Ratio of water to cement and supplementary cementitious materials on mechanical and impact resistance properties of reactive powder concrete

Reactive powder concrete (RPC) is a novel high-performance building material widely used in large-scale engineering structures due to its superior mechanical properties and durability. However, structural failure can still occur under dynamic load impacts. Therefore, optimizing the mechanical properties and impact resistance of RPC remains a critical issue for enhancing its engineering applications. In this study, the mechanical properties and impact resistance of RPC were investigated by adjusting the water-cement ratio and incorporating supplementary cementitious materials (SCMs), such as fly ash microspheres (FAM) and silica fume (SF). The effects of these adjustments on water absorption, strength, and impact resistance were assessed. Three water-cement ratios (0.16, 0.18, and 0.20) and various proportions of FAM and SF were selected to evaluate water absorption, compressive strength, bending strength, and impact resistance. The results indicated that reducing the water-cement ratio enhanced the densification of the concrete, reduced water absorption, and improved both compressive and bending strength. Specifically, when the water-cement ratio was 0.16 and FAM and SF were synergistically incorporated, the compressive strength reached 134.4 MPa, the bending strength reached 16.86 MPa, and the impact resistance was 22,838.4 J. Impact test results revealed that combining a low water-cement ratio with an appropriate amount of SCMs effectively increased energy absorption capacity and significantly slowed crack propagation. Analysis based on the Weibull distribution model demonstrated a more pronounced probability distribution of the number of impacts, suggesting that the optimization measures improved the impact resistance of RPC.