connections transfer only horizontal loads. PREFABRICATION EXAMPLES The use of prefabricated brick masonry in construction has become quite widespread. Prefabricated brick panels have some very dramatic and aesthetically pleasing applications throughout the United States. Most of the projects built in the United States use single wythe, reinforced brick panels as non-loadbearing curtain wall panels. However,

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panelized brick construction is not limited to curtain wall applications and some loadbearing panels have been constructed. Figures 6 through 10 show several recent construction projects using prefabricated brick masonry panels. The panels for these projects have been built utilizing the full spectrum of methods previously outlined. CONCLUSION Prefabricated brick masonry panels are an excellent solution to a multitude of problems commonly found on jobsites such as material storage concerns, tight construction schedules, and quality assurance issues. Also, there are a wide variety of possibilities that can be achieved with prefabricated panels that would either be cost prohibitive or impossible to construct with brick otherwise. Architects, engineers, and specifiers are urged to work with the manufacturer of the panels to ensure that the desired effects and final goals can be realistically met as addressed previously in Considerations for Prefabrication; they can also reference ASTM C 901 for industry standards and material requirements. Prefabrication of brick masonry is a rapidly developing field and future innovations and needs could greatly affect its value as a design solution. The information and suggestions contained in this Technical Notes are based on the available data and the experience of the engineering staff of the Brick Industry Association. The information contained herein must be used in conjunction with good technical judgment and a basic understanding of the properties of brick masonry. Final decisions on the use of the information contained in this Technical Notes are not within the purview of the Brick Industry Association and must rest with the project architect, engineer and owner. REFERENCES 1. Standard C901-00a Specification For Prefabricated Masonry Panels, American Society for Testing and Materials, Vol. 04.05, 2001. 2. ³Reinforced Brick Masonry - Materials and Construction², Technical Notes on Brick Construction 17A, Reston, VA, August 1997. 3. ³Thin Brick Veneer², Technical Notes on Brick Construction 28C, Brick Industry Association, Reston, VA, February 1990.

FIG.1

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The The Wendel Wyatt Building, Portland, Oregon ZGF Architects, Portland, Oregon (Courtesy of L.C. Pardue, Inc.)

FIG. 2 Complex Shapes With Different Bonding Patterns (Courtesy of Vet-O-Vitz)

FIG. 3 Panel Prefabrication Plant, Automated Scaffolding (Courtesy of Vet-O-Vitz)

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FIG. 4 Placing Panel (Courtesy of Vet-O-Vitz)

FIG. 5 Connection Detail

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FIG. 6 Turn Pike Metroplex, East Brunswick, New Jersey Gatarz Venezia Architects, East Brunswick, New Jersey (Courtesy of Vet-O-Vitz)

FIG. 7 The Center for Molecular Studies University of Cincinnati, Cincinnati, OH Frank O. Gehry & Associates, Santa Monica, CA (Courtesy of Vet-O-Vitz)

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FIG. 8 Sand Lake Plaza, Dayton, OH Hixson Architects and Engineering, Cincinnati, OH (Courtesy of Vet-O-Vitz)

FIG. 9 The Port of Portland Headquarters Portland, Oregon ZGF Architects, Portland, Oregon (Courtesy of L.C. Pardue, Inc.)

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FIG. 10 Safeco Field, Seattle, Washington NBBJ Architects, Seattle, Washington (Courtesy of L.C. Pardue, Inc.)

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TECHNICAL NOTES on Brick Construction 41 1850 Centennial Park Drive, Reston, Virginia 20191 | www.gobrick.com | 703-620-0010 January 2008

Hollow Brick Masonry Abstract: This Technical Note presents information about the use of hollow brick in both structural and anchored veneer applications. Basic properties of hollow brick units are presented, including applicable ASTM standards. Issues specific to hollow brick masonry are discussed, including design details, structural performance and construction methods.

Key Words: compressive strength, hollow brick, reinforced masonry, veneer.

SUMMARY OF RECOMMENDATIONS: Material Selection • Use hollow brick units conforming to the requirements of ASTM C652 • Specify Grade SW brick for most exterior exposures and Grade MW for interior projects and exterior exposures protected from freezing • Specify Type HBS brick for typical projects, Type HBX for projects where higher precision units are desired, and Type HBA for projects where unique variations in dimension or appearance are desired

Structural (Non-Veneer) Construction • When placing mortar, use face-shell mortar bedding • Place reinforcement in accordance with applicable building codes

• In single-wythe walls, add a drainage space to the interior and through-wall flashing where additional water penetration resistance is necessary

Veneer Construction • When placing mortar, use full mortar bedding • Use typical brick veneer details

Other Details • For corbelling, use solid units or solidly filled units with approval of building official • For fireboxes and chimney construction, use solid units or fully grouted units

INTRODUCTION Originally, brick was formed by placing moist clay in a mold by hand. As modern industrial methods were implemented in the brick manufacturing process, the majority of production was changed from a molded process to an extrusion process. Extrusion more easily accommodates the inclusion of holes in a brick unit, which in turn can make the manufacture and use of brick more cost-effective and material-efficient. Traditionally, the size and number of holes in a brick unit have varied based on manufacturer capabilities, type of clay being extruded, type of firing process, and intended use of the product. As part of the evolution of brick unit manufacture and classification, these various hole patterns were categorized into two basic designations: solid brick and hollow brick. Solid brick are defined as having holes (or voids) not greater than 25 percent of the unit’s bed area. Hollow brick are defined as having greater than 25 percent and at most 60 percent void areas. Hollow brick are further classified into those with a void area not greater than 40 percent and those with greater than 40 percent voids. In today’s construction, the majority of hollow brick produced are used in two basic applications. The first is in reinforced or unreinforced single-wythe structural walls. Hollow brick units provide both the structural component and the brick finish without the need for additional materials. Hollow brick for this type of use generally range in size from 4 to 8 in. (102 to 203 mm) in nominal thickness with void areas in the 35 to 60 percent range. Typical single-wythe applications of hollow brick include commercial, retail and residential buildings; hotels; schools; noise barrier walls; and retaining walls. The second application of hollow brick is as veneer units. These brick are generally 3 to 4 in. (76 to 102 mm) in nominal thickness with void areas typically between approximately 26 and 35 percent.

© 2008 Brick Industry Association, Reston, Virginia

Page 1 of 9

Figure 1 presents the three typical configurations of hollow brick units. Actual coring patterns vary by manufacturer and may depend on raw materials, extrusion equipment, firing methods or other factors. Note that as used in Figure 1 and throughout this Technical Note, a “core” is a void having a crosssectional area of 1.5 in.² (968 mm²) or smaller, and a “cell” is a void larger than a core.

Solid Face Shell

Many designers are familiar with the design, construction and performance of masonry built with solid units. Hollow brick masonry is similar in many instances. This Technical Note describes the classifications, properties and uses of hollow brick. Further information regarding single-wythe walls is presented in Technical Note 26. Information on brick veneer construction can be found within the Technical Note 28 Series.

End Shell or Web

PROPERTIES OF HOLLOW BRICK MASONRY

Cell or Core Cell Webs

(a) Solid Shell Hollow Brick

Double Face Shell Cell or Core Cell Webs End Shell or Web (b) Double Shell Hollow Brick

Strength The structural design of hollow brick masonry is governed by model building codes and ACI 530/ ASCE 5/TMS 402 Building Code Requirements for Masonry Structures, also known as the Masonry Standards Joint Committee (MSJC) Code [Ref. 4]. Hollow brick masonry can be designed by empirical requirements or by rational design procedures. Depending on materials and mortar bedding, prescriptive stresses can be different for hollow brick masonry than for solid brick masonry. The following sections highlight some of the specific requirements for hollow brick units.

Cored Face Shell Webs Cell End Shell or Web (c) Cored Shell Hollow Brick Figure 1 Hollow Brick Configurations

Compressive Strength of Units. Compressive strength of hollow brick can be reported on either a gross or net cross-sectional area basis, depending on how the value is to be used. The gross area compressive strength is used to determine compliance with ASTM C652, Standard Specification for Hollow Brick (Hollow Masonry Units Made From Clay or Shale) [Ref. 2] for purposes of durability and empirical design requirements. The net area compressive strength is needed for structural computations in structural applications using rational design of masonry. An internal BIA survey conducted in 1994 showed that the range of compressive strength of 6 to 8 in. (152 to 203 mm) thick hollow brick based on gross cross-sectional area is between 2190 psi (15.1 MPa) and 12,795 psi (88.2 MPa), with an average compressive strength equal to 6740 psi (46.5 MPa). More recent testing indicates hollow brick of 3- to 4-in. (76- to 102-mm) nominal thickness have similar compressive strengths as solid units of the same size [Ref. 5]. Brick units generally have higher compressive strengths than other loadbearing masonry materials. This makes hollow brick particularly well-suited for reinforced masonry applications where the increased strength of the unit can allow thinner wall sections to handle the same loading. Compressive Strength of Masonry. The compressive strength of hollow brick masonry depends on unit strength, mortar type, mortar bedding area, grouting and thicknesses of face shells and webs. The design strength of the masonry can be determined by testing sample prisms (prism test method). During construction, strength can be verified using prism testing or from tabulated values based on brick strength and mortar type (unit strength method). Ungrouted prisms exhibit failure in compression by a splitting of the unit through the cross webs due to www.gobrick.com | Brick Industry Association | TN 41 | Hollow Brick Masonry | Page 2 of 9

Prism Net Area Comp. Strength, psi (MPa)

7,000 (48)

Mortar Type: M S Grouted: Ungrouted:

6,000 (41)

N

5,000 (34) 4,000 (28) 3,000 (21) 2,000 (14) 8,000 (55)

10,000 (69)

12,000 (83)

14,000 (97)

16,000 (110)

18,000 (124)

Unit Net Area Compressive Strength, psi (MPa) Figure 2 Hollow Brick Prism Compressive Strengths

the lateral expansion of the mortar. Filling the cells of hollow brick with grout will generally increase the masonry’s capacity; however, the result is a decrease in the net area compressive strength due to the increased area of the grouted section. The strength of grouted hollow prisms is significantly affected by both the tensile strength of the unit and by the compressive strength of the mortar [Ref. 8]. The compressive strength of hollow brick masonry is based on the minimum net cross-sectional area. This is normally the net mortar bedded area (face-shell bedding) and is used in structural calculations. When using prism testing to determine or verify compressive strength, the MSJC Code requires that the prisms be built with units fully bedded in mortar (i.e., all face shells and webs fully mortared). Values obtained from prism tests must be corrected based on the height-to-thickness (h/t) ratio of the prism. The h/t ratio provides a uniform basis for the determination of compressive strength. Codes stipulate the correction factors to use for masonry prisms. An h/t of 2 has been adopted as the base level. Research shows typical values of ungrouted hollow brick masonry compressive strength based on net area ranging from 3470 psi (23.9 MPa) to 6620 psi (45.6 MPa). Figure 2 shows typical values of the net area compressive strength of grouted and ungrouted hollow brick masonry prisms from the research [Refs. 3, 8]. Flexural Strength. The flexural tensile strength of hollow brick masonry is influenced by mortar and unit configurations and the use of reinforcing steel. Previous research has indicated that face-shell bedded hollow brick masonry exhibits a lower flexural tensile strength than solid brick masonry laid with the same mortar, fully bedded. This is likely due to the relative thickness of the face-shell bedded mortar joints and the drying of the mortar before the hollow unit is laid (face-shell bedding has more surface area exposed to air relative to its volume than does a full mortar bed). More recent research has indicated that the percentage of voids, ranging from approximately 22 to 35 percent, in nominal 4-in. (102-mm) brick has no significant effect on the flexural strength of the resulting fully bedded masonry prism [Ref. 5].

Fire Resistance The excellent fire-resistant qualities of brick masonry are well known. However, there have been relatively few full-scale fire tests of hollow brick masonry walls. This is due in part to the acknowledgment that brick masonry is inherently fire-resistant. Fired clay products provide superior fire resistance. Fire resistance ratings for hollow brick www.gobrick.com | Brick Industry Association | TN 41 | Hollow Brick Masonry | Page 3 of 9

masonry assemblies can be taken from results of actual testing or can be calculated using industry standards. Results from actual wall tests performed in accordance with ASTM E119 are listed in Table 1 [see Ref. 6 and Technical Note 16]. TABLE 1 Fire Resistance Ratings of Hollow Brick Masonry1 Wall Assembly2

Fire Resistance Rating3, Hours

3-in. (76-mm) hollow brick veneer, 1-in. (25.4-mm) air space, building felt, OSB sheathing, wood studs, ½-in. (12.7-mm) gypsum wallboard (fire exposure on brick side)

1

4-in. (102-mm) hollow brick veneer, 1-in. (25.4 mm) air space, building felt, OSB sheathing, wood studs, ½-in. (12.7mm) gypsum wallboard (fire exposure on brick side)

1

4-in. (102-mm) hollow brick masonry, solid grouted

1

5-in. (127-mm) hollow brick masonry

1

6-in. (152-mm) hollow brick masonry

1

8-in. (203-mm) hollow brick masonry, units at least 71% solid, combustible members framed in

1

5-in. (127-mm) hollow brick masonry, solid grouted

2

6-in. (152-mm) hollow brick masonry, solid grouted

3

8-in. (203-mm) hollow brick masonry, units at least 71% solid, with noncombustible members or no members framed in

3

10-in. (254-mm) hollow brick masonry

3

8-in. (203-mm) hollow brick masonry, units at least 60% solid, with noncombustible members or no members framed in, cells filled with loose fill insulation

4

8-in. (203-mm) hollow brick masonry, solid grouted

4

1. Adapted from Refs. 1 and 6. 2. Nominal thicknesses given for masonry. 3. When a ⅝-in. (15.9-mm) layer of plaster is added to the surface of the masonry, the fire resistance rating may be increased by one hour.

An alternative way of determining the fire resistance of a wall assembly is by calculating the equivalent thickness of the brick. This approach has been approved by the model building codes to determine fire resistance ratings of walls not physically tested by ASTM E119. The fire resistance rating of hollow brick masonry is determined by its equivalent solid thickness. The equivalent thickness is calculated by subtracting the volume of core or cell spaces from the total gross volume of a brick unit and dividing by the exposed face area of the unit. The resulting thicknesses can be compared with the requirements given within the building code. As an example, the 2006 International Building Code requires that for a one-hour rating, an equivalent thickness of 2.3 in. (58 mm) of hollow brick be provided [Ref. 1]. For a 28 percent void area, this would equate to an actual brick thickness of 3.2 in. (81 mm). By contrast, the requirement for solid brick is an equivalent thickness of 2.7 in. (69 mm), meaning that a unit with 22 percent coring would need to be 3.5 in. (88 mm) in actual thickness. For additional information on fire resistance ratings and calculations, refer to Technical Note 16.

Water Penetration Resistance The water penetration resistance of hollow brick masonry depends upon the materials, wall construction and workmanship used. The best water penetration resistance is provided by drainage wall systems, such as those incorporating brick veneer. For hollow brick veneer applications, water penetration resistance is provided by proper detailing, including clean air spaces, through-wall flashing and weeps. Testing has shown fully mortarbedded hollow brick veneer to have water penetration resistance similar to that of solid brick veneer [Ref. 5]. For all brick veneer, water penetration resistance depends on proper design and detailing, as presented in Technical Note 7 and the Technical Note 28 Series. Flashing should be provided at the wall base, below and above all wall openings, at roof/wall intersections, and at the tops of parapet walls. Flashing and weeps will collect water that enters the wall and direct it back to the exterior. Many hollow brick used as single-wythe walls are designed to act as a variation of a barrier wall, relying on the thickness and mass of the materials to act as a barrier to water penetration. The single-wythe wall design is not www.gobrick.com | Brick Industry Association | TN 41 | Hollow Brick Masonry | Page 4 of 9

inherently as resistant to water penetration as are drainage wall systems or multi-wythe barrier wall systems and may not be appropriate for some severe exposures. With careful detailing and good construction practices, however, they can perform well. For example, vertically reinforced and grouted brickwork often provides good water penetration resistance. With single-wythe masonry, it is especially important to use a mortar joint profile that sheds, rather than collects, water. Concave and “V” joints are recommended over raked joints, for example. Appropriate details and methods to increase the water penetration resistance of single-wythe hollow brick masonry walls can be found in the Technical Note 7 Series and Technical Note 26. In cases where water penetration resistance is critical, a drainage space should be provided on the interior of the wall assembly. The interior may be furred out and insulation and gypsum board attached. Flashing and weeps are used to drain the space. Another precaution may be the use of a water-resistant membrane placed on the inside face of the wall. Waterproof membranes or polyethylene sheets have been used to resist water that has penetrated the hollow brick wall. Any puncture in the membrane must be properly sealed.

Sound Resistance Because sound insulation increases with increasing wall weight, brick masonry provides very good sound penetration resistance. The sound transmission class (STC) rating is used to determine the sound insulation of walls. Hollow brick veneer generally has an STC of approximately 40 to 45, slightly less than the STC of 45 for solid brick veneer of the same thickness. The STC for through-the-wall brick units is typically calculated as a linear function of weight. A grouted 8-in. (203-mm) brick wall generally has an STC of approximately 50 to 55. In the absence of test results for a particular wall, calculated values of STC ratings can be determined from the following equation: STC = 19.6W 0.23 (Imperial)

or

913.6W 0.23 (SI)

The STC rating is a function of the weight of the wall, W, expressed in pounds per cubic foot (kg/m3). This equation is a best-fit curve based on the average of historical test data [Ref. 7].

DESIGN AND DETAILING Mortar Bedding Requirements for brickwork constructed of hollow brick vary depending on the intended use of the brickwork. For larger hollow brick units used in structural (non-veneer) walls, mortar should be applied to the full thickness of the face shell (face-shell bedding). For smaller hollow brick units that are used in veneer applications, mortar should be applied to the full width of the brick veneer (full bedding) to maintain proper anchor embedment and cover.

Reinforcement Although reinforcement is not always used in hollow brick masonry, the large cells allow the units to be easily reinforced and grouted. The reinforcing must be embedded in grout, not mortar. Reinforcing is most often positioned in the center of the wall but may be placed to one side to maximize the distance from the compression face. Reinforcement is grouted into hollow brick walls to increase the flexural strength, to provide ductility and to carry tensile forces. The flexural strength of a reinforced hollow brick wall depends primarily on the amount of vertical reinforcement because the compressive strength is rarely the limiting factor. The reinforcement resists the flexural tension and the brickwork resists the flexural compression. Building codes may dictate a minimum amount of reinforcement for improved ductility in seismic regions. In reinforced masonry design, any tension resistance provided by the masonry is neglected.

Corbelling and Other Design Details Certain construction details require the use of solid masonry units while others require either solid units or solidly filled hollow units. The use of hollow brick is restricted by the model building codes as follows: Corbelling. For corbelling, use solid units or solidly filled hollow units with approval of building official. Masonry Piers. The height of masonry piers constructed of unfilled hollow units is limited to four times their least dimension. www.gobrick.com | Brick Industry Association | TN 41 | Hollow Brick Masonry | Page 5 of 9

Parapet Walls. An unreinforced hollow unit masonry parapet must be no less than 8 in. (203 mm) thick, and its height must not exceed three times its thickness. Fireboxes and Chimneys. Fireboxes and chimneys constructed of hollow units are required to be grouted solid.

HOLLOW BRICK SPECIFICATION AND SIZES Hollow brick should be specified to comply with ASTM C652, Standard Specification for Hollow Brick (Hollow Masonry Units Made from Clay or Shale [Ref. 2]. When initially issued in 1970, ASTM C652 covered units with void areas up to and including 40 percent in any plane parallel to the surface containing the voids. In 1987, the standard was modified to allow void areas up to and including 60 percent of the unit’s gross area.

Grade Two Grades exist in ASTM C652: Grades SW and MW. As with solid units (governed by ASTM C216, Standard Specification for Facing Brick [Ref. 2]), the Grade establishes requirements to ensure adequate freeze/thaw resistance. Grade SW units provide high and uniform resistance to frost action while saturated with water. Grade MW units are intended for applications that are unlikely to be saturated with water when exposed to freezing temperatures. When the Grade is not specified, ASTM C652 stipulates that the requirements for Grade SW govern. The physical property requirements are shown in Table 2. Two alternates exist in the specification to demonstrate durability without meeting the requirements of Table 2. Brick with a cold water absorption less than 8 percent are exempt from the saturation coefficient requirements. Brick passing a 50-cycle freezing and thawing test are exempt from the boiling water absorption and saturation coefficient requirements. Brick meeting Table 2 requirements or the cold water absorption alternate are not required to be subjected to the freeze/thaw test. TABLE 2 ASTM C652 Physical Property Requirements for Hollow Brick

Designation

Compressive Strength, Gross Area, min.1, psi (MPa)

Five-hour Boiling Water Absorption, max., %

Saturation Coefficient, max.

Average of 5

Individual

Average of 5

Individual

Average of 5

Individual

Grade SW

3000 (20.7)

2500 (17.2)

17.0

22.0

0.78

0.80

Grade MW

2500 (17.2)

2200 (15.2)

22.0

25.0

0.88

0.90

1. Unit in stretcher position with load applied perpendicular to bed surface.

Type Four Types of hollow brick are defined by ASTM C652: Types HBS, HBX, HBA and HBB. Each of these Types relates to the appearance requirements for the brick. Dimensional variation, chippage, warpage and other imperfections are qualifying conditions of Type. The most common, Type HBS, is considered to be standard and is specified for most applications. When the Type is not specified, ASTM C652 stipulates that the requirements for Type HBS govern. Type HBX brick are specified where a higher degree of precision is required. Type HBA brick are unique units that are specified for nonuniformity in size or texture. Where a particular color, texture or uniformity is not required, Type HBB brick can be specified (these applications are typically unexposed locations).

Class The extent of void area of hollow brick is separated into two Classes: H40V and H60V. Brick with void areas greater than 25 percent but not greater than 40 percent of the units’ gross cross-sectional area in any plane parallel to the surface containing the voids are classified as Class H40V. Brick with void areas greater than 40 percent but not greater than 60 percent of the gross cross-sectional area are classified as Class H60V. When the Class is not specified, ASTM C652 stipulates that the requirements for Class H40V govern.

Hollow Spaces (Voids) Hollow spaces may be cores, cells, deep frogs or combinations of these. In ASTM C652, a core is defined as a void having an area equal to or less than 1½ in.² (968 mm²), while cells are voids larger than a core. A deep frog is an indentation in the bed surface of the brick that is deeper than ⅜ in. (9.5 mm). The thickness of face www.gobrick.com | Brick Industry Association | TN 41 | Hollow Brick Masonry | Page 6 of 9

shells and webs are limited by ASTM C652. Figure 1 and Table 3 define the nomenclature associated with hollow brick units and the minimum required thickness of face shells and cross webs. TABLE 3 ASTM C652 Hollow Brick Cross-Sectional Requirements Type of Void

Minimum Distance from Void to Exposed Edge,1, 2 in. (mm)

Minimum Distance from Void to Unexposed Edge,3 in. (mm)

Minimum Web Thickness (Between Void and Core), in. (mm)

Minimum Web Thickness (Between Void and Cell), in. (mm)

Core

⅝ (15.9)

½ (12.7)

¼ (6.4)

⅜ (9.5)

Cell

¾ (19.1)

½ (12.7)

⅜ (9.5)

½ (12.7)

Additional Requirements for Class H60V Units Nominal Width of Units, in. (mm)

Minimum Solid Face-Shell Thickness, in. (mm)

Minimum Cored or Double Face-Shell Thickness, in. (mm)

Minimum End-Shell or End Web Thickness, in. (mm)

3 and 4 (76 and 102) 6 (152)

¾ (19.1)

N/A

¾ (19.1)

1 (25.4)

1½ (38)

1 (25.4)

8 (203)

1¼ (32)

1½ (38)

1 (25.4)

10 (254)

1⅜ (35)

1⅝ (41)

1⅛ (29)

12 (305)

1½ (38)

2 (51)

1⅛ (29)

1. Cored-shell hollow brick with cores greater than 1 in.² (650 mm²) in cored shells shall be not less than ½ in. (12.7 mm) from any edge. Cores not greater than 1 in.² (650 mm²) in shells cored not more than 35 percent shall be not less than ⅜ in. (9.5 mm) from any edge. 2. Double-shell hollow brick with inner and outer shells not less than ½ in. (12.7 mm) are permitted to have cells not greater than ⅝ in. (15.9 mm) in width nor 5 in. (127 mm) in length between the inner and outer shell. 3. Permitted where recess in unexposed edge is ½ in. (12.7 mm) or greater.

The dimensions of the unit and the configuration of its voids are critical for reinforced brick masonry. The cells intended to receive reinforcement must align so that reinforcing bars can be properly placed. Most Class H60V hollow brick contain two cells that are aligned when laid in running and stack bonds. Other bond patterns, such as one-third bond and bonds at corners, may require different unit configurations to permit placement of reinforcement. Size of cores will also influence grout type and grout placement methods. It is advisable to check with the brick manufacturer to determine the coring patterns available. Sizes and Shapes. Hollow brick are commonly available in a variety of sizes, as listed in Table 4. Hollow brick are also made in a variety of special shapes. Special shapes include radial, bullnose, interior and exterior angled corner units and others. Bond beam units are often used where horizontal reinforcing is required. They may be specially made at the plant or cut on site. The brick manufacturer should be consulted for the availability of special shapes. TABLE 4 Typical Nominal Hollow Brick Sizes Unit Designations1

Thickness, in. (mm)

Height, in. (mm)

Queen

3 (76)

2⅔ or 3 ⁄5 (68 or 81)

8 (203)

King

3 (76)

2⅔ or 31⁄5 (68 or 81)

10 (254)

Modular, Engineer Modular

4 (102)

2⅔ or 31⁄5 (68 or 81)

8 (203)

Engineer Norman, Utility

4 (102)

3 ⁄5 or 4 (81 or 102)

12 (305)

Meridian, Double Meridian

4 (102)

2⅔, 4 or 8 (68, 102 or 203)

16 (406)

6" Through-Wall Meridian 8" Through-Wall Meridian, Double Through-Wall Meridian

1

1

Length, in. (mm)

4 (102)

8 (203)

8 (203)

5 (127)

31⁄5 (81)

10 (254)

6 (152)

4 (102)

12 (305)

6 (152)

4 or 8 (102 or 203)

16 (406)

8 (203)

31⁄5 or 8 (81 or 203)

12 (305)

8 (203)

4 or 8 (102 or 203)

16 (406)

12 (305)

4 (102)

16 (406)

1. Unit designations given are standardized nomenclature and encompass the vast majority of current brick production. Additional sizes may be available from individual or regional manufacturers. Refer to Technical Note 10B for a complete list of standardized designations.

