Warm Mix: The Lights Are Green

This article describes the use of warm-mix asphalt (WMA), which implements additives and processes that allow for temperatures for mix production at 50 to 100 degrees cooler than those used for hot-mix asphalt (HMA). Such reductions allow for the reduction or elimination of some smoke and fumes from the mix as well as stack gas emissions. Another major benefit is that of the reduction of fuel consumption by 11 to 30 percent in addition to an increased allowance for reclaimed asphalt pavements (RAP) in the mix. Success has been found with the implementation of WMA for stone-matrix asphalts (SMA), dense-graded mixes, and graded friction courses. Test results from various municipalities are presented.