Optimization of rapid-repair material ratio and performance analysis based on orthogonal test

Through orthogonal experimental design, the influence of the water-binder ratio, binder-sand ratio, ultrafine mineral admixture content, and steel fiber content on the fluidity and basic mechanical properties of rapid-repair materials was studied. The optimal mixing ratio parameters were determined, and its swelling and shrinkage performance and microstructure were analyzed. The results showed that the water-binder ratio and steel fiber content were the most significant factors affecting the properties of rapid-repair materials. The steel fiber content in the rapid-repair material led to pull-out failure and significantly affected flexural strength but had a relatively small effect on compressive strength. With the determined optimal mix proportion, the rapid-repair material had good fluidity and high early strength, bonding strength, and volume stability. At age 3 h, the material’s flexural strength and compressive strength were 13.7 MPa and 27.8 MPa, respectively, and the adhesive strength was 3.65 MPa. The limited expansion rate of 56 d-age repair material was 326.5 × 10−6, which can better meet the requirements of repairing highway pavement and bridge expansion joints to reopen to traffic within 3 h of repair.