Hot mix asphalt services

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.

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. It can be designed in the laboratory at four 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.

Aggregate and Performance Graded (PC) 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.

8,683 animals crossed the Snoqualmie Pass East Project area

as recorded by WSDOT and partners in 2020 and 2021.

46% increase in Amtrak Cascades ridership to 251,000 passengers

in 2021 compared to 172,000 in 2020.

Nine wetland and stream mitigation sites across 32.7 acres added

to our monitoring program in 2021 to help offset climate change impacts.