This study describes an experimental investigation of the degradation of the tensile properties of basalt fibers and epoxy-based composites in various corrosive environments, including alkaline, acid, salt and water solutions, and clarifies the corresponding degradation mechanisms. Carbon and glass fibers and their composites are adopted as references. Accelerated experiments were conducted at temperatures of 25℃ and 55℃ and the variation in tensile properties was studied by means of tension testing, mass loss weighing, scanning electron microscope imaging and energy spectrum analysis. The experimental results show that basalt fibers posses relatively strong resistance to water and salt corrosion, moderate resistance to acid corrosion and severe degradation in an alkaline solution. The tensile properties of basalt FRP composites are much better than those of basalt fibers. The degradation mechanism of basalt fibers involves damage by etching in salt, water and alkaline solutions and by change in the chemical composites in an acid solution. The fracture properties of basalt FRP composites are controlled by the failure of corroded interfaces between the fibers and the resin, making the interface the critical factor, rather than the fiber itself.

This paper introduces a newly developed steel-fiber-reinforced polymer (FRP) composite bar (SFCB) and proposes the ideal configuration based on a large number of exploratory tests on handmade products. Based on factory production of SFCB, uniaxial tensile tests and cyclic tensile tests were conducted to determine the initial elastic modulus, postyield stiffness, yield strength, ultimate strength, unloading stiffness, and residual deformation. Test results showed that the stress-strain curve of the SFCB was bilinear before the fiber fractures. After the inner steel yielded, the SFCB showed a stable postyield stiffness, small residual deformation, and good reparability. Because the theoretical model for the stress-strain curve of SFCB under a uniaxial load based on the mixture rule had large error with data from cyclic tests, the corresponding restoring force model under cyclic tensile loading was constructed by statistical analysis of the stress-strain test curve under cyclic tension. The generated restori...