Experimental research on the degradation law of the bond performance between steel bars and concrete with rust expansion cracking

Chloride ion attack leads to the corrosion of steel bars, causing cracking of the concrete protective layer and affecting the bonding performance between steel bars and concrete. Through electrochemical accelerated-drywet cycle corrosion method(EDWCM), pull-out test, XRD microanalysis, the similarity between EDWCM and natural corrosion as well as the law of deterioration of bond performance caused by chloride salt erosion to steel bars corrosion and concrete rust expansion and cracking were investigated. The experimental results showed the similarity between the EDWCM proposed in this paper and natural corrosion, the power function change rule between the rust expansion crack width and the rate of steel bar quality loss, and the exponential decreasing trend of bond strength, peak slip, bond energy, and residual bond coefficient with the increase of concrete rust expansion crack width. Based on the experimental data, a formula for calculating the ultimate bond strength with the width of rust expansion crack as the control variable was established, and the reliability of the established formula was proved by comparing it with other formulas as well as the research data of other scholars.