Aggregate Properties: Soundness and Durability
Soundness: The ability of aggregate to withstand weathering. Also called durability.
Soundness is desired in severe climatic conditions. Water freezing in the voids of aggregates generates stresses that can fracture the stones.
ASTM C88 – Simulates weathering by soaking the aggregates in either a sodium sulfate or magnesium sulfate solution. Sulfates cause crystals to grow in the aggregates, simulating the effects of freezing.
A sample is subjected to cycles of sulfate-soaking for 16 hours. Drying follows the soaking process. After five cycles, the aggregates are washed and dried, weighed, and the average percentage loss the entire sample is computed. The result is compared with allowable limits to determine whether the aggregate is acceptable.
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