Fly ash as a substitute for cement and polypropylene fibers in concrete mix design

Abstract

The research focused on analyzing the effect of fly ash (FA) and polypropylene fibers (PPF) on the mechanical properties of concrete with a compressive strength of f’c = 280 kg/cm². The objective was to determine the influence of adding FA and PPF on the mechanical properties of the concrete. Concretes with FA in proportions of 5%, 10%, and 15%, and PPF in amounts of 350 g/m³, 480 g/m³, and 530 g/m³ were analyzed, evaluating their compressive strength (CS) at 7, 14, and 28 days, and their indirect tensile strength (ITS) at 28 days. Regarding CS, the results showed that at 7 days, the concrete without additives reached 128.05 kg/cm², while with 10% FA and 480 g/m³ of PPF, the strength increased to 256.81 kg/cm². At 14 days, the concrete without additives achieved 155.80 kg/cm², improving to 280.88 kg/cm² with the additives. At 28 days, the concrete without additives reached 281.68 kg/cm², while with 10% FA and 480 g/m³ of PPF, the strength increased to 383.75 kg/cm². Regarding ITS, it was observed that with 10% FA and 480 g/m³ of PPF, the highest strength was obtained, with 49.57 kg/cm². In conclusion, the appropriate proportion of additives to improve the mechanical properties of the concrete is 10% FA and 480 g/m³ of PPF.