Aging degradation of anhydride-cured epoxy asphalt binder subjected to ultraviolet exposure

This research investigated the aging degradation of anhydride-cured epoxy asphalt (EA) subjected to ultraviolet (UV) exposure. A UV accelerated aging test was applied to age EA binders with graduated asphalt contents at 25%, 35%, 45%, 55%, and 65%. The effects of aging on the mechanical, chemical properties, and microstructure of EA were investigated. Results show that the more asphalt is introduced, the higher the mass loss rate of the EA binders, and the more prominent the decrease in elongation and fracture energy during aging. The storage modulus and hardness of EA binders increased after aging. The tensile strength and glass transition temperature of EA binder with 25%-45% asphalt content decreased, while those of EA binder with 55%-65% asphalt content increased. Besides, several carbonyl compounds formation, hydroperoxides formation, and loss of alkyl compounds were observed. Also, when the asphalt content was lower than 45%, holes and microcracks appeared on the surface, while above 45% asphalt content wrinkles. Degradation of the resin network in EA binders was evident by the loss of ester compounds and the microcrack of the resin phase. Overall, the resin network can reduce UV damage to asphalt and improve the photo-oxidative aging resistance of EA materials.