Numerical modelling and underlying electrochemical mechanism characterisation of cathodic protection for chloride contaminated reinforced concrete structures

Cathodic Protection (CP) as an effective electrochemical repair technique has been widely employed in the rehabilitation of deterioratedReinforced Concrete (RC) structures worldwide. However, the quantitative specifications of CP technology for RC structures in national and international standards mainly depend on empirical experience and qualitative assessment, which lead to conservativeresults and poor economic benefits. Numerical modelling and simulation have been proved as the effective tools to help understand the CP fundamental electrochemical mechanisms. They are useful to investigate the effects of environmental and operational factors on the performance of the CP system providing the optimum operation. A large number of CP numerical studies for RC structures have been carried out in the past couple of decades. However, most of the previous CP numerical studies, in terms of the literature research in this study, have some deficiencies of concern. For example, most CP numerical modelling cases neglected the variability of the concrete electrical resistivity and the steel polarisation resistance. Meanwhile, many modelling works did not consider the coupling effect of the transportation of different ionic species in concrete and the applied CP electric field effect. This research aims to improve the CP numerical modelling for the RC structures to comprehensively take into account the major electrical and electrochemical mechanisms involved in CP process. Three major contributions have been made in this study. 1) Based on a previous experimental research, this study proposed and developed a concrete electrical resistivity model takingaccount of the coupling influence of the varied water and chloride contents; 2) presented a characterisation for the steel polarisation state under CP conditions; 3) considered the coupling effect of the ionic behaviour and electric field action in the process of CP numerical simulation. At last, combining these two developed models, put forward an improved CP numerical modelling of RC structures