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Hollow Brick Masonry Wythe

Hollow Brick Veneer

Additional Masonry

Backing

Min. 1/ 2 in. (12.7 mm) Embedment

Min. 1 1/ 2 in. (38 mm) Embedment

Min. 5/ 8 in. (15.9 mm) Cover

Min. 5/ 8 in. (15.9 mm) Cover

Wire Tie or Joint Reinforcement

Veneer Anchor (Style Varies)

Figure 3 Wall Tie Placement in Hollow Brick Masonry

Figure 4 Anchor Placement in Hollow Brick Veneer

CONSTRUCTION REQUIREMENTS Mortar Bedding In structural (non-veneer) applications, hollow brick units are typically laid with face-shell bedding. Face-shell bedding consists of mortar coverage on the inner and outer face shells of the unit. Cross webs or end webs of the unit may require mortar bedding when grout must be confined within certain cells of partially grouted masonry or on the first course of brickwork. In veneer applications, hollow units should be laid in full mortar beds. Field experience has demonstrated that a veneer constructed of hollow brick units with a nominal thickness of 3 to 4 in. (76 to 102 mm) and laid in a full mortar bed has not significantly increased mortar usage compared to the same veneer constructed of solid brick units. Care should be taken to avoid using excessively plastic mortar or placement methods that would force excessive amounts of mortar into the cells or cores of the brick below. If these steps are taken, the rule of thumb to use seven bags per thousand brick for estimating mortar usage is valid for most hollow brick veneer applications.

Anchors and Ties In some loadbearing and all veneer applications, hollow brick masonry is connected to either another wythe of masonry or to some other structural system. For face-shell bedded hollow brick masonry, the rectangular wire tie or joint reinforcement used must be embedded across one face shell of the hollow masonry and at least ½ in. (12.7 mm) into the other face shell, as depicted in Figure 3. For hollow masonry veneer, where full mortar bedding is required, anchors must be fastened to the backing and embedded into the mortar a minimum of 1½ in. (38 mm), as depicted in Figure 4. Wire ties, joint reinforcement or sheet-metal ties are used for veneer applications. When a backing of wood stud framing is used, corrugated sheet-metal anchors can be used to anchor hollow masonry veneer. Both wall ties and veneer anchors must be recessed from the exposed exterior face of the mortar by a minimum of ⅝ in. (15.9 mm).

SUMMARY Hollow brick are a natural evolution of clay brick manufacturing, providing durable brick units with less raw material. For typical veneer applications, hollow brick can provide a water-resistant drainage wall system. For single-wythe applications, the cells of larger hollow brick units can be reinforced to provide a structural solution. In all applications, hollow brick provide the durability, aesthetics, fire resistance, thermal resistance and overall performance characteristic of clay brick masonry.

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The information and suggestions contained in this Technical Note are based on the available data and the experience of the engineering staff and members of the Brick Industry Association. The information contained herein must be used in conjunction with good technical judgment and a basic understanding of the properties of brick masonry. Final decisions on the use of the information discussed in this Technical Note are not within the purview of the Brick Industry Association and must rest with the project architect, engineer and owner.

REFERENCES 1. 2006 International Building Code, International Code Council, Inc., Country Club Hills, IL, 2006. 2. Annual Book of Standards, Vol. 04.12, ASTM International, West Conshohocken, PA, 2007: C216 C652

“Standard Specification for Facing Brick (Solid Masonry Units Made From Clay or Shale)” “Standard Specification for Hollow Brick (Hollow Masonry Units Made From Clay or Shale)”

3. Brown, R.H., and Borchelt, J.G., “Compression Tests of Hollow Brick Units and Prisms,” Masonry: Components to Assemblages, ASTM STP 1063, J.H. Matthys, ed., ASTM, Philadelphia, PA, 1990. 4. Building Code Requirements for Masonry Structures (ACI 530-05/ASCE 5-05/TMS 402-05), The Masonry Society, Boulder, CO, 2005. 5. Sanders, J.P., and Brosnan, D.A., “The Effect of Void Area on Brick Masonry Performance,” Journal of ASTM International, Volume 4, Issue 1, ASTM International, West Conshohocken, PA, 2007. 6. Southwest Research Institute, “Fire Performance Evaluation of Load-Bearing Brick-Veneer Wall Assemblies Tested in Accordance with ASTM E119-00a, Standard Test Methods for Fire Tests of Building Construction and Materials,” San Antonio, TX, 2007. 7. “Standard Method for Determining the Sound Transmission Class Rating for Masonry Walls,” (TMS 0302), The Masonry Society, Boulder, CO, 2007. 8. Whitlock, A.R., and Brown, R.H., “Compressive Strength of Grouted Hollow Brick Prisms,” Masonry: Materials, Properties, and Performance, ASTM STP 778, J.G. Borchelt, ed., ASTM, Philadelphia, PA, 1982.

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Technical Notes 42 - Empirical Design of Brick Masonry November 1991 Abstract: This Technical Notes provides requirements for the empirical design of masonry structures. These requirements are based on past proven performance. The provisions are taken from ACI 530-92/ASCE 5-92, "Building Code Requirements for Masonry Structures", Chapter 9. Subjects discussed pertaining to ACI 530/ASCE 5 are: lateral stability; allowable stresses; lateral support; thickness of masonry; bonding; anchorage and miscellaneous requirements. Seismic considerations and material requirements are also included.

Key Words: brick, building codes, design standards, empirical design, masonry, stresses.

INTRODUCTION

Empirical design is a procedure for sizing and proportioning masonry elements to form an entire structure or parts of a structure. Empirical design does not require a rational analysis. It is based on rules of thumb and formulas developed over many years of experience. This design method has been used successfully for many decades. Empirical design is generally used for buildings of a small scale nature. The basic premise is that masonry walls are incorporated into two directions of the building along with floor and roof systems for lateral support. Chapter 9 of ACI 530-92/ASCE 5-92 is devoted solely to empirical design procedures. The provisions of earlier empirical standards have been modified to reflect contemporary construction materials and methods. Many requirements remain the same as earlier standards but new restrictions have been added to reflect recent developments. The current model building codes contain requirements for empirical design of masonry. Until the development of ACI 530/ASCE 5, most of the model building code empirical design procedures were based on the ANSI A41.1 (R1970) document which has been discontinued. It is the purpose of this Technical Notes to review many of the pertinent design and construction requirements included in Chapter 9 of ACI 530/ASCE 5. In this Technical Notes, sections of ACI 530/ASCE 5 referenced are given in parenthesis.

SCOPE (9.1)

Chapter 9 of ACI 530/ASCE 5 covers empirical design criteria which can be used for masonry components and masonry buildings in lieu of the design requirements in Chapters 5, 6, 7 and 8. Chapters 5 through 8 contain a rational design for masonry based on the working stress method. The scope of Chapter 9 has three basic restrictions that have not been incorporated in other previous empirical procedures: 1) buildings cannot be located in Seismic Zones 3 and 4 as defined in ASCE 7-88, "Minimum Design Loads for Buildings and Other Structures"

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(formerly referred to as ANSI A58.1); 2) lateral load forces, i.e. wind loads, are restricted to a maximum of 25 psf (1.2 kPa) as referenced in ASCE 7; 3) buildings relying on masonry walls for lateral load resistance cannot exceed 35 ft (10.7 mm) in height. Chapter 9 permits empirical design of masonry elements not acting as a portion of the lateral force resisting system even though the main lateral force resisting system is rationally designed by other chapters contained in ACI 530/ASCE 5. Further, Chapter 9 can be used to design masonry elements in frame structures.

DESIGN

Consideration of lateral stability and lateral support are of prime importance in empirical design. Compressive stresses, thickness of masonry, bonding and anchorage requirements are incorporated in this design methodology.

Lateral Stability (9.3) Shear walls are necessary when lateral support is provided by masonry construction. Shear walls must be provided in two directions, parallel and perpendicular to the assumed direction of the lateral load resisted. The minimum cumulative length of shear walls in any one direction must be at least 40 percent of the long dimension of the building. Portions of walls with openings cannot be included when determining the cumulative length of shear walls. BIA recommends that the cumulative length of shear walls include only wall lengths greater than or equal to one-half the story height of the building. Bearing walls are permitted to serve as shear walls. Shear walls must be a minimum nominal thickness of 8 in. (200 mm). Figure 1 provides an example calculation to determine the cumulative shear wall length.

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MINIMUM CUMULATIVE LENGTH OF SHEAR WALLS = 0.4 X LONG DIMENSION MINIMUM CUMULATIVE LENGTH = 0.4 X 36 FT = 14.4 FT X-DIRECTION = 2 ( 6 + 6 + 6 + 6 ) = 48 FT > 14.4 FT OK Y-DIRECTION = 2 ( 24 + 10 +10 ) = 88 FT > 14.4 FT OK

Cumulative Length of Shear Walls FIG. 1

Shear wall spacing requirements are based on the type of floor or roof construction used in the building under consideration. When using stiffer elements such as cast-in-place concrete floors, the shear wall spacings are greater. Table 1 provides the maximum ratio of shear wall spacing to shear wall length based on the type of floor or roof construction.

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Allowable Stresses (9.4)

Allowable compressive stresses permitted in Chapter 9 are given in Table 2. Compressive stress calculations are based on gross area, not minimum net area as is the case in the rational analysis chapters of ACI 530/ASCE 5. Gross area is based on the actual dimensions of the masonry unit under consideration. When multi-wythe walls are used in construction, the allowable stress taken from Table 2 should be based on the weakest combination of the unit and mortar used for each wythe. The allowable stresses in Table 2 are considered as allowable average stresses, not maximum fiber stresses. These allowable stresses only pertain to vertically applied loads reasonably centered on the wall. Any influence of an eccentrically applied load is limited by the minimum wall thickness and maximum lateral support requirements.

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1Linear interpolation for determining allowable stresses for masonry units having compressive strengths which are intermediate between those given in the

table is permitted 2 1 psi = 6.9 kPa 3 Where floor and roof loads are carried upon one wythe, the gross cross-sectional area is that of the wythe under load; if both wythes are loaded, the gross

cross-sectional area is that of the wall minus the area of the cavity between the wythes. Walls bonded with metal ties shall be considered as non-composite walls unless collar joints are filled with mortar or grout.

Lateral Support (9.5)

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Chapter 9 contains arbitrary limits on the ratios of wall thickness to distance between lateral supports. These limits provide controls on the flexural tension stresses within the wall and limit possible buckling under compressive stresses. Maximum h/t or l/t ratios and minimum thickness used for determining distance between lateral supports are consistent with past masonry standards. Definitions for height (h), length (l) and thickness (t) for use in the allowable lateral support ratios are as follows: h = the vertical distance or height between lateral supports; I = the horizontal distance or length between lateral supports: and t = the nominal thickness of the masonry wall under consideration. ACI 530/ASCE 5 does not provide guidance for computing the thickness of masonry bonded hollow walls or cavity walls bonded with metal ties. BIA suggests that the value for thickness be the sum of the nominal thicknesses of the inner and outer wythes. Masonry walls should be laterally supported in either the horizontal or vertical direction at intervals not exceeding those given in Table 3. Lateral support should be provided by cross walls, pilasters, buttresses or structural frame members when the limiting distance is taken horizontally. Floors, roofs or structural frame members should be used when the limiting distance is taken vertically (see Fig. 2).

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Lateral Support Requirements FIG. 2

Cantilever type walls also have a minimum lateral support criteria. The h/t ratio for cantilever walls should not exceed 6 for solid masonry walls nor 4 for hollow masonry walls.

Thickness of Masonry (9.6) Empirical design requirements pertaining to the thickness of bearing walls and foundation walls are found in Section 9.6. Masonry walls must conform to thickness requirements as well as lateral support and allowable stress requirements. Thicknesses given are nominal dimensions. These requirements are more conservative than empirical design criteria in previous masonry standards. Bearing Walls. The minimum thickness of masonry bearing walls more than one story in height must be 8 in. (200 mm). Bearing walls of one story buildings may be reduced to 6 in. (150 mm). The height to thickness limitation in Table 3 requires a wall of 6 in. (150 mm) in thickness to have a maximum height of 10 ft (3.1 m) Specific provisions are incorporated due to a change in wall thickness between floor levels or floor and roof levels. If a change in wall thickness between floors or between floor and roof levels is desired, the greater wall thickness

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must extend to the lower support level. Wall thicknesses may be changed to meet fire, sound or thermal requirements. Where walls of hollow masonry units or masonry bonded hollow walls are decreased in thickness, a course or courses of solid masonry should be constructed between the thicker wall below and the thinner wall above. Special units or construction are permitted to be used as long as the loads from face shells or wythes of masonry above are transmitted to the wall system below. Foundation Walls. Foundation walls have empirical thickness requirements which are shown in Table 4. Foundation walls must be constructed of either Type M or S mortar. The height of unbalanced fill (height of finished ground above the basement floor or inside ground level) and the height of the wall between lateral supports must not exceed 8 ft (2.4 m), and the equivalent fluid weight of unbalanced fill must not exceed 30 pcf (480.5 kg/m3). Most well-drained sand and gravel backfills have an equivalent fluid weight of less than 30 pcf (480.5 kg/m3). When these conditions are not met, foundation walls must be designed in accordance with Chapters 5 and 6 or 5 and 7 of ACI 530/ASCE 5.

11 in = 25.4 mm 2

1 ft = 0.3048

Parapets. Parapets are required to have a minimum thickness of at least 8 in. (200 mm). Their height cannot exceed three timed their thickness.

Bonding (9.7) Multi-wythe masonry walls may be bonded together by either masonry headers or metal wall ties. Limitations on the area and spacing of masonry headers or metal ties for both solid and hollow units are contained in Chapter 9 of the code. Masonry headers are typically used when bonding barrier type walls (walls of solid units built without air spaces) or hollow walls composed of solid masonry units. Metal ties can be used for barrier type walls (with grouted collar joints) and drainage type walls (a clear air space between wythes of masonry).

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The necessary requirements for bonding multi-wythe walls with masonry headers is shown in Fig. 3. Masonry headers of solid units must comprise not less than 4 percent of wall surface area and extend at least 3 in. (75 mm) into each wythe. The distance between adjacent full-length headers should not exceed 24 in. (610 mm) horizontally or vertically along the wall surface.

Multi-Wythe Bond With Masonry Headers FIG. 3 Two options exist when bonding multi-wythe walls with metal ties, the use of unit metal ties and the use of prefabricated horizontal joint reinforcement. When using unit metal ties, such as Z-ties or rectangular ties (box ties), one tie must be provided for each 4 1/2 ft2 (0.42 m2) of wall area. Ties should be at least 3/16 in. (4.76 mm) in diameter and be corrosion resistant. The maximum vertical distance between ties should not exceed 24 in. (610 mm), and the maximum horizontal distance should not exceed 36 in. (914 mm). Z-ties may not be used with hollow masonry units. Additional metal ties should be provided at all openings, spaced not more than 3 ft (0.91 m) apart around the perimeter and within 12 in. (300 mm) of the opening. These provisions are similar to those for cavity wall construction. When bonding multi-wythe walls with horizontal joint reinforcement, there should be one crosswire metal tie for each 2 2/3 ft2 (0.25 m2) of wall area. The vertical spacing should not exceed 16 in. (400 mm). Crosswires should not be smaller than No. 9 gage wire (W 1.7) and be corrosion resistant.

Pattern Bond. Masonry walls can be laid in either running or stack bond. Running bond is defined by each wythe of masonry head joints in successive courses being offset by at least one-quarter the unit length (see Fig. 4). It is considered stack bond if the longitudinal bond is offset less than one-quarter the unit length, and horizontal joint reinforcement or bond beams with a maximum spacing of 4 ft (1.2 m) vertically with a minimum area of steel equal to 0.0003 times the vertical cross-sectional area of the wall must be provided.

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Typical Foundation Details FIG. 4

Anchorage (9.8)

Masonry elements must be anchored to various components of the building which provide lateral support when using empirical design. Anchorage must occur at intersecting walls, at floors and roofs which adjoin masonry walls and where masonry walls abut structural framing. Anchorage requirements for masonry walls contained in ACI 530/ASCE 5 are as follows:

"9.8.2 Intersecting walls - Masonry walls depending upon one another for lateral support shall be anchored or bonded at locations where they meet or intersect by one of the following methods: 9.8.2.1 Fifty percent of the units at the intersection shall be laid in an overlapping masonry bonding pattern, with alternate units having a bearing of not less than 3 in. (75 mm) on the unit below. 9.8.2.2 Walls should be anchored by steel connectors having a minimum section of 1/4 in. (6.4 mm) by 1 1/2 in. (38.1 mm) with ends bent up at least 2 in. (50 mm) or with cross pins to form anchorage. Such anchors shall be at least 24 in. (600 mm) long and the maximum spacing shall be 4 ft (1.22 m). 9.8.2.3 Walls shall be anchored by joint reinforcement spaced at a maximum distance of 8 in. (200 mm). Longitudinal rods of such reinforcement shall be at least 9 gage (W 1. 7) and shall extend at least 30 in. (762 mm) in each direction at the intersection. 9.8.2.4 Interior non-loadbearing walls shall be anchored at their intersection, at vertical intervals of not more than 16 in. (400 mm) with joint reinforcement or 1/4 in. (6.4 mm) mesh galvanized hardware cloth.

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9.8.2.5 Other metal ties, joint reinforcement or anchors, if used, shall be spaced to provide equivalent area of anchorage to that required by this section. 9.8.3 Floor and roof anchorage - Floor and roof diaphragms providing lateral support to masonry shall be connected to the masonry by one of the following methods: 9.8.3.1 Wood floor joists bearing on masonry walls shall be anchored to the wall at intervals not to exceed 6 ft (1.8 m) by metal strap anchors. Joists parallel to the wall shall be anchored with metal straps spaced not more than 6 ft (1.8 m) on centers extending over or under and secured to at least 3 joists. Blocking shall be provided between joists at each strap anchor. 9.8.3.2 Steel floor joists shall be anchored to masonry walls with 3/8 in. (9.5 mm) round bars, or their equivalent, spaced not more than 6 ft (1.8 m) on center. Where joists are parallel to the wall, anchors shall be located at joists cross bridging. 9.8.3.3 Roof structures shall be anchored to masonry walls with 1/2 in. (12.7 mm) bolts 6 ft (1.8 m) on center or their equivalent. Bolts shall extend and be embedded at least 15 in. (381 mm) into the masonry, or be hooked or welded to not less than 0.20 in2 (129 mm2) of bond beam reinforcement placed not less than 6 in. (150 mm) from the top of the wall.

9.8.4 Walls adjoining structural framing - Where walls are dependent upon the structural frame for lateral support they shall be anchored to the structural members with metal anchors or otherwise keyed to the structural members. Metal anchors shall consist of 1/2 in. (12. 7 mm) bolts spaced at 4 ft (1.2 m) on center embedded 4 in. (100 mm) into the masonry, or their equivalent area. "

Miscellaneous Requirements (9.9) General limitations for masonry structures such as masonry over chases and recesses, lintels over openings, noncombustible supports for masonry walls and corbeling have empirical requirements for proper design and construction. Chases and recesses in masonry walls are sometimes used for visual effects or to receive pipes, conduits or ducts. When chases or recesses are wider than 12 in. (300 mm), the masonry above the chase must be supported by noncombustible lintels, which could be steel angle lintels or reinforced brick masonry lintels. The design of lintels must be in accordance with Section 5.6 which stipulates that the deflection of lintels due to vertical loads should not exceed the span divided by 600 nor 0.3 in. (7.6 mm) when supporting unreinforced masonry. Minimum bearing for lintels is 4 in. (100 mm) on each end of the masonry opening. Masonry is not permitted to be supported by combustible construction, i.e. wood. Even though wood construction may meet the deflection requirements for lintels, this restriction is a fire safety requirement. Corbeling limitations are the same as those required by the model building codes used throughout the country. The maximum corbeled projection beyond the plane of the wall should not be more than one-half of the wall thickness or one-half the wythe thickness for hollow walls. The maximum projection of any single course of masonry should not exceed one-half the unit height or one-third the unit thickness. Solid units are required for corbeled courses of Masonry. Figure 5 illustrates these criteria for corbeling masonry.

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Corbeling Limitations FIG. 5

Seismic Considerations for Empirically Designed Masonry

Appendix A of ACI 530/ASCE 5 contains special requirements for masonry in seismic zones as specified in ASCE 7 (formerly ANSI A58.1). The provisions of Chapter 9 on empirical design of masonry may be used in Seismic Zones 0, 1 and 2, and are modified by Appendix A. Empirical design cannot be used in buildings located in Seismic Zones 3 and 4. For Seismic Zones 0 and 1, all provisions of Chapter 9 apply without modification. There are no restrictions on materials or design methods since these areas of the country represent low seismic risk. Masonry elements in Seismic Zone 2 must meet more stringent requirements. Connections are strengthened and minimum vertical and horizontal reinforcement is required in order to provide more ductility in the structure. All materials also are permitted to be used in the structure. Seismic requirements for buildings or structures in Seismic Zone 2 as contained in Appendix A are as follows:

"A.3.5 Veneer and units not specifically intended for structural use shall not be designed to resist loads other than their own weight or their own shear loads. A.3.6 Masonry walls shall be anchored to all floors and roofs which provide lateral support for the walls. Such anchorage shall provide direct connection capable of resisting horizontal forces required in Section 5.2 or a minimum of 200 lb (90.9 kg) per lineal foot (meter) of wall, whichever is greater. Walls shall be designed to resist bending between anchors where anchor spacing exceeds 4 ft (1.2 m). Anchors in masonry walls shall be embedded in reinforced bond beams or reinforced vertical cells. A.3.7 Structural members framing into or supported by masonry columns shall be anchored thereto. Anchor bolts located in the tops of columns shall be set entirely within the reinforcing cage composed of column

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bars and lateral ties. A minimum of two #4 lateral ties shall be provided in the top 5 in. (127 mm) of the column. Welded or mechanical connections for reinforcing bars in tension shall develop 125 percent of the yield strength of the bars in tension. A.3.8 Vertical reinforcement of at least 0.20 in.2 (129 mm2) in cross-sectional area shall be provided continuously from support to support at each corner, at each side of each opening and at the ends of walls. Horizontal reinforcement not less than 0.20 in.2 (129 mm2) in cross section area shall be provided: (1) at the bottom and top of wall openings and shall extend not less than 24 in. (610 mm) nor less than 40 bar diameters past the opening, (2) continuously at structurally connected roof and floor levels and at the top of walls, (3) at the bottom of the wall or in the top of the foundations when doweled to the wall, (4) at maximum spacing of 10 ft (3.1 m) unless uniformly distributed joint reinforcement is provided. Reinforcement at the top and bottom openings when used in determining the maximum spacing specified in Item No. (4) above shall be continuous in the wall. "

Minimum reinforcement requirements are shown in Fig. 6.

Minimum Reinforcement Requirements for Seismic Zone 2 FIG. 6

"A.3.9 Where head joints in successive courses are horizontally offset less than one-quarter of the unit length, the minimum horizontal reinforcement shall be 0.0007 times the gross cross-sectional area of the wall. This reinforcement shall be satisfied with uniformly distributed joint reinforcement or with horizontal reinforcement spaced not over 4 ft (1.2 m) and fully embedded in grout or mortar "

MATERIALS AND CONSTRUCTION General

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The provisions of ACI 530.1-92/ASCE 6-92, "Specifications for Masonry Structures" have minimum material and construction requirements for masonry structures designed in accordance with Chapter 9 empirical provisions. Masonry units, mortar, grout, reinforcement and accessories are included. This document should be referenced in the project specifications and can be modified as required for the particular project.

Masonry Units The products section permits the use of clay brick, concrete masonry units and stone masonry in empirically designed masonry structures. ASTM standards for clay or shale masonry covered by ACI 530.1/ASCE 6 are ASTM C 34, C 56, C 126, C 212, C 216 and C 652. Grade or class of the units to be used in construction are determined by exposure conditions and required durability. For further information on the manufacture, designation and selection of clay masonry units, see Technical Notes 9 Series.

Mortar and Grout Mortar is required to conform to ASTM C 270 Mortar for Unit Masonry. When job site pigments are used to color mortar there are maximum percentages of color pigment by weight of the cement content which can be added. For portland cement-lime mortars, the maximum content of the coloring pigment is limited to 10 percent for mineral oxide pigments and 2 percent for carbon black. If masonry cements are used, the percentage by weight for color pigments are halved. Grout is required to conform to ASTM C 476 Grout for Unit Masonry. This is a proportion specification for either fine or coarse grout used in construction.

Reinforcement and Accessories ACI 530.1/ASCE 6 contains provisions for reinforcement and metal accessories. All reinforcement and metal accessories are required to be corrosion resistant. Procedures described represent current construction practices and are consistent with model building codes now in existence. Topics that are covered are ASTM standards for the materials, inspection, and detailing and placement of reinforcement and accessories which include tolerances. Corrosion Resistance. Conventional corrosion protection methods attempt to protect metals embedded in masonry by isolating them with impervious coatings, by using metals that are corrosion resistant or by providing cathodic protection. ACI 530.1/ASCE 6 provides requirements for corrosion protection for carbon steel by galvanized coatings. The amount of galvanizing required increases with the severity in exposure of the masonry wall. Anchors, ties and joint reinforcement must meet minimum corrosion protection requirements. Table 5 shows the minimum corrosion protection requirements needed for metal accessories used in masonry walls.

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Construction

Construction requirements within ACI 530.1/ASCE 6 cover the conventional construction practices used in projects that involve empirically designed masonry. The provisions are similar to those found in the model building codes. The basic premise under the construction requirements is to ensure proper placement of materials. Mortar joint filling depends on the type of unit used in construction. Solid units have full head and bed joints. Hollow units are laid with face shell bedding. Requirements include tolerances for erection, collar joints and placement of embedded items such as wall ties and reinforcement. Grout placement is also covered.

SUMMARY

This Technical Notes reviews empirical design procedures contained in ACI 530/ASCE 5. The discussion centers on the requirements which are needed by engineers and architects to fully understand the empirical design of masonry structures within the limits of Chapter 9. The information and suggestions contained in this Technical Notes are based on the available data and the experience of the engineering staff of the Brick Institute of America. The information contained in this publication must be used with good technical judgment. Final decisions on the use of materials and suggestions contained herein are not within the purview of the Brick Institute of America and must rest with the project architect, engineer and owner.

