An experimental study on the influence of fine and coarse aggregates on the strength of polyurethane concrete for highway maintenance

This study seeks to assess the impact of the fine-to-coarse aggregate ratio (FA/CA) on the early-age mechanical properties of polyurethane concrete (PUC) designed for quick repair applications. Three sample FA/CA ratios (0.42, 0.54, 1.00) were established based on an optimized particle packing model. The critical characteristics, including compressive and flexural strength, were evaluated after 24 hours. Each test group had at least five specimens, and the results were statistically evaluated using one-way ANOVA and Tukey’s post hoc test (p < 0.05) to verify data reliability. The findings demonstrate that an FA/CA ratio of 0.54 produces enhanced overall strength performance (compressive: 74 MPa; flexural: 8.5 MPa), due to optimized particle dispersion and minimized voids. The FA/CA ratio of 1.00 enhances workability but markedly diminishes mechanical strength. Although this study lacks in-depth discussions of microstructure, long-term durability evaluation, and some transport-related characteristics, the results confirm the potential of PUC. Preliminary results show that PUC is a viable alternative to conventional repair mortars, not only for pavement overlays but also for bridge decks, expansion joints, and other concrete surfaces that require rapid rehabilitation.