The fire resistance of concrete with low fire resistance and meagre fire resistance can be improved by replacing the cement in the concrete mixture with different GGBS ratios. By partially substituting cement with GGBS (ground blast furnace slag), which can be used as an additive to assure excellent heat resistance in concrete, the GGBS can help lower the price of concrete mixtures, prevent concrete from cracking, reduce high temperatures and increase compressive strength. For OPC concrete mixtures, the exact optimal cement substitution rate of GGBS (15-60%, in steps of 15%) must be reached for mechanical (compressive strength, tensile strength and flexural strength) analysis, durability (constant pressure and water absorption), GGBS concrete mixture mass loss due to acid attack and microstructure characteristics (FESEM and FTIR), assuming a water-cement ratio of 0.4. (Mixture 1 with 100% and Mixture 2 with the best GGBS percentage) After exposure to the flame, the resistance is calculated. Curing HSC performance is observed under the influence of thermal annealing. Higher temperature is observed in various mixtures and densities.