Low-Temperature Reversible Aging Properties of Selected Asphalt Binders Based on Thermal Analysis

The objectives of this paper are twofold: (1) Investigate the low-temperature reversible aging discrepancy mechanism of the asphalt binders with similar regular low-temperature performance grade; and (2) evaluate the effects of commercial wax on the reversible aging properties of asphalt binder. First, the mechanisms of reversible aging in asphalt binder were reviewed. Then, regular performance grading tests and extended bending beam rheometer tests were used to comprehensively evaluate the effect of base asphalt binder type and commercial wax content on regular performance and reversible aging properties. Moreover, a modulated differential scanning calorimetry test was applied to analyze the phase transition, crystallization, and melting behavior of selected asphalt binder samples before and after long-term conditioning. The results showed that commercial wax-based warm mix additive increased the degree of reversible aging (physical hardening) in asphalt binder. There is a strong relationship between endotherm peak enthalpy and commercial wax content. For asphalt sample with a higher degree of reversible aging (physical hardening), glass transition temperature (Tg) increased and two separate amorphous domains formed with the extension of conditioning time.