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Technical Notes 43 - Passive Solar Heating with Brick Masonry - Part 1 Introduction June 1981 Abstract: Brick masonry passive solar energy systems can be used to significantly reduce the use of fossil fuels for heating and cooling buildings. The basic concepts and necessary considerations for the design of passive solar heating systems are discussed. The basic concepts involve the incorporation of the passive solar heating system into the architectural design of the intended use and operation of the building. Consideration of environmental factors is also discussed. Key Words: attached sunspaces, bricks, buildings, cavity wall systems, climatology, conservation, direct gain systems, energy, masonry, passive solar heating systems, solar radiation, system operation, thermal storage walls. INTRODUCTION Energy conservation and fuel consumption have become a major concern in recent years. Much of the nation's fuel is used in the heating of buildings. The use of solar heating systems will help to reduce this consumption of non-renewable energy resources. Solar energy is an immediately available renewable energy source. Most buildings can easily be designed to benefit from solar heating. Two types of solar energy systems may be used to heat buildings, active and passive. Active solar heating systems are those which require mechanical equipment for operation. Pumps and other mechanical devices are required to circulate liquids or gases through solar collectors, to storage media, and then to transfer the collected heat to the occupied spaces of the building. Passive solar heating systems do not require the use of mechanical equipment. The heat flow in passive solar heating systems is by natural means: radiation, convection, and conductance. The thermal storage is in the structure itself. Although passive solar heating systems do not require mechanical equipment for operation, this does not mean that fans or blowers may not, or should not, be used to assist the natural flow of thermal energy. The passive systems assisted by mechanical devices are referred to as ''hybrid" heating systems. Passive solar systems utilize basic concepts incorporated into the architectural design of the building. They usually consist of: buildings with rectangular floor plans, elongated on an East-West axis; a glazed South-facing wall; a thermal storage media exposed to the solar radiation which penetrates the South-facing glazing; overhangs or other shading devices which sufficiently shade the South-facing glazing from the summer sun; and windows on the East and West walls, and preferably none on the North walls. Passive solar systems do not have a high initial cost or long-term payback period, both of which are common with many active solar heating systems. This Technical Notes introduces the general features and requirements for the development and application of passive solar heating systems. Passive solar cooling systems are discussed in Technical Notes 43C. Due to the variations in building type and environment which must be considered, it is not normally feasible for passive solar systems to be the sole source of heat in most climatological areas. Construction details are provided in Technical Notes 43G.

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Passive Solar Building with Thermal Storage Wall Under Construction FIG. 1

Combined Thermal Storage Wall System and Attached Sunspace FIG. 2 ENVIRONMENTAL DATA AND REQUIREMENTS Many environmental factors must be considered to fully utilize the concepts of passive solar heating systems. Environmental data is given in Tables 1 and 2 of this Technical Notes. Temperature Exterior design temperatures are important considerations in developing passive solar heating systems. The size of the system will depend upon daily, monthly and annual temperature fluctuations. In mild, sunny climates, the required glazing and thermal storage areas may be relatively small. In temperate, cloudy climates, the required glazing area may be small, but the thermal storage requirements may be greater. In colder climates, the amount of glazing and thermal storage is usually large. The average monthly heating degree days are related to exterior temperature conditions. These values are necessary to determine the total monthly thermal load of the building. Average monthly heating degree days and exterior temperatures are given in Table 2 at the end of this Technical Notes. Latitude Latitude is important to determine the amount of solar radiation and the appropriate summertime shading provided by overhangs and other devices. The further North the building is to be located, the less winter solar radiation it will receive. This is because the sun is above the horizon for a shorter period of time and the solar radiation must penetrate more of the atmosphere. Values of solar radiation at various latitudes are given in Table 1. At higher latitudes, the sun appears lower in the sky. At these latitudes, where the position (altitude) of the sun in the sky is low, larger overhangs are required to shade the South-facing wall from the summer sunlight. Figure 3 shows how the altitude of the sun changes from winter to summer, demonstrating how the South-facing wall may be shaded from summer solar radiation and still be exposed to winter solar radiation by using an overhang. The length of projection required to shade a South-facing wall from the summer sun is given in Table 3.

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Sun Altitude-Winter and Summer

aReprinted with permission from the 1972 ASHRAE Handbook of Fundamentals Volume. ASHRAE HANDBOOK & Product Directory. bProjection greater than 20 ft required.

Solar Radiation Data Solar radiation data is required to determine the amount of radiation transmitted through the South-facing glazing. Actual average solar radiation data for various geographical locations is given in Table 2. The amount of solar radiation is dependent on climate, elevation and latitude. Clear day solar radiation for various latitudes is given in Table 1. Orientation Orientation is extremely important in the design of passive solar buildings. The best performance will usually result when the passive solar system faces true South. True South may be obtained from isogonic (magnetic variation) charts developed by the United States Department of Commerce, Coast and Geodetic Survey, or by consulting a local land surveyor. When the passive solar system faces true South, the system will be exposed to the maximum amount of winter solar o radiation. Deviations of more than 30 East or West of true South are not recommended, especially where maximum performance is desired. Site Topography The topography of the site is of major concern. If the South-facing wall of the building is shaded by natural or man-made elements, it will probably not be feasible to consider passive solar systems. An ideal siting for a passive solar building is to be bermed into a South-facing slope. This provides a South wall exposed to the sun, and a North wall protected from environmental changes by the earth berm. Berming the North wall of the building should be done cautiously to avoid problems caused by ground water and earth pressure. BUILDING TYPE AND USE In addition to environmental considerations building type and use are very important in developing and applying passive solar heating systems. Building type and use are flexible requirements which allow the designer to make

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appropriate adaptations to the structure to provide the desired energy performance. Thermal Load Requirements Thermal load requirements are important in the selection and sizing of passive solar heating systems. The effects of building type and use on the thermal load are determined by the interior design temperature and the allowable temperature fluctuation. A warehouse may not require the same interior design temperature as a residential structure. Many commercial buildings are only occupied during daylight hours and do not have to maintain the higher interior working hour temperatures overnight. In many applications, the passive solar heating systems may provide similar performance as conventional heating systems with night-time setbacks. Another aspect which affects the requirements of the building's use is human comfort. Passive solar systems provide conditions which contribute to human comfort. The brick storage areas of the system are warm. When surrounded by warm surfaces, the human body receives radiation from the warm surfaces. This permits the occupants to feel comfortable at lower interior air temperatures because heat is radiated to the body rather than from the body. Glazing and Lighting Quality The amount of natural lighting required will affect the selection of the type of passive solar heating system. Fabrics and even the glazing material itself may suffer from ultraviolet degradation when exposed to direct sunlight. In applications such as studios, admitting large quantities of diffuse solar radiation provides appropriate lighting. The amount of glazing for most conventional structures is typically determined by the need or desire to provide contact with the exterior or to meet building code egress requirements. This is not usually a primary design consideration for the passive solar heating system Material Properties Massive brick masonry is recommended for thermal storage because of its inherent ability to store heat. Typically, brick exposed to direct sunlight should be of a dark color wherever it is to perform as a thermal storage media. The American Society of Heating, Refrigerating and air-conditioning Engineers (ASHRAE) defines dark colors as dark blue, red, brown and green. The properties of brick as related to passive solar applications are discussed in Technical Notes 43D. System Operation Passive solar heating systems may be shaded from the summer sun by fixed, adjustable or removable shading devices. Adjustable or removable overhangs or shading devices require operation, but permit the optimum use of the winter sun and can completely eliminate any solar exposure on the South-facing glass in the summer. The performance of passive solar systems may be greatly enhanced by the use of night insulation. The insulation may be applied on the interior in the form of drapes or panels. Insulation may also serve as reflector panels or shading devices. Reflector-insulating panels may be hinged at the base of the South-facing glazing so that, when opened during the day, they reflect additional solar radiation through the glazing and when closed, provide night insulation. Night insulation may be operated manually or automatically. Building Design and Appearance There is no reason for passive solar heating systems to have an extremely unconventional design or appearance. The only required variations are: additional South-facing wall glazing, reduced glazing on the East and West walls, and preferably no glazing on the North wall; sufficient overhang or some other shading device to prevent the Southfacing glazing from being exposed to the summer sun; and interior brick masonry. The interior brick masonry exposed to direct sunlight is used as the thermal storage component of the passive solar energy system. Additional interior brick masonry unexposed to direct sunlight is used to provide a thermal flywheel which reduces interior temperature fluctuations. Spatial Requirements The spatial requirements may dictate the type of system used. The depth of penetration of solar radiation into the

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structure may affect the system type selected. Buildings should be arranged with a longitudinal East-West orientation to maximize the solar exposure of the South-facing glazing. This minimizes the distance from the South wall to the North wall, across which the thermal energy from the passive solar energy system has to be distributed. Building energy performance may be increased by heating the North wall with solar radiation entering through the South-facing glazing. DIRECT GAIN SYSTEMS The direct gain system is simple and often used. The system consists of South-facing glazing which allows winter sunlight to enter the habitable spaces of the building. This thermal energy is stored in brick floors and walls. A schematic of a direct gain system is shown in Fig. 4. The South-facing glazing may be windows (operable or fixed), or glass doors. The brick masonry exposed to the solar radiation should generally be a dark color and 4 to 8 in. thick. All walls or other components not exposed to solar radiation should have light-colored surfaces. In the direct gain system, the South-facing glazing permits sunlight to strike the brick masonry construction. The brick masonry, because of its color, mass and thermal properties, provides the thermal storage for the system. The brick masonry absorbs the thermal energy from the sunlight striking its surface. The heat, which is stored during the daylight hours, is released gradually. The heat that is reflected from the brick masonry provides heat to the habitable space during the daylight hours. The light-colored surfaces reflect the heat radiated or reflected from the brick masonry to the air and surroundings in the habitable space. If large amounts of heat are required during the daytime hours and less during night-time hours, this may be accomplished by using lighter colors of brick masonry. Direct gain systems provide rapid temperature increases in the habitable space and may have large temperature fluctuations. This is because such systems often must be designed to prevent overheating. The systems may have limited amounts of brick masonry exposed to the winter sunlight. This is especially true in the lower latitudes where the winter sun has a higher altitude. This may be overcome by providing clerestories to obtain solar radiation on the North wall, as shown in Fig. 4.

Increased Building Depth Using Direct Gain System with Clerestory FIG. 4 Ultraviolet degradation is of the greatest concern when direct gain systems are utilized. Materials subject to ultraviolet degradation should not be exposed to direct sunlight. This may become an inconvenience in the living areas heated by direct gain. The walls and floors exposed to the sunlight and used for thermal storage should not be covered. Wall hangings and carpet greatly decrease the performance of the system. THERMAL STORAGE WALL SYSTEMS The thermal storage wall system, often referred to as a Trombe Wall System, is schematically represented in Fig. 5. The thermal storage wall may be vented, as shown in Fig. 5, and provide heat by radiation and convection, or it may

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be unvented and supply heat by radiation alone. A thermal storage wall system is shown on the left of Fig. 2. It consists of glazing, usually spaced 2 to 4 in. on the exterior of a South-facing wall, constructed of brick masonry. The massive brick wall, usually 10 to 18 in. thick, may be loadbearing, or non-loadbearing.

Vented Thermal Storage Wall System FIG. 5 The winter sunlight penetrating the South glazing heats the brick, the heat slowly penetrates the brick wall and warms the interior. Thermal storage walls may have sufficient heat storage to maintain comfortable temperatures in buildings for periods up to three completely overcast days. The thermal storage wall systems have considerably less temperature fluctuation than do direct gain systems, but usually do not achieve the same high initial interior temperatures. The massive brick thermal storage wall prevents ultraviolet degradation of materials contained in the living space because solar radiation does not directly enter the habitable space. The performance may be substantially increased by providing vents at the top and bottom of the brick wall to provide convection in addition to the heat radiated from the interior face of the wall. Vented walls may be used to decrease the temperature fluctuations and increase the maximum temperature achieved in the living space. Fig. 1 shows a vented thermal storage wall under construction. When venting the storage wall system, vents with automatic or manual closures should be used so that the system does not reverse at night, creating a heat loss. If controlled vents are not installed on the vented thermal storage wall systems, night insulation is essential to prevent heat losses at night. Night insulation may be required on unvented thermal storage walls and those with controlled vents to increase the efficiency of the system. COMBINED SYSTEMS The best thermal performance and living conditions result by combining the thermal storage wall system and the direct gain system. This combination permits some direct sunlight into the living spaces, achieves higher interior temperatures than the thermal wall system alone, provides less temperature fluctuation than the direct gain system alone and provides natural lighting. The combination essentially utilizes the best of the two systems. ATTACHED SUNSPACES Attached sunspaces are a combination of the components of the direct gain system and the thermal storage wall system, as shown in Fig. 2 on the right, and in Fig. 6. The sunspace is a room, or space, which typically has both a glass roof and a glass South-facing wall. The East and West walls may also be glass. The floor is similar to that of the direct gain system. It consists of 4 to 8-in. thick brick masonry. The North wall is a 10 to 18-in. thick brick thermal storage wall. The room is vented or ducted to other areas of the structure. With the assistance of fans and blowers, the structure is heated by the extreme temperatures achieved in the sunspace. The sunspace usually has severe temperature fluctuations and is often unbearably hot during daylight hours. They do require removable shading devices to prevent solar gains in the summer. They will also require night insulation if they are to become useable living space in the evening hours.

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Attached Sunspace FIG. 6

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CAVITY WALL SYSTEM The cavity wall system, shown in Fig. 7, is a modification of the double envelope system. The concept of the cavity wall system is that the South-facing thermal storage wall heats up and creates a convective loop around the entire building envelope. The warmed air space minimizes the temperature differential from the interior of the building through the inner wythe of the cavity wall. There are no generally accepted design procedures for this type of system presently available. Some experts in the passive solar design field feel that the increased thermal

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performance may be accounted for by the insulation in the interior and exterior shells of the double envelope system. Others feel that there is no convective loop occurring, i.e., the air between the double envelope shells is stagnant.

Cavity Wall System FIG.7 The use of a properly constructed, insulated brick cavity wall on the North side of the building could be used to provide a moderate heat loss to drive the convective loop through the air space in the building envelope. This would reduce the temperature of the air being circulated through the cavity, but the air should still reach high enough temperatures as it passes through the air space of the thermal storage wall system to provide a net heat gain. Since there is still considerable controversy regarding this type of system, and since accurate performance analysis is not easily accomplished, these systems should only be designed and constructed with the appropriate awareness of the expected and achievable performance level of the system. METRIC CONVERSION Because of the possible confusion inherent in showing dual unit systems in the calculations, the metric (SI) units are not given in this Technical Notes. Table 13 in Technical Notes 4 provides metric (SI) conversion factors for the more commonly used units. SUMMARY This Technical Notes has provided general information concerning passive solar heating systems. It has described several passive solar heating systems, the basic principles of their operation and general design consideration. This introduction to passive solar heating systems hopefully provides sufficient familiarization with concepts so that the design of such systems will be understood. Passive solar cooling is discussed in Technical Notes 43C. The material properties of brick masonry, as related to passive solar energy systems, is provided in Technical Notes 43D.. Details and construction information are provided in Technical Notes 43G. This Technical Notes does not and is not intended to provide information for specific designs and applications, but rather offers general information to assist in the consideration and use of brick masonry in passive solar heating systems. The decision to use these concepts in the design specific applications is not within the purview of the Brick Institute of America, and must rest with the owner or designer of any specific project. Environmental Data for Passive Solar Systems TABLE 2a,b

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aReprinted from the U.S. Department of Commerce, National Oceanic and Atmospheric Administration, Environmental Data and Information Service, National Climate Center, Asheville, North Carolina - "Input Data for Solar Systems," by V. V. Cinquemani. J. R. Owenby, Ir., and R. G. Baldwin. b Based on 1941 - 1970 Period. Zeros appearing for all values appearing in these columns signify that 1941 - 1970 period normals were not available.

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aReprinted with permission from the 1972 ASHRAE Handbook of Fundamentals Volume, ASHRAE HANDBOOK & Product Directory

Projection greater then 20 ft required.

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Technical Notes 43C - Passive Solar Cooling with Brick Masonry - Part 1 - Introduction [March 1980] (Reissued Feb. 2001) Abstract: Brick masonry passive solar energy systems can be used to significantly reduce the use of fossil fuels for heating and cooling buildings. The concepts of passive solar cooling systems discussed here are simple modifications to passive solar heating systems. For locations where humidity is high, or there is little exterior temperature fluctuation, or applications where low interior design temperatures are required, passive solar cooling may not be viable. Several methods of pre-cooling and the concept of dehumidifying air with these systems are introduced. Key Words: attached sunspace, bricks, buildings, cavity wall systems, climatology, conservation, direct gain systems, effective temperature, energy, masonry, passive solar cooling systems, passive solar heating systems, solar radiation, system operation, temperature, thermal storage wall systems. INTRODUCTION The application of passive solar energy systems using brick masonry can help to significantly reduce the amounts of fossil fuels and electric energy currently being used for heating and cooling buildings. Other Technical Notes in this Series address passive solar heating systems with brick masonry. They discuss the general concepts, the procedures for sizing the systems, and the performance calculations. This Technical Notes introduces the concept of passive solar cooling systems using brick masonry. PASSIVE SOLAR COOLING The terminology "passive solar cooling" does not necessarily refer to the actual reduction of the interior air temperature of the building. "Passive solar cooling" is a means of providing comfortable interior conditions by properly using the natural flow of thermal energy to create air movement. These "cooling" systems provide comfort by controlling the effective temperature of the interior of a building. The effective temperature is a measure of the comfortable air conditions in a building dependent upon the actual temperature of the air, the level of relative humidity, and the amount of air movement. By properly varying any one, or any combination of these factors, more comfortable interior conditions can be achieved. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) provides methods which may be used to determine the amount of change or fluctuation necessary to achieve comfortable interior conditions. These methods are described in ASHRAE 1997 Handbook of Fundamentals, and ASHRAE Standard 55-92, Thermal and Environmental Conditions for Human Occupancy. The actual determination of the effectiveness of passive solar cooling is complex and its performance is not yet satisfactorily predicted with calculation procedures alone. The type of passive solar cooling system selected, and its performance can be greatly affected by the site and the climatological conditions. SYSTEMS AND OPERATION The basic passive solar heating systems, utilizing brick masonry, are discussed in Technical Notes 43, These systems are: thermal storage wall systems, direct gain systems, attached sunspaces and combinations of these. These passive solar heating systems can be easily modified to provide interior comfort during the cooling season. Obtaining all the necessary cooling with passive solar cooling systems usually is neither economically nor thermally feasible for the entire cooling season. These simple modifications to passive solar heating systems can be used to create more comfortable interior conditions for at least part of the cooling season in most climates. The necessary modifications to passive solar heating systems to provide passive solar cooling are provisions for 1) exhausting air from the interior, and 2) intaking exterior air. Schematics are shown in Figs. 1, 2, and 3 for the direct

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gain system, attached sunspace, and thermal storage wall system, respectively. The principal modification is to provide controlled openings for exhausting the internal heat gained by the passive solar heating system. The controlled openings should be at the highest points of the structure, preferably in the roof/ceiling, or gable. Control of the openings may be provided with operable vents, or registers. Similar openings can be placed at the low points of the structure for intaking exterior air. The openings for intaking exterior air may be the windows or doors of the structure. The operation of each of these systems is very similar in the cooling mode: (1) sunlight strikes the south-facing glazing, (2) solar energy is transmitted through the south-facing glazing to the brick masonry thermal storage media, (3) the brick masonry absorbs and stores the heat, (4) radiant heat from the surface of the brick masonry rises, (5) the heated air is exhausted through the controlled openings at the top of the structure, (6) as the heat is exhausted, exterior air is drawn into the structure, and (7) the air movement created by exhausting and intaking air through the structure creates the effect of cooling and provides more comfortable interior conditions.

Cooling With the Direct Gain System FIG.1 Direct Gain System The direct gain system, when applied as passive solar cooling, is the most economical, but probably the least effective. The minimum 4-in. ( 100 mm) thick brick masonry floors and walls on the interior are exposed to direct sunlight to absorb and store heat. The interior brick masonry should be dark to absorb most of the heat and radiate and reflect only a small portion during the day. The gradual release of radiant heat through the night draws the cool night air into the structure and cools the structure. The system is only advantageous when the nighttime temperatures consistently fall below the interior design temperature and when internal solar heat gain can be adequately controlled to prevent overheating in the daytime. A major problem with using a direct gain system is that the interior space used to store heat is also an integral part of the habitable space of the building. Attached Sunspace Using the attached sunspace for passive solar cooling is probably more effective but less economical than direct gain cooling. In the attached sunspace, the heat storage element is not usually part of the space that is to be cooled. The system schematic is shown in Fig. 2. Although the intent in many applications is to use the attached sunspace as a greenhouse, this is not advantageous in most applications because the greenhouse will be vented to the interior and the humidity from watering plants may result in uncomfortable interior conditions and condensation problems. The major disadvantage of this system is the

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cost of the additional floor area which has limited use.

Cooling With the Attached Sunspace FIG. 2

The system consists of minimum 4-in. ( 100 mm) thick brick masonry floors, south-facing glazing and preferably a 10 to 18-in. (250 to 450 mm) thick vented brick masonry thermal storage wall between the sunspace and the habitable portion of the building. In the cooling mode, the top vents of the brick masonry storage wall are closed and the bottom vents are open. The air in the sunspace is heated by radiant heat from the brick masonry. The heated air rises through operable openings in the roof of the sunspace, drawing air from the habitable spaces through the bottom vents of the brick masonry thermal storage wall. The air drawn from the habitable space is replaced by exterior air drawn in through operable windows or doors. Thermal Storage Wall System One of the most economical and effective passive solar cooling systems is the vented thermal storage wall, shown schematically in Fig. 3. The greatest advantage of the thermal storage wall is that the heat used for the passive solar cooling does not directly enter the interior spaces of the habitable portion of the building. The system consists of exterior glazing 2 to 4 in. (50 to 100 mm) in front of a 10 to 18-in. (250 to 450 mm) thick vented brick masonry wall used for storing heat. Operation is similar to that of the attached sunspace. The operable openings for exhausting the heated air may be located at the top of the exterior glazing. The exhaust system may also be operable vents at the top of the airspace from which the air may be exhausted through additional vents in the roof. When using the latter exhaust system, additional vents from the habitable space through the roof/ceiling component may be used to increase the heat flow from the interior, thereby drawing additional air into the building.

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Cooling With the Vented Thermal Storage Wall System FIG. 3

CONTROLS These three basic passive solar heating systems, as modified for passive solar cooling, require controls to regulate internal heat gain and the level of comfort, "cooling", achieved. These controls may be automatically or manually operated vents, or registers. The controls should be such that the system can be totally "shut down" when it is not being effective, i.e., when exterior conditions are such that a comfortable effective temperature cannot be maintained inside the building. Shading devices are required as a means of controlling the amount of sunlight permitted to enter the structure for operation of the passive solar cooling system. These may be automatic or manual devices, but are necessary to prevent overheating that can occur during the cooling season when the interior temperature, i.e., effective temperature, will no longer be within the comfort range. The entire system must be completely shut down before mechanical/refrigeration cooling systems are put into operation. Shading the south-facing glazing and closing openings are required for efficient use of any conventional cooling system. Obviously, operation is a critical factor in the performance of "passive solar cooling systems". CAVITY WALL SYSTEM A system which may be effectively used for cooling, with less consideration of the climatic conditions, is the cavity wall system, schematically represented in Fig. 4. The north and south walls of the structure are uninsulated cavity walls (see Technical Notes 21 Series). The south-facing wall, above grade, is an unvented thermal storage wall. The airspace in the thermal storage wall system is open at the bottom to the cavity of the basement or foundation wall, and at the top to the roof/ceiling. The cavity of the wall is open to ductwork extended in the north-south direction through the basement floor, or crawl space. As shown in Fig. 4, this provides an air passageway within the building envelope components. A ductwork system is provided from the base of the cavity to vents on the exterior. Exhaust vents are provided in the roof or gable ends.

Cavity Wall System Cooling Mode FIG. 4

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With the cavity wall system, the south-facing glazing exposes the brick thermal storage wall to sunlight, which heats up and causes air to rise through the cavity. As the air rises, it is vented to the exterior from the top of the cavity, and exterior air is drawn into the cavity via the ductwork system and exterior vents. This provides a means of keeping the entire building envelope cooled. Since the surfaces warmed during the daytime hours retain heat, this continues through the evening hours, further cooling the building envelope. The cooled building envelope and interior require a longer time period to be heated up to uncomfortable temperatures during the daytime hours of the next day. The advantages of passive solar cooling with the cavity wall system are: (1) shutdown is not essential for conventional cooling to work effectively (the cooling systems are isolated from each other), and (2) since the exterior air for cooling is not brought into the habitable space, the effects of humidity (a major drawback in most passive solar cooling systems, depending on climate), may be reduced. The east and west walls do not have to be uninsulated cavity walls. By keeping all walls cavity walls, the east and west walls may perform as a buffer zone between the north and south walls. This may increase the overall performance of the system. A schematic of the system in the heating mode is shown in Fig. 5. The vents are closed, which creates a convective loop around the entire shell of the building; through the floor, wall and roof/ceiling components. This thermal convective loop warms both the interior and exterior wythes of the building envelope. Since this operation warms the interior wythe, there is little or no heat loss through those portions of the building envelope. This system, properly designed and operated, may provide the most effective passive solar heating and cooling.

Cavity Wall System Heating Mode FIG. 5

FACTORS AFFECTING PERFORMANCE The effects of the environmental conditions and building use on passive solar heating systems are discussed in Technical Notes 43. These must also be considered for passive solar cooling systems, however, the necessary considerations of these factors vary for passive solar cooling systems. The major variations and additional effects which must be addressed specifically are: temperature, humidity and shading. Exterior Design Temperature The exterior design temperature may be such that the effective temperature range cannot be achieved or maintained within the structure. Since the effects of cooling are principally achieved by air movement, this may make the cooling system ineffective. One option is to take maximum advantage of the daily temperature swing. When the nighttime temperatures drop below the interior design temperature, the structure may be cooled during the night, delaying the time to heat up the next day. Caution must be used when considering the daily temperature swing to guard against

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overcooling in moderate climates. Humidity Humidity is an additional environmental factor not generally addressed in passive solar heating systems. In areas where the effects of high humidity cannot be eliminated by air movement, these simple versions of passive solar cooling systems may not be effective. Additional complex modifications to the basic passive solar cooling systems may be necessary to dehumidify the air. Shading Devices Operable shading devices are usually required in passive solar cooling systems. The shading devices are used to control the amount of solar radiation permitted to strike the system. This is necessary to prevent overheating, especially when the system is marginal because the effective temperature cannot be attained by natural air flow. In this case, the system should be completely shaded from the summer sunlight. In instances where the system is providing cooling by night air intake, it may be advantageous to have the system shaded from the morning and possibly early afternoon sunlight. Exposure to only the late afternoon sunlight may result in sufficient performance to draw cool night air through the structure. SPECIAL CONSIDERATIONS The performance of the passive solar cooling system may be greatly increased by pre-cooling, or dehumidifying the air before introducing it into the structure. Pre-cooling and dehumidifying the air are both fairly straightforward concepts. Adapting the system for pre-cooling air is usually simple, but dehumidifying the air is much more complicated. Pre-Cooling Air Air may be cooled before it is introduced into the structure by providing underground ductwork or piping, and venting it to the surface as shown schematically in Figs. 6, 7 and 8. This is easily adaptable for direct gain, attached sunspace and thermal storage wall cooling systems. The ductwork should be corrosion-resistant and installed for a sufficient length and at the appropriate depth to pre-cool the air. The number of ducts and their length and depth requirements are beyond the scope of this Technical Notes because they are a function of climate, soil type, elevation of ground water and other related factors, all of which affect the amount of pre-cooling, both required and attainable. General design information and calculation procedures may be obtained from the References 1, 2, 6 and 7 of this Technical Notes.

