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Testing Standards for Sandstone, Lime stone, Marble and Slate Praveena Das Jennifer*, G.M.Nagaraja Rao** P.C.Nawani @ 1

National Institute of Rock Mechanics, Kolar Gold Fields - 563 117, Karnataka, India

1. Introduction Dimension stone includes granite, sandstone, limestone, marble and slate. They can be in the form of tiles, slabs, circle, steps etc. They differ in their properties, colors and textures, and usage depending on the application. In today’s building environment, the emphasis is on safe, permanent, low maintenance products, of which stone leads the list in the minds of architects, designers, and consumers worldwide. Before putting the material into usage it is prerequisite to ascertain whether the material is having the basic engineering properties or not. Without a consistent, realistic set of standards and testing procedures for stone products, the stone industry as a whole would be in disarray. The standards that have been developed and set in place for these products are important tools to help protect end users, individual companies, and the industry from negative effects related to product failures. Materials standards help to prevent the use of stone products for unsuitable applications. These standards also serve as benchmarks for quality limits of products. To determine the properties of stones, two important International Standards are available 1. ASTM Standards 2. European Standards These standards give the procedures for determining the various properties and also property value for accepting the stone. European standards give detailed methodology for CE marking. Every one is more or less familiar with ASTM standard, but European standards are of recent one. In this paper we shall discuss about the required tests to be carried out for sandstone, limestone, marble, and slate as per ASTM and European Standards for better marketability of the stone. 2. International Standards 2.1 ASTM (American Society for Testing and Materials) Standard The following American Standards (Table 1) gives the specification (i.e. property values) for sandstone, lime stone, marble and slate, which may be used as acceptance criteria for each of the stone.

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* Scientist, ** Corresponding author @ Director

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TABLE 1 Code C568 C503 C616 C620 C406

Title Specifications for Limestone Dimension Stone Specifications for Marble Dimension Stone (Exterior) Specifications for Quartz-based Dimension Stone (Sandstone) Specifications for Slate Dimension Stone Specifications for Roofing Slate

In the following tables, the properties required to be tested and the test code reference as per the ASTM standard for sandstone, limestone, marble and slate for the benefit of quarry owners and suppliers of dimensional stones, have been given. 2.1.1 SANDSTONE-Requirement TABLE 2 Sl no.

Property

Test Requirement*

ASTM test Code

1.

Absorption, max, (%)

8

C97

2.

Density, min, (kg/m3)

2003

C97

3.

Modulus of rupture, min, (MPa)

2.4

C99

4.

Compressive strength, min, (MPa) 27.6 Abrasion resistance subjected to foot traffic, min, 2a 5. (H) a Not recommended for paving in areas subject to heavy foot traffic * for sandstone with 60% minimum free silica content

C170 C241/ C1353

2.1.2 LIMESTONE - Requirements ASTM has classified limestone into three categories according to their density ranges as follows: TABLE 3 Type 1: limestone having a density ranging from 1760 to 2160 kg/m3 - Low Density Sl no. 1. 2. 3. 4. 5.

Property Absorption, max, (%) Density, min, (kg/m3) Modulus of rupture, min, (MPa) Compressive strength, min, (MPa) Abrasion resistance subjected to foot traffic, min, (H)

Test Requirement 12 1760 2.9 12 10

ASTM test Code C97 C97 C99 C170 C241/ C1353

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TABLE 4 Type 2: limestone having a density ranging from 2160 to 2560 kg/m3 - Medium Density Sl no. 1. 2. 3. 4. 5.

Property Absorption, max, (%) Density, min, (kg/m3) Modulus of rupture, min, (MPa) Compressive strength, min, (MPa) Abrasion resistance subjected to foot traffic, min, (H)

Test Requirement 7.5 2160 3.4 28 10

ASTM test Code C97 C97 C99 C170 C241/ C1353

TABLE 5 Type 3: limestone having a density greater than 2560 kg/m3 - High Density Sl no. 1.

Property Absorption, max, (%) 3

Test Requirement

ASTM test Code

3

C97

2560

C97

2.

Density, min, (kg/m )

3.

Modulus of rupture, min, (MPa)

6.9

C99

4.

Compressive strength, min, (MPa) Abrasion resistance subjected to foot traffic, min, (H)

55

C170 C241/ C1353

5.

