1) The document examines how replacing cement and fine aggregates with mineral admixtures like fly ash and bottom ash at different percentages, along with the addition of steel and carbon fibers, affects the compressive strength of concrete when subjected to high temperatures. 2) Cubes of concrete with various replacement levels were cured for 28 days and then exposed to 1000C temperature for 1 hour, after which compressive strength was tested. 3) Results showed that compressive strength decreased with temperature exposure but the decrease was less as the fly ash and bottom ash replacement levels increased, with up to a 29.89% lower strength reduction at 50% replacement compared to normal concrete. This is because the mineral admixtures have better heat