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Pre-Cooling and Dehumidification of Exterior Air for Cooling With the Direct Gain System FIG. 6

Pre-Cooling and Dehumidification of Exterior Air With Attached Sunspace FIG. 7

Pre-Cooling and Dehumidification of Exterior Air With Vented Thermal Storage Wall System FIG. 8 DEHUMIDIFICATION Air may be dehumidified by using the concept shown in Figs. 6 through 8, for pre-cooling. Dehumidifying the air with

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the passive solar system alone can be very difficult. Again, it is a function of climate, soil type, level of ground water and other related factors. The procedure for determining the amount of dehumidification involves fairly complex calculations. These calculation procedures are similar to those in the ASHRAE 1997 Handbook of Fundamentals and ASHRAE Standard 55-92. The temperature fluctuations necessary to saturate air and condensate water by the natural flow of air further complicates the use of passive solar cooling systems for providing dehumidification. SUMMARY This Technical Notes provides general information concerning passive solar cooling systems. In addition to describing modifications of the passive solar heating systems which may be used to supply successful passive solar cooling, it introduces an innovative system - the cavity wall system - which may be quite effectively used for heating and cooling buildings. The basic concepts of the passive solar cooling systems and the principles of their operation are also discussed. The purpose of this Technical Notes is to provide general information on passive solar cooling systems with brick masonry. It discusses type, operation, advantages and disadvantages of these systems. This Technical Notes does not and is not intended to provide information for specific designs or applications, but rather offers general information to assist in the consideration of the use of passive solar cooling systems of brick masonry. The information and suggestions contained in this Technical Notes are based on the available data and the experience of the engineering staff of the Brick Industry Association. The information contained herein must be used in conjunction with good technical judgement and a basic understanding of the properties of brick masonry. Final decisions on the use of information contained in this Technical Notes are not within the purview of the Brick Industry Association and must rest with the project architect, engineer and owner. REFERENCES 1. Proceedings of the Fourth Passive Solar Conference, October 3-5, 1979, Kansas City, Missouri, published by the publishing office of the American Section of the International Solar Energy Society, Incorporated, McDowell Hall, University of Delaware, Newark, Delaware, 1979. 2. Proceedings of the International Solar Energy Society, Silver Jubilee Congress, Atlanta, Georgia, May 1979, Pergamon Press, Inc., Maxwell House, Fairview Park, Elmsford, New York 10523, 1979. 3. Technical Notes 43 Revised, "Passive Solar Heating with Brick Masonry, Part I - Introduction" Brick Industry Association, Reston, Virginia, May/June 1981. 4. ASHRAE 1997 Handbook of Fundamentals, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., Atlanta, GA, 1997. 5. ASHRAE Standard 55-92, Thermal Environmental Conditions for Human Comfort, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., Atlanta, GA, 1992.

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Technical Notes 43D - Brick Passive Solar Heating Systems - Part 4 - Material Properties Reissued September 1988 Abstract: The inherent properties of brick masonry make it one of the most advantageous storage media materials for passive solar energy systems. Brick masonry may be used to provide an aesthetic effect, structural capacity and other design considerations in addition to thermal storage. Most of these inherent properties of brick masonry are already well understood for conventional applications. However, in order to properly use brick masonry as a thermal storage media for passive solar energy systems additional information may be needed by the designer. This additional information has to do with the effective thermal storage of brick masonry.

Keywords: absorptivity, brick, density, emissivity, energy heat transfer, masonry, material properties, passive solar energy systems, reflectance, solar radiation, specific heat, temperature, effective thermal storage, thermal conductivity, thermal diffusivity.

INTRODUCTION

Brick masonry can be used most advantageously as the thermal storage media in direct gain systems, thermal storage wall systems and attached sunspaces. The general concepts, empirical procedures for sizing systems and performance calculations are discussed in Parts I through III of this Technical Notes Series. This Technical Notes provides information and references regarding the material properties of the basic components of passive solar energy systems. This information includes the properties of brick masonry when used for thermal storage, with major emphasis on the effective thermal storage of brick masonry and a general discussion of the properties of glazing materials when used as collectors.

BRICK MASONRY General

Most of the design requirements and performance of brick masonry as a general building material are discussed in other Technical Notes. The inherent properties of brick masonry offer many design advantages in addition to those required for use as a thermal storage material.

Structural Brick masonry has many applications as a structural element in buildings. Brick masonry is commonly used as loadbearing elements in commercial and residential structures. Brick masonry when considered as a thermal storage media for passive solar energy systems may also be considered as a structural element. Information on loadbearing brick masonry is provided in Technical Notes 24 Series.

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One of the reasons brick masonry is less frequently considered as a structural element in one and two-family construction is because of the difficulties in insulating solid masonry walls to meet prescriptive energy code requirements for the reduction of heat loss. This can be overcome by using loadbearing insulated cavity walls which provide a durable facade, sufficient space for insulation and interior brick masonry which may be used as thermal storage in direct gain systems. Cavity wall construction is addressed in Technical Notes 21 Series. The structural design may require reinforced brick masonry. Reinforcement in brick masonry usually has little if any effect on the thermal performance of the wall. This is because the reinforcement is usually horizontal and/or vertical in the plane of the wall, and occurs at or near the center of the wall section resulting in very little increase of thermal transmission through the wall. Information regarding reinforced brick masonry is provided in Technical Notes 17 Series.

Durability Brick masonry is an extremely durable building material requiring little or no maintenance. It does not require coatings or coverings which could reduce its thermal performance as a storage media. Coatings and coverings may decrease the emissivity and thermal conductivity of the brick masonry. This is not desired when trying to optimize on the available thermal storage and thermal energy retrieval. Since coatings and coverings are not required, brick masonry may be exposed to enhance the aesthetics of the building. The use of coating applied to exterior brick masonry is discussed in Technical Notes 6A.

Aesthetics Brick masonry is normally used as an exterior facade, not only because of its durability but also because it provides architectural freedom. Brick masonry offers many bond patterns, colors and textures. As elements of the building, brick masonry provides options for architectural freedom that no other building material can offer. For instance, not only the texture of the brick itself is available in many varieties, but brick allows variation in wall texture, also. The texture of the wall may be varied by using projected or recessed brick or even sculptured brickwork. The typical modular sizes of brick masonry are given in Technical Notes 10B and common bond patterns are given in Technical Notes 30. Brick masonry used as paving is discussed in Technical Notes 14 Series. Information on the use of brick masonry sills and soffits is provided in Technical Notes 36 Series. The use of brick masonry arches and reinforced brick masonry lintels are discussed in Technical Notes 31 Series and 17H, respectively.

Fire Resistance Depending upon the specific application of brick masonry in passive solar energy systems, brick masonry may be designed and placed to offer fire protection. The fire resistance of brick masonry is discussed in Technical Notes 16 Series.

Sound Transmission Resistance Brick masonry, because of its inherent properties offers considerable reduction in sound transmission. Thus, depending on specific design applications, strategically placed thermal storage elements may be used to reduce sound transmission from one area of the building to another or from the exterior to the interior of the building. Information on the sound transmission classification of brick masonry is provided in Technical Notes 5A.

Effective Thermal Storage

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The overall performance of the brick masonry as a passive solar energy system thermal storage component is dependent on its absorptivity, emissivity, and ability to store heat. The ability of a material to store heat is usually referred to as heat capacity which is a function of the specific heat and density of a material. In addition to the heat capacity, the way the wave of thermal energy penetrates the material being used to store heat should also be considered. The performance as a thermal storage media may be estimated using the value of the thermal diffusivity of the material. Thermal diffusivity is not only a good value for assisting in the selection of materials but is also useful in simplified heat flow calculations to determine the amount of heat penetrating a material and the number of hours it takes for the heat transmission to occur. This information is useful for selecting the thickness of thermal storage. The thermal diffusivity is a function of the specific heat, density and thermal conductance of a material. Specific Heat. The specific heat, c, of material is the amount of heat required to increase the temperature of a unit weight of material one degree. The specific heat, c, in Btu per pound per degree Fahrenheit, for brick may vary from 0.20 to 0.26. Typically this variation is due to the impurities in the clay used to manufacture the brick. The greater the percentage of metallic oxides in the clay, usually the greater the specific heat. Building brick which usually have a o low percentage of metallic oxides by weight have low specific heats usually between 0.20 to 0.22 Btu/lb/ F, whereas face brick which contain larger amounts of metallic oxides, typically up to 35%, have specific heats ranging between o 0.22 to 0.26 Btu/lb/ F. A value of specific heat of face brick which may be used when the actual specific heat is not o known is 0.24 Btu/lb/ F. For building brick or brick containing a low percentage of metallic oxides, a value of 0.22 Btu/lb/oF may be used. Generally red, brown and blue brick contain high amounts of metallic compounds. The value of the specific heat for brick may be assumed for brick masonry. The specific heat of grouted hollow brick may be approximated by determining the percent of the brick masonry which is to be grouted, and averaging the specific heat, accordingly. This may be done by adding the product of the specific heat of face brick times the fraction of the brick which is solid, at least 0.60, and the specific heat of grout times the fraction of the brick which is cored, less than or equal to 0.40. For grouted hollow walls, the specific heat for the masonry wall may be modified for the grout by using Equation 1: cw = [(tb1 X cb1) + (tb2 X cb2)+ (tg X cg)] / (tb1 + tb2 + tg) (1) o

where: cw = Average specific heat of a grouted brick masonry wall, in Btu/lb/ F. tb1 = Nominal thickness of the exterior wythe of brick masonry, in inches. cb1 = Specific heat of the brick in the exterior brick masonry wythe, in Btu/lb/oF. tb2 = Nominal thickness of the interior wythe of brick masonry, in inches. o

cb2 = Specific heat of the brick in the interior brick masonry wythe, in Btu/lb/ F. tg = Nominal thickness of the grout, in inches. o

cg = Specific heat of the grout, in Btu/lb/ F.

Consider a 14-in. thick brick thermal storage wall constructed of 4-in. face brick, a 4-in. grouted space and a 6-in. grouted hollow brick wythe. Although this example is not representative of typical brick masonry thermal storage components, it is offered to include the available combinations of brick masonry construction. The specific heat of the wall assembly components may be determined by using Table 1 where: o

tb1 = 4 in., cb1 = 0.24 Btu/lb/ F tb2 = 6 in., cb2 = 0.22 Btu/lb/oF tg = 4 in., cg = 0.20 Btu/lb/oF

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aThese values are representative of the information available to the Brick Institute of America, and are typical for brick being manufactured today. These values may vary by plus or minus 10 % depending on the specific brick being considered. b

Hollow brick are assumed to be 60 % solid and the core space fully grouted.

cSource is Reference 3. dThe thermal conductivity of grouted hollow brick should be determined by dual path analysis. Typically grouted hollow brick, 60 % solid, fully grouted will have

o a thermal conductivity of approximately 10 Btu/hr/ F/ft2, per inch.

The approximate average specific heat of the wall assembly is found by substituting these values into Equation 1: cw = [(4 X 0.24) + (6 X 0.22) + (4 X 0.20)] / (4 + 6 + 4) cw = 0.22 Btu/lb/oF Density. The density, r, of brick varies with the type of clay, the additives used in manufacturing and with the extent

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of firing. Generally the longer the firing and the higher the temperature, the more dense the brick. Typical densities for various brick are provided in Table 1. These values are average densities. The density for grouted hollow brick assumes 130 lb per cu ft density brick and 120 lb per cu ft density grout. Hollow brick may range from 75% to 60% solid. This may significantly change the density, however the values provided in Table 1 are for grouted hollow brick assuming 60% solid.

The density, as the specific heat, of brick masonry is slightly less than that of brick, however for simplified effective thermal storage calculations these differences are usually insignificant. Typically, the maximum amount of mortar in solid brick or grouted hollow brick walls constructed with full collar joints would be about 30% of the wall volume; however, considering that mortar has a density of about 120 lb per cu ft. this results in a less than 3% reduction in the density of the wall as compared to the density of the brick. when considering the use of a grouted hollow wall, two wythes of masonry constructed with a grouted space in between, the density of the wall should be approximated by calculation using Equation 2:

rw = [(tb1 X rb1) + (tb2 X rb2) + (tg X rg)] / (tb1 + tb2 + tg) (2) where:

rw = Average density of the wall, in Ib/cu ft.

rb1 = Density of exterior brick, in Ib/cu ft. rb2 = Density of interior brick, in Ib/cu ft. rg = Density of grout, in Ib/cu ft.

For a 14-in. thick brick thermal storage wall, constructed of a wythe of 4-in. face brick, a 4-in. grouted space and a 6-in. grouted hollow brick wythe, the densities may be selected from Table 1 where: tb1 = 4 in.,

rb1 = 130 Ib/cu ft

tb2 = 6 in.,

rb2 = 26 Ib/cu ft

tg = 4 in.,

rg = 120 Ib/cu ft

By substituting these values into Equation 2, the average density of the wall,

rw, is found to be:

rw = [(4 X 130) + (6 X 126) + (4 X 120)] / (4 + 6 + 4) rw = 125 Ib/cu ft

Thermal Conductivity. The thermal conductivity, k, of brick is discussed in Technical Notes 4 Revised. Typical values of the thermal conductivity of brick are provided in Table 1. The thermal conductivity of brick varies with density. The denser the brick, generally the greater the thermal conductivity. The thermal conductivity of grouted brick should be determined by the dual path procedure described in Technical Notes 4 Revised.

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For hollow brick which is grouted, there are two paths for heat flow, one path is through the webs of the hollow brick and the other path is through the face shells and grout. The average thermal resistivity of grouted hollow brick may be determined by using Equation 3: rh = [(rb X tw) / l ] + [[(rb X 2tf) + rg x (t - 2tf)] X [(I - tw) / (l X t)]] (3) o

where: rh = Average thermal resistivity of grouted hollow brick, in ( F ft2 hr)/Btu. in. o

rb = Thermal resistivity of brick, in ( F ft2 hr)/Btu. in. rg = Thermal resistivity of grout, in (oF ft2 hr)/Btu. in.

t = Thickness of the brick, in inches. tf = Thickness of the face shell, in inches. tw = Total thickness of the webs, in inches.

/ = Length of the brick, in inches.

Considering the thermal resistivities and thickness of a 6 X 4 X 12 grouted hollow brick: rb = 0.11 (oF ft2 hr)/Btu. in. t = 6 in. rg = 0.08 (oF ft2 hr)/Btu in. tf = 1.25 in. / = 12 in. tw = 4 in.

and substituting these values into Equation 3, the average thermal resistivity of a 6 X 4 X 12 grouted hollow brick would be: rh = [(0.11 X 4) / 12] + [[(0.11 X 2.50) + 0.08 X (6 - 2.50)] X [(12 - 4) / (12 x 6)]] rh = 0.037 + [[0.275 + 0.280] X 0.11] rh = 0.098 (oF ft2 hr)/Btu in. or approximately 0.10 (oF ft2 hr)/Btu. in. The average thermal conductivity is the inverse of the average thermal resistivity. The average thermal conductivity, kh, for a 6 X 4 X 12 grouted hollow brick would be: kh = 1/rh (4) o

kh = 1/0.10 ( F ft2 hr)/Btu in. o

kh = 10.00 Btu/hr/ F/ft2 per inch of thickness

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The average thermal resistivity of a storage media is the summation of the thermal resistivity times the thickness of the materials divided by the total thickness. This is expressed in Equation 5: rw =[(r1 X t1) + (r2 X t2) + . . . ] / (t1 + t2 + . . . ) (5) where: rw = The average thermal resistivity of the storage media, in (oF ft2 hr)/Btu. in. r = The thermal resistivity of each component, in (oF ft2 hr)/Btu. in.

t = The thickness of each component, in inches.

Thus consider again the 14-in. grouted hollow wall constructed of a 4-in. wythe of face brick, a 4-in. grouted space, and a 6-in. wythe of grouted hollow brick. The nominal thickness and respective average thermal resistivities of each component would be: t1 = 4 in., r1 = 0.11 (oF ft2 hr)/Btu in. t2 = 4 in., r2 = 0.08 (oF ft2 hr)/Btu. in. t3 = 6 in., r3 = 0.10 (oF ft2 hr)/Btu in. Substituting these values into Equation 5, the average thermal resistivity of the wall, rw, is determined to be: rw = [(0.11 x 4) + (0.08 x 4) + (0.10 x 6)] / (4 + 4 + 6) o

rw = [1.36( F ft2 hr)/Btu in.] / 14 in. rw = 0.097 (oF ft2 hr)/Btu per inch of thickness

Thermal Conductance. Thermal conductivity and thermal resistivity refer to the value of heat loss for one inch of thickness. The thermal conductance is the value of heat loss for a specified thickness. The average thermal conductance for a one foot thickness of the storage media is used in the simplified equations of heat transfer for determining effective thermal storage. The average thermal conductance for a one foot thickness of the brick storage media may be determined using Equation 6: Ca = 1 / (rw X 12 in./ft) (6) where: Ca = The average thermal conductance of the storage media for o one foot of thickness. in (Btu/hr/ F/ft2) / ft.

The 4-in wythe of face brick, 4-in. grouted space and 6-in. wythe of grouted hollow brick is calculated to have a thermal conductance per foot of thickness of: o

Ca = 1 / [0.097 ( F ft2 hr) / Btu in. X 12 in./ft] Ca = 0.859 (Btu/hr/oF/ft2) / ft

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Thermal Diffusivity. Typically the storage capacity of a material is represented by the amount of heat which can be stored in the material, the heat capacity of the material. The heat capacity may be determined by using Equation 7:

b = c X r (7) where:

b = Heat capacity, in Btu/cu ft/oF.

Typical values for the heat capacity of various brick are provided in Table 1. Thermal diffusivity is a function of the heat capacity and thermal conductance per foot of material thickness. The thermal diffusivity of a material may be determined by using Equation 8:

d = Ca/ b or d = Ca / (c X r) (8) where:

d = Thermal diffusivity, in ft2 /hr.

The values of thermal diffusivity for typical brick masonry are provided in Table 1. The value of thermal diffusivity may be used to provide the designer with a better concept of heat storage in the passive solar energy system thermal storage component. The use of the thermal diffusivity in simplified heat transfer equations may provide a more rational approach for selecting the thickness of thermal storage walls. The average value of thermal diffusivity may be determined by using Equation 9:

da = Ca / (cw X rw) (9) where:

da = Average thermal diffusivity, in ft2 /hr.

Thus for the 14-in. thick wall assembly constructed of 4-in. solid brick wythe, a 4-in. grouted space, and a 6-in. wythe of grouted hollow brick the average thermal diffusivity may be determined using Equation 9. Ca for this wall o o was determined to be 0.859 (Btu/hr/ F/ft2)/ft, rw was determined to be 125 Ib/cu ft and cw = 0.22 Btu/Ib/ F. Thus, the average thermal diffusivity would be:

da = 0.859 (Btu/hr/oF/ft2)/ft/(0.22 Btu/lb/oF X 125 Ib/cu ft) da = 0.031 ft2/hr

The value of the average thermal diffusivity is useful in simplified heat transfer equations, however if precise values are desired, each component in section should be analyzed individually. Emissivity. The emissivity of a surface is its ability to radiate heat to the surroundings. This is the basis of heat retrieval in passive solar energy systems as discussed here. The radiant heat from the surface of the brick masonry

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is what causes the useable natural flows of thermal energy; i.e., surface to air conduction, convection between surfaces and radiation to surfaces and the air, which heat the interior spaces of the building. Typical values of emissivity for brick are provided in Table 1. Exposed brick masonry allows the use of various bond patterns, projections and even sculptured brick work to increase the aesthetic value of the thermal storage media. Although at first the idea of leaving the brick exposed seems merely aesthetic, it does serve a function important to the thermal performance of the thermal storage media. Brick masonry does not require nor should it have any coverings; i.e., gypsum wall board, paints, wall papers, or carpeting which could decrease the emissivity of the surface. The addition of coatings and coverings not only may reduce the emissivity of the thermal storage element but will usually decrease the thermal conductivity thus decreasing the surface temperatures and the amount of surface radiant heat available. If the value of emissivity, the surface temperature of the thermal storage element, and the surface temperature of the interior materials being radiated to are known, the amount of radiant thermal energy emitted may be approximated. The approximate amount of thermal radiation emitted per square foot of thermal storage surface area may be calculated using Equation 10: qr = [0.174 X e X [Tr4 - Tc4]] / 108 (10) where: qr = Radiation, in Btu/hr/ft2

e = Emissivity. Tr = Temperature of the radiant surface measured from absolute zero, degrees Fahrenheit plus 459.6. Tc = Temperature of the receiving surface measured from absolute zero, degrees Fahrenheit plus 459.6. For most applications in passive solar o energy systems, the value of Tc is usually interior design temperature in F plus 459.6, typically 72oF + 459.6 or 531.6. Consider an average surface temperature of a radiating surface at 83oF and an interior design temperature of 72oF. Measuring these temperatures from absolute zero would result in Tr = 83 + 459.6 or 542.6 and Tc = 72 + 459.6 or 531.6. The radiation from a dark brown brick wall, with e = 0.93, may be determined using Equation 10 to be: qr = [0.174 X 0.93 X [(542.6)4 - (531.6)4]] / 108 qr = [0.168 X (8.668 X 1010)] / 108 qr = (1.103 X 109) / 108 qr = 11.03 Btu/hr/ft2

Absorptivity. The solar absorptivity of a material is mostly dependent on color. The solar absorptivity is the ratio between how much solar radiation is absorbed by a material to that absorbed by a standard black surface. Typically, passive solar thermal storage components (or any finish applied to such components) should be as dark a color as possible to provide sufficient energy absorption. However, trade-offs do exist between color, wall thickness and the amount of surface area exposed to sunlight. Trade-offs also exist between darkness of color and how much heat is desired and when the available heat is wanted. These trade-offs can only be adequately determined by rigorous analysis and are not recommended for use with rule-of-thumb approaches. Surfaces (such as frame walls) not being used for storage should be painted light colors in order to reflect as much energy as possible to the darker storage material. Although black is the most desirable storage material color from a thermal point of view, it has been determined that the darker natural brick colors (browns, blues and reds) will perform almost as effectively, without deterioration problems which may result when using paint or other coverings. Typical values for solar

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absorptivity of brick are given in Table 2. Brick with glossy glazed ceramic coatings should be avoided as they will reflect too great a percentage of the solar radiation striking them. Several brick manufacturers can supply brick with dull black ceramic glazed faces, which may increase the solar radiation absorbed.

Although it would seem at first glance that rough-textured brick, by providing more surface area for the collection of energy, would be more effective than smooth brick as an energy storage media, but it has been determined that this is not the case. It appears that brick texture does not have a major impact on the performance of passive solar installations and that any desired texture can be used without significant loss or gain in effectiveness.

GLAZING MATERIALS General

Information regarding the transmittance, reflectance, absorptance, thermal performance and durability of glazing materials for passive solar energy systems should be obtained from the glazing manufacturer. Some general suggestions to assist in the design and selection of glazing materials for passive solar energy systems applications are discussed.

Transmittance The glazing material used should have a high transmittance, low absorptance and low reflectance of solar radiation. The high transmittance is important so that the maximum amount of solar energy may be transmitted to the interior of the passive solar building where it can be absorbed and stored in the interior brick masonry. Generally, the higher the transmittance the lower the absorptance and reflectance. When the glazing is desired to provide specific daylighting requirements, it may be preferred to use a glazing material which diffuses the direct solar radiation.

Absorptance Depending on the glazing material and the frame assembly, absorptance should be a factor in selecting the glazing material or a proper framing assembly. The higher the absorptance, the lower the amount of energy transmitted to the interior. Typically, the absorptance of most glazing materials is low. The amount of solar absorptance may be important because of thermal stress that may occur within the glazing material itself or between the glazing material

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and framing assembly. The framing assembly should be such that it allows for thermal expansion of the glazing material being used to avoid structural failure of the collector component.

Reflectance The reflectance of the glazing material should be kept to a minimum, so that the maximum amount of solar radiation may be transmitted to the interior. In addition to the consideration of reflectance, as related to transmittance and maximum solar performance, reflectance might also require consideration of exterior glare which may be annoying or even hazardous because of impairing vision.

Thermal Conductivity Typical values for overall coefficient of heat transmission of glass are given in Table 3. Table 3 also provides solar transmittance correction factors for glass. The solar transmittance correction factors are based on double glass having a solar transmittance value of 1. Information regarding plastics or other glazing materials must be obtained from the material manufacturer. The basic material properties for single, double and triple glass given in Table 3 may be used as a means of selecting the appropriate glazing material by considering the trade-offs between the transmittance and U value. Single glass has about a 21% increase in transmittance and 124% increase in heat loss, over double glass, and thus should only be used in lieu of double glass when night insulation is used. However, triple glass has approximately an 18% reduction in transmittance and a 37% reduction in heat loss over double glass and may be used in lieu of double glass with night insulation, to increase economic feasibility at only a slight reduction in overall performance. When considering such trade-offs it is extremely important to consider the specific environmental factors at the site. Triple glass in lieu of double glass may be excellent in areas of high solar radiation and cold exterior temperatures, but not effective in areas of low solar radiation and moderate exterior temperatures. The effectiveness should be determined by steady-state heat loss calculations and passive solar performance analysis.

aValues may vary with material, see manufacturers recommendations.

Durability

The durability of the glazing material must be such that it resists failure due to thermal stresses and that it does not degrade or discolor when exposed to solar radiation for extended periods of time. Of course these considerations will vary with economics. If a material degrades frequently but is inexpensive to replace, it may be more economical than a more expensive, more durable glazing material. Additional considerations in selection of a glazing material may be resistance to impact, and ease of replacement due to breakage. No matter what glazing material is selected, the designer should be assured it will maintain an expected condition that is not detrimental to the performance of the passive solar energy system for its intended period of use. Materials that discolor or degrade rapidly and have significant reduction of solar radiation transmittance should not

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be used.

METRIC CONVERSION

Because of the possible confusion inherent in showing dual unit systems in the calculations, the metric (Sl) units are not given in the examples. Table 13 in Technical Notes 4 provides metric (Sl) conversion factors for the more commonly used heat transmission units.

SUMMARY

This Technical Notes provides information on the component materials for passive solar energy system applications. This offers a designer or owner sufficient information regarding the material properties of brick to assist in the design and use of brick masonry in passive solar applications. Consideration of the properties of brick masonry could result in a thermal storage media that is an aesthetic, durable, maintenance free, fire resistant structural component of a building that provides sound transmission reduction. In addition, sufficient values of the material properties of brick masonry are provided for passive solar energy system analysis techniques, manual or computer calculations. The decision to use the information and concepts presented in this Technical Notes is not within the purview of the Brick Institute of America, and must rest with the designer or owner of any specific project.

