The major problem with the fly ash concrete is lower early strength because of the addition of fly ash. The main objective of the present investigation is to improve the compressive and tensile properties of polypropylene fiber-reinforced concrete at elevated temperatures by add- ing activated and inactivated fly ash. Polypropylene (PP) fibers (0.5% by volume of concrete) with fly ash (40% replacement of cement) were uti- lised to check the compressive strength and split tensile strength both at normal and elevated temperatures. No spalling of concrete occurred with testing temperature ranging between 100 and 650 ◦C by using PP fibers. By using an activator with fly ash in concrete, the compressive strength of activated fly ash concrete (CAF) was 52% and 29.8% greater than inac- tivated fly ash concrete (CIF) at 7-days and 28-days, respectively. The use of fly ash enhanced the concrete strengths at elevated temperatures especially up to 200 ◦C. For elevated temperatures up to 650 ◦C, the com- pressive strength of PP fiber reinforced concrete with activated and inac- tivated fly ash was higher than that of the control concrete at normal temperature. A similar trend of amelioration was observed for the split tensile strength of CIF and CAF. Up to 650 ◦C, the PP fiber reinforced con- crete with activated and inactivated fly ash reported a greater tensile strength than the control model. The statistical analysis using the ANOVA test reported that the activation of fly ash along with the amalgamation of PP fibers ameliorated the compressive and tensile strength results of concrete efficiently