Research Pays Off: Warm-Mix Asphalt Heating Up in Virginia

Warm-mix asphalt (WMA) promises potential constructability and environmental benefits.  Without proof that the technology provides an equivalent level of performance, however, some transportation agencies in the United States have questioned implementation.

In 2006, the Virginia Department of Transportation (DOT) and the Virginia Center for Transportation Innovation and Research (formerly the Virginia Transportation Research Council) constructed maintenance overlays on trial sections to evaluate the laboratory and field performance of WMA materials. The objective was to determine the potential use of the materials on Virginia’s roadways.

The field trials indicated that WMA can be placed at lower temperatures, using conventional HMA paving practices and procedures. After 2 years, cracking was observed along the center line of the HMA and WMA sections in one trial, although the cracking in the WMA section was much less extensive.

In 2008, Virginia DOT developed special provisions allowing contractors to use WMA technologies for maintenance overlay projects. In 2009, Virginia DOT adopted a supplemental specification incorporating WMA into standard practice.

The research supported Virginia DOT’s use of WMA as an alternative to HMA. The construction and environmental improvements benefit the agency, the industry, and the public. Contractors can increase the hauling distances from the plant to the project, can reduce energy consumption during production, and can reduce plant emissions, improving air quality.

Crews benefit from the cooler mat temperatures and reduced fumes during paving. The improved compaction can increase the durability and the performance of WMA.