This paper presents the effects of using quartz as a partial replacement for fine aggregate and hooked-end steel fibers in concrete with ground granulated blast furnace slag (GGBS) as a supplementary cementitious material. The study investigates the mechanical properties of concrete, including compressive and tensile strength, before and after exposure to elevated temperatures. Fresh properties of concrete, such as slump and compaction factor, were also evaluated to understand the effects of fiber ratio. The optimum value of hooked-end steel fiber was found to be 0.5% in terms of achieving higher compressive and tensile strength compared to conventional concrete, both before and after elevated temperature testing. The replacement of 15% of fine aggregate with quartz resulted in higher strength in both normal and oven-impassioned samples at 28 days of age. Furthermore, the combination of 0.5% hooked-end steel fiber and 15% replacement of quartz from fine aggregate showed the best mechanical properties, both before and after exposure to 4000 °C. The workability of fiber concrete increased with increasing quartz percentage from M sand, but the maximum strength was achieved with 15% replacement of quartz and 0.5% hooked-end steel fiber after elevated temperature testing. Overall, the findings suggest that the use of hooked-end steel fibers and quartz as partial replacement of fine aggregate can effectively enhance the mechanical properties of concrete, especially when subjected to elevated temperatures

Keywords: Quartz, Compressive strength, Concrete