What significantly affects the performance of HMA in the field?

The performance of Hot Mix Asphalt (HMA) in the field is influenced by a combination of several factors, which includes the type of binder used, environmental conditions during placement, and aggregate gradation. Each of these elements plays a crucial role in the overall quality and longevity of the HMA.

The type of binder used is vital because it determines the flexibility, temperature susceptibility, and resistance to deformation and aging of the asphalt mix. Different binders have various properties that can enhance or detract from the asphalt's performance based on the traffic loading and environmental stresses it will face.

Environmental conditions during placement are equally significant. Factors such as temperature, humidity, and wind can affect the cooling of the asphalt, compaction, and ultimately the bond between aggregate particles and binder. Adequate conditions for placement ensure that the asphalt achieves the desired density and durability. For example, if placed in cooler temperatures, the mix may not compact properly, resulting in a weaker pavement structure.

Aggregate gradation refers to the distribution of particle sizes within the aggregate mix, which impacts the mixture’s voids, density, and water permeability. Proper gradation ensures that the right balance of coarse and fine aggregates maximizes strength and workability, optimizing the HMA's resistance to cracking