REFERENCES

1. ASHRAE Handbook and Product Directory, 1977, Fundamentals Volume, American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc., 345 East 47th Street, New York City, New York 10017. 2

. Brick Masonry for Thermal Storage by Stephen S. Szoke, a paper presented at "Passive Solar Building Construction Program," 21-22 November 1980, Madison, Wisconsin. 3. Brick Walls for Passive Solar Use by G. C. Robinson, C. C. Fain, Stephen M. Jansen and Paul Harshman, February 1980, Clemson University, South Carolina. 4. Chemical Engineers' Handbook prepared by a staff of Specialists, John H. Perry, Ph.D., Editor, Third Edition, 1950, McGraw-Hill Book Company, Inc., New York, Toronto, and London. 5. The Chemistry and Physics of Clays and Other Ceramic Materials, by Alfred B. Searle and Rex W. Grimshaw, Third Edition, 1959, Ernest Benn Limited, London, England. 6. Heating and Ventilating's Engineering Handbook by Clifford Strock, First Edition, 1948, The Industrial Press, New York City, New York. 7. Proceedings of the Solar Glazing 1979 Topical Conference 22-23 June 1979 Stockton State College, Pomona, New Jersey, Sponsored by the Mid-Atlantic Solar Energy Association. 8. Properties of Engineering Materials by Glenn Murphy, C.E., Ph.D., Second Edition, 1952, International Textbook Company, Scranton, Pennsylvania.

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9. Smithsonian Physical Tables by William Elmer Forsythe, Ninth Edition, 1956, Smithsonian Institute, Washington, D.C. 10. Thermal Environmental Engineering by James L. Threlkeld, Second Edition, 1970, Prentice-Hall Inc.. Englewood Cliffs. New Jersey.

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Technical Notes 43G - Brick Passive Solar Heating Systems - Part 7 - Details and Construction [Mar./Apr. 1981] (Reissued Sept. 1986) Abstract: Details and construction of brick masonry for passive solar energy system applications vary only slightly from conventional residential and commercial brick masonry construction. Typical construction details are provided for direct gain and thermal storage wall systems. These details, with slight modifications, are also applicable for attached sunspaces. Construction variations from conventional construction and considerations for compliance with the major model building codes are also discussed.

Key Words: attached sunspaces, bricks, building code requirements, details, direct gain systems, energy, masonry, passive solar energy systems, thermal storage wall systems.

INTRODUCTION

Brick masonry construction and recommended details for passive solar energy systems are similar to conventional residential and commercial brick masonry construction and details. The general concepts of direct gain systems, attached sunspaces and thermal storage wall systems are discussed in Technical Notes 43. Empirical sizing, rational approaches for determining the thickness of brick masonry as a storage medium, material properties and performance calculations are discussed in other Technical Notes in this series. In these passive solar applications, brick masonry may be used as a storage medium and structural component of the building. Brick masonry also offers the capability for esthetic designs, fire resistance and sound transmission reduction. These recommended details are presented in an effort to show as many applications of brick masonry in passive solar heating systems as possible and are not offered as typical combinations of details. The details may be slightly varied and different combinations of the details may be used to satisfy the requirements of any specific passive solar heated building design.

DIRECT GAIN General

Details for brick masonry floors and walls used for thermal storage in direct gain systems are provided in Figs. 1 through 3. Each of these figures shows a typical connection detail for the ground floor, interim floors and roof.

Exterior Loadbearing Walls Exterior loadbearing brick masonry walls may be constructed as insulated cavity walls to provide an interior brick masonry wythe for thermal storage and an exterior brick masonry wythe for durability, as shown in Fig. 1. The brick

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masonry should be continuous through all floor intersections so that the brick masonry bears on the foundation or foundation wall, provides adequate support and complies with building code fire safety requirements. Where wood joists frame into brick masonry wall construction, the wood joists should be fire cut.

Cavity Wall Construction FIG. 1

The design should consider the local code requirements for minimum bearing. A thicker interior wythe may be required for bearing or special provisions incorporated into the detail so that both the exterior and interior wythes may be used for bearing. Bearing on both wythes should only be used when other alternatives are not practical,

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since there may be difficulty in properly constructing and detailing such a connection without interfering with the performance of the cavity wall. Additional information on the design, detailing, construction and insulating of cavity wall construction is provided in Technical Notes 21 Series. Providing clerestories with the appropriate pitched roof in conjunction with a cathedral type ceiling and exposed beams or trusswork may allow even the North wall to be exposed to sunlight and used for thermal storage. This type of detailing may require consideration of exposed trusses in the roof/ceiling component. The trusses or other means of eliminating the thrust at the top of the cavity wall is necessary because the building codes do not allow lateral thrust on cavity wall construction. When considering the use of trusses or other members to relieve a cavity wall of this thrust, the spacing of the trusses or other members should be such that the interior of the wall is subjected to only minimal shading if it is to be used as thermal storage for direct gain. When considering the use of insulated cavity walls, the exterior wythe of brick masonry is thermally isolated from the rest of the wall system. Thus, the exterior wythe of the cavity wall is usually subjected to greater temperature fluctuations than the interior wythe used for thermal storage. For cavity wall construction, both the interior and exterior wythes may require expansion joints for thermal movement.

Exterior Non-Loadbearing Walls Cavity wall construction may also be used for exterior non-loadbearing walls. East or West-facing walls may be positioned in the structure so that they are exposed to morning or afternoon sunlight for direct gain storage. Typically, passive solar buildings require a large amount of additional interior mass which may be unexposed to direct sunlight. This mass provides supplementary thermal storage, resulting in a thermal flywheel for reduced interior temperature fluctuations. The interior wythe of the cavity wall may be considered when determining the amount of additional mass.

Interior Loadbearing Walls Typical details for interior loadbearing brick masonry walls are shown in Fig. 2. These details are similar to conventional loadbearing construction. Wood floor joists bearing on the brick should be fire cut.

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Interior Loadbearing FIG. 2

A roof construction detail is provided, offering the option to use a skylight to expose the brick masonry loadbearing wall to sunlight. The interior brick masonry wall may be exposed to direct sunlight through South-facing windows and doors, or a clerestory may be used, depending on the distance from the South-facing wall. The use of interior loadbearing brick masonry construction does not require any special consideration over and above conventional construction. The only exception is that provisions for thermal expansion may be required.

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Interior Non-Loadbearing Walls Interior non-loadbearing brick wall construction is quite similar to conventional brick veneer construction. The brick veneer should be constructed as shown in Fig. 3. The brick masonry should be continuous through all floor intersections so that all the brick masonry bears on the foundation or foundation wall and complies with building code fire safety requirements. Additional information on brick veneer construction is provided in Technical Notes 28 Series.

Interior Non-Loadbearing FIG. 3

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The requirements in Technical Notes 28 Series apply to interior brick veneer construction, except that the requirements for the effect of weathering may be disregarded. The backup material; wood frame, metal stud, etc., should be constructed as in conventional construction. If the interior brick veneer is constructed with wood frame or metal studs without sheathing between the backup and the brick veneer, the 1-in. airspace between the brick and the backup, as recommended in Technical Notes 28 Series, may be eliminated. If the brick veneer is constructed with a framing system that requires sheathing on the side to be veneered, it is recommended that a 1-in. airspace be maintained. This provides ''finger room" to facilitate the laying of the brick. The use of the sheathing on the side of the backup material which is to be veneered may be required to provide the appropriate structural rigidity of the backup system. This sheathing may also be used to increase the fire resistance and sound transmission classification of the wall.

Interior Flooring Typical details for brick flooring are provided in Figs. 1 through 6. The interim floor details show mortarless paving, and the ground floor details show brick masonry set in a mortar bed. These details are interchangeable. The interim floor detail shown in Fig. 3 is a typical detail for mortarless brick paving in a sand bed. The difference in thermal performance of mortarless paving as compared to paving units set in a mortar bed is insignificant. There may be a slight reduction in heat transfer from unit to unit, but this will typically have a negligible effect on overall thermal performance of the floor system being used as direct gain thermal storage. Paving units are used as the flooring in the thermal storage wall details, Figs. 4 through 6. These paving units in combination with glazing incorporated into the thermal storage wall for daylighting and visual contact with the exterior may be used to form a direct gain system. The brick flooring may also be used to achieve the additional interior mass required by many passive solar heated buildings.

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Solid Brick Thermal Storage Wall FIG. 4

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Grouted Hollow Thermal Storage Walls FIG. 5

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The Use of Hollow Brick in Thermal Storage Walls FIG. 6

A soft joint should be installed around the perimeter of the brick paving, mortarless or set in a mortar bed, to provide relief of the stresses due to thermal movement, deflection and differential movement between the brick flooring and adjacent construction. Additional soft joints may be required for thermal expansion. Supporting brick masonry paving on floor systems requires sufficient stiffness of the system to adequately support the additional weight in such a manner as to satisfy the minimum deflection requirements of the brick paving. For mortarless brick paving, the maximum deflection should be less than or equal to L/360. For brick paving set in a mortar bed, the maximum deflection should be less than or equal to L/600. For wood floor systems supporting brick flooring, the sizing and spacing of the floor joists should be adequate to support the additional weight, satisfy the floor joist structural requirements and the deflection requirements of the brick flooring. The floor connection details shown in Figs. 2 and 3 should be such that the top surface of the brick flooring is level

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with other floor finishes. If this is not desirable, or possible, the appropriate riser distance between the surfaces of the different floor finishes should be provided to comply with the governing building code. The use of brick paving is discussed in detail in Technical Notes 14B. The brick flooring may also be constructed by laying face brick in a rowlock position. Another option is to use reinforced brick masonry floors, as discussed in Technical Notes 14B.

THERMAL STORAGE WALLS General

Figures 4 through 6 show the thermal storage wall being used as a structural component of the building, supporting various floor and roof systems. These combinations are not typical, but are offered to demonstrate the various alternatives available. The thickness required for thermal storage walls is usually sufficient for the wall to be used as a loadbearing component of the building without any special considerations. However, it may be necessary to check the structural adequacy of the wall. The thermal storage wall may be several wythes of solid brick, as shown in Fig. 4; solid through-the-wall units; a grouted cavity wall system, as shown in Fig. 5; or grouted hollow units or combinations of grouted hollow units and solid units, as shown in Fig. 6.

Details

Details for solid brick thermal storage walls are shown in Fig. 4. Corbeling the thermal storage wall to provide support for the exterior glazing is one way to eliminate the need for thick foundation walls. Brick masonry may be laid as projected headers to provide a durable support for attaching the glazing assembly to the wall. This eliminates the use of combustible materials exposed to high temperatures for extended periods of time. Projected headers may provide a durable non-combustible, horizontal separation between individual floors for multi-story vented thermal storage wall systems. This may be used to comply with the building code requirements regarding the fire-stopping of plenums. Vertical separation to provide a means of closing the sides of the thermal storage wall air space may also be achieved with projected headers. Depending upon the structural loads imposed on the projected headers and to avoid exposing cores, corbeling may be required, as shown in Fig. 4. The air space between the glazing and the thermal storage wall should be of a thickness that satisfies the building code requirements for unreinforced corbeling. If these limitations cannot be met, an alternate means of support for the glazing will be required. Additional glazing is provided in each detail to show that the thermal storage wall need not be a solid barrier eliminating any view of the exterior or daylighting. This glazing may be used as a direct gain collector with interior brick masonry floors and walls as the thermal storage. The air space between exterior glazing and the thermal storage wall may be interrupted at various intervals and the thermal storage wall made discontinuous, as shown in Fig. 7. This may be used to incorporate direct gain and thermal storage walls into a combined system. Operable or stationary shading devices may be attached to the structural framing of the glazing assemblies. The

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glazing assemblies should be sufficiently anchored to the brick masonry to accommodate these additional loads.

a Solar Savings Fraction as determined by using Method I of Technical Notes 43B Vents If the thermal storage wall is to be vented, each opening through the thermal storage wall should be approximately 64 sq in. The length of the opening should be about 4 times the height of the opening. The vents should occur as sets, one at the top of the wall directly over one at the bottom of the wall, to facilitate air flow. The number of sets of vents may be approximated by using Equation 1. nv' = Fv [(lw X hW ) / (lv X hv)] (1) where: nv' = approximate number of sets of vents. Fv = vent area factor from Table 1. lw = length of the vented thermal storage wall, in ft. hw = height of the vented thermal storage wall, in ft. Iv = length of the vent opening, in inches, approximately 4 X hv hv = height of the vent opening, in inches.

The actual number of sets of vents to be installed, nv, should be a whole number. Performance tends to decrease as the percentage of vent area to wall area increases. The next lower whole number to nv' should typically be used as the actual number of vents to be installed, if nv' is less than nv plus 0.70. If the value of nv' is greater than or equal to nv plus 0.70, the next larger whole number would typically be used as the number of sets of vents to be installed.

Both the vertical and horizontal spacing of vents will also affect performance. Top vents should be located as close

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to the ceiling as possible and the bottom vents as close to the floor as possible. The vertical distance between top and bottom vents should be at least 6 ft for full story height vented thermal storage walls. The horizontal spacing of vents, sv, may be determined by using Equation 2. sv = lw / nv (2)

Example. A 25-ft long vented thermal storage wall system 8 ft high is expected to supply about 35% of a building's heating load, SSF = 0.35. Vent openings are formed by omitting one and one-half courses of standard modular brick vertically and two standard modular brick horizontally as shown in Fig. 7. Thus, the opening has a height of about 4 in. and a length of about 16 in. The dimensions of the vent opening satisfy the criteria of the length being approximately 4 times the height and the area being approximately 64 sq in. If other size brick are used, the courses and number of brick omitted to meet the area and height-to-length requirements of the vent opening will vary.

Locating Vents FIG. 7 Using Equation 1, and Fv = 1.58 from Table 1 for a solar savings fraction of 0.35, the approximate number of vents would be: nv' = 1.58 (25 X 8) / (16 X 4) nv' = 4.94

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Thus, nv is 5 sets of vents to be installed.

The horizontal spacing of vents may be approximated by using Equation 2. sv = 25/5 = 5 ft

The result is that the 25 ft long vented thermal storage wall should have 5 sets of top and bottom vents, each having an opening of approximately 64 sq in., spaced horizontally at 5 ft o.c.

ATTACHED SUNSPACES

The typical details for direct gain thermal storage and thermal storage walls may be used for attached sunspaces with only modifications to the glazing details. Depending on the type of attached sunspace, the thermal storage components may be direct gain floors and walls or direct gain floors and vented or unvented thermal storage walls.

CONSTRUCTION

Solid brick masonry used as a thermal storage medium, as in all brick masonry construction, requires that all head, bed and collar joints be solidly filled with mortar. Solid brick are units which are cored less than 25 percent of the gross cross-sectional area parallel to the bedding plane. In typical running bond or stack bond construction, the brick should be shoved into full bed joints. This results in sufficiently filled cores so that there is little or no effect on the overall thermal performance of the wall. When soldier courses or projected headers are being considered, uncored units may be preferred. Hollow brick are brick units in which the coring is less than 40 percent and greater than 25 percent of the gross cross-sectional area in the bedding plane. Hollow brick masonry used for thermal storage requires all head and collar joints and bedding surfaces to be solidly filled with mortar and all cores fully grouted. Projected headers and corbels may best be achieved by combining solid brick masonry with hollow brick masonry construction. Grouted hollow walls are discussed in Technical Notes 17, 17C and 17D. When considering the use of grouted hollow walls, constructed of two wythes of brick separated by a fully grouted space, the only control over thickness will be requirements for adequate thermal storage. Thus, grouted hollow brick masonry walls may be advantageous when the thickness desired is not easily achieved by using modular sizes of brick. As in all brick masonry construction, the brick wythes should have all head and bed joints solidly filled with mortar.

MISCELLANEOUS CONSIDERATIONS Thermal Expansion

For most applications of brick masonry as interior direct gain thermal storage, the temperatures within the brick masonry will probably range from 72 to 96ƒF. Thus, thermal expansion will not normally be a problem except where long interior walls or floors are used. Interior brick masonry used for direct gain thermal storage occurring in lengths

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longer than 100 ft or exposed to a higher maximum temperature should be analyzed for thermal expansion. The thermal expansion of brick masonry is discussed in Technical Notes 18A. Thermal storage walls may be subjected to larger temperature fluctuations than direct gain thermal storage components. Usually, the difference between the maximum temperature and minimum temperature at the center of the thermal storage wall is small and no provision for thermal expansion is necessary. Generally, thermal expansion need only be considered for long or high thermal storage walls or for walls exposed to extreme temperature fluctuations. The maximum mean temperature of brick thermal storage walls may be determined by using the temperature fluctuation equation in Technical Notes 43. The minimum mean temperature may be determined by using the steady-state temperature gradient through the wall as discussed in Technical Notes 7C.

Flashing Flashing brick masonry thermal storage components is usually not required because the brick masonry is on the interior of the building. Cavity walls will require flashing as discussed and shown in Technical Notes 21B. Flashing may be required for thermal storage wall systems, depending on the type of glazing assembly and how it is mounted in front of the thermal storage wall.

Reinforced Brick Masonry Reinforced brick masonry, as discussed in Technical Notes 17 Series, may be required depending on the structural design loads. For thermal storage walls, this is easily accomplished by using reinforced grouted hollow brick or reinforced hollow wall construction. Reinforced brick masonry may be designed so that the wall will be able to sustain lateral thrust. Typically in reinforced brick masonry construction, the reinforcement is both horizontal and vertical, placed as near to the center of the wall as practical. This, in combination with the minimum required spacing to sufficiently reinforce a brick masonry wall does not result in any significant decrease in the wall's thermal performance due to thermal bridges.

Lintels and Sills The thermal storage wall details provide several options for constructing lintels and sills. Additional information on lintels is provided in Technical Notes 17H and 31B. Information regarding the construction of brick masonry arches is provided in Technical Notes 31 Series. Brick masonry sill details are provided in Technical Notes 36 Series, however, most sills for thermal storage walls do not require a sloped top surface or a drip since they are not exposed to exterior weather.

Fireplaces Interior fireplaces may be used to obtain additional mass to decrease the interior temperature fluctuations. Brick masonry fireplaces may be incorporated in the thermal storage component in any of these passive solar heating systems. A fireplace may be used for direct gain storage or may be constructed in a thermal storage wall. The design and construction of fireplaces is discussed in Technical Notes 19 Series.

Glazing

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It is desirable that the glazing component of these passive solar energy systems be operable to facilitate cleaning, exhausting excess heat, providing a means of egress or a combination of these. The glazing may be sliding glass doors, awning type windows, hinged glass doors or other options. Hinged doors installed vertically or horizontally may greatly facilitate the cleaning of vented or unvented thermal storage wall collectors. Depending upon building classification, building codes may require a 3-ft vertical separation between openings located vertically one above the other. This is not typically a requirement for residential buildings, or any building under 3 stories in height.

METRIC CONVERSION

Because of the possible confusion inherent in showing dual unit systems in the calculations, the metric (SI) units are not given in this Technical Notes. Table 13 in Technical Notes 4 provides metric (SI) conversion factors friar the more commonly used units.

SUMMARY

This Technical Notes provides information on the construction and detailing of brick masonry thermal storage components for passive solar energy systems. The information, recommendations and details contained in this Technical Notes are based on the available data and experience of the Institute's technical staff. They should be recognized as suggestions and recommendations for the consideration of the designers and owners of buildings when using brick in passive solar energy applications. All of the possible variations cannot be covered in a single Technical Notes. However, it is believed that the information is presented in a form such that specific details are interchangeable. The final decision for details to be used is not within the purview of the Brick Institute of America, and must rest with the project designer, owner or both.

REFERENCES

1. Passive Solar Design Handbook, Volume Two of Two Volumes: Passive Solar Design Analysis, January 1980, prepared by Los Alamos Scientific Laboratory, University of California, J. Douglas Balcomb, Dennis Barley, Robert McFarland, Joseph Perry, Jr., William Wray and Scott Noll, prepared for the U.S. Department of Energy, Office of Solar Applications, Passive and Hybrid Solar Buildings Program, Washington, D.C.

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Technical Notes 44 - Anchor Bolts for Brick Masonry April 1986 Abstract: Anchor bolts are used extensively in brick masonry to make structural attachments and connections. To date, a limited amount of information has been available to aid designers in the selection and design of anchor bolts in brick masonry. This Technical Notes addresses the types of anchor bolts available, detailing of anchor bolt placement and suggested design procedures. A discussion of current and proposed codes and standards is also presented.

Key Words: anchors, bolts, conventional anchors (bent bar, plate, sleeve, wedge), edge distance, headed bolts, loads, proprietary anchors (adhesive, expansion), shear, tension, through bolts.

INTRODUCTION

Anchor bolts are used in masonry construction with few or no guidelines for the practicing designer to follow. This Technical Notes offers basic information covering 1) the types of anchor bolts available for structural applications in brick masonry, 2) typical details of proper anchor bolt installation, 3) suggested allowable anchor bolt design loads and 4) the current and proposed codes and standards governing anchor bolts in brick masonry construction. In new masonry construction, anchor bolts are commonly embedded in walls and columns to support beams, plates and ledgers. In prefabricated panel construction, anchor bolts are used to facilitate connections to the structural frame. Renovation and rehabilitation of existing masonry structures usually require that anchor bolts be used to attach stair risers, elevator tracks and various frame assemblages for equipment installation. This is only a fraction of the possible uses of anchor bolts in masonry construction and with the increase of new, innovative architectural masonry designs, the uses of anchor bolts in masonry construction are likely to increase. This Technical Notes is the first in a series on masonry anchors, fasteners and ties, and addresses anchor bolts for brick masonry. Other Technical Notes in this series will address brick masonry fasteners and ties.

ANCHOR BOLT TYPES

Anchor bolts can be divided into two major groups: conventional (unpatented) anchors and proprietary (patented) anchors. Conventional anchor bolts are usually embedded in the masonry during construction and require careful attention to bolt location and grip length requirements to avoid problems with connection alignment and erection. Proprietary anchors, however, are typically installed after completion of construction and therefore, permit a larger degree of freedom in anchor placement. For this reason, proprietary anchors are becoming popular in masonry construction and add new concerns in the area of anchor bolt design.

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Conventional Anchor Bolts Conventional bolts are usually made to the specific project requirements by steel fabricators or they may be purchased in standard sizes (diameters and lengths) from steel suppliers. The availability and cost of conventional bolts are generally based on demand and fabrication requirements. The types of conventional anchor bolts most often used are discussed below. Headed Bolts. Square or hex-headed ASTM A 307 bolts are frequently used as anchor bolts due to their wide availability and relatively low cost (see Figure 1). Higher strength bolts, such as ASTM A 325 bolts, are available and can be used, but are more expensive. A washer placed against the bolt head is often used with the intention of increasing the bearing area and thus increasing the anchor strength. However, the actual strength increase obtained by adding a washer is small, if any, and under certain conditions (small edge distances), may actually decrease the tensile strength.

Headed Bolts FIG. 1

Bent Bar Anchors. Bent bar anchors, frequently used in masonry construction, are usually made in "J" or "L" shapes (see Fig. 2). Even though the "J" and "L" shapes are the more popular, a variety of shapes (see Fig. 3) is available since there currently is no standard governing the geometric properties of bent bar anchors. These anchors are usually made from ASTM A 36 bar stock and are shop-threaded.

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"L" and "J" Bent Bar Anchors FIG. 2

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Other Bent Bar Anchors FIG. 3

Plate Anchors. Plate anchors are usually made by welding a square of circular steel plate perpendicular to the axis of a steel bar that is threaded on the opposite end (see Fig. 4). There are no standards governing the dimensions (length, width or diameter) of the plate. The American Institute of Steel Construction does limit the fillet weld size based on the plate thickness (see Table 1). Both the plate and bar are usually made from ASTM A 36 steel.

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Plate Anchors FIG. 4

Through Bolts. As the name implies, through bolts extend completely through the thickness of the masonry and are composed of a threaded rod or bar with a bearing plate located on the surface opposite the attachment (see Fig. 5). In the early 1900's, through bolts were used in loadbearing masonry structures to tie floor and wall systems together. Often decorative cast bearing plates were used since through bolts were visible on the exterior masonry surfaces (see Fig. 6). Today, through bolts are primarily used in industrial construction where aesthetics are not a principal concern, or in retrofitting existing structures. Through bolt rods are usually made from ASTM A 307 threaded rod or threaded ASTM A 36 bar stock. Bearing plates are typically made from ASTM A 36 steel plate.

Through Bolt FIG. 5

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Decorative Through Bolt Bearing Plate FIG. 6

* American Institute of Steel Construction

Proprietary Anchor Bolts

Proprietary anchors are available through a number of manufacturers under numerous brand names. Although the style and physical appearance of the anchors differ between manufacturers, the basic theories behind the anchors are very similar. For this reason, proprietary anchors can be divided into two generic categories: expansion-type anchors and adhesive or chemical-type anchors. Expansion Anchors. Two different types of expansion anchors are generally recommended by their manufacturers for use in brick masonry: the wedge anchor and the sleeve anchor (see Fig. 7). These anchors develop their strength by means of expansion into the base material. Wedge anchors develop their hold by means of a wedge or wedges that are forced into the base material when the bolt is tightened. The wedges create large point bearing stresses within the hole; therefore, this anchor requires a solid base material to develop its full capacity. For this reason, voids formed by brick cores and partially filled mortar joints in some brick masonry may make the construction unsuitable for wedge anchor installation.

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Proprietary Expansion Anchors FIG. 7

Sleeve anchors develop their strength by the expansion of a cylindrical metal sleeve or shield into the base material as the bolt is tightened. The expansion of the sleeve along the length of the anchor provides a larger bearing surface than the wedge anchor, and is less affected by irregularities and voids in the base material than is the wedge anchor. For this reason, sleeve anchors are recommended by their manufacturers for use in brick masonry more often than wedge anchors. Drop-in and self-drilling anchors (see Fig. 8) are two other types of expansion anchors available, but are typically not recommended by their manufacturers for use in masonry. The reason for this is due to the embedment and setting characteristics of the two anchors. Both anchors are produced to allow shallow embedment depths and are expanded or set by an impact setting tool. The combination of shallow embedment and high stresses imparted by the expansion tend to cause cracking or splitting in masonry. Depending on the extent of cracking or splitting, the anchor could experience a reduction in load-carrying capacity or undergo complete failure during installation.

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Other Proprietary Expansion Anchors FIG. 8

There are several considerations that should be examined when contemplating the use of expansion-type anchors in brick masonry. These are: 1) Expansion anchors should not be used to resist vibratory loads. Vibratory loads tend to loosen expansion anchors. 2) Specific torques are required to set expansion anchors. Excessive torque can reduce anchor strength or may lead to failure as excessive torque is applied. 3) Expansion anchors require solid, hard embedment material to develop their maximum capacities. Some brick construction may not provide a good embedment material due to voids formed by brick cores and partially filled mortar joints. Adhesive Anchors. Two basic types of adhesive anchors are currently available. The major difference between the two is that one anchor is manufactured as a pre-mixed, self-contained system, whereas the second type requires measurement and mixing of the epoxy materials at the time of installation. The more popular self-contained types use a double glass vial system (see Fig. 9) to contain the epoxy. The outer vial contains a resin and the inner vial contains a hardener and aggregate. The glass vial is placed in a pre-drilled hole and a threaded rod or bar is driven into the hole with a rotary hammer drill, breaking the vials and mixing the adhesive components. The other type of adhesive anchor requires that the epoxy components be hand-measured and mixed before the epoxy is placed into a pre-drilled hole. A threaded rod or bar is then set into the epoxy mixture, as shown in Fig. 10. Adhesive epoxies usually vary slightly between manufacturers, but the steel rods or bars are typically ASTM A 307 or ASTM A 325 threaded rod, or ASTM A 36 shop-threaded bar.

