Laboratory Evaluation of Reduced-Temperature Warm-Mix Asphalt for Balanced Performance during Plant Production

This study aims to evaluate the use of warm-mix asphalt (WMA) at reduced production temperatures to achieve balanced rutting and cracking resistance through performance testing of both laboratory-prepared and plant-produced asphalt mixtures from two field projects in Virginia and Missouri, U.S. Each project included a volumetric control hot-mix asphalt (HMA) mixture, a balanced mix design (BMD) HMA mixture, and a BMD WMA mixture at reduced production temperatures. The Missouri project also included a volumetric control WMA mixture at reduced production temperatures. The performance testing plan for the Virginia mixtures included the asphalt pavement analyzer and high-temperature indirect tensile tests for rutting evaluation, the Cantabro test for durability evaluation, and the indirect tensile asphalt cracking test (IDEAL-CT) for cracking evaluation. The rutting and cracking resistance of the Missouri mixtures were evaluated using the Hamburg wheel tracking test and IDEAL-CT, respectively. Laboratory testing of the Virginia mixtures showed that the BMD WMA mixture exhibited significantly improved cracking resistance compared with the two HMA mixtures and achieved balanced performance with satisfactory rutting resistance both in mix design and during production. In the Missouri project, all mixtures consistently exhibited balanced rutting and cracking resistance. The BMD mixtures, regardless of the use of lower-production-temperature WMA, significantly outperformed the control mixtures in cracking resistance in mix design but showed similar cracking resistance during production. These findings suggest that using lower-production-temperature WMA is a promising approach to achieve balanced mixture performance during mix design; however, the benefits observed in the laboratory may not always translate to production because of variations in mixture proportions and properties associated with plant operations.