When magnesium sulfate is used for fine aggregate soundness testing, what is the maximum allowable weight average loss?

The correct maximum allowable weight average loss for fine aggregate soundness testing when using magnesium sulfate is 15%. This percentage is significant as it is determined through standardized testing methods which assess the durability of fine aggregates. The use of magnesium sulfate in this context helps evaluate the aggregate's resistance to leaching and volume changes when subjected to cycles of wetting and drying.

A loss of 15% indicates that the aggregate is still within acceptable limits for soundness, meaning it is relatively durable and suitable for use in concrete. Higher losses would suggest that the aggregate may not perform well in harsh conditions, leading to potential structural issues in concrete applications. This standard is set to ensure that only aggregates meeting durability requirements are utilized in construction, thereby promoting the longevity and reliability of concrete structures.