Self-Contained Adhesive Anchor FIG. 9

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Site-Mixed Adhesive Anchor FIG. 10

There are special requirements and limitations. that should be considered when contemplating the use of adhesive anchors in brick masonry. They are: 1) Specially designed mixing and/or setting equipment may be required. 2) Dust and debris must be removed from the pre-drilled holes to insure proper bond between the adhesive and base material. 3) The adhesive mixture tends to fill small voids and irregularities in the base material. 4) Large voids (due to brick cores, intentional air spaces and partially filled joints) may cause reductions in anchor capacities. This is especially true with the self-contained adhesive anchors since a limited volume of epoxy is available to fill the voids and provide a bond to the anchor. 5) The adhesive bond strength is reduced at elevated temperatures and may also be adversely affected by some chemicals (see Table 2 and Fig. 11).

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aThe manufacturer should always be consulted when adhesive anchors are to be used in areas where contact with chemicals is likely.

Effect of Temperature on Ultimate Tensile Capacity FIG. 11

INSTALLATION DETAILS Conventional Anchor Bolts

Typical embedment details for each type of conventional anchor used in grouted collar joint construction are shown in Fig. 12. The conventional embedded anchors (headed bolts, bent bar and plate anchors) are usually placed at the intersection of a head joint and bed joint. By using this location, the brick units adjacent to the anchor can be chipped

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or cut to accept the anchor without altering the joint thickness.

Conventional Anchors in Grouted Collar Joints FIG. 12

Typical embedment details of conventional anchors in multi-wythe brick construction are shown in Fig. 13. A brick, or portion of a brick, is left out of the inner wythe to form a cell for the embedded anchor (Fig. 14). After the anchor is placed, the cell is filled with mortar or grout prior to placement of the next course.

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Conventional Anchors in Multi-Wythe Brick Masonry FIG. 13

Plan View of Grout Cell in Multi-Wythe Brick Masonry

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FIG. 14

In hollow brick construction, the units are laid so that the cells are aligned and provide continuous channels for reinforcing steel placement and for grouting. Depending on the design, every cell or intermittent cells may be reinforced and grouted (see Technical Notes 41 Revised). The anchor embedment detail will depend on the reinforcing pattern used in the construction. Figure 15 shows typical embedment details for conventional anchors embedded between reinforcing cells. The anchor should be solidly surrounded vertically and horizontally by grout for a minimum distance of twice the embedment depth (1b) (Figs. 14 and 15) for full tension cone development. The tension cone theory is discussed in following sections. This may require that some cells be partially grouted. A wire mesh screen can be placed in the bed joint across cells that are to be partially grouted to restrict the grout flow beyond a certain point. Figure 16 shows typical embedment details for conventional anchors embedded in reinforced cells. In this detail, the anchor may be tied with wire to the reinforcing to secure the anchor during the grouting process. Again, the anchor should be solidly surrounded by grout to a minimum distance of twice the actual anchor embedment depth, both vertically and horizontally.

Conventional Anchors in Reinforced Hollow Brick FIG. 15

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Conventional Anchors in Partially Grouted Hollow Brick FIG. 16

Two typical embedment details for conventionally embedded anchor bolts installed in composite brick and concrete block construction are shown in Fig. 17. As shown, anchor bolts may be placed in the collar joint between the brick and block wythes or placed into cells in the concrete block wythe and grouted into place. In details similar to Fig. 17(a), the anchor bolt type and diameter may be controlled by the width of the collar joint. Collar joints should be a minimum of 1 in. (25 mm) wide when fine grout is used, or a minimum of 2 in. (50 mm) wide when coarse grout is used (see Technical Notes 7A Revised). When the collar joint dimension is in the 1 in. (25 mm) range, it may become difficult to position anchor bolts in the collar joint and maintain the recommended clear distance between the masonry and the anchor (Fig. 17). The practice of using soaps to accommodate anchors larger than the collar joint is not recommended because the reduction in the brick masonry thickness around the anchor could lead to strength reductions. If the anchor dimensions required are larger than the collar joint, a detail similar to that shown in Fig. 17(b) should be considered.

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Conventional Anchors in Composite Brick/Block Masonry FIG. 17

Through bolts are typically installed after construction and grouting by drilling through the completed masonry work. When through bolts are to be installed after construction in reinforced brick masonry, care should be taken during installation to avoid cutting or damaging reinforcement while drilling the through bolt holes. Reinforcing bar locations can be identified by specially tooled joints or other marks made during construction.

Proprietary Anchors Proprietary expansion and adhesive anchors typically require special installation procedures and equipment. The manufacturer should be contacted to determine the appropriate anchor for a particular application, the correct installation procedure and if any special installation equipment is required. Improper application and installation of proprietary anchors may lead to less than satisfactory structural performance. Typical proprietary anchor details are shown in Fig. 18. It is suggested that proprietary anchors be embedded in head joints when facing or building brick are used. This reduces the possibility of placing anchors in brick cores that occur within the thickness of the brick and adjacent to the bed joint surfaces. Anchors set in grouted hollow brick should be placed in holes drilled in the bed joints so that they intersect grouted cells, or should be placed in holes drilled through the faces of the units into the grouted cells. As with conventional anchors, proprietary anchors should be solidly surrounded vertically and horizontally by grout for a minimum distance of twice their embedment depth.

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Typical Proprietary Anchor Details FIG. 18

ANCHOR BOLT DESIGN

Anchor bolts are used as a means of tying structural elements together in construction and therefore, provide continuity in the overall structure. In virtually all applications, anchor bolts are required to resist a combination of tension and shear loads acting simultaneously due to combinations of imposed dead loads, live loads, wind loads, seismic loads, thermal loads and impact loads. For this reason, and also to insure safety, anchor bolt details should receive the same design considerations as would any other structural connection. However, due to a lack of available research and design guides, anchor bolt designs are based largely on past experience with very little engineering backup. This situation may lead to conservative, uneconomical designs at one extreme, or nonconservative designs at the other. Recently, however, research investigating the strength of conventional and proprietary anchors in masonry has been completed. Reports have been issued that evaluate anchor performance and suggest equations to predict ultimate anchor strengths. By combining the research findings with design practices currently used in concrete design, equations for allowable tension, shear and combined tension/shear loads for plate anchors, headed bolts and bent bar anchors are under consideration for adoption in the proposed "Building Code Requirements for Masonry Structures" (ACI/ASCE 530). These equations are outlined below.

Tension The tensile capacity of an anchor is governed either by the strength of the masonry or by the strength of the anchor

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material. For example, if the embedded depth of an anchor is small relative to its diameter, a tension cone failure of the masonry is likely to occur. However, if the embedded depth of the anchor is large relative to its diameter, failure of the anchor material is likely. For these reasons, the allowable tensile load is based on the smaller of the two loads calculated for the masonry and anchor material. Thus, the allowable load in tension is the lesser of:

or

where: TA = Allowable tensile load, lb, Ap = Projected area of the masonry tension cone, in.2, f'm = Masonry prism compression strength (In composite construction, when the masonry cone intersects different materials, f'm should be based on the weaker material), psi, AB = Anchor gross cross-sectional area, in.2, fy = Anchor steel yield strength, psi. The value of Ap in Eq. 1 is the area of a circle formed by a failure surface (masonry cone) assumed to radiate at an angle of 45o (see Fig. 19) from the anchor base. When an anchor is embedded close to a free edge, as shown in Fig. 20, a full masonry cone cannot be developed and the area Ap must be reduced so as not to over-estimate the masonry capacity. Thus, the area Ap, in Eq. 1 will be the lesser of:

or

where: Ap = Projected area of the masonry tension cone, in.2,

1b = Effective embedded anchor length, in., 1be = Distance to a free edge, in.

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Full Masonry Tension Cone FIG. 19

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Reduced Masonry Tension Cone FIG. 20a

Reduced Masonry Tension Cone FIG. 20b

The effective anchor embedded length (1b) is the length of embedment measured perpendicular from the surface of the masonry to the plate or head for plate anchors or headed bolts. The effective embedded length of bent bar bolts (1b) is the length of embedment measured perpendicular from the surface of the masonry to the bearing surface of the bent end minus one bolt diameter. Where the projected areas of adjacent anchors overlap, Ap of each bolt is reduced by one-half of the overlap area. Also, any portion of the projected cone falling across an opening in the masonry (i.e., holes for pipes or conduits) should be deducted from the value of Ap calculated in Eqs. 3 or 4.

Shear The allowable shear load is based on the same logic as the allowable tension load. That is, the anchor capacity is governed by either the masonry strength or the anchor material strength. The distance between an anchor and a free masonry edge has an effect on the masonry shear capacity. Calculations have shown that for edge distances less than twelve times the anchor diameter, the masonry shear strength controls the anchor capacity. (Calculations based on masonry with f'm = 1000 psi and anchor steel yield strength with fy = 60 ksi. Therefore, where the edge distance equals or exceeds 12 anchor diameters. the allowable shear load is the lesser of:

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or

where: VA = Allowable shear load, lb.

When anchors are located less than 12 anchor diameters from a free edge, the allowable shear load is determined by linear interpolation from a value of VA obtained in Eq. 5 at an edge distance of 12 anchor diameters to an assumed value of zero at an edge distance of 1 in. (25 mm). This takes into consideration the reduction in the masonry shear capacity due to the edge distance.

Combined Tension and Shear

Allowable combinations of tensile and shear loads are based on a linear interaction equation between the allowable pure tension and pure shear loads calculated in Eqs. 1, 2, 5 and 6. Anchors subjected to combinations of tension and shear are designed to satisfy the following equation: T / TA + V / VA £ 1.0 (Eq. 7) where: T = Applied tensile load, lb.,

V = Applied shear load, lb.

Proprietary Anchor Bolts

The allowable load equations previously presented are intended for use with plate anchors, headed bolts and bent bar anchors and have been proposed to the ACI/ASCE 530 Committee on Masonry Structures. However, when the allowables from these equations are compared to test results for proprietary anchors, they appear to produce acceptable safety factors. Allowable Loads. Average factors of safety are 4.0 for tensile tests and 5.0 for shear tests on proprietary anchors. The combined tension/shear interaction equation produced an average safety factor of 7.0 when compared to test results on proprietary anchors. Therefore, based on comparison to test results, the allowable load equations proposed in this Technical Notes are suggested for use in the design of proprietary anchors in brick masonry. The embedment depth used to calculate the allowable load values should be equal to the embedded depth of the proprietary anchor. Edge Distance. Edge distance is of particular concern when expansion anchors are used in brick masonry, due to

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lateral expansion forces produced when the anchors are tightened. These forces are often large enough to cause cracking or spelling of the brick when edge distances become small. To date, no research has been conducted in this area. Therefore, due to the lack of information, it is suggested that a minimum edge distance of 12 in. (300 mm) be maintained when expansion anchors are installed in brick masonry.

Through Bolts There are no known published reports available addressing the strength characteristics of through bolts in brick masonry. However, based on the conservatism in the allowables for bent bar anchors and proprietary anchors, the allowable load equations should provide acceptable allowable load values for through bolts used in brick masonry. The embedment depth used to calculate the allowable load values should be taken as equal to the actual thickness of the masonry.

Current Codes and Standards At the present time, one model code and one design standard contain provisions for anchor bolt design in brick masonry. The BIA Standard, Building Code Requirements for Engineered Brick Masonry, and the Uniform Building Code cover design allowables and embedment depths for anchors loaded in shear. There are no provisions for axial tensile loads or combined tension/shear loads in these documents. Tables 3 and 4 show the allowable shear loads and minimum embedment depths from the two documents. The values in Table 4(a) are based on rational analysis and in Table 4(b) on empirical analysis. As can be seen, the tables are very similar and are generally more conservative than the allowable shear loads obtained from Eqs. 5 and 6 for the same embedment depths (Table 5).

* From Building Code Requirements for Engineered Brick Masonry, Brick Institute of America, August 1969. 1In determining the stresses on brick masonry, the eccentricity due to loaded bolts and

anchors shall be considered. 2Bolts and anchors shall be solidly embedded in mortar or grout. 3No engineering or architectural inspection of construction and workmanship. 4

Construction and workmanship inspected by engineer, architect or competent representative.

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* Reproduced from the Uniform Building Code, 1985 Edition, Copyright 1985 with permission of the publisher, The International Conference of Building Officials."

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*American Concrete Institute/American Society Of Civil Engineers Committee 530 on Masonry Structures. 1Assuming: f'm = 2,000 psi

ASTM A36 steel fy = 36 ksi Edge Distance = 12 Bolt Diameters

SUMMARY

This Technical Notes is the first in a series on brick masonry anchors, fasteners and ties. It covers anchor bolt types, detailing and allowable loads for anchor bolts in brick masonry. Other Technical Notes in this series will address brick masonry fasteners and ties.

The information and suggestions contained in this Technical Notes are based on the available data and the experience of the technical staff of the Brick Institute of America. The information and recommendations contained herein should be used along with good technical judgment and an understanding of the properties of brick masonry. Final decisions on the use of the information discussed in this Technical Notes are not within the purview of the Brick Institute of America and must rest with the project designer, owner or both.

REFERENCES

1. Manual of Steel Construction, 8th Edition, American Institute of Steel Construction, Inc., Chicago, Illinois, 1980.

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2. Whitlock, A.R. and Brown, R.H., Strength of Anchor Bolts in Masonry, NSF Award No. PRF-7806095, "Cyclic Response of Masonry Anchor Bolts", August 1983. 3. Brown, R.H. and Dalrymple, G.A., Performance of Retrofit Embedments in Brick Masonry, NSF Award No. CEE-8217638, "Static and Cyclic Behavior of Masonry Retrofit Embedments (Earthquake Engineering)", Report No. 1, April 1985. 4. Hatzinikolas, M.; Lee, R.; Longworth, J. and Warwaruk, J., "Drilled-In Inserts in Masonry Construction", Alberta Masonry Institute, Edmonton, Alberta, Canada, October 1983. 5. Building Code Requirements for Engineered Brick Masonry, Brick Institute of America, McLean, Virginia, August 1969. 6. Uniform Building Code, International Conference of Building Officials, Whittier, California, 1985. 7. Technical Notes on Brick Construction 17 Revised, "Reinforced Brick Masonry, Part I of IV", Brick Institute of America, McLean, Virginia, October 1981. 8. Technical Notes on Brick Construction 41 Revised, "Hollow Brick Masonry-Introduction", Brick Institute of America, McLean, Virginia, 1983. 9. Specification for the Design and Construction of Load-Bearing Concrete Masonry, National Concrete Masonry Association, McLean, Virginia, April 1971. 10. The BOCA Basic/National Building Code, 9th Edition, Building Officials and Code Administrators, International, Country Club Hills, Illinois, 1984. 11. Standard Building Code, Southern Building Code Congress, International, Inc.. Birmingham, Alabama, 1985. 12. Technical Notes on Brick Construction 7A Revised, "Water Resistance of Brick Masonry-Materials, Part II of III", Brick Institute of America, Reston, Virginia, 1985.

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Technical Notes 44A - Fasteners for Brick Masonry May 1986 (Reissued Aug. 1997) Abstract: Fasteners are used extensively in brick masonry construction to attach fixtures, equipment and other objects. This Technical Notes discusses the different types of fasteners used in brick masonry construction, their applications, appropriate fastener selection based on brick type, fixture weight, environmental exposure and aesthetics. Key Words: adhesives, bolts, brick, fasteners, fixtures, hardware, masonry, screws. INTRODUCTION This Technical Notes is the second in a series that addresses brick masonry anchor bolts, fasteners and ties. The term "fastener", as used in this text, refers to devices for securing equipment, fixtures or other objects to brick masonry. This Technical Notes discusses the different fastener types used to attach these items to brick masonry. When other materials, fixtures, etc., are to be attached to brick masonry, the procedure is relatively simple and can be executed either during or after construction. The designer or builder has a wide variety of fastening methods from which to choose. The final selection will depend largely upon what is to be attached, when it will be attached and the type of brick used in the construction. TYPES OF FASTENERS Fasteners can be divided into two general categories: those installed during the construction of the masonry, and those that are installed after the completion of the masonry work. Fasteners Installed During Construction Nailing Blocks and Wall Plugs. Wooden nailing blocks and metal wall plugs are placed in mortar joints as the brick are laid (see Figure 1). Wooden nailing blocks are not used today as frequently as they were in the past, but do provide an acceptable means of attachment to brick masonry walls. If wooden blocks are used, they should be of seasoned soft wood to prevent shrinkage and treated to inhibit deterioration. Wooden blocks should be placed only in head joints.

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Fasteners Installed During Construction FIG. 1 Metal wall plugs are made of galvanized metal, and may contain wooden or fiber inserts. Metal plugs are preferred over wooden blocks since problems with shrinkage and decay are not associated with metal plugs. Metal plugs may be placed in either head joints or bed joints of masonry. The primary consideration when using fasteners installed during construction is location. Their exact location is not a serious problem when used to attach moldings, such as baseboards, chair rails, etc., but it may be difficult to predetermine fastener locations for fixtures, cabinets, shelving, etc. For this reason, post-construction fasteners have virtually replaced wooden blocks and metal nailing plugs for fastening to masonry. Post-Construction Fasteners Screw Shields and Plugs. Screw shields and plugs are produced in plastic, fiber, rubber, nylon and lead (see Fig. 2). Some are advertised by their manufacturers as vibration-resistant, chemical-resistant or water-resistant. These fasteners are generally used for lightweight attachments and are typically installed in mortar joints or may be placed directly into solid masonry units (see Fig. 3).

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Shields and Plugs FIG. 2

Shields and Plugs Installed FIG. 3

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Bolts and Screws. Several types of bolts and screws are available for use in both solid and hollow masonry. These fasteners are generally used to attach medium to heavy-weight fixtures. Toggle bolts (made of steel or plastic), hollow wall screws, small diameter sleeve anchors and screws are used to attach fixtures to walls constructed of hollow units (see Fig. 4). These fasteners may be placed in holes drilled through bed joints or through the unit faces into hollow cells (see Fig. 5). Small diameter sleeve anchors, wedge anchors, screws and lag bolt shields (see Fig. 6) are used to attach fixtures to solid masonry and are usually installed in mortar joints (see Fig. 7).

Fasteners for Hollow Masonry Units FIG. 4

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Fasteners Installed in Hollow Units FIG. 5

Fasteners for Solid Masonry Units FIG. 6

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Fasteners Installed in Solid Masonry Units FIG. 7 Nails. Case-hardened cut and spiral nails (masonry nails) are often used to attach furring strips to masonry walls (see Fig. 8). If used, the nails should be hammered directly into the mortar joints and not into the brick units. Caution should be exercised when nails are used in single-wythe walls with exposed exterior faces. The nails could open small cracks in the mortar joints, allowing water to penetrate the wall (see Technical Notes 7F for problems associated with water penetration).

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Masonry Nails FIG. 8 Powder-Driven Fasteners. Powder-driven fasteners are hardened steel pins that are driven into masonry by means of a powder-actuated tool (Fig. 9). The power for the tool is provided by a powder charge typically ranging from .22 to .38 caliber with varying charges, depending on the material and required pin penetration. Powder-driven fasteners are generally used on commercial or industrial projects where large volumes of fasteners are required. Several pin styles and lengths are produced for different fastening requirements (see Fig. 10).

Powder-Driven Fastening Tool FIG.9

Powder-Driven Pins FIG. 10

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Powder-driven fasteners require special installation equipment, safety equipment and inspection procedures. For this reason, the manufacturer should be contacted to determine proper equipment and installation specifications. Adhesives. A multitude of adhesives, such as epoxies, mastics and contact cements, is produced for various bonding applications. Many of these produce high bond strengths, have short setting times and offer versatility in bonding different materials. Adhesives may be used to attach furring, electrical boxes, wall paneling, etc. (see Fig. 11). The manufacturer's literature should be referred to when determining the suitability of an adhesive for a particular application. Some adhesives may not bond properly to masonry, may not have the elasticity required to accommodate movements of dissimilar materials and may be affected by exposure to weather, chemicals or temperature extremes.

Adhesive Fastening FIG. 11 FASTENER SELECTION The selection of an appropriate fastener can usually be based on four considerations: 1) the type of brick used in the construction, 2) the weight of the attachment, 3) the environmental exposure (i.e., interior or exterior) and 4) aesthetics. Construction and Attachment The type of brick used in construction will determine the choice of a fastener as either a solid or hollow wall type fastener; the weight of the fixture will determine the size of the fastener required. The fastener selection chart shown in Table 1 can be used as a general guide in selecting a fastener type based on the brick type, installation location and fixture weight.

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Environment Environmental factors may have a definite impact on the long-term service life of fasteners and should be considered in their selection. Environmental factors do not, in general, influence the type of fastener selected, but should influence the choice of fastener based on the material from which the fastener is made. Corrosion is a major concern, especially when fasteners are exposed to the elements or when fasteners are used in areas where contact with corrosive agents is likely. Steel fasteners used for applications under normal exposure conditions should be galvanized (zinc-coated) to resist corrosion. Lead, copper-coated or brass fasteners also provide adequate corrosion resistance for normal exposures. In applications where fasteners are subject to severe exposure conditions or exposed to chemicals, stainless steel fasteners should be used. Aesthetics In most applications, the fastener or fasteners installed will be hidden by the attachment (i.e., cabinets, baseboards, electrical boxes or furring), and the physical appearance of the fastener (usually the head of a screw or bolt) will not be of importance. However, when fasteners are used to attach privacy partitions, lighting fixtures or rails, the head of the fastener is usually visible and required to match or accent the finish of the fixture. In these cases, finished screws or bolts (i.e., chrome or brass-plated, solid brass or painted) can be purchased to match the fixtures. The manufacturers should be contacted to determine the availability and range of finishes available in their products. SUMMARY This Technical Notes is the second in a series on brick masonry anchors, fasteners and ties. It addresses the types of fasteners available for use in brick masonry construction. Other Technical Notes in this series address brick masonry anchor bolts and wall ties.

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The products described in this Technical Notes may involve the use of hazardous materials, operations and/or equipment. This Technical Notes does not purport to address all of the safety practices associated with the use of these products. It is the responsibility of the user of this Technical Notes to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to the use of the products described. The information and suggestions contained in this Technical Notes are based on available data and experience of the technical staff of the Brick Institute of America. This information should be recognized as recommendations and should be used with judgment. Final decisions on the use of the information discussed herein are not within the purview of the Brick Institute of America, and must rest with the project owner, designer or both. REFERENCES 1. Technical Notes on Brick Construction 7F, "Moisture Resistance of Brick Masonry - Maintenance", Brick Institute of America, Reston, Virginia, February 1986. 2. Construction Sealants and Adhesives, 2nd Edition, J. R. Panek and J. P. Cook, John Wiley and Sons, New York, 1984. 3. Architectural Graphic Standards. 7th Edition, C. G. Ramsey and H. R. Sleeper, John Wiley and Sons, New York, 1981.

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Tech Notes 44B - Wall Ties for Brick Masonry [Revised May 2003] Abstract: The use of metal ties in brick masonry dates back to loadbearing masonry walls in the 1850's. Historically, the size, spacing and type of ties have been entirely empirical. Over time, ties of various sizes, configurations and adjustability have been developed for loadbearing masonry, cavity walls and brick veneer construction. These ties are used to connect multiple wythes of masonry, often of different materials; anchor masonry veneer to backing systems other than masonry; and connect composite masonry walls. This Technical Notes addresses the selection, specification and installation of wall tie systems for use in brick masonry construction. Information and recommendations are included which address tie configuration, detailing, specifications, structural performance and corrosion resistance. Key Words: anchors, brick, cavity walls, corrosion, design, differential movement, fasteners, grout, masonry, structural masonry, ties, veneer, walls.

INTRODUCTION This Technical Notes is the third in a series that addresses anchor bolts, fasteners and wall ties for brick masonry. This Technical Notes discusses wall ties commonly used in brick construction, their function, selection, specification and installation. The term "wall tie", as used in this Technical Notes, refers to wire or sheet metal devices used to connect two or more masonry wythes or used to connect masonry veneers to a structural backing system. The later of these are more properly identified as veneer anchors.

GENERAL The first use of wall ties in brick masonry construction can be traced to England in the mid-nineteenth century, where wrought iron ties were used in brick masonry cavity walls. Use of wall ties in the United States grew after testing showed that metal-tied walls were more resistant to water penetration than were masonry-bonded walls. Bonders, or "headers", used in masonry-bonded walls may provide direct paths for possible water penetration. Testing also indicated that the compressive strength of metal-tied cavity walls and solid walls, and the transverse strength of metal-tied solid walls were comparable to those of masonry-bonded walls. The use of wall ties has continued to increase over the years due to a trend away from massive, multi-wythe masonry walls to relatively thin masonry cavity walls, double-wythe walls and veneers. The use of backing systems other than masonry, i.e., steel, concrete and wood, has rendered bonding with masonry headers impossible, leading to the development of a number of different metal tie systems. Investigation into the performance of masonry-bonded walls in which the bonded wythes are of different materials indicates frequent shear failures in the headers. During this period of transition, little progress was made in the area of rational design of wall tie systems. Typically, the sizing and spacing of wall ties has been based largely on empirical information and the designer's judgment. Questions concerning strength, stiffness, corrosion and the effects of these on the long-term performance of wall ties, have been posed. Selection of a tie system to function properly under these conditions is further complicated by the vast number of tie types available and the variety of materials from which they are fabricated. Most tie systems perform well for their intended application. Some tie systems, however, are poorly designed and do not provide adequate load transfer for brick masonry. The distinction is often subtle and requires an understanding of the properties and characteristics of brick masonry. With the addition of Chapter 6 on Veneers to the Building Code Requirements for Masonry Structures (ACI 530 / ASCE 5 / TMS 402-02), the empirical requirements for type, size and spacing of metal ties have been reviewed and refined. This Code, known as the MSJC Code, contains requirements for most types of tie systems. Function of Wall Ties Typically, wall ties perform three primary functions between a wythe of brick and its backing or another wythe of masonry: 1) provide a connection, 2) transfer lateral loads, 3) permit in-plane movement to accommodate differential movements and, in some cases, restrain differential movement. In addition to these primary functions, metal ties (as joint reinforcement) may also be required to serve as horizontal structural reinforcement or provide longitudinal continuity. For a tie system to fulfill these functions, it must: 1) be securely attached to both masonry wythes or the brick veneer and its backing, 2) have sufficient stiffness to transfer lateral loads with minimal deformations, 3) have a minimum amount of mechanical play, 4) be corrosion-resistant and 5) be easily installed to reduce installation errors and damage to the tie system. This listing is far from complete; special project conditions, unusual details and special building code requirements must also be considered. Availability and cost are always factors in product specifications. However, cost should not have a major influence on the selection of a wall tie system since the cost of ties is typically a very small part of the total wall cost.

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TYPES OF WALL TIES

General There are a number of different wall tie systems available for brick masonry wall systems. These include unit ties, continuous horizontal joint reinforcement, adjustable ties (unit and continuous) and re-anchoring systems. Placement requirements for ties are shown in Figure 1.

