What is the function of aggregates in asphalt mixtures?

The function of aggregates in asphalt mixtures is primarily to provide structural support and stability to the pavement. Aggregates form the skeleton of the asphalt mix, contributing significantly to the strength, durability, and overall performance of the pavement. The correct choice emphasizes that the mechanical properties of aggregates, such as their size, shape, and gradation, directly affect the load distribution and resistance to deformation when the asphalt is subjected to traffic and environmental conditions.

While color and aesthetics may be a consideration in some applications, the primary role of aggregates is not to enhance appearance but to ensure the pavement can withstand the stresses it experiences. Cost reduction is a secondary factor and does not reflect the essential physical role that aggregates play. Similarly, while moisture drainage can be a property of some specific aggregate materials or mix designs, it is not a fundamental function of aggregates in the context of all asphalt mixtures. This reinforces that the main purpose of aggregates is their contribution to the mechanical stability and structural integrity of the pavement system.