Tensile behavior of FRP and hybrid FRP sheets in freeze–thaw cycling environments

This study presents the results of an experimental investigation of the freeze–thaw (FT) resistance, including the hybridization of fibers, of carbon, basalt and glass fiber-reinforced polymer (CFRP, BFRP and GFRP) sheets commonly used in civil engineering practice. Coupon tests were conducted to investigate the tensile properties of FRP sheets and their corresponding epoxy resins and dry fiber sheets after up to 300 FT cycles. Sustained loading was included in the testing to reflect the behavior of FRP sheets in real structures. The test results indicate that (1) BFRP and hybrid FRP sheets have better FT resistance than CFRP and GFRP sheets, and the hybridization of fibers can contribute to the stability of the tensile properties of these materials after FT exposure; (2) the tensile properties of the resin matrix deteriorate significantly with increasing FT cycles; (3) further degradation of the tensile properties of FRP sheets is caused by sustained loading during FT cycling; and (4) the tensile behavior of dry glass fiber sheets is more sensitive to FT cycling than dry carbon and basalt fiber sheets. Lastly, the degradation mechanism of FRP sheets in FT environments is discussed.