Investigation of Mechanical Properties of High-Performance Steel and Polypropylene Fiber Reinforced Concrete

Fiber reinforcement significantly enhances the strength, toughness, and durability of concrete by reducing the propagation of microcracks in the concrete matrix. With the rising demand for high-performance concrete (HPC), this study investigates the mechanical properties of HPC with varying proportions of polypropylene (PP) and steel (ST) fibers. Supplementary cementitious materials (SCMs) toward partial replacement of ordinary Portland cement (OPC) were incorporated to prepare HPC mixes as a ternary composite system using Fly Ash (FA), Silica Fume (SF), and Ground Granulated Blast Furnace Slag (GGBS). Each HPC mix comprised two SCMs, accounting for 20% of the mass fraction of the OPC binder. The study encompassed fiber percentages ranging from 0 to 0.075% PP and 0 to 2% ST, incorporating them into the HPC mixes with gradual increases of 0.025% for PP and 0.5% for ST fiber by mass fraction. All HPC mixes were tested for mechanical properties using compressive and split tensile strength tests. The influence of SCMs on HPC was studied using X-ray diffraction (XRD) for microstructural analyses. It was found that the compressive and split tensile strengths of HPC increased up to an optimal fiber percentage and then decreased. A comparison of the test results of high-performance fiber-reinforced concrete with those of plain HPC revealed significant improvements in compressive and splitting tensile strengths by 26.59% and 57.74%, respectively. Also, the XRD analysis revealed that the composition of the SCMs in HPC was a significant and effective solution for the mechanical properties of the concrete.