Mechanical characterization of high-strength and ultra-high-performance engineered cementitious composites reinforced with polyvinyl alcohol and polyethylene fibers subjected to monotonic and cyclic loading

This paper aims to comparatively evaluate the compressive and flexural response of high strength and ultra-highperformance polyvinyl Alcohol (PVA)- and polyethylene (PE)-reinforced ECCs at fiber contents of 1.75 vol% and 2.25 vol%, utilizing the same base mixture design. The base mixture was formulated with the objective of reducing the reliance on Portland cement by replacing 55% of it with supplementary cementitious materials (fly ash and silica fume). The flexural loading protocol consisted of monotonic loading with a displacement rate of 0.3 mm/min and 2.0 mm/min, and a repeated/cyclic loading with a displacement rate of 2.0 mm/min. The developed PVA- and PE-reinforced ECCs exhibited significant enhancements in average compressive strength, with PVA-reinforced ECC showing a 19% improvement and PE-reinforced ECC demonstrating a 39% improvement compared to the control specimen. In terms of flexural strength, PVA-reinforced ECC exhibited a 51% enhancement, while PE-reinforced ECC achieved an impressive 199% improvement. Furthermore, a digital image correlation system (DIC) was employed to characterize the cracking behavior and strain response of the specimens. The developed ECCs exhibited multiple cracking and strain-hardening behavior, exceeding a flexural strain of 3%. PE-reinforced ECCs displayed narrower cracks under low loading rates, whereas PVA-reinforced ECCs demonstrated reduced crack widths subjected to high loading rates.