Non-isothermal low-temperature reversible aging of commercial wax-based warm mix asphalts

Abstract

ABSTRACT Low-temperature reversible aging is one of the most important forms of asphalt hardening, especially for cold regions. However, there are few researches about the influence of wax-based warm additive on the low-temperature reversible aging of asphalt, especially under non-isothermal conditioning. For this reason, simplified extended bending beam rheometer (Ex-BBR) test, non-isothermal rheological analysis and differential scanning calorimetry (DSC) test are performed on asphalt binders containing selected four kinds of commercial wax modifiers (Fischer-Tropschbased wax, linear aliphatic hydrocarbon-based wax, polyethylene-based wax, and fatty acid amides based wax). The results show that all commercial waxes used in this study will accelerate the degree of physical hardening in unaged asphalt binders. Compared with wax-based warm mix additive, oxidative aging has a greater impact on the low-temperature reversible aging properties of asphalt binder. Independent of cooling rate, the base asphalt has the highest phase angle value while the F–T wax modified asphalt has the lowest value. The crystallizable fraction increases with the decrease of cooling rate for both unaged and PAV aged sample. The magnitude of Ozawa exponent has the same order as grade loss for PAV aged sample. However, no obvious rule is observed for unaged asphalt binders.