Skip Top Navigation

Hot Mix Asphalt (HMA) For Local Agency Applications

Hot Mix Asphalt (HMA) is a combination of aggregate and asphalt binder mixed at an elevated temperature to form a hard, strong pavement construction material. HMA allows mixes to be designed in the laboratory at four different levels (50, 75, 100, and 125 gyrations) simulating four different 20-year traffic levels in the field.

The majority of WSDOT highway mixes are designed at the 100-gyration level. While appropriate for WSDOT highways, this system is not likely to be appropriate for facilities with lower traffic volume, such as the majority of city streets and county roads in the State of Washington.

Getting the right pavement for local agency roads requires designing the correct pavement section and mix, asking for the correct mix in contract documents, and incorporating specification changes for the construction process.

Aggregate and PG Binder alone will not improve bad roads. To effectively utilize HMA, local agencies need to do four things:

  1. Design the correct pavement section for the roadway needs
  2. Select the correct gyration level mix during pavement design
  3. Ask for the correct mix in the contract documents
  4. Incorporate appropriate specification changes to implement the process you want during construction