What is the target air void content for a compacted asphalt mixture?

The target air void content for a compacted asphalt mixture is typically set between 3% to 8%. This range is critical as it ensures the mixture has sufficient void space to accommodate changes in temperature and pressure without compromising the pavement's durability and performance. Air voids are essential for allowing the asphalt to expand and contract and for minimizing the risk of moisture damage and raveling.

In this range, the asphalt mixture can achieve optimal performance characteristics, including resistance to deformation and adequate load-bearing capabilities. The control of air voids also impacts other properties like permeability, where too many voids can lead to water infiltration, while too few can restrict the flexibility of the mixture, leading to premature cracking.

The other ranges provided are outside the optimal target. A content of 1% to 3% is too low and may result in a dense mixture that lacks necessary flexibility. A target of 9% to 12% is higher than desired, which can lead to a reduced structural integrity as there may be insufficient asphalt binder to coat the aggregate properly. A range of 15% to 20% is excessively high, leading to significant performance issues such as increased susceptibility to moisture damage and raveling. Thus, maintaining the air void content between