FIG. 1

Unit Ties Unit ties are rectangular “box”ties, "Z" ties and corrugated ties, as shown in Figure 2. Rectangular and "Z" ties are usually fabricated from cold-drawn steel wire conforming to ASTM A 82. Rectangular and "Z" ties made of stainless steel conforming to ASTM A 580 are also available for use in more corrosive environments. Corrugated sheet steel ties are typically manufactured from steel sheet conforming to ASTM A 1008 and are also available in stainless steel conforming to A 240.

Unit Ties FIG. 2

Rectangular and "Z" ties are used to bond walls constructed of two or more masonry wythes. "Z" ties should only be used to bond walls constructed with solid units (not less than 75% solid) or grouted units. Rectangular ties may be used with either solid or hollow units. Such wire ties should not have a bend or drip to reduce water transfer. Such a bend in the tie reduces the capacity of the tie to transfer lateral load. Corrugated ties are typically used in low-rise, residential veneer over wood frame construction and are not recommended for construction incorporating brick veneer over steel studs, masonry-backed cavity walls, multi-wythe walls or grouted masonry walls. Typical installation details are shown in Fig. 3.

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Unit Tie Placement Details FIG. 3

Joint Reinforcement Continuous horizontal joint reinforcement is typically made from #8, 9, 10, or 11 gage wire, or 3/16 in. (5 mm) diameter wire, conforming to ASTM A 951, in lengths of 10 to 12 ft (3 to 4 m). The most common configurations are the ladder, truss, and tab types (see Fig. 4).

Continuous Joint Reinforcement FIG. 4

Structural testing performed in the early 1960's indicated that multi-wythe walls tied with joint reinforcement performed as well as walls tied with unit ties or masonry bonders. Joint reinforcement may be used in multi-wythe solid walls, masonry cavity walls, brick veneer with masonry backing, and grouted masonry walls (see Fig. 5). As with wire ties, the cross wires should be without drips. Truss-type joint reinforcement is not recommended for use in cavity walls or brick veneer with masonry backing. Test results also indicated that truss-type joint reinforcement, in such wall systems, did not contribute to any composite action in the vertical span, but did develop a degree of composite action in the horizontal span .The configuration of the truss diagonals can restrain differential movement between wythes and possibly result in bowing of the walls.

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Joint Reinforcement Details FIG. 5

Adjustable Ties Adjustable tie systems were initially developed to accommodate the use of face brick whose bed joints did not align vertically with interior masonry wythes. This concept has been extended to ties used to attach brick to other systems, resulting in the use of both adjustable unit ties and adjustable ties with joint reinforcement. The use of adjustable ties has increased rapidly for a number of reasons: 1) Adjustable ties permit the construction of interior masonry wythes and other backings prior to the construction of exterior facing wythes, permitting the structure to be enclosed faster. 2) Adjustable ties are two-piece systems. One piece is installed as the backing is constructed and the other piece is installed as the facing wythe is constructed, reducing the risk of damage to exposed ties that might occur when unit ties or standard joint reinforcement are used. 3) Adjustable ties can accommodate construction tolerances common in multi-material construction. 4) Adjustable ties can accommodate larger differential movements than standard unit ties or joint reinforcement. The advantages offered by adjustable tie systems are not without possible problems: 1) Mislocation of adjustable ties placed prior to construction of facing wythes, if extreme, can render the ties useless. 2) Adjustable ties may encourage less than perfect layout of the wall system since a built-in adjustment allowance is available. 3) Large variations in construction tolerances may not allow full engagement of ties installed before facing wythes are constructed. 4) Improperly positioned ties may result in large vertical tie eccentricity. 5) The structural performance of some adjustable ties in regard to strength and stiffness is less than that of standard unit ties or joint reinforcement. Adjustable Unit Ties. Adjustable unit ties produced for use with masonry backing, concrete backing, steel frames and steel studs are shown in Figs. 6 and 7. Slot-type ties (dovetail, channel slot, etc.) have been used for a number of years with concrete, steel frame and steel stud backing systems, and are recognized as tie systems capable of accommodating differential movement, as further discussed in Technical Notes 18 Series (see Fig. 6). Other types of adjustable unit tie systems are available for brick with masonry backing and other backing systems. These ties are typically two-piece systems, consisting of a single or double eye and pintle arrangement (see Fig. 7). The Building Code Requirements for Masonry Structures (ACI 530 / ASCE 5 / TMS 402-02) requires that for veneer masonry all pintle anchors have at least two pintle legs of wire size W2.8 (3/16 in., MW18) each and have an offset not exceeding 1 ¼ in. (31.8 mm). Typical installation details are shown in Fig. 8

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. Adjustable Unit Ties for Steel, Concrete and Stud Backup FIG. 6

Adjustable Unit Ties for Masonry Backup FIG. 7

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Adjustable Unit Tie Details FIG. 8

Adjustable Assemblies. Adjustable ladder and truss-type joint reinforcement assemblies are available for use in masonry backedcavity wall, veneer and grouted wall construction. This joint reinforcement typically consists of rectangular tab type extensions, connected to standard joint reinforcement by means of an eye and pintle arrangement (see Fig. 9). Installation details are shown in Fig. 10.

Adjustable Joint Reinforcement Assemblies FIG. 9

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Adjustable Assembly Details FIG. 10

Masonry Re-anchoring Systems. Masonry re-anchoring systems are the most recent development in masonry tie systems. Three general types of systems are being produced and typically consist of a mechanical expansion system, helical screw system and an epoxy adhesive system (see Fig. 11).These systems are primarily used to: provide ties in areas where ties were not installed during original construction, 2) replace existing ties, 3) replace failed masonry bonding units, 4) upgrade older wall systems to current code levels, or 5) attach new veneers over existing facades.

Masonry Re-Anchoring Systems FIG. 11

As stated, re-anchoring systems are relatively new and many designers and contractors may not be fully familiar with their installation or limitations. For this reason, consultation with the tie system manufacturer is essential to assure proper application, detailing, installation, inspection, and performance.

TIE SELECTION Strength and Deformation The strength and deformation characteristics of tie systems are not generally analyzed nor investigated during the project design or specification phase. Building codes and standards have typically required minimum tie size (diameter or gage) and maximum tie spacing limits to control tie loading and deformation. Present tie size and spacing requirements have been derived from some testing and from the past performance of traditional tie systems (rectangular ties, "Z'' ties and standard joint reinforcement). The growing use of adjustable tie systems has caused some concerns in regard to tie strength and deformation. Most adjustable ties permit vertical adjustment up to approximately one-half the height of a standard brick unit, some permit greater adjustments. Depending on the tie configuration, the deflections of adjustable ties can become quite large as vertical adjustment eccentricities are increased. This deflection is further increased if mechanical play is present in the tie system. Analytical and experimental investigations of cavity wall and veneer wall systems have shown that tie loads and deformations are a

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function of: 1) the relative stiffness between facing and backing materials, 2) tie spacing, 3) tie stiffness, 4) support conditions of the facing and backing systems, 5) location of edges and openings, 6) cavity width and 7) applied loads. Estimating tie loads based on tributary area can lead to large errors, depending on the geometry and properties of the wall system. Fig. 12 shows tie loads and deflections calculated from a simplified model of a cavity wall system. As shown, adjustable tie deflections become large as the adjustment eccentricity becomes large. These values were calculated assuming that no mechanical play existed in the tie system. Mechanical play must be added to these values to determine the total deflection of the exterior wythe. Typical adjustable ties have values of mechanical play ranging from approximately 0 to 0.3 in. (0 to 8 mm). Some adjustable ties may have an extreme amount of mechanical play when not properly installed (see Fig. 13). The MSJC Code limits mechanical play to a maximum of 1/16 inch (1.6 mm). If satisfactory performance is to be expected, total tie and backing deflections must be maintained within the working range of the masonry facade under full design loads.

Calculated Tie Loads and Deflections

FIG. 12

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Mechanical Play FIG. 13

Recommendations. At present, analysis techniques that accurately model metal-tied wall systems are still in the developmental stage and require further refinement and verification through testing. Until more accurate methods are available, the Brick Industry Association feels that acceptable strength and deformation characteristics can be achieved by one or more of the following measures: 1) Reduce or eliminate lateral mechanical play in adjustable tie systems. Limit the total mechanical play to 1/16 in. (1.6 mm), see Fig. 13. 2) Reduce or eliminate adjustment eccentricity in adjustable tie systems. This can be accomplished by installing ties as facing wythes are constructed or by using starter courses or ledges when facing wythes are constructed over masonry backing. 3) Eliminate possible disengagement of adjustable ties by providing positive vertical movement limitations. 4) Provide additional ties within 8 in. (200 mm) of openings and discontinuities, i.e., windows, shelf angles, vertical expansion joints, etc. 5) Do not specify ties with formed drips. Testing has shown that drips can reduce the ultimate buckling load by approximately 50 percent. 6) Space ties as shown in Table 1, based on the tie system and wall system. 7) Specify stiff ties. This can be accomplished by specifying ties with maximum deflections of less than 0.05 in. (1.2 mm) when tested at an axial load of 100 lb in tension or compression. When adjustable ties are specified, the deflection limit should be satisfied at the eccentricity expected in the field. See Table 2 for minimum tie gage and diameter recommendations. 8) Select an appropriate tie system for the wall system (see Table 3). Many of these recommendations have been incorporated in the MSJC Code.

TABLE 1 Tie Spacing Requirements1,2

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Masonry laid in running bond. Consult applicable building code for special bond patters such as stack bond. Based on the requirements in the 2002 MSJC Code. Maximum allowable distance between inside face of veneer and framing material, per MSJC Code, unless noted otherwise.

TABLE 2 1

Required Tie Sizes

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1 Based on the requirements in the 2002 MSJC Code.

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1See Table 1 for spacing; Table 2 for sizes and gages; Table 5 for corrosion protection.

Corrosion General. Awareness of possible corrosion problems in metal-tied masonry walls has increased due to corrosion damage found on reinforcement in concrete highway pavements, bridge decks and some masonry structures. The potential for corrosion problems in masonry has increased as construction and design philosophies have changed and as environmental conditions have changed over the last decades. These changes include use of thinner masonry walls and masonry veneers that are more susceptible to water penetration, increases in atmospheric pollutants, use of accelerators containing calcium chloride, increased use of insulated cavities (resulting in the relocation of the dew point within the wall section) and combinations of different metals in brick veneer wall systems. This list is not all-inclusive; corrosion potential can also be affected by the function of a structure, geographic location, compatibility of construction materials, detailing and workmanship. Corrosion Protection. In order to provide corrosion protection, environmental factors must be controlled or metals used in construction must be protected. Conventional corrosion protection methods attempt to protect metals embedded in masonry by isolating them with impervious coatings (barrier protection), by using metals that are corrosion-resistant, or by providing cathodic protection in which one metal becomes sacrificial to protect another. Galvanizing — Galvanizing (zinc-coating) provides resistance to corrosion by two methods. First, the zinc coating acts as a barrier shielding the underlying steel from corrosive action. Second, it acts as a sacrificial element that is consumed before the base steel is attacked. This sacrificial nature protects the base steel at scratches and discontinuities in the zinc coating caused by fabrication, handling or installation, until most of the adjacent zinc coating is consumed. Studies have shown that the protective value of zinc coating is proportional to its thickness. Thus, for longer periods of protection, a thicker zinc coating is required. Also, when the protective zinc coating is depleted, the corrosion of the base steel will progress as if no galvanizing were present. Two methods of galvanizing are used to protect metal masonry ties: mill galvanizing and hot-dip galvanizing. Mill galvanizing takes place after steel wire or sheets have been processed to their specified dimensions and prior to fabrication of the tie. During the mill galvanizing process, zinc can be applied in a variety of thicknesses, as shown in Table 4. Hot-dip galvanizing is performed by dipping completely fabricated assemblies into molten zinc until a specified amount of zinc is bonded to the base metal. Hot-dip galvanized coatings are typically thicker than mill galvanized coatings and therefore, provide longer periods of protection.

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TABLE 4 Coating Requirements

1Class B — Rolled, pressed or forged articles. B-1: 3/16 in. (4.8 mm) and over in thickness and over 15 in. (381 mm) in length B-2: Under 3/16 in. (4.8 mm) in thickness and over 15 in. (381 mm) in length. B-3: Any thickness and 15 in. (381 mm) and under in length.

Stainless Steel - Stainless steel ties are often specified for use in very corrosive environments. Stainless steel ties are specified under ASTM A 240 or A 580 and are generally made from one of the austenitic stainless steels. Stainless steel resists corrosion well; however, if in contact with carbon steel, a galvanic cell can result and actually increase the potential for corrosion. For this reason, combining stainless steel ties or screws with carbon steel or galvanized steel components is not recommended. Fusion-Bonded Epoxy — Epoxy coating is the newest process used to provide corrosion protection for metal ties. The process has been adapted from epoxy-coated reinforcement bars used successfully in concrete systems with severe environmental exposures. Epoxy coating provides protection by acting as an impervious barrier. The epoxy coating is bonded to the base steel by a heat-induced chemical reaction through which a chemical and mechanical bond is formed. The combination of the two types of adhesion helps to prevent cracking of the coating due to handling, installation or stress reversals. The epoxy coating is not sacrificial like zinc; therefore, nicks and voids in the coating can lead to corrosion of the base steel. Epoxy coatings for joint reinforcement should meet the requirements of ASTM A 884, Class A, Type 1 - 7 mils. Epoxy coatings for wire ties and anchors are specified in ASTM A 899, Class C - 20 mils. Sheet metal ties and anchors should be coated with 20 mils of epoxy per surface or per manufacturer's specification. Recommendations. The past performance of metal ties in regard to corrosion has generally been satisfactory. The American Galvanizers Association has developed a Zinc Coating Life Predictor program that provides an estimate of service life for zinc coating in an exposed environment. This does not specifically address performance of ties in masonry walls. Until research can produce accurate methods of assessing corrosion potential and predicting adequate levels of protection, the Brick Industry Association suggests minimum levels of corrosion protection for metal ties and hardware as indicated in Table 5. As with all other engineering considerations minimum recommendations may not be adequate in every situation, and should not serve as substitutes for engineering investigation or judgment. Decisions must be based on individual project conditions, performance requirements and safety. TABLE 5 Recommended Minimum Corrosion Protection

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SUMMARY This Technical Notes is the third in a series addressing brick masonry anchor bolts, fasteners and wall ties. It is primarily concerned with the types of wall ties commonly used in brick masonry construction, their function, selection, specification and installation. Other Technical Notes in this series individually address anchor bolts and fasteners for brick masonry. The information and suggestions contained in this Technical Notes are based on the available data and the experience of the engineering staff of the Brick Industry Association. The information contained herein must be used in conjunction with good technical judgment and a basic understanding of the properties of brick masonry. Final decisions on the use of the information contained in this Technical Notes are not within the purview of the Brick Industry Association and must rest with the project architect, engineer and owner.

REFERENCES 1. DeVekey, R.C., ''Corrosion of Steel Wall Ties: Recognition, Assessment and Appropriate Action”, Building Research Establishment Information Paper, IP 28/79, Building Research Establishment, Garston, Watford, England, October 1979. 2. Fishburn, C.C., ''Water Permeability of Walls Built of Masonry Units”, Report BMS 82, National Bureau of Standards, Department of Commerce, Washington, D.C., April 1942. 3. Allen, M. H., Research Report No. 10, “Compressive and Transverse Strength Tests of Eight-Inch Brick Walls”, Structural Clay Products Research Foundation, Geneva, Illinois, October 1966. 4. Allen, M.H., Research Report No. 14, “Compressive Strength of Eight-Inch Brick Walls with Different Percentages of Steel Ties and Masonry Headers”, Structural Clay Products Research Foundation, Geneva, Illinois, May 1969. 5. Bortz, S.A., “Investigation of Continuous Metal Ties as a Replacement for Brick Ties in Masonry Walls”, Summary Report ARF 6620, Armour Research Foundation, Chicago, Illinois, June 1960. 6. ”Investigation of Masonry Wall Ties”, ARF Project B870-2 (Revised), Armour Research Foundation, Chicago, Illinois, December 1962. 7. ''Flexural Strength of Cavity Walls”, ARF Project B870, Armour Research Foundation, Chicago, Illinois, March 1963. 8. Brown, R.H. and Elling, R.E., ''Lateral Load Distribution in Cavity Walls”, Proceedings of the Fifth International Brick Masonry Conference, Washington, D.C., October 1979. 9. Bell, G.R. and Gumpertz, W.H., ''Engineering Evaluation of Brick Veneer/Steel Stud Walls, Part 2 —Structural Design, Structural Behavior and Durability”, Proceedings of the Third North American Masonry Conference, Arlington, Texas, June 1985. 10. Arumala, J.O. and Brown, R.H., ''Performance of Brick Veneer With Steel Stud Backup”, Clemson University, Clemson, South Carolina, April 1982. 11. ''Development of Adjustable Wall Ties”, ARF Project No. B869, Armour Research Foundation, Chicago, Illinois, March 1963. 12. Catani, Mario J., ''Protection of Embedded Steel in Masonry”, The Construction Specifier, January 1985. 13. Catani, Mario J. and Whitlock, A. Rhett, ''Coping With Wide Cavities”, The Construction Specifier, August 1986. 14. Zhang, X. Gregory, Zinc Coating Life Predictor, The International Lead Zinc Research Organization, published online at http://zclp.galvanizeit.org:8180/zclp/index.html, 2002.

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Technical Note 45 - Brick Masonry Noise Barrier Walls - Introduction [Feb. 1991] (Reissued July 2001) Abstract: Because our national highway system has grown significantly over the last few decades, public awareness of traffic noise on neighborhood communities has increased. Neighborhood associations and governmental bodies look for ways to reduce traffic noise without adversely affecting the surrounding environment. A solution to this problem lies in brick masonry noise barrier walls. Brick masonry noise barrier walls can easily blend into the environment and give residential communities protection from unwanted highway noise. Key Words: acoustics, brick, noise barrier walls. INTRODUCTION Continued growth of our national highway system combined with an increase in public awareness of environmental issues has focused on a need to evaluate the impact of traffic noise associated with highway systems on neighboring communities. When noise levels exceed acceptable limits, community action generally alerts governmental bodies to the problem or potential problems. Governmental bodies then investigate measures to prevent or alleviate noise problems. The severity of the noise and the stage at which the problem is identified determine the measures available to reduce the impact of highway noise. Measures to alleviate highway noise include traffic controls and regulations, modification of the highway configuration, land-use planning and zoning, and brick noise barrier walls. When new highway systems are in the planning and design stages, a comprehensive analysis of and consideration to noise abatement measures can be given. However, when existing highway systems are renovated or if restrictions are placed on the routing of new highway systems or use of adjacent land, the most practical solution to noise control may be the use of noise barrier walls to isolate the highway noise sources from the surrounding communities. Three major types of noise barriers are currently being used in the United States: earth berms, walls and berm-wall combinations. Of these three, the noise barrier wall is typically the most common means of achieving noise abatement and is the primary topic of this Technical Notes. This Technical Notes, the first in a series, addresses acoustical, visual, structural, construction, detailing and maintenance considerations of brick masonry noise barrier walls. The other Technical Notes in this series addresses the structural design of brick masonry noise barrier walls. ACOUSTICAL CONSIDERATIONS To understand the function of a noise barrier wall or how the wall reduces the noise level perceived by a receiver, it is necessary to discuss some of the fundamental principles involved in sound propagation and noise reduction. When there are no obstacles or barriers between highway noise sources and receivers, sound travels in a direct path from the source to the receiver (Figure 1). When a noise barrier wall is placed between the noise source and the receiver, the barrier disperses the sound along three paths: a diffracted or bent path over the top of the wall, a reflected path away from the receiver and a transmitted path through the wall (Fig. 2).

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Direct Noise Path FIG. 1

Noise Path With Barrier Wall FIG. 2 Diffraction of sound over the top of the wall produces a shadow zone behind the barrier. The boundary of this shadow zone is outlined by a straight line drawn from the noise source over the top of the barrier wall (Fig. 3). All receivers located within the shadow zone will experience some degree of sound attenuation. The amount of reduction or attenuation is directly related to the diffraction angle Ø-. As this angle increases, the barrier attenuation increases. Thus, barrier attenuation is a function of the wall height and the distances between the source, barrier and receiver. Two other factors also affect the amount of attenuation: the sound transmission characteristics of the material from which the barrier is constructed and the length of the barrier.

Noise Barrier Shadow Zone FIG. 3 The sound transmission characteristics of a material are related to its weight, stiffness and loss factors. The sound transmission characteristics of materials can be assessed and compared by means of transmission loss values. The sound transmission loss is related to the ratio of the incident noise energy to the noise energy transmitted through the material. Typically, transmission loss values can be expected to increase with increasing square foot surface weights of barrier materials. Table 1 lists the transmission loss values at a frequency of 550 hertz (Hz) for materials commonly used in noise barrier wall construction. 550 Hz is the accepted frequency used to determine the transmission loss of highway noise barrier wall materials. As a general rule for design, the transmission loss value should be a minimum of 10 decibels (dB) above the attenuation resulting from the diffraction over the top of the barrier. The transmission loss values for brick masonry are at the higher end of the range and sound transmission through a brick barrier will not significantly affect the attenuation. However, when less massive materials are used, the transmission loss values may not be adequate and the noise reduction provided by the barrier can

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be severely affected. 1

Grouted cavity is 2 3/4 in.

The actual acoustical design of a barrier system to determine the length and height requirements are beyond the scope of this Technical Notes. A detailed discussion of noise barrier acoustical design procedures and considerations can be found in Reference 1. VISUAL CONSIDERATIONS General Highway noise barriers tend to dominate the visual environment adjacent to roadways (Fig. 4). They are often thousands of feet long and can be as high as 25 ft (7.6m) above the road surface. When noise barrier walls higher than 16 ft (4.9m) are acoustically required, visual consideration of surrounding features should be evaluated. Exceptionally high walls can have an unsightly impact on the aesthetic features of the territory and can give the driver a claustrophobic feeling. For safety reasons, the designer should reduce the visual impact of the noise barrier wall. The motorist must pass the barrier with as little visual disruption as possible. The primary attention of the driver should be on the road ahead and adjacent traffic conditions. This can be achieved by doing one of several things.

Brick Noise Barrier Wall FIG. 4 For relatively low walls, the line of the noise barrier should reflect similar lines of the surrounding environment. For instance, in rolling terrain, a straight line will be out of place and attention will be drawn to that line. However, in a flat terrain where the horizon is visible as a straight line, a straight line in a noise barrier wall may not appear to be visually dominant. The introduction of vertical lines, such as with pilasters, placed along relatively low walls is recommended to achieve visual balance. Plantings such as columnar trees can emphasize vertical lines in a noise barrier wall. Further, shrubbery can be used to soften the transition between ground and wall intersection. Wherever possible, the wall should step back to open up the view for the motorist (Fig. 5). However, this can only be practically achieved in rolling or hilly terrain. In an urban environment where the horizon is composed of alternating heights of buildings, an appropriate wall may vary in height as a reflection of the city's profile.

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Effect of Wall Placement on Sight Lines FIG. 5 Another way to reduce the visual impact on the environment is through changes in height and location of the wall. A wall with offsets can break the monotony of a straight wall and create pockets which can be used for plantings (Fig. 6). These transitions may further be used as areas for change in texture, color or wall height. A serpentine wall can create the same visual interest as a wall with offsets (Fig. 7). Moreover, due to their geometry, both of these walls have the added advantage of being more resistant to seismic and wind forces than their straight counterparts.

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Offset Wall FIG. 6a

Offset Wall FIG. 6b

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Serpentine Wall FIG. 7a

Serpentine Wall FIG. 7b Regardless of the shape, noise barrier walls should not begin or end abruptly. The best transition of beginning and end is to tie the wall into a natural hillside or a man-made earth berm. If no natural hills or berms are available, the wall termination should taper down and angle away from

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the roadway. Not only is this visually pleasing, it is also functional. This transition can effectively reduce the amount of noise traveling around the end of the wall as a result of approaching traffic. Access through noise barrier walls may be needed in certain instances. Maintenance personnel may require doors for equipment or service. Firefighters may require access to hydrants or water sources on the opposite side of the barrier wall. The appropriate highway and emergency agencies should be consulted regarding access locations and requirements. Openings through noise barrier walls must not reduce the acoustic or structural performance of the noise barrier. Larger openings are best located at offsets in the wall, or with piers or pilasters at the jamb of the opening. This geometry provides an easier means of accommodating loads and reducing sound penetration. Openings in straight wall sections change the load distribution and this influence must be considered. Loose steel lintels or reinforced masonry beams should be used to span over the openings. Texture A change of texture on noise barriers helps to create a pleasant variety for motorist, adjacent residents and pedestrians. The requirements of each are different, however, and must be treated separately. Since motorists usually drive at high rates of speed, they have little opportunity to examine details. To be effective, textures along the highway need to be bold or coarse and visible at a glance because the motorists' attention should not be diverted from the highway. However, textures on the opposite of the highway should be more detailed. The residents and pedestrians on this side view the barrier at much slower speeds and at closer distances. Bold textures can be overbearing and monotonous to them and, therefore, should not be used. Unlike other materials, masonry can be adapted to create the bold textures for the motorist and the subtle, more detailed textures for those on the other side. Because of its versatility, the possibilities for brick masonry are almost limitless. Bold textures can be created by offsetting brick in random patterns which can cast varying textural shadows during the day. The use of pilasters, special shape brick and copings can also create bold textural interest. Further, brick sculpture can create detailed textures for residents (Fig. 8). Brick can be carved to portray a desired logo, mural or composition.

Brick Sculpture FIG. 8 Color Color The color of the wall plays an important role in blending the wall into the surrounding environment. Since brick barrier walls are man-made structures placed in a natural environment, their color should not attempt to match the color of trees, grass, or shrubbery because they are not related to such natural features by form. Earthen colors, such as browns, grays, and rusts of varying

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tones, when used on barrier walls help to blend the structures into their environment. Repetitious polychromatic patterns are not recommended on the highway side of the barrier. These types of patterns draw the motorists' attention away from the road ahead. However, they can be used on the side of the wall opposite of the highway. Moreover, placing units of different color in alternating bonding patterns can also easily create visual interest. Further, color interest and variety may be achieved through the use of plants and trees. Foliage which changes color will impart a pleasing seasonal variation. STRUCTURAL CONSIDERATIONS Structurally, brick masonry noise barrier walls can be designed in various ways. The most popular designs though are the pier and panel, pilaster and panel, and the cantilever walls. Pier and Panel Wall The pier and panel wall is composed of a series of single-wythe panels, usually four inches in thickness. These panels are braced periodically by piers (Fig. 9). This type of wall is relatively easy to build and is economical due to the efficient use of materials. It is easily adapted to varying terrain and is acoustically adequate for a highway noise barrier. The pier and panel wall can also be built with returns of varying angles. However, the most easily constructed and economical return is one which is perpendicular to an adjacent panel. The panels, usually built from 8 to 20 ft long (2.4 to 6.1 m), are placed between piers of reinforced masonry, concrete, or steel. The panels can either be prefabricated or built in place and can be as high as acoustically or aesthetically necessary. However, any space left between the bottom of the wall and the ground must be adequately backfilled to prevent noise penetration underneath the wall. .

