Flexural toughness of extruded fiber-reinforced mortar with preferentially aligned fibers

Abstract

This study explored the flexural toughness properties of polyvinyl alcohol (PVA) fiber-reinforced concrete (FRC) using a modified ASTM C1609 third-point bending test, and it established a comparative study between two methods of casting: traditional casting and pump-driven extrusion. The primary hypothesis posited that the extrusion process would promote fiber alignment parallel to the tensile stresses, thereby enhancing the flexural performance of the concrete. The study corroborated previous research findings that introducing fibers enhances the ductility and post-peak performance of the concrete. Moreover, this research introduced a unique observation that strategic fiber alignment through extrusion could serve to further enhance the concrete's flexural performance. The research employed digital image correlation to capture the full displacement field during testing, facilitating an examination of the crack propagation process and strain localization. The findings showed that the extrusion-based casting method improved the residual strengths by an average of 39% and 87% compared to conventional cast method for the 0.5% and 1% fiber volume specimens, respectively. Additionally, the base of the extruded specimens exhibited a greater incidence of crack initiation and displayed enhanced energy absorption through multiple cracking events. These observations underscore the concept that fiber alignment, when facilitated by extrusion, plays a significant role in influencing crack propagation and, consequently, in improving the flexural properties of the composite material.