IS 1126 prescribes the testing procedure to evaluate the durability of natural building stones. It primarily uses a sodium sulphate crystallization test to simulate natural weathering, freeze-thaw cycles, and salt attack to determine the stone's resistance to disintegration over time.
Method of test for determination of durability of natural building stones
Quick Reference Values
specimen dimensions50 mm cylinders or cubes
number of test specimens3
sodium sulphate solution density1.055 kg/litre
immersion duration16 to 18 hours per cycle
oven drying temperature105 ± 5 °C
total test cycles30 cycles
Key Formulas
Percentage change in weight = [(W1 - W2) / W1] × 100 — where W1 is original dry weight and W2 is final dry weight after test cycles
Practical Notes
Maintain the density of the sodium sulphate solution precisely at 1.055 kg/litre, as variations heavily impact the severity of the simulated weathering.
Ensure loose particles are carefully brushed off the specimens after the final drying cycle before weighing to accurately calculate mass loss.
This test is critical for stones intended for exterior cladding or use in harsh, exposed, or coastal environments.