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2.1.3 MARBLE- Requirements TABLE 6 Sl Property no. 1. Absorption, max, (%) 2. Density, min, (kg/m3) 3. Modulus of rupture, min, (MPa) 4. Compressive strength, min, (MPa) Abrasion resistance subjected to foot traffic, min, 5. (H) 6. Flexural strength, min, (MPa)

Test Requirement 0.20 2595 7 52 10 7

ASTM test Code C97 C97 C99 C170 C241/ C1353 C880

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2.1.4 SLATE -Requirements ASTM has classified slate into two categories according to its use as follows: Type 1: slate used for Exterior applications TABLE 7 Sl no. 1. 2. 3. 4.

Property

Test Requirement

ASTM test Code

0.25

C121

62.1 49.6

C120

Absorption, max, (%) Modulus of rupture, min, (MPa) Across grain Along grain Abrasion resistance subjected to foot traffic, min, (H) Acid resistance, max, (mm)

C241/ C1353 C217

8.0 0.38

Type 2: slate used for Interior applications TABLE 8 Sl no. 1. 2. 3. 4.

Property

Test Requirement

ASTM test Code

0.45

C121

49.6 37.9

C120

Absorption, max, (%) Modulus of rupture, min, (MPa) Across grain Along grain Abrasion resistance subjected to foot traffic, min, (H) Acid resistance, max, (mm)

C241/ C1353 C217

8.0 0.64

2.2. Properties for intended use Depending on the application or usability of the dimensional stone, the test properties to be determined are listed in the following table. TABLE 9 Sl No 1. 2.

Test Method → External Cladding Load Bearing Masonry units

Absorption, (%)

Density, (kg/m3)

Compressive strength, (MPa)

Flexural strength, (MPa)

-

Abrasion resistance subjected to foot traffic, (H)

Acid resistance, (mm)

-

-

-

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Sl No

3. 4. 5. 6. 7. 8. 9.

10.

3.

Test Method →

Absorption, (%)

Density, (kg/m3)

Non load Bearing Masonry units Copings Sills/ Lintels Roofing Internal Flooring External Pavements Counter Tops Food Areas (Commercial, Residential, kitchen and Dining areas)

Compressive strength, (MPa)

Flexural strength, (MPa)

Abrasion resistance subjected to foot traffic, (H)

Acid resistance, (mm)

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

(flooring only)

-

EUROPEAN STANDARDS

European standards do not give separate standard for lime stone, sandstone and marble. The standards are broadly classified in to two groups: 1. Standards for granite, lime stone, sandstone and marble. 2. Standards for slate. The standards which are applicable for Granite are also applicable to lime stone, sandstone and marble are given in TABLE 10 TABLE 10 European Standards for Natural Stones prepared by the CEN TC 246 Code Title EN 12371 Determination of Frost Resistance EN 14581 Determination of Thermal Dilatation Coefficient EN 14579 Determination of the Sound Speed Propagation EN 14157 Determination of Abrasion Resistance EN 14205 Determination of Knoop Hardness EN 14066 Determination of Thermal Shock Resistance EN 14231 Determination of Slip Coefficient EN 14580 Determination of Static Elastic Modulus EN 14158 Determination of Rupture Energy EN 13373 Determination of Geometric Characteristics on Units EN 14147 Determination of Ageing by Salt Mist Determination of Resistance to Ageing Actions by SO2 in presence of EN13919 Humidity Determination of Dynamic Elastic Modulus (by Fundamental Resonance EN 14146 Frequency) EN 13161 Determination of Flexural Resistance (under Constant Moment)

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EN 1467 EN 1468 EN 12057 EN 1469 EN 12059 EN 12058 EN 1925

Rough Blocks - Specifications Semi-Finished Products (Rough Slabs) - Specifications Finished Products, Modular Tiles - Specifications Finished Products, Slabs for Cladding - Specifications Finished Products, Dimensional Stone Work - Specifications Finished Products, Slabs for Floors and Stairs - Specifications Determination of Water Absorption Coefficient by Capillarity Determination of Real Density and Apparent Density and of Total and Open EN 1936 Porosity EN 1926 Determination of Compressive Strength EN 12370 Determination of Resistance to Salt Crystallization EN 12372 Determination of Flexural Strength under Concentrated Load EN 12407 Petrographic Examination EN 12440 Denomination Criteria EN 13364 Determination of the Breaking Load at the Dowel Hole EN 12670 Terminology EN13755 Determination of Water Absorption at Atmospheric Pressure EN = European Norm EN 12326 is one of the series of standards for slate and stone products for roofing, the details are as follows. TABLE 11 Sl no. Title

Code no.

