Effect of chloride-induced corrosion on the bond behaviors between steel strands and concrete

The corrosion of steel strands due to the chloride contamination is one of the most common causes for the degradation of prestressed concrete infrastructure. In this paper, an experimental study was performed to investigate the bond behaviors between steel strands and concrete after suffered the chloride corrosion. Total twenty central and off-center pull-out specimens with different corrosion levels were prepared and tested, in which the electrochemical acceleration method was employed to induce various corrosion levels. The effects of corrosion rate, stirrup configuration and holding condition of concrete to the steel strands on the bond behaviors of steel strands were studied and compared, in terms of the failure mode, bond-slip relationship, bond strength, and bond toughness. The results show that both the ultimate bond strength and characteristic bond strength decreased with the increase of corrosion degree. The presence of stirrups can significantly enhance the bond performance, indicating the more ductile failure characteristic and increased bond toughness. Moreover, the prediction results using empirical and analytical models are also compared with the experimental results to verify their applicability and accuracies in predicting the bond strength of steel strands after corrosion.