Evaluation of physical hardening and oxidative aging effects on Delta T_c of asphalt binders

The Delta (Formula presented.) ((Formula presented.)) is a rheological parameter for asphalt binders, which has been adopted in the past years by many highway agencies in North America for asphalt binder selection. In this study, the effects of the low-temperature physical hardening and oxidative aging on (Formula presented.) are experimentally investigated and analysed. The experimental study is performed on both plain and polymer-modified binders. The results show that both physical hardening and oxidative aging have strong effects on decreasing (Formula presented.). An approximate linear relationship is identified between (Formula presented.) and rheological parameters, such as the creep stiffness (S) and the m-value. The linear relationship is theoretically explained by analytical derivation. Based on the linear relationship, a graphical method is proposed for interpreting (Formula presented.) using the log(S)-m diagram. By this method, it is found that polymer modification increases the susceptibility of (Formula presented.) to oxidative aging, while it does not significantly affect the susceptibility of (Formula presented.) to physical hardening.