Warm-Mix Asphalt

Warm-mix asphalt (WMA) represents a group of technologies that lower the temperature at which asphalt pavement material is produced, placed, and compacted. This temperature reduction offers several environmental sustainability benefits, including reduced fuel consumption, lower asphalt plant emissions, and the ability to incorporate higher percentages of recycled asphalt product into pavement mixes.

WMA production processes and equipment are essentially the same as those for traditional hot-mix asphalt pavements. However, WMA technologies use either water or chemical additives to create a foaming action during production, which results in an asphalt mix that can be produced and placed at lower temperatures compared to conventional hot-mix alternatives.

Depending on plant capabilities, the selected production technology, environmental conditions, and other factors, the National Asphalt Pavement Association (NAPA) indicates WMA production temperatures can range from 215 to 275 degrees, compared to 280 to 340 degrees for hot-mix asphalt.

WMA technologies offer many environmental sustainability advantages:
– An approximate 10% reduction in fuel usage when production temperatures are 50 degrees lower
– An approximate 20-50% decrease in carbon emissions, thus lowering the carbon footprint (these percentage reductions are based on averages reported by studies in five countries)
– Less smoke (vapor) and corresponding odor
– WMA is a 100% recyclable product

– When a higher percentage of reclaimed asphalt pavement (RAP, or recycled asphalt) is combined with WMA technologies, it produces a rut-resistant, longer life pavement
– More miles of pavement can be paved at less cost 
– WMA mixes produce higher density pavements
– WMA is compactable at lower temperatures than hot mixes, which allows for colder weather paving and longer distance hauling to construction sites

More Information
Contact Grimes Asphalt and Paving Corporation to find out more about warm-mix asphalt or click on the links below

National Asphalt Paving Association
United States Department of Transportation Federal Highway Administration