Slate and Stone products for Discontinuous Roofing and EN 12326 - 1 Cladding - Part 1 : Product Specification

1.

Slate and Stone products for Discontinuous Roofing and EN 12326 - 2 Cladding - Part 2 : Methods of test EN = European Norm 2.

According to EN 12326-2:2000 the following tests are to be carried out depending on the application. TABLE 12 Sl no.

Property to be tested

1.

Failure load in bending

4.

Sulfur dioxide exposure test

2.

Water absorption

5.

Thermal cycle test

3.

Freeze - thaw test

3.1 Determination of failure load in bending Tests are carried out on prepared test pieces to measure the failure load in bending. From the results, the modulus of rupture is calculated.

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3.2 Water absorption test Dried test pieces are immersed in water at ambient temperature for 48 hrs and the absorption is determined from the difference of the wet and dry mass. The samples are dried to a constant weight in an oven at 105 degree C +/- 5 degree C over a period of 48 hours. The samples are submerged in distilled water in a suitable receptacle provided with a reflux condenser and are kept gently and continuously boiling for 48 hours. After cooling in air for 5 min they are placed in cold water and allowed to stand for 30 minutes in the room. At the end of this period the samples are removed from the water bath one at a time, surface dried with damp cloth and weighed. Absorption of water is calculated by using the formula given in the relevant standard. 3.3 Freeze - thaw test Test samples are prepared as given in the Standard. Divide the paired test pieces into two lots, the test lot and the control lot. Conduct the failure load in bending test( refer standard EN12372:1999/EN13161:2001) on the control lot. Immerse the test lot in the water bath at (23+5) 0C for 48 hrs. When soaking is complete, place the test pieces in the freezing cabinet until the temperature has held (-20+2) 0C for at least 3 hrs. Then replace the test pieces in the water bath for at least 1 hr. This constitutes 1 cycle. Repeat the freeze-thaw cycle 99 times to give a total of 100 cycles. When the 100 cycles are complete dry the test pieces in the oven at (110+5) 0C for (17+2) hr and then cool to ambient temperature. Carry out the bend strength test on these samples. Calculate the mean value and standard deviation of the modulus of rupture of the test lot and compare with the mean value and standard deviation of the control lot using a one-sided student’s t-test at the 2.5% significance level. 3.4 Sulfur dioxide exposure test EN has classified Sulfur dioxide exposure test for slates into two categories according to its calcium carbonate content as follows: a.) Sulfur dioxide exposure test for slates with a calcium carbonate content less than 20% b.) Sulfur dioxide exposure test for slates with a calcium carbonate content 20% or more a.) Sulfur dioxide exposure test for slates with a calcium carbonate content less than 20% Pairs of test pieces sawn from roofing slates, one dry and one soaked in water, are exposed to sulphur dioxide atmospheres at each of two concentrations for upto 21 days. Depending on the physical changes observed during or on completion of the exposure, a code as specified in EN 12326-1:1999 is assigned to the slates. b.) Sulfur dioxide exposure test for slates with a calcium carbonate content 20% or more The softening of slate resulting from exposure to an atmosphere of moist sulfur dioxide is determined by scraping the surface under a standard load before and after exposure, and measuring the increased depth of the scratches. 3.5 Thermal cycle test Test pieces sawn from slates are subjected to cycles of drying at (110+5) 0C and immersion in water at (23+5) 0C. On completion of 20 cycles the test pieces are

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inspected for physical changes indicative of the presence of harmful mineral components. A code, as specified in TC128 WI 00128032 is assigned to the slates. 3. Comparison between the ASTM Standards and the European Standards Although both these standards are widely used for characterizing the stone, there exist certain differences among these standards, and some of them are presented in the TABLE 13. TABLE 13 Sl ASTM Standards no. The ASTM Standards are user 1. friendly and have been in use, since ages. The accepted test values are clearly mentioned in the standards for each the Dimensional stone 2. of individually along with their ASTM code of reference. Limited tests have been recommended and the existing 3. facilities in the materials testing laboratory can also be used for testing of dimensional stones. Methodology of CE marking is not 5. available. 6.

7.

European Standards The European standards have recently come into use, a little complicated, not user friendly. The accepted test values are not mentioned in the standards for each of the Dimensional stone. A large number of tests are recommended, requires heavy capital investment to carryout some of the tests. Methodology is available for CE marking.

