Prediction of the bond strength between non-uniformly corroded steel reinforcement and deteriorated concrete

This paper investigates the influence of non-uniform corrosion on the bond strength of the steel reinforcement in concrete. To achieve the non-uniform corrosion, partial surface of the steel reinforcement was coated by an epoxy resin which could prevent effectively that part of steel from corrosion. Thus, corrosion only happened to the bare (un-protected) zone of the surface. A series of reinforced concrete (RC) specimens were cast and stored in a chloride environment. An impressed current was applied to accelerate the corrosion of the steel reinforcement. Pull-out tests were conducted on the specimens with different corrosion degrees. The experimental results showed that the bond strength was higher than that of the control (non-corroded bar) when the corrosion degree was smaller than 0.8% and was the highest (1.6 times of the control) when the corrosion degree was about 0.2%. The bond strength started to decrease significantly with further increases in corrosion degree. By considering the corrosion of the steel reinforcement and the pressure induced by the expansion of the corrosion products, analytical models were proposed to predict the bond degradation due to pitting corrosion and uniform corrosion. The models were also validated by the test results from existing literature.