Laboratory Evaluation of Warm Asphalt Properties and Performance

Rising energy costs and increased environmental awareness have brought attention to the potential benefits of warm asphalt in the United States. Warm mix asphalt (WMA) is produced by incorporating additives into asphalt mixtures to allow production and placement of the mix when heated to temperatures well below the 150°C+ temperatures of conventional hot mix asphalt (HMA). Potential benefits such as reduced plant emissions, improved compaction in the field, extension of the paving season into colder weather, and reduced energy consumption at the plant may be realized with different applications. Trial installations of WMA, including two sections using the Sasobit WMA additive, have been investigated in Virginia. This study presents the results of laboratory testing to evaluate the performance of the mixtures used in the two trial sections. The evaluation included comparisons of volumetric properties, moisture susceptibility, rutting resistance, and fatigue performance between the HMA and WMA mixtures used in each section. Few differences were found. In addition, the findings indicated that the performance of HMA and WMA should be equal when proper construction methods are used.