Test methodology is available for Freeze Test methodology is not available thaw resistance and Slip resistance. However for Freeze thaw resistance and Slip the methodology of freeze thaw test is too resistance. complicated. Testing Standards are available for the Testing Standards are available for following properties common for all stones: the following properties for each particular stone: Real Density, Apparent Density Physical Properties Total and open Porosity Absorption Water Absorption at Atmospheric Pressure Specific gravity and by Capillarity Thermal Dilation Coefficient Sound Speed Propagation Flexural Resistance under Concentrated load Mechanical Properties Flexural Resistance (under Constant Flexural strength Moment) flexural modulus of elasticity Compressive strength Modulus of rupture Static & Dynamic Elastic Modulus Compressive strength Knoop Hardness Rupture Energy

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Durability Properties Abrasion resistance Weather resistance (for slate only)

Abrasion Resistance Breaking Load at Dowel Hole Frost Resistance Thermal shock resistance Resistance to Ageing Actions by SO2 in presence of humidity Resistance to ageing by Salt mist Resistance of Salt Crystallisation Design Standards are not available.

Design Standards 1. Structural performance of exterior dimension stone cladding systems by uniform static air pressure difference. 2. Static coefficient of friction of ceramic tile and other like surfaces by the horizontal dynamometer pull meter method. 3. Strength of individual stone anchorage in dimension stone. 4. Guide for design, selection and installation of exterior dimension stone anchors and anchoring systems. Surface finish properties Slip resistance Standard is not available 8.

9.

10.

Recommends large number of samples to be No. of samples required for determining each property is about 3 tested for each property, about 10 to 20 numbers. to 5 numbers. Calculation of Flexural Strength : a.) Modulus of rupture (3 point bend test) R = 3*F*l/2*b*h2 (MPa)

a.) Flexural Resistance under Concentrated load-( 3 point bend test)

b.) Flexural strength of stone (4 point bend test)

b.) Flexural Resistance (under Constant Moment) - 4 point bend test

Rtf = 3*F*l/2*b*h2 (MPa)

σ = 3*F*L/4*b*h2 Rtc = F*L/b*h2 (MPa) (MPa) Common notations: F = failure load in N ; L = span in mm ; l = length of span in mm ; h = thickness in mm ; b = width of specimen in mm ; ∆ = the average net mid span deflection in mm ; Rtf = Flexural strength under conc. load ; Rtc = Flexural strength @ const. moment The Breaking load for Slabs can be calculated from flexural stress (Rtf ) value it self, the formula is as below: P = Rtf *W*t2/1500*L*1.6 No particular formula is available for the calculation of breaking load. W = width of slab, mm ; L = length of span, mm ; t = thickness of slab, mm ; P = breaking load , (kN)

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Note: In both the Standards, the standards for physical properties like Gloss / Reflectivity and Hardness are not available. 5. Other Standards Apart from the ASTM and European Standards, other testing standards are also available and are briefly mentioned in this section. 5.1 Australian testing standards Two sets of standards are available and are given below. TABLE 14: CSIRO (Commonwealth Scientific and Industrial Research Organization) ‘BEST’ TEST Methods for Evaluating Stone Tiles CSIRO METHOD BEST - 0 CSIRO METHOD BEST - 1 CSIRO METHOD BEST - 2 CSIRO METHOD BEST - 3 CSIRO METHOD BEST - 4 CSIRO METHOD BEST - 5 CSIRO METHOD BEST - 6 CSIRO METHOD BEST - 7 CSIRO METHOD BEST - 8 CSIRO METHOD BEST - 9 CSIRO METHOD BEST - 10 CSIRO METHOD BEST - 11 CSIRO METHOD BEST - 12 CSIRO METHOD BEST - 13 CSIRO METHOD BEST - 14

Introduction Determination of petrography of Stone Tiles Determination of Water absorption, Apparent porosity, and Bulk density of stone Tiles Determination of Flexural Strength of Stone Tiles Determination of Impact Resistance of Stone Tiles Determination of Scratch Hardness of Stone Tiles Determination of Resistance to abrasion of Stone Tiles (Capon method) Determination of Co-efficient of Thermal Expansion of Stone Tiles Determination of Resistance to Thermal Shock of Stone Tiles Determination of Dimensional Stability of Stone Tiles Determination of Frost Resistance of Stone Tiles Determination of Chemical Resistance of Stone Tiles Acid Immersion test for Stone Tiles Determination of Stain Resistance of Stone Tiles Determination of Weatherability of Stone Tiles

TABLE 15: Australian Stone Standards 1.

