What is the fineness modulus range for fine aggregates in structural products to conform to ASTM C33?

The fineness modulus for fine aggregates in structural products according to ASTM C33 is specifically established to ensure that the aggregates are suitable for use in concrete. This standard specifies that the fineness modulus for fine aggregates should fall within the range of 2.3 to 3.1.

This range is important because it affects the workability, strength, and durability of concrete mixes. A fineness modulus that is too low may lead to a mix that is too coarse, while a modulus that is too high can result in excess fine material, compromising the concrete's performance. The stated range indicates materials that have adequate particle size distribution, which contributes to proper packing in the mixture and, consequently, the structural integrity of the finished product.

In contrast, other ranges either fall below or exceed the accepted specifications outlined in ASTM C33, which are not suitable for ensuring the desired properties in concrete applications. Thus, the choice of 2.3 to 3.1 aligns with the requirements intended for fine aggregates in structural concrete.