Warm-mix asphalt has the potential to allow the producers of hot-mix asphalt pavement material to lower the temperatures at which the material is mixed and placed on the road. Reductions of 50 to 100 degrees Fahrenheit have been documented. Such drastic reductions would have the obvious benefits of cutting fuel consumption and decreasing the production of greenhouse gases.

In addition, research at the National Center for Asphalt Technology and elsewhere has shown that lowering the production temperature can drastically reduce the production of emissions. By cutting emissions, warm-mix asphalt would therefore improve conditions for workers and enhance relationships with neighbors.

NAPA first brought warm-mix technology to the United States from Europe in 2002, spurring intense interest among hot-mix asphalt producers, contractors, researchers, and government agencies. Since that time, new technologies have been developed in the United States.

Research

Several warm-mix asphalt demonstration projects have been constructed around the country. In addition, research under way at NCAT includes several test sections on the NCAT Test Track. The Federal Highway Administration is partnering with NCAT on this research, both by providing funds and by supporting innovative approaches to warm mix.

In exploring whether warm mix is the wave of the future, we must address many questions. 

Can warm-mix pavements be opened to traffic quickly after construction?
What are the performance characteristics of these pavements?
In the case of technologies developed in other countries, can they be adapted to the U.S., where climate conditions are often more extreme?
If the production temperature is lower, does that mean that the binder does not age as much?
Will the potential for thermal cracking be reduced?
Will the potential for rutting be different?
Will the contractor have to use a different grade of asphalt binder?
What changes for the mix design procedure will be required?
Will the performance-graded binder in a warm mix perform differently from pavements produced at higher temperature?