Environmental Effects On Tensile Properties Of FRP Laminates Made Using Wet-Lay-Up Method

The demand for Fiber Reinforced Plastics (FRP) in rehabilitation of infrastructures is increasing. New techniques utilize the lightweight, high strength and formability of FRP fabrics and laminates in various retrofitting projects. This paper presents the results of a study on the long-term behavior of different types of FRP laminates made using the wet-lay-up technique. A total of 525 specimens were prepared using one type of epoxy and seven different types of fabrics. Unidirectional and bidirectional fabrics made from glass, carbon and aramid were used in this study. The samples were exposed to nine different environments. These environments were simulated using four different chemical solutions with pH of 12.5, 10, 7 and 2.5, and substitute seawater. In addition, four chambers for exposure to ultraviolet radiation, temperature of 60°C, temperature of 50°C with 95% relative humidity and soil with 25% moisture content and active microorganisms were considered. Uniaxial tension tests were performed on the samples after 6000, 12000 and 20000 hours of exposure as well as on control samples, and tensile properties were measured for each specimen. The results showed a significant loss of strength and ultimate strain for glass fiber reinforced plastics (GFRP) in solutions, especially in high pH values, while carbon and hybrid glass-carbon laminates showed very little loss of mechanical properties.