Tensile Durability of Cement-Based FRP Composite Wrapped Specimens

Abstract

Fiber-reinforced polymer composite (FRPC) wraps are increasingly being used for rehabilitation and strengthening of concrete structures. This paper presents the results of an experimental study on the tensile performance of cement-based specimens wrapped with FRPC sheets subjected to wet-dry and freeze-thaw cycles. The tensile strength values were evaluated using the ASCERA hydraulic tensile tester. This simple testing technique provides a uniform stress distribution throughout the specimen, thus minimizing eccentricity and gripping effects, which can be of a significant source of error. Cement-based specimens 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 three different environments, as follows: (1) room temperature (23°C); (2) 300 wet-dry cycles using salt water; and (3) 300 freeze/thaw cycles. At the end of each exposure, ultimate strength and load-extension behavior were obtained and then compared to the performance of unconditioned samples. Results show that specimens wrapped with carbon-fiber-reinforced polymer experienced no reduction in strength due to exposure, whereas specimens with glass-fiber-reinforced polymer experienced a significant reduction in strength. Specimens subjected to wet-dry cycles experienced a reduction of 20%, and those subjected to freeze-thaw cycles experienced about 12%. The exposure to wet-dry and freeze-thaw cycles showed no effect on the load-extension behavior of the wrapped specimens. The tensile strength values were presented using Weibull statistics to study the reliability of the test data.