| Abstract: |
Fire resistance is one of the most critical performance requirements for structural concrete in modern construction, particularly in high-rise buildings, tunnels, industrial structures, and underground facilities. Ordinary Portland Cement (OPC) concrete undergoes progressive deterioration including strength loss, spalling, and microcracking when exposed to temperatures above 300°C. This study investigates the development of fire-resistant concrete (FRC) mixes using advanced supplementary cementitious materials (SCMs) including silica fume (SF) and fly ash (FA), polypropylene (PP) fibers, and refractory aggregates. Four concrete mix designs were systematically formulated and experimentally evaluated: a control mix (M1), an SF-blended mix (M2), and FA-blended mix (M3), and a hybrid SF–PP fiber mix (M4). Specimens were subjected to ISO 834 standard fire exposure at temperatures of 25°C, 200°C, 400°C, 600°C, and 800°C. Evaluation parameters included residual compressive strength, flexural strength, splitting tensile strength, thermal conductivity, mass loss, spalling resistance, water absorption, and chloride ion penetration. Results demonstrate that Mix M4 retained 27.2% of its ambient compressive strength at 800°C nearly twice the retention of the control achieved a fire resistance rating exceeding four hours, and exhibited markedly superior spalling resistance attributed to the vapor pressure relief mechanism of PP fibers. The findings provide actionable material design strategies for fire-resistant structural concrete meeting international standards. |
