A laboratory study of epoxy/polyurethane modified asphalt binders and mixtures suitable for flexible bridge deck pavement

Abstract

Asphalt binder is prone to thermal cracking, which limits its application in flexible bridge deck pavement. Binders of rubbery characteristics, such as polyurethane (PU) and epoxy resin (EP), having high strength, modulus and toughness, could be applicable to resolve cracking issues at low temperatures. This research proposes a novel approach of using PU and EP to prepare an epoxy/polyurethane (EPU) modified asphalt binder. Properties and microstructure of the EPU modified asphalt binder were explored, and the appropriate formula was determined. Besides, the technical properties of the EPU asphalt mixture were also studied. The results show that EPU modified asphalt binder has satisfactory mechanical strength, flexibility and storage stability. 8 wt% PU and 32 wt% EP is determined as the optimal content. The results of Fourier transform infrared spectrum testing show that PU inserts into the three-dimensional network structure of EP, which plays a positive role in improving the flexibility and heat resistance of the modified asphalt binder. The growth of viscosity is greatly affected by temperature and modifier content, and the construction retention time is shorter than the specification requirements. Besides, the low-temperature cracking resistance of EPU modified asphalt mixture is significantly improved compared to epoxy asphalt mixture, which exhibits a good application prospect in flexible bridge deck pavement engineering.