Toughness modification of waterborne epoxy emulsified asphalt by waterborne polyurethane elastomer

Waterborne epoxy emulsified asphalt (w-EA) is prone to cracking at low temperatures after curing, making it vulnerable to damage in plateau zone. In order to solve poor performance at low-temperature of w-EA, waterborne polyurethane (w-PU) is used as a toughening agent to modify waterborne epoxy emulsified asphalt (w-PUEA). Furthermore, the microstructure, creep resistance, dynamic mechanical properties, low-temperature performance, and tensile mechanical properties of both w-EA and w-PUEA are studied in this paper. As the amount of w-PU is increased, the resin network structure in w-PUEA becomes more complex. In addition, w-PU significantly improves the long-term creep behavior of w-EA. The glass transition temperature of w-PUEA gradually shifts to a higher temperature with increasing amounts of w-PU. It is worth noting that the damping properties of w-EA are also significantly improved. The results from low-temperature stress relaxation tests show that the relaxation rate of 10% w-PUEA (0.27 MPa·s−1) is 1.93 times higher than that of w-EA (0.14 MPa·s−1). The flexible long chain of w-PU improves the elongation at break and toughness of 10% w-PUEA by 300% and 171%, respectively, in comparison with w-EA. The pavement performance of the mixture indicates that the addition of 10 wt% w-PU can significantly enhance the low-temperature crack resistance of w-EA.