Field-aged asphalt binder performance evaluation for Evotherm warm mix asphalt: Comparisons with hot mix asphalt

Evotherm is one of the chemical warm mix asphalt (WMA) technologies that has been widely used in sustainable asphalt pavement construction. But the long-term performance of such warm mix asphalt pavement has not been studied comprehensively. This study investigated the field-aged asphalt binder performance with three different Evotherm additives (ET, DAT and 3G) based on fourteen field projects across the United States. Their performance was compared with corresponding HMA control binder. Asphalt binders were extracted and recovered, and were subjected to tests including continuous grading high temperature and low temperature, multiple stress creep recovery, and fracture. The results showed that after 2-6 years of field aging, the HMA binder had relative higher continuous grading high temperature than the Evotherm binder. All HMA and Evotherm binders regardless of types were m-value controlled, indicating of a significant aging level. The thermal cracking resistance of both HMA and Evotherm binders were similar and quite poor. The failure strain value of HMA binder is comparable with that of Evotherm binder at 20 °C as well as at 5 °C. The addition of Evotherm additive did not compromise the elastic response of polymer-modified binders.