Study on Mechanical Performance and Enhancement Effect of Steel-Polypropylene Hybrid Fiber-Reinforced Concrete

As research on fiber-reinforced concrete progresses, investigating the enhancement effect of hybrid fiber-reinforced concrete becomes increasingly crucial. In the present research, the contents of steel fiber (SF) and polypropylene fiber (PP) were set as variable parameters to study the mechanical performance of steel-polypropylene hybrid fiber-reinforced concrete (SPFRC). Mechanical performance tests were undertaken on 16 groups of standard specimens. The failure modes were observed, the strength variation patterns were analyzed, and both a strength prediction equation and a complete stress–strain curve equation were established. Research results indicated that the specimen containing 1.5% SF and 0.25% PP exhibited the maximum strength enhancement compared with plain concrete: cube compressive strength improved by 27.78%, and splitting tensile strength surged by 41.18%. When the SF content was 1.5% and that of PP was 0.5%, the specimen’s elastic modulus experienced the greatest enhancement, reaching 58.59%. Hybrid fibers significantly enhanced the mechanical performance of SPFRC, simultaneously exerting strengthening, crack-resistance, and toughening effects. The research findings offer both experimental evidence and theoretical support for promoting research and engineering applications of SPFRC.