Preliminary results of three-point bending tests of concrete notched beams with different content of PVA fibers

Abstract

During the last few decades, fiber-reinforced concrete (FRC) has been widely used in the construction industry to increase strength and toughness of concrete structural members. Different types of fiber have been used in FRC, with different dimensions, shapes, and mechanical properties. The addition of short, dispersed steel fibers in concrete gained large popularity in recent years and steel FRC (SFRC) is commonly used in specific structural applications (e.g., precast tunnel segments) and to partially substitute conventional internal transverse steel reinforcement. Nowadays, the addition of synthetic fibers in concrete is becoming increasingly popular, thanks to the ability of these fibers to delay the occurrence of microcrack and/or provide post-cracking tensile residual strength. Furthermore, synthetic fibers have better durability than steel fibers. Among different synthetic fibers, polyvinyl alcohol (PVA) fibers have shown promising results. In this paper, a preliminary experimental campaign is carried out to investigate the effect of micro and macro PVA fibers on concrete tensile strength and toughness. To this aim, three-point bending (TPB) tests are performed on concrete notched beams with different contents of PVA fibers. Results obtained with PVA-FRC are evaluated with respect to a corresponding plain concrete specimen, and the possible synergy between micro and macro PVA fibers embedded in concrete is assessed. Results show that PVA macrofibers increase the concrete post-cracking tensile residual strength.