Toughness Reinforcement Design of Grouting Materials for Semi-Flexible Pavements Through Water-Based Epoxy Resin and Emulsified Asphalt

Semi-flexible pavement (SFP) mixture consists of porous matrix asphalt mixture and cement-based grouting material. This composite material gains advantages from both the rigid cementitious material and flexible asphalt mixture. It exhibits excellent anti-rutting capability while no joints are needed. However, SFP is prone to cracks in the field. This study employs water-based epoxy resin and emulsified asphalt as polymer additives to modify the grouting material. A response surface methodology (RSM) model was employed for multi-factor and multi-response optimization design. The ratio of water-based epoxy resin to emulsified asphalt (w/e ratio), polymer content, defoamer content, and mixing speed were considered in the model. Fluidity, compressive strength, and fracture energy were selected as response indicators. It was found that a low mixing speed was not able to produce grouting slurry with acceptable fluidity. The addition of higher polymer contents would lower the compressive strength of the grouting material due to the low stiffness of the polymer and entrained air produced during mixing. The addition of defoamer eliminated the bubbles and, therefore, increased the strength and fracture energy of the samples. By solving for the optimal model solution, the values of optimized parameters were determined to be a w/e ratio of 0.64, polymer content of 3.3%, defoamer content of 0.2%, and mixing speed of 2000 rpm. Microstructural analysis further confirmed that the synergistic effect of water-based epoxy resin and emulsified asphalt can effectively make the microstructure of the hardened samples denser. The anti-cracking ability of the SFP mixture can be increased by 22% using optimally designed grouting material. The findings in this study shed light on the design of toughness-reinforced SFP materials.