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Pier and Panel Assembly FIG. 9 The panels, supported on piles or clip angles attached to piers, essentially act as thin, simply supported beams. The panel, which spans horizontally between the piers, will develop flexural tensile stresses parallel to the bed joints due to out-of-plane wind and seismic loads (Fig. 10). Horizontal joint reinforcement is required if the calculated flexural stresses exceed the allowable stresses found in the local building code. If horizontal reinforcement is required, it must be distributed the full height of the panel.

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Out-of-Plane Deflection of Panel in Pier and Panel Wall FIG. 10 The panel also develops in-plane flexural stresses due to its own dead weight and any incidental vertical loading which may occur (Fig. 11). The in-plane bending will cause flexural tensile stresses at the bottom of the panel. Although the building codes do not now define allowable flexural tensile values for in-plane bending, the allowable flexural tensile stresses parallel to the bed joint for out-of-plane bending can conservatively be used. Both the in-plane and out-of-plane flexural tensile stresses must be calculated and added because the bottom of the panel is subjected to both maximum in-plane and out-of-plane moments. If the sum of the calculated stresses exceeds the out-of-plane allowable flexural tensile stress parallel to the bed joint the panel must be reinforced. This reinforcement is usually placed in the bottom two or three courses of masonry.

In-of-Plane Deflection of Panel in Pier and Panel Wall FIG. 11 The piers, on the other hand, act as vertical cantilevers and must be designed to resist all lateral loads transferred from the panels. The piers are usually anchored to or embedded in reinforced concrete piles, which vary in depth due to local soil conditions. The piles must be designed to resist all shear and axial loads and the overturning moment caused by the panel due to

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out-of-plane wind and seismic forces (Fig. 12). Vertical reinforcement may be required in a panel if the out-of-plane deflection of the pier exceeds the maximum allowable deflection of the panel. This maximum allowable deflection for an unreinforced panel is based on the allowable flexural tensile stress perpendicular to the bed joints. If vertical reinforcement is required, then hollow brick units can be used to facilitate the reinforcement and grouting process. However, it is recommended that the piers be stiff enough so vertical reinforcement in the panels is not necessary.

Out-of-Plane Deflection of Pier and Panel FIG. 12 Due to the deflection requirements of the panel, the web length of the pier may be larger than the width of the panel, especially for piers made of steel. The space between the pier and panel must be filled with a non-compressible material, placed either uniformly or intermittently along the height of the pier. This non-compressible material ensures proper load transfer from the panel to the pier. However, if intermittent supports are used, a filler material must be placed between supports to block noise transfer around the end of the panel. Further, a clear space the entire height of the panel must be maintained between the end of the panel and the web of the pier. This space allows for the in-plane expansion and contraction of the brick panel (Fig. 13).

Steel Pier/Panel Detail FIG. 13 When reinforced concrete or masonry piers are used, the flanges should be analyzed to ensure that the shear and bending forces imposed on them by the adjacent panel do not exceed allowable stresses. If for aesthetic reasons, an exposed steel pier is not desirable, brick can be built around the steel in the form of a pilaster (Figs. 13 through 15). Corrosion protection of the pier should be considered when steel piers are used. Finally, the panels can bear directly on the pile or a steel clip angle which is attached to the pier. The bearing stress requirements of each material must be considered in the design.

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Steel Pier and Panel Wall FIG. 14

Steel Pier and Panel Wall with Brick Surround FIG. 15 Pilaster and Panel Walls The pilaster and panel and the pier and panel wall appear to be very similar. Both are composed of single-wythe panels periodically braced by vertical elements and both are equally adaptable to varying terrain and returns. However, there are some fundamental differences which must be carefully analyzed. First, unlike the pier and panel wall, the panel in the pilaster and panel wall is integrally bonded to the pilaster at most intersections (Fig. 16). This seemingly innocuous difference actually has a marked effect on the structural characteristics of the wall. The end condition of the panel in a pier and panel wall is considered simply supported while that in a bonded pilaster and panel is considered fixed. Because of the fixed-end condition, the designer must satisfy the negative moments which are generated at the pilaster (Fig. 17). Depending on the geometry of the wall, horizontal reinforcing steel may be required in both the top and bottom courses of brick due to vertical in-plane bending. If required, it must be fully developed and adequately anchored in the pilaster. The horizontal out-of-plane deflection of the panel will also generate negative moments at the pilaster (Fig. 18). Any horizontal reinforcement will help resist negative moments due to out-of-plane bending. However, the reinforcement must also be fully developed in the pilaster. The pilaster should be stiff enough so the allowable flexural tension developed in the panels due to the out-of-plane deflection of the pilaster is not exceeded. The pilaster must be rigidly attached to the pile below, and the pile must be designed to resist all shear and axial loads and overturning moments.

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Pilaster and Panel Assembly FIG. 16

In-Plane Deflection of Panel in a Pilaster and Panel Wall FIG. 17

Out-of-Plane Deflection of Panel in a Pilaster and Panel Wall FIG. 18

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Another difference between the pier and panel and pilaster and panel wall is the placement of expansion joints. Since the pier and panel are not bonded together, the in-plane horizontal movement can be accounted for at the end of each panel. However, this is not the case with the pilaster and panel wall because they are integrally bonded together. A vertical break provided by an expansion joint is necessary to permit horizontal expansion. The best location for an expansion joint is at the pilaster and panel intersection. The expansion joints should not be placed more than a maximum of 30 ft (9.1m) on center, and the pilaster must not restrict horizontal in-plane movement due to expansion. Further, the connection between pilaster and panel must be able to resist the out-of-plane loads imposed on it. Finally, because the pilaster and the panel are bonded together, the pilaster and panel wall must be built in place. Forms or centering must support the panel during construction and can only be removed after the wall is adequately cured. However, a continuous footing running between the piles could be used to support the dead weight of the panel. Cantilever Walls The cantilever wall acts, as its name implies, like a vertical cantilever supported on a continuous footing. Unlike the panel walls, this type of wall is subjected primarily to out-of-plane bending (Fig. 19). The cantilever wall must be built of either reinforced grouted hollow or multi-wythe masonry (Fig. 20). To function properly this wall must be supported on a continuous foundation, usually made of reinforced concrete. The foundation must be designed to support the weight of the wall and be able to resist rotation caused by out-of-plane loads imposed on the wall. The reinforced masonry wall is anchored to the foundation by steel reinforcement placed in the cells of hollow masonry or between wythes in a multi-wythe wall. The steel reinforcement should be designed to resist the flexural tension developed in the wall and be fully developed in both the foundation and grouted masonry.

Out of Plane Deflection of Cantilever Wall Fig. 19

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Cantilever Wall Cross Sections FIG. 20 Expansion joints should be placed at a maximum of 30 ft (9.1m) on center and may be detailed in a staggered fashion for multi-wythe construction (Fig. 21). This detail ensures that the sound from a highway cannot pass directly through the wall if the sealants fail.

Staggered Expansion Joint FIG. 21

Other Load Considerations Foundations. Additional stresses can be introduced in brick masonry noise barrier walls by differential settlement or rotation of the foundation system. Soil conditions should be evaluated to keep both differential settlement and differential rotation to a minimum in all wall systems. However, horizontal reinforcement can be used to resist in-plane loads resulting from differential settlement in pilaster and panel and in cantilever walls. Further, more frequent spacing of vertical expansion joints can reduce the effect of differential settlement in these walls. Traffic Impact. The possibility of vehicles hitting a noise barrier wall must be considered. This is of special concern if the wall is immediately adjacent to the shoulder. Concrete deflector barriers

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are recommended in this instance, and any time such devices are used traffic impact loads on the noise barrier walls need not be considered. If traffic can reach the noise barrier wall, then these additional loads must be considered. Horizontal and vertical reinforcement may be necessary in the brick noise barrier wall to add ductility and post-cracking integrity. Due to the varying traffic and site conditions it is beyond the scope of this Technical Notes to evaluate traffic impact effects. Local highway officials should be consulted to establish these design parameters. Seismic. If brick masonry noise barrier walls are built in Seismic Performance Categories C or D, they must be reinforced with a minimum amount of both horizontal and vertical reinforcement. These reinforcement requirements can be found in the Building Code Requirements for Masonry Structures (ACI 530 / ASCE 5 / TMS 402-02) or the local building codes. Moreover, an analysis should be made to ensure that sufficient reinforcement is present to resist the seismic forces.

CONSTRUCTION AND DETAILING CONSIDERATIONS Good workmanship and detailing are key to the success of all masonry assemblages, including noise barrier walls. Full head and bed joints and proper location and installation of reinforcement, ties, flashing and expansion joints are required for proper performance. Any unfilled joint will result in water penetration and will degrade the effectiveness of the noise barrier wall. Proper mixing and consistency between batches of mortar and grout is necessary. All spaces to be grouted must be completely filled, and grouting procedures found in the local building codes must be followed. Generally, Type S mortar as specified by proportion in ASTM C 270 Mortar for Unit Masonry is recommended for construction of noise barrier walls. Grout should conform to ASTM C 476 Specification for Grout for Masonry. Two critical details in a noise barrier wall are the location and placement of copings and flashing. Copings should project beyond the faces of the wall a minimum of 1 in. (2.5 cm) on both sides. Stone or masonry copings should have a minimum slope of 15 degrees from horizontal and contain a positive drip to keep water from flowing down the face of the wall. It is important that the copings be anchored to the brick wall with metal anchors or bolts, especially in high wind and seismic areas. Natural stone, cast stone, terra cotta, metals, and brick are suitable for copings. If metal copings are used, they should extend down each side of the wall a minimum of 4 in. (10 cm). A sealant should be placed between the metal coping and the wall to prevent wind uplift and water penetration (Fig. 22). When stone or concrete copings are used, an elastic sealant should be placed between the head joints of the coping pieces (Fig. 23). If brick is used as a coping (Fig. 24), it may be prudent to use units which have the same physical requirements as brick pavers. ASTM C 902 Standard Specifications for Pedestrian and Light Traffic Paving Brick is the specification for these units. However, brick units that have been used successfully as a coping in the past, should be adequate.

Metal Coping FIG. 22

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Stone Coping FIG. 23

Brick Coping FIG. 24 Through-wall flashing is required directly under the coping. The flashing should extend beyond the faces of the wall to form a drip. All penetrations through the flashing made by the anchors must be adequately sealed with a compatible material. Brick in noise barrier walls should not be in direct contact with the ground. Salt laden ground water could be absorbed into the brick causing efflorescence or possible spalling in the lower courses. In some instances it may be visually and functionally necessary to have the base of the wall in contact with the ground. In these cases, gravel instead of earth should be placed in contact with the wall. The gravel not only keeps ground water from being absorbed by the brick masonry but also keeps the lower courses free from staining by rain splashed earth.

MAINTENANCE CONSIDERATIONS Brick masonry walls maintain their aesthetic appeal and remain virtually maintenance free throughout their life. The expansion joint sealant and any sealants used in conjunction with copings are the only elements in the wall which will require intermittent inspection and maintenance. In some areas the noise barrier wall may be subjected to graffiti. In such an instance, an anti-graffiti coating should be considered. However, some coatings may reduce the durability of clay brick. Also, to remain effective, these materials may have to be re-applied. Further, sufficient rights-of-way should be established where possible to allow for accumulations of snow on the leeward side of the wall. The location and alignment of noise barriers should be analyzed in order to prevent or reduce problems of drifting snow across roadways.

SUMMARY Because our national highway system has grown significantly over the last few decades, public awareness of traffic noise on neighborhood communities has increased. Neighborhood associations and governmental bodies look for ways to reduce traffic noise without adversely

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affecting the surrounding environment. A solution to this problem lies in brick masonry noise barrier walls. Brick masonry noise barrier walls can easily blend into the environment and give residential communities the protection from highway noise. The information and suggestions contained in this Technical Notes are based on the available data and the experience of the engineering staff of the Brick Industry Association. The information contained herein must be used in conjunction with good technical judgment and a basic understanding of the properties of brick masonry. Final decisions on the use of the information contained in this Technical Notes are not within the purview of the Brick Industry Association and must rest with the project architect, engineer and owner.

REFERENCES 1. Noise Barrier Design Handbook, Report No. FHWA-RD-76-58, United States Department of Transportation, Federal Highway Administration, 1976. 2. A Guide to Visual Quality in Noise Barrier Design, Implementation Package 77-12, United States Department of Transportation, Federal Highway Administration, 1977. 3. Guide Specifications for Structural Design of Sound Barriers, American Association of State Highway and Transportation Officials, 1989. 4. Technical Notes on Brick Construction 5A, “Sound Insulation-Clay Masonry Walls”, Brick Institute of America, Aug. 1986.

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Technical Notes 45A - Brick Masonry Noise Barrier Walls - Structural Design April 1992 Abstract: Rationally designed brick masonry noise barrier walls provide an attractive wall form with reliable structural function. This Technical Notes addresses the structural design of pier and panel, pilaster and panel, and cantilever brick noise harrier walls. Suggested design methodology and design examples are provided. The information presented in this Technical Notes can be applied with slight modifications to the many design schemes and loading demands of noise barrier walls. The result is an attractive noise barrier wall with the durability and versatility inherent in brick masonry structures.

Key Words: brick, cantilever, noise barrier, pier, pilaster, structural design, wall system.

INTRODUCTION

Technical Notes 45 presented an introduction to acoustical, visual, structural, and construction considerations for brick masonry noise barrier walls. In continuation of the series, this Technical Notes addresses structural design considerations in greater detail and provides design examples. Recommended procedures are presented on the structural design of the wall system assuming acoustic and visual considerations are previously addressed. Design recommendations for noise barrier wall footings and caissons have not been addressed in this Technical Notes. A design approach is presented which follows criteria contained in the Building Code Requirements for Masonry Structures (ACI 530/ASCE 5/TMS 402-92) and, where applicable, the Load and Resistance Factor Design Manual of Steel Construction-First Edition (AISC LRFD). Refer to Technical Notes 3 series for a discussion of the ACI/ASCE/TMS document.

NOTATION1 As Area of steel, in.2 b Width of section, in. c Distance from extreme compression fiber to the neutral axis of the cross section, in. d Distance from extreme compression fiber to the centroid of tension reinforcement, in. Em Modulus of elasticity of masonry in compression, psi Es Modulus of elasticity of steel, psi

fa Calculated compressive stress in masonry due to axial load only, psi

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fcr Modulus of rupture, psi fb Calculated compressive stress in masonry due to flexure only, psi Fb Allowable compressive stress in masonry due to flexure only, psi

fm Compressive stress in masonry, psi Specified compressive strength of masonry, psi

fs Calculated tensile or compressive stress in reinforcement, psi Fs Allowable tensile or compressive stress in reinforcement, psi

ft Calculated tensile stress in masonry, psi Ft Allowable flexural tensile stress in masonry, psi

fv Calculated shear stress in masonry, psi Fv Allowable shear stress in masonry, psi

fy Specified yield stress for reinforcement, psi h

Height of wall or panel, ft

Icr Moment of inertia of cracked masonry cross section, in.4 Ie Effective moment of inertia, in.4 Ig Moment of inertia of uncracked masonry cross section, in.4 Ix Moment of inertia of steel pier about the strong axis, in.4 j Ratio of distance between centroid of flexural compressive forces and centroid of tensile forces to depth k Ratio of distance between compression face and neutral axis to distance between compression face and centroid of tensile forces M Design moment, ft-lb Mn Nominal moment strength, ft-lb Mo Overturning moment, ft-lb Mpx Moment due to spanning between piers, ft-lb Mpy Moment induced by Mpx due to plate effects, ft-lb Mr Resisting moment, ft-lb Mu Ultimate moment strength, ft-lb Mw Moment due to spanning between caissons, ft-lb

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n Elastic moduli ratio, Es /Em P Design axial load, lb p Reinforcement ratio, As/bd r Radius of gyration, in. t Thickness of wall or panel, in. V Design shear force, lb Vn Nominal shear strength, lb Vpx Shear due to spanning between piers, lb Vu Ultimate shear strength, lb W Lateral load, lb/ft x Width of footing, ft y Depth of footing, ft D Deflection, in. fb Resistance factor

1

Metric equivalents:

1 in. = 25.4 mm 1 ft = 0.3048 m 1 lb = 4.448 N 1 psi = 0.006895 N/mm 2

SELECTION OF A WALL SYSTEM

As discussed in Technical Notes 45, there are three typical brick masonry noise barrier wall systems: cantilever walls, pier and panel walls, and pilaster and panel walls. Preliminary consideration of design parameters can help select the wall system that is most appropriate and efficient without having to develop and compare three separate designs.

Cantilever Noise Barrier Walls A cantilever wall system is better suited for shorter noise barriers, i.e. walls that are 12 ft (3.7 m) or less in height.

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In most instances, taller cantilever walls are less desirable because strip footings become too massive. Cantilever walls are more efficient for shorter heights because they are likely the easiest and most economical to construct, and will require the least quality control and inspection. This is because construction techniques used are similar to building wall construction familiar to mason contractors.

Pier and Panel Noise Barrier Walls Pier and panel wall systems are best for quick site erection. Brick panels can be prefabricated on or off site, or laid in place. Also, pier caissons are typically constructed faster and require less concrete than strip footings. Strip footings under the panel are not required, as the panel can span from pier to pier. Material costs for pier and panel wall systems will typically be the least of the three systems. Disadvantages of the pier and panel system include increased construction supervision and inspection, tight construction tolerances for pier-to-panel connections, and increased costs to install the panels.

Pilaster and Panel Noise Barrier Walls Pilaster and panel walls, like pier and panel walls, typically utilize caissons for quick foundation construction. Wall construction is done on site, as the panel is built integral with the pilaster. This requires panel support between caissons during construction. Supervision and inspection are required to ensure proper construction. However, construction tolerances are more liberal than those for pier and panel systems. Generally, pilaster and panel wall systems permit longer pier spacing and taller wall height. A pilaster and panel wall assembly is structurally more efficient than a pier and panel wall assembly, as a fixed condition may be developed at the pilaster-panel connection.

DESIGN ASSUMPTIONS

It has been widely accepted that masonry stress-strain behavior is similar to that of concrete. Thus, design assumptions made for masonry under working stress and strength conditions are analogous to assumptions made in concrete design. Figure 1 depicts the assumed stress-strain relationship for masonry in flexure under working loads. In all cases, the principles of equilibrium and compatibility of strains of masonry materials are assumed to apply. Assumptions made following a working stress design are as follows: 1) plane sections before bending remain plane after bending, 2) moduli of elasticity of masonry and steel remain constant, 3) reinforcement is completely bonded to masonry, and 4) in cracked masonry members, the tensile capacity of masonry is neglected.

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Straight Line Stress Distribution FIG. 1

In this Technical Notes, a number of additional assumptions will be made to facilitate design. It is assumed that the brick masonry will be reinforced. Most noise barrier wall applications demand tall slender walls to meet acoustic requirements and minimize material costs and land use. Reinforcing is required for brick masonry to meet these criteria. Additional assumptions placed on both material properties and wall behavior are as follows.

Material Properties Grout and concrete are assumed to have compressive strength equal to or greater than the masonry compressive strength, and elastic moduli of the masonry and the grout are assumed to be equal. The method of transformation of areas may be used in lieu of these assumptions.

Wall Behavior Masonry walls are plate structures. Thus, a masonry wall loaded perpendicular to its plane will experience strain along its length and its height. However, the traditional masonry wall design approach is to use the strip method. In this method, a one foot wide section of wall is designed considering one span direction. Strains perpendicular to the strip span direction are ignored. For cantilever walls, this method is nearly exact, as plate effects are negligible. Pier and panel and pilaster and panel walls, however, exhibit wall behavior which can make plate effects significant. This does not mean a rigorous plate analysis is necessary for these walls. Rather, a few simple observations and assumptions can be made to simplify design. For pier and panel and pilaster and panel wall systems, the panel is subject to three different deflection conditions: a horizontal simple span between piers or pilasters subject to wind or seismic load, a horizontal simple span between caissons subject to panel weight, and a vertical cantilever span subject to deflection of the pier or pilaster. If the panel is free to deflect both in-plane and out-of-plane, the moment due to simple spanning between piers or pilasters, Mpx, and the moment due to simple spanning between caissons, Mw, are combined by vector addition to calculate the maximum design moment for the horizontal span of the panel. However, the panel must be flush with the ground to avoid noise penetration under the wall. Thus, the panel may, in fact, be supported along its entire length by the ground. This is significant, because the design moment in this case is solely Mpx, the moment about the weak axis of the panel. This condition will require the most amount of horizontal reinforcement for the panel. In the panel design examples that follow it is assumed that the ground supports the entire length of the panel. Because of plate effects, Mpx will induce moment about the horizontal axis as well, denoted as Mpy. The strip solution does not and cannot calculate Mpy, as plate effects are ignored in this method. However, plate analysis shows that Mpy can be significant and that the ratio of Mpy to Mpx increases as the height to length ratio of the panel increases. As an approximation, Mpy is calculated as one tenth the height to length ratio times Mpx. Mpy is a maximum at the middle of the panel. However, moment due to vertical cantilever deflection of the wall is a maximum at the bottom of the panel. Thus, the design moment about the horizontal axis is the greater of: 1) the moment due to vertical cantilever deflection at the bottom of the panel, or 2) the sum of Mpy and the moment due to vertical cantilever deflection at the middle of the panel.

Vertical cantilever deflection of the panel is a function of the rigidity of the piers or pilasters. If the piers or pilasters are very rigid, cantilever deflection of the panel will be negligible. However, optimal flexural design may result in less rigid piers or pilasters with considerable deflection, especially when steel piers are used. Induced tensile stresses in the panel must be within allowable tensile stresses for unreinforced masonry if the panel cannot be reinforced in the vertical direction. Thus, deflection criteria will often govern pier and pilaster design.

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Reinforced brick masonry pilaster and panel and pier and panel wall systems are typically very rigid, so deflections in many cases will be small. However, the deflection of the pilaster must be calculated considering the ratio of applied moment to cracking moment. Cracking moment is calculated using the gross moment of inertia of the pier or pilaster. In the pilaster and panel design example that follows, a two span continuous panel is assumed. Thus, the pilaster panel interface is assumed to be a fixed connection for the middle pilaster, and a simple connection for the two exterior supports. This allows for expansion joints at the simple supports to accommodate horizontal expansion of the panels. Lastly, compression steel in the pilaster is usually ignored in design. If consideration of the increased compressive strength due to the compression steel is made, the steel must be properly confined within the pilaster with lateral or spiral ties.

DESIGN PROCEDURE

It is important to establish a set design procedure to ensure an accurate and comprehensive noise barrier wall design. The following nine steps are presented as a guide to the structural design of a brick masonry noise barrier wall. Additional criteria may be warranted for a particular wall design scheme. 1) Determine required wall height based upon acoustical considerations. 2) Determine critical lateral and axial load combinations on wall elements. Loads should be determined according to the recommendations of the local building code or as contained in the document Minimum Design Loads for Buildings and Other Structures (ASCE 7). For the examples that follow, inertial wall force due to seismic base shear is divided by wall surface area for comparison with wind loads. 3) To determine required reinforcement, assume j = 0.9:

As req'd=M/Fsjd 4) Calculate masonry compressive stresses and the steel tensile stress:

fb = 2M/jkbd2 fa = P/bkd fs = M/Asjd 5) Check the allowable compressive stress in masonry and the tensile stress in steel (Table 1). Axial compression and buckling seldom govern design of noise barrier wall elements. However, axial compression must be included to calculate the maximum flexural compression. Note that allowable stresses for wind or seismic load conditions may be increased by one-third over those given in Table 1.

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1

Allowable stresses for wind and seismic loading conditions may be increased by one-third.

6) Calculate shear stress:

fv = V/bjd 7) Check the allowable shear stress in masonry (Table 1). If exceeded, member must be reinforced for shear and the shear stress checked. 8) Design the pier or pilaster, if applicable. If the pier or pilaster is made of reinforced masonry, design will follow steps 3 through 7. If a steel pier is used, follow the design recommendations given in the Load and Resistance Factor Design Manual of Steel Construction. Flexural tensile stresses developed in unreinforced masonry panels due to pier or pilaster deflection may not exceed the allowable flexural tensile stresses given in Table 2.

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1Allowable stresses for wind and seismic loading conditions may be increased by one-third. 2

For partially grouted masonry allowable stresses shall be determined on the basis of linear interpolation between hollow units which are fully grouted or ungrouted and hollow units based on amount of grouting.

9) Calculate overturning and resisting moments, and sliding resistance (Fig.2). These are functions of the wall, footing, and caisson dimensions, as well as the soil pressure resistance. The factor of safety is the ratio of resisting moment, Mr, to the overturning moment, Mo. A factor of safety of 2 or greater is recommended.

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Wall/Footing Forces FIG. 2

Hollow Brick Cantilever Wall FIG. 3

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DESIGN EXAMPLES Design Example #1: Hollow Brick Cantilever Noise Barrier Wall Type S portland cement/lime mortar, f'm = 3600 psi, Em = 3.0 x 106 psi, n = 9.7 Wall dimensions shown in Fig. 3, running bond, face shell bedding Grade 60 reinforcement, Loads: wind = 20 psf, wall weight =73 psi Step 1: Based on acoustical considerations, the wall height shall be 10 ft minimum. Step 2: Critical load combinations result in the following design values (per ft of wall):

M = (0.5)(W)(h)2 = (0.5)(20 psf) (10ft)2 = 1000 ft-ob V = (W)(h) = (20 psf)(10ft) = 200 lb P = (wall weight)(h) = (73 psf)(10 ft) = 730 lb

Step 3: Calculate required reinforcement.

Try #5 bars @32 in. o.c., per foot of wall (Table 3).

Step 4: Calculate the masonry compressive stress and the steel tensile stress.

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1Area of steel listed is for one wire.

Step 5: Check compressive stress in masonry and the tensile stress in steel.

Step 6: Calculate shear stress.

Step 7: Check shear stress.

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Step 8: Does not apply. Step 9: Neglect the soil pressure resistance to overturning. Calculate overturning and resisting moments, and the safety factor on overturning (Fig. 2). Note: Sliding must also be considered. Sliding is a function of the soil conditions, and is beyond the scope of this Technical Notes.

Design Example #2: Steel Pier with 4 Inch Panel Noise Barrier Wall Type S portland cement/lime mortar, f'm = 3000 psi, Em = 2.8 x 106 psi Wall dimensions shown in Fig. 4 Running bond, full bedding, spacing of piers shall be 15ft Ladder type joint reinforcement: Pier I-beam: Grade 50 W Section, Loads: wind = 15psf, panel weight = 40psf, seismic = 25psf

Noise Barrier Wall Design Example #2

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Steel Pier With 4 Inch Panel FIG. 4

Step 1: Based on acoustical considerations, the wall height shall be 16 ft minimum.

Step 2: Critical load combinations result in the following design values: a) For the panel span between piers (per foot of wall): 2

Mpx = (1/8)(W)(L) = (1/8)(25 psf)