Which component of asphalt mix design determines the amount of asphalt binder used?

The component of asphalt mix design that determines the amount of asphalt binder used is aggregate gradation. Aggregate gradation refers to the particle size distribution of the aggregates used in the asphalt mix. It significantly influences the voids in the mix, the packing of the aggregates, and ultimately the effective coating of the aggregate particles by the asphalt binder.

When designing an asphalt mix, the gradation helps to establish the balance between the coarse and fine aggregate fractions, which affects how much binder is required to fill the voids between the aggregates and to achieve the desired workability and stability of the mix. Proper gradation ensures that there are enough voids to accommodate the optimal amount of asphalt binder without excess, which can lead to issues such as bleeding or rutting in the finished pavement.

While the other options—aggregate shape, binder type, and mix temperature—are important factors in the overall performance and characteristics of the asphalt mix, they do not directly correlate to determining the volume of asphalt binder needed. Aggregate shape can affect the stability and workability of the mix, binder type influences the properties of the asphalt at different temperatures, and mix temperature affects the mix's viscosity during production and placement, but none of these directly regulate the binder quantity required based on the mixture's