What role does air void content play in asphalt performance?

Air void content plays a crucial role in the performance of asphalt by impacting several key characteristics such as durability, strength, and resistance to moisture damage.

When air voids are present in asphalt mixtures, they can potentially reduce the density of the asphalt, which can lead to an increase in the permeability of the mix. Higher permeability allows water to infiltrate the asphalt, which can weaken the material and lead to issues such as stripping, where the bond between the asphalt and aggregate is compromised. This can ultimately decrease the lifespan of the pavement.

A well-balanced air void content also contributes to effective load distribution across the pavement surface, helping to maintain its structural integrity under traffic loads. Furthermore, proper air void levels support the overall durability of the asphalt, ensuring it can withstand environmental factors such as freeze-thaw cycles and moisture intrusion. Conversely, insufficient air voids can lead to inadequate flexibility and a higher risk of cracking under stress.

Therefore, maintaining the correct air void content is essential for optimizing asphalt performance, making it a critical consideration in pavement design and construction.