Durability Characteristics of Concrete Columns Wrapped with FRP Tow Sheets

Abstract

Fiber-reinforced polymer composite (FRPC) wrap has been established as an effective method for rehabilitation and strengthening of concrete structures. This paper presents the results of an experimental study on the performance of concrete columns wrapped with carbon and glass FRP composite sheets subjected to wet-dry and freeze-thaw conditions. Concrete columns were wrapped with three different types of FRP tow sheets: two carbon and one glass. Test variables included the type of fiber (C1, C5, and GE) and the environmental exposure conditions. The specimens were conditioned in the following three different environments: (1) room temperature (+20°C); (2) 300 wet-dry cycles using salt water; and (3) 300 freeze-thaw cycles. At the end of each exposure, stress-strain behavior in compression was obtained to evaluate their strength, stiffness, and ductility, which were compared with the performance of unconditioned samples. Results show that the specimens wrapped with carbon fiber–reinforced polymer (CFRP) experienced no reduction in strength or ductility caused by wet-dry exposure, whereas samples with glass fiber–reinforced polymer (GFRP) experienced reduction in both strength and ductility. In the case of freeze-thaw exposure, both CFRP- and GFRP-wrapped specimens experienced significant reductions in strength and ductility. The specimens subjected to freeze-thaw cycling also exhibited more catastrophic brittle failure as compared with the unconditioned and the wet-dry conditioned specimens.