Experimental study on durability of FRP sheets under wet-dry cycles in various solutions

Fiber-reinforced polymer (FRP) is being extensively used in repair and rehabilitation of concrete structures due to their excellent performance and ease of application. Externally bonded FRP hydraulic structures in fluctuating backwater area are likely being exposed to wet-dry cycles and unavoidably being attacked by chloride ions, sulfate ions in water. Therefore, the long-term durability of FRP composites under wet-dry cycles in various corrosive solutions becomes a major consideration in the selection of these composites. This paper evaluates the durability of three kinds of FRP sheets under four kinds of wet-dry cycles, which represent the hydraulic structures various conditions. Tensile tests of FRP sheets for periods up to one year have been presented. Test results indicate that: (1) Degradation of FRP sheets is primarily observed on the level of tensile strength rather than of elastic modulus; (2) Degradation of FRP sheets under wet-dry cycles in sulfate and chloride solutions is more significant than in alkali and acid solutions; (3) AFRP sheets and CFRP sheets show better resistance against wet-dry cycles in various solutions than BFRP sheets.