The selected test pieces of stone are crushed or broken and the material passing 20 mm IS Sieve and retained on 10 mm IS Sieve is used for the test.
Absorption Test (IS: 1124)
The selected test pieces of stone are crushed or broken and the material passing 20 mm IS Sieve and retained on 10 mm IS Sieve is used for the test. The test piece weighing about 1 kg is washed to remove particles of dust and immersed in distilled water in a glass vessel at room temperature 20 to 30° C for 24 hours. Soon after immersion and again at the end of soaking period, entrapped air is removed by gentle agitation achieved by rapid clock-wise and anti-clock-wise rotation of the vessel. The vessel is then emptied and the test piece allowed to drain.The test piece is then placed on a dry cloth and gently surface dried with the cloth. It is transferred to a second dry cloth when the first one removes no further moisture. The test piece is spread out not more than one stone deep on the second cloth and left exposed to atmosphere away from direct sunlight or any other source of heat for not less than 10 minutes untill it appears to be completely surface dry. The sample is then weighed (B).
The sample is then carefully introduced in a 1000 ml capacity measuring cylinder and distilled water is poured by means of 100 ml capacity measuring cylinder while taking care to remove entrapped air, untill the level of water in the larger cylinder reaches 1000 ml mark. The quantity of water thus added is recorded in ml or expressed in gram weight (C).
The water in the larger cylinder is drained and the sample is carefully taken out and dried in an oven at 100 to 110°C for not less than 24 hours. It is then cooled in a desiccators to room temperature and weighed (A). The room temperature during the test is recorded.
Apparent specific gravity = A/1000C
Water absorption = BA – 100 / A
Apparent Porosity = BA-100 / C . 1000
The true porosity shall be calculated from the following formula:
True Porosity = [ True specific gravity – Apparent specific gravity ] / True Specific gravity
A = Weight of oven-dry test piece (g)
B = Weight of saturated surface-dry test piece (g)
C = Quantity of water added in 1000 ml jar containing the test piece (g)
Hardness: This test is performed by scratching a stone with knife on Mohs scale.
Toughness: This test is performed by breaking the stone with a hammer. Toughness is indicated by resistance to hammering.