Deterioration laws of static and fatigue bond performance between rebar and concrete with initial cracks under salt-freeze conditions

• Published in: Construction & building materials 2024-11, Vol.452, p.138754, Article 138754
• Main Authors: Shi, Jingrong, Zhu, Weiqing, Zhang, Lihua, Jia, Jinqing, Zhang, Yafei
• Format: Article
• Language: English
• Subjects: Bond performance; Fatigue; Initial crack; Pull-out test; Reinforced concrete; Salt-freeze cycle; Static
• ISSN: 0950-0618
• DOI: 10.1016/j.conbuildmat.2024.138754

The static and fatigue bond performance between rebars and concrete in cracked reinforced concrete (RC) bridges are inevitably deteriorated under the action of salt-freeze cycles. To investigate the laws of bond performance deterioration, central pull-out specimens with initial cracks of varying widths were prepared and subjected to salt-freeze cycles. Some specimens were subjected to static pull-out tests, and the bond-slip curves, peak bond strength and corresponding slip were analyzed. The remaining specimens were subjected to fatigue load, and the slip development curves as well as bond-slip hysteresis curves were analyzed. Based on static pull-out data and a Weibull distribution function, a damage index for bond performance considering different crack widths was proposed. A bond-slip constitutive model under static loading conditions and a slip development curve model under fatigue loading conditions were established. The results showed that increasing the initial crack width significantly reduced the frost resistance of the specimens. In the same salt-freeze environment, peak bond stress under static loading conditions decreased with increasing crack width, but the corresponding peak slip value showed no clear correlation with crack width. It was positively correlated with the number of salt-freeze cycles. Under fatigue loading conditions, the slip at the interface and the area of the bond-slip hysteresis loops continuously increased with increasing crack width, while fatigue bond life gradually shortened. Furthermore, the proposed damage index effectively characterized the degradation patterns of bond strength. The established bond-slip constitutive model under static loading conditions and the slip development curve model under fatigue loading conditions were in good agreement with the experimental results. •Pull-out specimens with initial cracks were tested under salt-freeze cycles.•Subsequent static and fatigue pull-out tests were conducted to evaluate the residual bond performance.•Initial cracks reduced the frost resistance of reinforced concrete structures in salt-freeze environment.•A bond-slip constitutive model and a slip development curve model were established.