Evolutionary regularity of bond property for reinforced concrete after electrochemical rehabilitation

Reinforcement corrosion, due to the presence of chloride ions, is a major cause of the degradation of reinforced concrete structures. Nowadays, electrochemical rehabilitation (ER) is becoming a common technique for repairing reinforced structures. Due to the transmission properties of the micro-pores in concrete, chloride ions can be transferred to the outside of the concrete through the pores under the driven force of electric field. Compared with other conventional technologies, ER presents many advantages, such as high efficiency and little influence on the environment and surroundings. However, previous studies indicate that ER exhibits negative effect on the interfacial bonding properties of steel concrete. As the main influence factor for ER, varying current densities may consequently change the bond loss between steel and concrete. In addition, large current density significantly reduces interfacial bond. However, current studies lack relevant quantitative research results and fail to propose an effective method to solve the problem after electrochemical repair since aiming at electrochemical rehabilitation will most likely result in the bond deterioration of reinforced concrete. In this study, the bond-slip curves were obtained through central pull-out specimens after ER with various electrochemical parameters, and the relationship between the electrochemical parameters (current density and conduction time) and the bond behaviors were investigated. Finally, a degradation model of bond strength considering the influences of the two parameters mentioned was established. Results show that the bond strength decreases significantly with high current density and long conduction time. Using a current density of 5 A·m^–2, reduction of the max bond force increased up to 22.6% and 56.9% under a conduction time of 15 and 28 d, respectively. The proposed model can be used to quantitatively characterize the reduction of bond strength after electrochemical rehabilitation. Good consistency of results was observed after comparing the evaluated results with that of the experiment.