Test (IS 1126): Three test pieces of 50 mm diameter and 50 mm
height are dried for 24 hours and are weighed (W1). The
specimens are suspended in 14 per cent sodium sulphate solution (density 1.055
kg/m3) for 16 to 18 hours at room temperature (20 o to 30 o C). The
specimens are then taken out of the solution and kept in air for 4 hours. They
are then oven dried at a temperature of 105 o ± 5 o C for 24 hours and then cooled
at room temperature. This process is repeated for 30 cycles. The specimens are
weighed (W2) and the difference in weight is found. This test is
repeated thirty times and the loss in weight after every five cycles is
obtained. The change in weight indicates the degree of decay of stone. Durability
should be expressed in percentage as change in the weight. The average of three
test results should be reported as durability value.
weight = W2/W1
where W1 is the
original weight of the specimen and W2 is the weight of the specimen
after 30 cycles of the test.