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Granite Quality Testing: Standard and Norms
With a sharp increase in granite demand at local, national, and international level, the factor of quality testing has become a prime concern for both buyers and sellers. There are a few granite quality testing processes at the national and international level that assay the quality of a granite product ready to be sold in the competitive market. Know what quality standards are popular in the natural stone industry.
Globally, there are about 300 granite varieties and out of which 200 varieties are supplied by India. These varieties are famous for their unique color, texture, and structure. The granite processing industry has developed over the years, so are the standards of testing.
Water absorption, gravity, thickness, density, strength, flexure, rupture, abrasion, and friction resistance are the prime factors considered for successful testing of granite stone products (finished slabs and tiles). Physical properties of granite, like porosity, permeability, thermal stability, coefficient of expansion, variegation, and hardness, matter the most in declaring granite a unique material. With this content, all granite enthusiasts will know more about various certified agencies, standards, and aspects associated with the concept of granite quality testing.
Globally popular ASTM codes for granite testing
There are several prestigious agencies, like CDOS, ASTM, and BSI that publish and set natural stone testing standards. For example, Centre for Development of Stones (CDOS) is an autonomous organization by the Rajasthan government and (RIICO) Rajasthan State Industrial Development & Investment Corpn. Ltd. It has been initiated in order to develop, support, and promote the Dimensional Stone Sector.
Among various organizations related to setting of natural stone testing standards, American Society for Testing and Materials has global recognition. It is an international organization for setting, developing, and publish different technical standards for a wide assortment of materials, including natural stones. Following are some of the important standards for assaying the value of natural stone products, including granite.
These are vital for granite quality testing. These include:
- ASTM C 1028 – Coefficient of friction
- ASTM C 1028 – Coefficient of friction
- ASTM C 1353 – Abrasion resistance of stone
- ASTM C 1354 – Strength of individual anchorages in dimensional stone
- ASTM C 170 – Compressive Strength (wet or dry)
- ASTM C 241– Abrasion resistance of stone
- ASTM C 666 – Freezing & thawing testing
- ASTM C 67 – Efflorescence testing
- ASTM C 67 – Freezing & thawing testing
- ASTM C 880 – Flexural strength of stone (wet or dry)
- ASTM C 97 – Absorption and bulk specific gravity
- ASTM C 99 – Modulus of rupture (wet or dry)
- ASTM D 5312 – Durability of freezing & thawing conditions
- ASTM E 96 – Water vapor Transmission
- Basic 5 Tests ASTM C 97, C 99, C 170, C 241(or C 1353) and C 880
Popular Indian standard codes for granite testing
Testing of granite quality in India is done in order to ensure the level and performance of natural stone finished and unfinished products. In India, there are several popular Indian standard codes set by the Bureau of Indian Standards (BIS), a governmental organization for setting natural building stones. Following is a list of the popular Indian Standard codes that all stone engineers follow for standardization in stonework industry in India. It includes:
- IS 1121(Part 1-4):1974 – Determination of compressive, transverse, tensile, and shear strength
- IS 1122:1974 – Determination of true specific gravity of natural stones
- IS 1123:1975 – Identification of natural stones
- IS 1124:1974 – Determination of water absorption, porosity, and specific gravity of stone
- IS 1125:1974 – Determination of weathering of natural stones
- IS 1126:1974 – Determination of durability of natural stones
- IS 1127:1970 – Dimensions and workmanship of stones for masonry work
- IS 1128:1974 – Specification for limestone (slab and tiles)
- IS 1129:1972 – Recommendation for stone dressing
- IS 1130:1969 – Specification for marble (blocks, slabs and tiles)
- IS 14223(Part 1):1994 – Specification for polished building stones
- IS 1706:1972 – Determination of resistance to wear by abrasion of natural stones
- IS 4121:1967 – Determination of water transmission rate by capillary action through
- IS 4122:1967 – Surface softening of natural stones
- IS 4348:1973 – Determination of permeability of natural stones
- IS 5218:1969 – Method of test for toughness of natural stones
- IS 6579:1981 – Specification for coarse aggregate for water bound macadam
- IS 8348:1977 – Stacking and packing of stone slabs for transportation
- IS 8381:1977 – Recommended practice for quarrying stones
- IS 8759:1977 – Code of practice for maintenance and preservation of stones
Lab test report of popular granite stones
A lab test report for granite stone testing shows the quality level of stone and its practical usefulness for various building construction purposes. Like ASTM and IS codes, there are also some EN testing codes that are popular in Europe. These testing codes are drafted and maintained by ETSI (European Telecommunications Standards Institute), CEN (European Committee for Standardization), and CENELEC (European Committee for Electrotechnical Standardization). Below-given is a sample test report for viscon white granite stone prepared by an ISO-certified organization in India.
Viscon white granite stone testing sample report
| Parameters | Test method | Results | Units |
| Water absorption | EN-13755 | 0.17% | % |
| Density | EN-1936 | 2650 | kg/m3 |
| Abrasion resistance | EN-13415 | 0.58 | mm |
| Skid resistance | EN-14231 | 59 (on dry surface) | 44 (on wet surface) |
| Flexural strength | EN-12371 & 72 | 23.2 & 25.1 | mpa |
Granites India an ISO-certified granite manufacturing, supplying, and exporting company offering a range of granite slabs and tiles, passed through granite testing procedures. The 20-year-old granite company offers high-quality stone products at competitive prices.