Experimental investigation of fiber hybridized ECC using PVA, polypropylene, and high-modulus glass fibers with class F Fly ash and OPC

Abstract Conventional concrete is inherently brittle and exhibits limited tensile strain capacity, leading to crack localization and reduced durability. Engineered cementitious composites (ECC) have been developed to overcome these limitations through strain-hardening behavior and improved ductility. In this study, polyvinyl alcohol (PVA), polypropylene (PP), and high-modulus glass (HMG) fiber-reinforced hybrid engineered cementitious composites (HECC) are investigated to evaluate their development and performance. The cementitious binder comprised OPC 53 grade, and Class F fly ash (FA), and fiber hybridization was employed to enhance strain hardening, strength, and ductility. Three ECC mixes were developed: a control mix (ECC) with 2.0% PVA fibers, HECC1 with 1.35% PVA and 0.65% PP fibers, and HECC2 with 1.35% PVA and 0.65% HMG fibers. Mechanical and microstructural properties were evaluated through comprehensive experimental investigations, including Fourier Transform Infrared Spectroscopy (FTIR), Field Emission Scanning Electron Microscopy (FESEM), compressive strength, flexural strength, elastic modulus, and uniaxial tensile tests. The results indicate that at 28 days, HECC2 achieved the highest compressive strength (53 MPa) and flexural strength (15.5 MPa), primarily due to the high stiffness of HMG fibers. In contrast, HECC1 exhibited superior ductility and energy absorption capacity owing to the high elongation characteristics of PP fibers. The findings emphasize the importance of optimal mix design, specifically the volume fraction and fiber type, in customizing the mechanical performance of ECC for structural applications.