What does the term "aggregate soundness" refer to?

The term "aggregate soundness" specifically refers to the ability of aggregate to resist deterioration due to freeze-thaw cycles. This property is crucial, particularly in climates where temperatures fluctuate around the freezing point, as these cycles can lead to the expansion and contraction of water within the aggregate's pores. When aggregates are exposed to such conditions, their ability to maintain integrity affects the strength and durability of the concrete mix.

Evaluating aggregate soundness involves standardized tests that simulate freeze-thaw processes and assess how much degradation the aggregate suffers over repeated cycles. Aggregates that retain their physical properties and do not break down under these conditions contribute to the longevity and performance of concrete structures. In contrast, while resistance to moisture segregation, particle size changes, and mechanical impact are important characteristics of aggregate, they do not directly relate to the definition of aggregate soundness.