Physical, Mechanical, and Durability Characterization of Preloaded GFRP Reinforcing Bars

This paper presents the physical, mechanical, and durability characterization of glass fiber-reinforced polymer (FRP) (GFRP) bars subjected to different tensile stress levels. FRP bars were first loaded at levels up to 20, 40, 60, and 80% of their ultimate tensile strength (UTS) which could create cracks and microcracks in the FRP bars and affect the long-term durability of the product. Microstructural observations were conducted on preloaded GFRP reinforcing bars to show the deterioration of fiber, matrix, and the fiber/matrix interface. Moisture absorption and tensile properties of loaded bars were also measured to estimate the potential effects of cracks and microcracks on durability-related properties and on short-term mechanical properties, respectively. Loaded bars were also embedded in a moist mortar at elevated temperature to perform accelerated aging. The measured tensile strengths of the loaded bars before and after exposure were considered as a measure of the durability performance of the specimens. Results showed that the GFRP bars start to be slightly affected by the tensile stress at 60% of the UTS. These results showed that the loading of GFRP bars did not have a dramatic effect on the durability of the bars even when a pronounced tensile stress, which was approximately 80% of the UTS, takes place.