What constitutes 85-90% of the overall volume of HMA?

The correct answer is aggregate, which constitutes 85-90% of the overall volume of Hot Mix Asphalt (HMA). Understanding the composition of HMA is crucial for any asphalt inspector or personnel involved in its production and laying.

The aggregate component serves multiple functions within the HMA. It provides the necessary structure and strength to the mix, influencing the overall durability, stability, and resistance to deformation under load. In HMA, the aggregates include a combination of stone, gravel, sand, and mineral filler, which are carefully graded to achieve optimal performance characteristics.

By focusing on the right proportions of aggregate, including size and gradation, producers can ensure the HMA meets the specific engineering requirements for various applications, such as road surfaces. The binder (the asphalt cement) and absorbed binder are important as well, but they typically make up a significantly smaller portion of the volume and primarily serve to coat and bind the aggregates together rather than providing the bulk of the mix.