Experimental investigation on bond strength between BFRP bars and concrete under freeze-thaw cycles (Publication with Expression of Concern)

To investigate the bond strength between BFRP bars and concrete under freezing and thawing cycles, a total of 36 specimens for freezing and thawing cycles tests and center pull-out tests were carried out with different times of freezing and thawing cycles (0, 10, 20, and 40 times) and different concrete strength grades (C30, C35, and C40). The results of this study showed that the specimens without freezing and thawing cycle (0 times) and specimens of C30 with freeze-thaw for 40 times were pulled out, and the remaining specimens were split. With the increase of the concrete strength grade, the debonding strength increases gradually and the ultimate bond strength does not increase in proportion. The debonding strength of BFRP bars and concrete decreases gradually with the times of freezing and thawing cycles. The ultimate bond strength and peak slip indicated a trend of increasing and then decreasing with the increasing times of freezing and thawing, while the peak slip of specimens of C30 with 40 times freeze-thaw increases slightly.