The Effect of a Chemical Warm Mix Additive on the Self-Healing Capability of Bitumen

Warm mix asphalt (WMA) technologies reduce the production temperature of hot mix asphalt (HMA) allowing for mixing and paving at lower temperatures. As a result, the use of WMAs reduces emissions and allows for longer transport times. Due to the recent increase of chemical warm mix additives in industry, the effect of a chemical warm mix additive (cWMA) on the intrinsic self-healing ability of the bitumen was investigated. Bitumen specimens containing three concentrations of cWMA were evaluated at four aging levels (unaged, RTFO-163 °C, RTFO-130 °C, and PAV aged) using the Simplified-LASH (linear amplitude sweep with a single rest period) fatigue-healing test. Results indicate that oxidative aging of bitumen is reduced with increasing cWMA concentration but may be more heavily influenced by the aging temperature. It was also observed that PAV aged bitumen samples demonstrate greater fatigue restoration ability compared to RTFO and unaged binders. This trend is counter to our current understanding of bitumen self-healing warranting further research on the factors that affect LAS-based fatigue healing tests.