What determines the flow characteristics of HMA?

The flow characteristics of Hot Mix Asphalt (HMA) are primarily determined by the binder's viscosity at various temperatures. Viscosity refers to the thickness or stickiness of the binder, and it significantly impacts how the HMA behaves under different conditions. As temperatures change, the viscosity of the binder also changes, affecting how well the mixture can flow during the paving process and how it performs under traffic loads.

Understanding the viscosity at different temperatures is crucial for achieving optimal workability, compaction, and durability of the asphalt mixture. If the viscosity is too high, the HMA may be difficult to work with during paving, while if it's too low, it may lead to excessive deformation or rutting under load. This relationship directly influences the mechanical performance, longevity, and quality of the asphalt pavement.

While factors like aggregate size, ambient temperature, and compaction methods do influence the overall performance and compaction of HMA, it is the binder's viscosity that fundamentally governs the flow characteristics of the mixture during the critical stages of application and subsequent service life.