Investigation of mechanical properties of PVA fiber-reinforced cementitious composites under the coupling effect of wet-thermal and chloride salt environment

Abstract

In this study, the mechanical properties of polyvinyl alcohol fiber-reinforced cementitious composites (PVA-FRCC) under the coupling effect of wet thermal and chloride salt environment were investigated through a series of experiments, including compressive strength, flexural performance, elastic modulus, three-point bending fracture, and scanning electron microscope (SEM) tests. An environmental simulation test chamber was used to simulate the wet-thermal and chloride salt environment, in which the parameters of temperature, relative humidity (RH), mass fraction of the NaCl solution, and action time were determined to be 50 °C, 100%, 5%, and 30 d, respectively. The volume contents of the PVA fibers incorporated in the cementitious composites were 0, 0.3%, 0.6%, 0.9%, 1.2%, and 1.5%. The results indicated that the mechanical properties of the cementitious composites decreased after being subjected to the coupling effect of the wet-thermal and chloride salt environment. The incorporation of the PVA fibers improved the mechanical properties of the cementitious composites under the coupling effect of the wet-thermal and chloride salt environment. When the addition content of PVA fiber was approximately 0.6–0.9%, the mechanical performance of PVA-FRCC was the best. Compared with the cementitious composite without fibers, the maximum growth rates of the cube, axial and residual compressive strength, elastic modulus, and flexural strength of the PVA-FRCC under the coupling effect of the wet-thermal and chloride salt environment owing to the addition of PVA fiber reached 29.96%, 46.92%, 29.71%, 46.15%, and 67.06%, respectively. In particular, the 1.5% PVA fiber dosage increased the initiation and unstable fracture toughness, and fracture energy by 145.57%, 333.01%, and 2656.38%, respectively.