Cracking resistance performance of epoxy asphalt mixture collected from in-service steel bridge deck pavement: Multiscale testing and evaluation

Epoxy asphalt (EA) mixture is commonly used in steel bridge deck paving due to its high strength and fatigue properties. However, cracking remains a problem on the steel bridge. The performance of damaged EA mixtures in the field after several years of service is unclear. Therefore, this study collected typical in-situ EA mixture and evaluated the attenuated performance of damaged materials at multiscale levels. The low- and intermediatetemperature cracking resistance and fatigue properties of field specimens from both the top and bottom layers were investigated by semi-circular bending (SCB) test. The micro-mechanics, microstructure, and element distribution of the interfacial transaction zone (ITZ) in damaged and fresh EA mixtures were characterized by the nano-indentation and energy dispersive spectrometer (EDS) tests. After 13 years of service at low and intermediate temperatures, the in-situ EA mixture exhibited a reduction in flexural tensile strength and fracture energy by approximately 31.4 % to 36.7 % and 54.9 % to 59.9 %, respectively. The top layer exhibited worse cracking resistance and fatigue properties than the bottom layer. The ITZ of the top layer showed more intense oxidation and significantly higher modulus than the bottom layer, contributing to the durability decay of the top layer EA mixture. The oxidative aging of the bottom layer was almost negligible compared to the new EA mixture, indicating that the degradation of the bottom layer was mainly caused by traffic or thermal loading from the steel bridge.