Viscosity, mechanical properties and phase-separated morphology of waterborne epoxy asphalt

This study aimed to investigate the viscosity, mechanical properties, and phase-separated morphology of waterborne epoxy asphalt (WEA). Adopting waterborne epoxy resin as the modifier, the rigid and flexible WEA with admixture amounts of 10 wt%, 20 wt% and 30 wt% were prepared by first emulsifying and then modifying. The Brookfield viscosity test and the tensile test were conducted to evaluate the viscosity, tensile strength, and ductility of WEAs. The phase-separated morphology of WEA were analyzed using the laser scanning confocal microscopy (LSCM) and image analysis software Image-Pro Plus. It was found that the viscosity of most WEAs increased with time. The best compaction time for WEA is 4–5 h after curing. With the addition of waterborne epoxy resin, WEA gradually changed from a continuous asphalt phase and a dispersed phase of cured epoxy resin to a three-dimensional network structure with the two-phase structure of asphalt and cured epoxy. This promoted a substantial increase in the viscosity and tensile strength of rigid WEA and a decrease in ductility. However, due to the rigidity of the cured products of flexible epoxy resin, the ductility of flexible WEA was significantly improved. Nevertheless, the increase in viscosity and tensile strength of flexible WEA was lower than that of rigid WEA. Different types of emulsifiers also had different effects on the viscosity, mechanical properties, and phase-separated morphology of WEA. The area ratio and average diameter of epoxy resin particles can be used as microscopic indicators to evaluate the influence of epoxy resin dosage on the viscosity, tensile strength, and ductility of WEA. Based on the macro and micro performance of WEA, the findings recommend A3T1 rigid WEA with 10–30 wt% waterborne epoxy resin and LBP1 rigid WEA with 30 wt% waterborne epoxy resin.