Which characteristic defines the mass percent of air voids in Item 310?

The mass percent of air voids in Item 310, which is typically associated with construction materials such as asphalt concrete, is critical for ensuring the performance and longevity of the material. The correct range of 3% to 5% is important because it reflects a balance that allows for proper compaction and stability while providing enough air voids to accommodate any expansion that may occur due to temperature fluctuations and loading conditions.

Having an air void content between 3% to 5% helps to prevent issues like moisture trapping and associated damage like stripping or degradation of the binder. It also ensures that the material has enough flexibility and durability to resist cracking and fatigue, which can ultimately impact the lifespan and safety of the pavement. Maintaining this percentage is crucial for good quality control in asphalt mix design, where achieving the right properties leads to optimal performance under traffic loads.

Other ranges may lead to inadequate air space, which can result in over-compacted materials that lack the necessary flexibility, or excessive air voids that compromise the structural integrity and wear characteristics of the asphalt.