Laboratory testing is one of the most important segments in the study of rock properties and behavior in different conditions. It is an integral part of geotechnical exploration and investigation works. There are several methods of laboratory testing of rock mass strength, and the most important are UCS (Uniaxial compressive strength), PLT (Strength index determined by the loading procedure at the point) and the Brazilian test (Tensile strength of rocks).
- Abrasion Resistance This test simulates long term wear effects on natural stone products (e.g. pedestrian trafficked areas) using an abrasive flow medium and abrasion wheel. BS EN 14157
- Breaking Load This test gives a breaking load of a pin which is grout anchored into a natural stone specimen. Typically done on proposed cladding stone destined for interior and exterior fixings. BS EN 13364
- Flexural Strength under concentrated load This test gives a flexural strength from a single load point. Typically done on proposed cladding stone for ventilated facades. This test can also be done in conjunction with the frost resistance test to determine strength deterioration over a cyclic temperature pattern.BS EN 12372
- Flexural strength under constant moment This test gives a flexural strength from two load points. Typically done on proposed cladding stone for ventilated facades. This test can also be done in conjunction with the frost resistance test to determine strength deterioration over a cyclic temperature pattern.BS EN 13161
- Frost Resistance This test subjects natural stone specimens to a cyclic temperature pattern of freezing air and thawing in water. Specimens are either “Scored” visually during test or tested mechanically (Flexural strength or uniaxial compressive strength) to determine performance. BS EN 12371
- Petrographic Examination This test involves subjecting a specimen of the natural stone to visual and low power microscopy. The analysis gives information of constituents present in the stone in addition to any features of interest. This could include minerals which give rise to discolouration’s in the stone. BS EN 12407
- Point Load Strength Test (Rock) This test is used to classify the strength of rock materials on samples with little to no preparation. This test can also be used to predict strengths with correlated specimens (Uniaxial compressive strength).
- Real and Apparent Density (total and open porosity) This test gives a density of stone and the porosity (Open voids ratio to volume). The density can be used to determine weight per volume for design purposes. The porosity can give an indication of the absorption properties. High porosity materials may also exhibit deterioration under frost cycling and salt crystallisation testing.BS EN 1936
- Resistance to Salt Crystallisation This test involves cycling specimens between an chemical solution, Air drying and then cooling. This cycle is run 15 times and then reported as a % Mass change. This test can be used in conjunction with the Frost Resistance test to determine durability over time in open weather conditions BS EN 12370.
- Water absorption at atmospheric pressure This test gives a water absorption by weight (%) of natural stone. This can be used to calculate the saturated weight of the natural stone for use in the design phase in addition to indicating expected water addition for durability purposes (e.g. material alteration via mechanically or chemically)BS EN 13755.
- Water absorption coefficient by capillarity. This test gives a water absorption by unit area of natural stone in contact with water. This can be used in conjunction with other tests to determine suitability of the stone for the intended use (E.g. cladding, tiles etc) BS EN 1925.
- Uniaxial compressive strength This test gives a compressive strength (MPa) of either cube or cylindrical specimens. This can be used in the design stage for structural or load bearing elements. This can also be used in addition to the frost resistance test to determine performance over time when exposed to cyclic freezing and thawing BS EN 1926.