Experimental study on the bonding strength of rebars in seawater sea-sand concrete under chloride erosion and freeze–thaw cycles

This study experimentally investigated the bond behavior between reinforcement and seawater sea-sand concrete (SSC) under the combined actions of chloride-induced corrosion and freeze–thaw (F–T) cycles. The coupled environmental effects were simulated through a slow freezing test and an accelerated electrification corrosion method. In the test program, the number of F–T cycles (0, 15, 25, and 50) and the chloride ion concentrations (3.5%, 7%, and 10%) were used as key environmental variables. The bond–slip behavior between rebars and SSC was then examined by push-out tests, taking into account the F–T cycles, salt solution concentration, rebar type (plain and deformed), and concrete strength grades. The results achieved in this study indicate that the interfacial bond strength between the rebars and SSC decreased with the increase in F-T cycles. After 50 F–T cycles, the bond strength of the specimens was reduced by more than 19% compared with that of the uncycled specimens. The variation trend of bond properties of specimens under the coupling effect of F-T cycles and chloride corrosion was related to the F-T cycles. The bonding slip strength exhibited a pattern of initial increase followed by a gradual decline with increasing F-T cycles. Finally, A theoretic bond-slip curve between rebars and SSC after chloride salt F-T cycles is proposed and is in good agreement with the experimental results.