Durability assessment of FRP-concrete bond after sustained load for up to thirteen years

Small-scale plain concrete notched beams strengthened with carbon and glass fiber reinforced polymer (CFRP and GFRP) sheets were tested in flexure to assess the change in debond onset strain following sustained flexural loading in indoor and outdoor environments for as long as 13 years. The bond tests were all conducted quasi-statically in a normal laboratory atmosphere. For indoor conditioning, debond onset strain was practically unchanged in the CFRP beams over 13 years, while a decrease was seen in the GFRP beams. For outdoor conditioning, which included freeze-thaw cycles, rain, hot weather, and ultraviolet exposure, clear reductions in debond onset strain were observed in both GFRP and CFRP strengthened beams.