High-strength concrete used in modern infrastructure is highly vulnerable to strength degradation and explosive spalling when exposed to elevated temperatures. This study investigates the combined effect of Ground Granulated Blast Furnace Slag (GGBS), Silica Fume, and Polypropylene (PP) fibers on the thermal resistance and residual mechanical performance of M60 grade concrete. GGBS and silica fume were used as partial replacements of cement to enhance strength and microstructural density, while PP fibers were incorporated to control cracking and mitigate spalling under thermal exposure. Concrete specimens were subjected to elevated temperatures of 400°C, 600°C, and 800°C using a controlled heating regime, followed by natural cooling to ambient conditions. Residual compressive strength and flexural strength tests were carried out to evaluate post-heating performance. The results demonstrate that the synergistic incorporation of GGBS, silica fume, and PP fibers significantly improves thermal stability and strength retention compared to conventional M60 concrete. The developed concrete mix shows strong potential for application in fire-prone structures such as high-rise buildings, tunnels, and industrial facilities using economical and locally available materials. The thermal mix retained higher residual strength at 400°C, 600°C, and 800°C compared to conventional concrete.
Jadav et al. (Sun,) studied this question.