What does specific gravity help determine in asphalt mix design?

Specific gravity is a critical parameter in asphalt mix design as it helps determine the binder content that is required to achieve the target densities of the asphalt mix. By measuring the specific gravity of both the aggregate and the asphalt binder, engineers can accurately calculate the volume of materials in the mix, which is essential for ensuring that the final product meets performance and durability specifications.

In mix design, the target density is aimed at achieving optimal performance under traffic loads and environmental conditions. Specific gravity allows for adjustments to the binder content based on the calculated voids and the desired density. By ensuring that the correct binder content is maintained, the mixture will properly adhere to the aggregates and provide the necessary strength and stability.

The other options do not relate directly to the use of specific gravity in asphalt mix design. While color, source of aggregates, and choice of polymers may be relevant in the broader context of asphalt production or modification, they do not utilize specific gravity as a determining factor in the same way that binder content and target density do.