This standard prescribes the method to determine the soundness of aggregates subjected to weathering action. It evaluates the aggregate's resistance to disintegration by simulating freeze-thaw cycles using crystallization forces of sodium sulphate or magnesium sulphate solutions.
Specifies methods for assessing the resistance of aggregates to weathering action (soundness test using sodium or magnesium sulphate).
Quick Reference Values
solution temperature21 to 25 °C
oven drying temperature105 to 110 °C
immersion duration per cycle16 to 18 hours
standard number of cycles5 cycles (unless otherwise specified)
specific gravity sodium sulphate1.151 to 1.174
specific gravity magnesium sulphate1.295 to 1.308
Key Formulas
Percentage loss = (Difference in weight of sample before and after test / Initial weight of sample) × 100
Practical Notes
Magnesium sulphate is generally more aggressive and yields a higher percentage loss compared to sodium sulphate; IS 383 provides different acceptable limits for each.
Strictly maintain the specific gravity of the sulphate solutions using a hydrometer to ensure repeatable and accurate test results.
After the final cycle, the sample must be thoroughly washed with hot water to remove all traces of salt (tested using barium chloride) before the final drying and weighing.