AS/NZS 3661.2:1994

Slip resistance of pedestrian surfaces - Guide to the reduction of slip hazards

2.

AS/NZS 4586:2004

3.

AS/NZS 4663:2004

4.

HB 197:1999

Slip resistance classification of new pedestrian surface materials Slip resistance measurement of existing pedestrian surfaces An introductory guide to the slip resistance of pedestrian surface materials

8.

AS 4204-1994

Headstones and cemetery monuments

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5.2 Chinese Standards: A list of Chinese standards are given in Table 16 TABLE 16 1. GB/T 13890-1992 2. GB/T 14319-1993 3. GB/T 14320-1993 4. GB/T 14685-2001 9. GB/T 17670-1999 10. GB/T 18250-2000 11. GB/T 9966.7-2001 12. GB/T 9966.8-2001

Terms for natural facing stone Super finishing stone Vitrified force-honing stone Pebble and crushed stone for building Unified catalogue for natural stone Test method for performance in plane deformation of curtain wall's Test methods for natural facing stones--Part 7: Test method for strength of individual stone anchorages Test methods for natural facing stones--Part 8: Test method for structural performance of dimension stone cladding systems by uniform static pressure difference

5.3 Indian Standard-Bureau of Indian Standards (BIS) In India, Bureau of Indian standard has recommended a list of standards for stones and is given in Table. TABLE 17 IS 1121 : Part 1 : 1974 IS 1121 : Part 2 : 1974 IS 1121 : Part 3 : 1974 IS 1122 : 1974 IS 1123 : 1975 IS 1124 : 1974 IS 1125 : 1974 IS 1126 : 1974 IS 1706 : 1972 IS 1805 : 1973 IS 4121 : 1967 IS 4122 : 1967

Methods of test for determination of strength properties of natural building stones: Part I Compressive strength Methods of Test for Determination of Strength Properties of Natural Building Stones - Part II : Transverse Strength Methods of Test for Determination of Strength Properties of Natural Building Stones - Part III : Tensile Strength Method of test for determination of true specific gravity of natural building stones Method of identification of natural building stones Method of test for determination of water absorption, apparent specific gravity and porosity of natural building stones Method of test for determination of weathering of natural building stones Method of test for determination of durability of natural building stones Method for determination of resistance to wear by abrasion of natural building stones Glossary of terms relating to stones, quarrying and dressing Method of test for determination of water transmission rate by capillary action through natural building stones Method of test for surface softening of natural building stones by exposure to acidic atmospheres

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IS 4348 : 1973 IS 8381 : 1977 IS 8759 : 1977 IS 3622 : 1977 IS 1128 : 1974 IS 1130 : 1969 IS 6250 : 1981

Methods of test for determination of permeability of natural building stones Recommended practice for quarrying stones for construction purposes Code of practice for maintenance and preservation of stones in building Specification for sandstone (slabs and tiles) Specification for Limestone (Slab and Tiles) Specification for marble (blocks, slabs and tiles) Specification for Roofing Slate Tiles

6. CONCLUSION NIRM laboratory is equipped with various testing facilities to carry out the tests as per the International standards. Presently few of the industries are using the NIRM facilities. With the above list of properties they will be able to market their product in a better way. Data generation on Indian stones is the prime requirement for improving the exporting of stones. It is to be understood it is not only aesthetic appearance i.e color of the stone, other engineering properties play a dominant role in selecting the stone for a particular application. 7. BIBLIOGRAPHY 1. ASTM standard 2. BIS Standards, European Standards, Australian Stone Standards and Chinese Standards 3. Standards and Specifications for Stone Products - 2007 Marble Institute of America 4.European Standards And CE Marking on Stone Construction Products - Angelica Frisa Morandini, Dipartimento Georisorse e Territorio,CNR IGAG – Politecnico di Torino 5. International standards on dimensional stone - Dott.ssa Paola Blasi ,Internazionale Marmi Macchine Carrara S.p.A., Italy 6. Selective guide to the Specification of Dimension Stone - Geoff Quick CSIRO Building, Construction and Engineering, Highett, Victoria, Australia, 3190. 7. A compilation of international standards for testing of material - Prodomea team – Hashemite University 2004 8. Guide for Testing of Dimension stone as per ASTM and European Standards G.M.Nagaraja Rao, S.K.Mohanty, S.Udayakumar, National Institute of Rock Mechanics, KGF

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