RESEARCH ON STATIC MECHANICAL PROPERTIES AND MICROSTRUCTURE OF COMPOSITE RUBBER CEMENT MORTAR BASED ON ORTHOGONAL EXPERIMENTS

Abstract

An L16 (4×4) orthogonal experiment was conducted to investigate the effect of rubber particle size, rubber content, fly ash content, and silica fume content on the fluidity and mechanical properties of composite rubber mortar, and the corresponding mechanisms were explored. The results indicated that silica fume exhibited the dominant influence on the fluidity of composite rubber mortar, while the rubber content demonstrated the most significant impact on the compressive strength, flexural strength, and flexural-compression ratio of rubber mortar. As the curing age increased, the reinforcing effect of fly ash and silica fume on the compressive and flexural strength of composite rubber mortar became more pronounced, indicating that an appropriate amount of fly ash and silica fume exerted a positive synergistic effect on the mechanical strength of composite rubber mortar. Furthermore, both fly ash and silica fume can improve the weak interfacial transition zone (ITZ) caused by rubber incorporation. This improvement leads to a denser pore structure in the composite rubber mortar. As a result, the enhanced mechanical properties significantly reduce the strength loss induced by rubber. Through orthogonal experimental analysis, the optimal combination A1B1C4D2 was identified, corresponding to a rubber particle size of 150 mesh, rubber content of 5%, fly ash content of 20%, and silica fume content of 5%. This specific formulation demonstrated the most favorable comprehensive performance characteristics for the composite rubberized mortar.