Durability and Strength Improvement of Ambient-Cured Geopolymer Concrete Using Polypropylene Fibers

This study uniquely investigates the effects of polypropylene fiber (PPF) reinforcement on the mechanical and durability properties of ambient-cured geopolymer concrete (GPC) composed of fly ash and ground granulated blast furnace slag (GGBS). The primary novelty lies in optimizing fiber content for ambient-cured GPC to enhance strength and environmental resistance. PPF was incorporated at varying dosages (0%, 0.5%, 1%, and 1.5%) to assess its impact. Results show that 1.0% PPF significantly improved flexural strength, achieving 3.35 MPa at 90 days. Further, OPI was reduced by 3.1% at fiber contents of 0.50% ( p  < 0.05), suggesting that PPF reduces oxygen permeability. Further, statistical analysis showed a strong correlation between mechanical properties ( R  > 0.96 at most fiber contents). X-ray diffraction (XRD) confirmed the formation of N-A-S-H and C-A-S-H gels, densifying the matrix and reducing permeability. These results show that PPF-reinforced GPC has strong potential for sustainable construction applications by optimizing mechanical performance and durability.