Experimental analysis, microstructural and predictive regression modelling of mechanical, durability properties of polypropylene fibre concrete

Polypropylene fibre-reinforced concrete (PPFRC) enhances mechanical properties and durability; nevertheless, the dose–response relationship and predictive modelling of fibre content remain unidentified. Experimental evaluation enhanced microstructural characterization, and regression-based predictive modelling are used to delineate definitive relationships between fiber dosage and concrete performance.M40 concrete mixtures containing 0–0.25% polypropylene fiber (PPF) was evaluated. Compressive, tensile, flexural, and impact resistance were quantified, together with water absorption and sorptivity. FTIR, TGA/DTA, XRD, FESEM-EDS, and micro-CT were used to investigate the pore structure and interfacial transition zone behaviour, focusing on microstructural development. Furthermore, MATLAB non-linear regression models evaluated the impact of fiber dosage on performance. The ideal concentration of 0.20% PPF enhances tensile, flexural, and impact resistance by 158%. Water absorption decreased by 50% due to pore refinement and matrix densification, enhancing durability. The regression models demonstrated strong predictive capability (R 2 > 0.90), showing non-linear dose–response relationships in critical variables. Microstructural analysis of fibre-modified concrete revealed reduced pore connectivity, enhanced interfacial transition zone quality, and stable hydration phases. The study offers a quantitative and predictive methodology for optimizing actual fiber dosage, rather than relying on qualitative assessments. These findings facilitate the development of high-performance, durability, and sustainable fiber-reinforced concrete solutions for optimal mix design and structural applications.