Determination of the production temperature of warm mix asphalt by workability test

Warm mix asphalt (WMA) is good technique to reduce temperature of 20–30 °C. It has developed for more than a decade, but it is still challenging to determine the mixing and compaction temperatures of asphalt mixture. The objective of this study is to use a “equi-torque temperature” method that determin the mixing and compaction temperatures conveniently and accurately. The workability of WMA was measured by a prototype workability device. A criterion torque range was proposed by measuring the workability of mixtures with virgin bitumen. Three different warm-mix additives (including Aspha-Min®, Sasobit®, and Evotherm DAT®) were studied by identical SBS modified asphalt mixture to assess the reasonableness of the mixing and compaction temperatures determined according to the torque range. The results indicated that the criterion torque range was reasonable and the production temperatures of WMA mixtures determined in this study were approximately consistent with other references. The final performance tests also indicated that the “equi-torque temperature” methodology was feasible and effective.