Experimental and theoretical study of bond stress distribution between recycled concrete and deformed steel bar after freeze–thaw damage

Abstract Pull‐out tests were conducted on 36 bond‐slip specimens with unslotted steel bars and 12 with slotted steel bars to analyze the effects of anchorage length and freeze–thaw damage on bond strength, and investigate the distributions of bond stress and slip between steel bar and recycled concrete at peak pull‐out load. The results show that, the bond strength decreases with the increase of freeze–thaw damage and anchorage length, and the effect of freeze–thaw damage on long‐anchored members is less than that on short‐anchored members. The presence of the arching effect changed the shape of the bond stress distribution curve, causing a second peak at the free end, and the arching effect was reduced accordingly after freeze–thaw damage. The calculated values using the modified softening sleeve theory proposed in this study are in good agreement with the experimental values.