AbstractThe object of this research was to study the influence of waterborne epoxy resin on the properties of emulsified asphalt and its microstructure. First, the proportions of curing agent and waterborne epoxy resin were determined based on the test results of three indexes. Then, modified emulsified asphalt emulsion samples with different waterborne epoxy resin contents were prepared. The evaporation residues of the modified emulsified asphalt samples were subjected to the three index tests, dynamic shear rheological (DSR) test, bending beam rheometer (BBR) test, and pullout test. In addition, the performance parameters of the waterborne-epoxy-resin modified emulsified asphalt were compared with those of the neat asphalt and the emulsified asphalt. Last, the microstructures of the modified emulsified asphalt samples were studied with scanning electron microscopy (SEM). The test results indicated that the optimal curing agent to waterborne epoxy resin ratio was 10∶1. As the waterborne epoxy resin content increased, the softening point of the evaporation residue of the modified emulsified asphalt samples increased and penetration decreased. The ductility suddenly decreased. The addition of waterborne epoxy resin significantly improved the high-temperature performance and bond behavior of the modified emulsified asphalt. However, its low-temperature performance deteriorated. The results of the microstructure analysis indicated that when the waterborne epoxy resin content was 10%, the waterborne epoxy resin was more evenly distributed throughout the modified emulsified asphalt. The comprehensive properties of the waterborne-epoxy-resin modified emulsified asphalt were superior to those of neat asphalt and emulsified asphalt.