Bending Behavior of Reinforced Concrete Beams Strengthened with Carbon Fiber Reinforced Polymer Laminates and Subjected to Freeze-Thaw Cycles

Thirty-six concrete beams strengthened with glued-on CFRP laminates were tested in bending after being subjected to different numbers of freeze-thaw cycles. In order to evaluate a possible deterioration of the interface bond between the concrete and the CFRP laminate, the development length of the glued-on plate was purposely made smaller than the required value. Parameters investigated were: (1) different strengthening systems; (2) precracking of the beams, prior to strengthening; and (3) number of freeze-thaw cycles (0, 100, 200 and 300). For each number of freeze-thaw cycles three control specimens (RC beams with no externally glued-on CFRP laminates) were also tested. It was generally observed that both the moment capacity and the ultimate deflection decreased with an increase in the number of freeze-thaw cycles. The rate of decrease was larger for precracked than for non-precracked beams.