Investigation on the Photo-Oxidative Degradation of Amine-Based Epoxy Asphalt Binder

Abstract

This study aims to analyze the degradation behavior and mechanisms of amine-cured epoxy asphalt (EA) under the combined effects of ultraviolet (UV) radiation, oxygen, and temperature. To achieve this, amine-cured epoxy resin (ER) and EAs containing 35%, 45%, and 55% asphalt content were prepared and subjected to simulated UV-based aging. Various analytical techniques were employed to investigate the mechanical properties, microstructure, morphology, and oxidation layer of ER and EAs. The results indicate that after UV-based aging, ER and EAs with 35%–45% asphalt content experienced an increase in mass, a decrease in strength and glass transition temperature. In comparison, EAs with 55% asphalt content exhibited the opposite trends. The elongation and (Tanδ)max of ER and EAs reduced, whereas the storage modulus and hardness at mid to high temperatures rose. At the microstructural level, the degradation of the resin phase was confirmed by changes in ether, ester, and amide groups, whereas the generation of sulfoxide groups was associated with the oxidation of the asphalt phase. Compared with ER, the surface of EA has obvious defects after aging, which is the main reason for the decrease in contact angle. As the asphalt content increases, EAs exhibit higher carbonyl concentration, more profound oxidation, and more obvious performance degradation. This trend suggests that the resin phase mitigates the aging of the asphalt phase by absorbing harmful UV radiation and oxygen.