Thermal aging degradation of recyclable epoxy asphalt for roadway application

With the growing emphasis on permanent and multifunctional asphalt pavements, the application of epoxy asphalt in roadway construction has been steadily expanding. However, the recycling of epoxy asphalt remains a significant challenge that requires effective solutions. Some studies have explored the synthesis of novel epoxy asphalt with superior mechanical performance, designed for recyclability through reversible crosslinks. However, the mechanical performance of these epoxy asphalts often surpasses the requirements for roadway applications, leading to unnecessarily high costs. To address this issue, we have developed and validated a recyclable epoxy asphalt for roadway applications, utilizing Diels–Alder reaction bonds. This study investigates the thermal aging degradation of recyclable epoxy asphalt, with a focus on dynamic and static mechanical property evolution and chemical composition analysis, particularly carbonyl ketone and sulfoxide groups. During the initial stage of thermal aging, post-curing occurs in recyclable epoxy asphalt due to a further increase in crosslinking, which enhances its relaxation ability and damping properties. With the progression of aging, the material demonstrates an elevated glass-to-rubber transition temperature. The thermal aging kinetics model for recyclable epoxy asphalt suggests that the formation of carbonyl ketones is more sensitive to temperature variations than the formation of sulfoxides. Furthermore, the correlation between mechanical performance and chemical functional group indices is examined. The elongation at failure of recyclable epoxy asphalt exhibits a linear relationship with the sulfoxide index. These findings contribute to a deeper understanding of the thermal aging mechanism of recyclable epoxy asphalt and facilitate degradation prediction throughout its service life.