Which property must be assessed to ensure aggregate durability in concrete?

To ensure aggregate durability in concrete, it is crucial to assess its resistance to weathering and wear. This property directly impacts the longevity and performance of concrete structures in various environmental conditions. Durable aggregates can withstand the physical and chemical forces imposed by weather factors such as freeze-thaw cycles, moisture ingress, and chemical attack from the environment.

When aggregates possess high resistance to weathering, they are less likely to degrade, crack, or break down over time, which helps maintain the integrity of the concrete. This strength against environmental stressors ensures that the concrete remains functional and aesthetically pleasing throughout its service life.

The other properties listed, such as electrical conductivity, thermal expansion, and optical clarity, do not directly correlate with aggregate durability in terms of weathering and wear. While these factors might have their significance in other contexts, they are not primary indicators of an aggregate's ability to withstand the rigors of environmental exposure that affect concrete performance.