What role does aggregate gradation play in asphalt mixture design?

Aggregate gradation plays a critical role in asphalt mixture design by influencing key performance aspects of the pavement. A well-designed gradation ensures that the mixture has the appropriate distribution of particle sizes, which can significantly affect porosity, strength, and durability.

When the gradation is properly balanced, it fills the voids between larger aggregates with smaller ones, resulting in a denser mix that can enhance the overall stability and resistance to deformation under traffic loads. This density directly contributes to the strength of the pavement, making it more resilient against factors like cracking and rutting. Additionally, a well-chosen gradation can help optimize the asphalt binder content needed, leading to more durable pavements that can withstand environmental conditions over time.

In contrast to this, options that suggest aggregate gradation has no significant impact or only affects color fail to recognize its fundamental influence on the physical and mechanical properties of the asphalt mixture. Similarly, the assertion that it reduces the overall weight of the mixture is misleading, as gradation primarily focuses on the balance and distribution of different aggregate sizes rather than overall weight.