Macro-cell corrosion in reinforcement of concrete under non-homogeneous chloride environment

This research study was carried out to identify the behavior of macro-cell corrosion when the embedded steel of concrete specimens is exposed to the effect of homogeneous and non-homogeneous chloride environments. Macro-cell corrosion currents were periodically measured using a segmented steel bar. Results show that macro-cell corrosion can be observed even when the surrounding chloride environment is homogenous. When the chloride environment is nonhomogeneous, higher macro-cell corrosion activity was observed between steel segments exposed to different levels of chloride contents. Macro-cell corrosion activity becomes more significant when the difference in chloride content is increased. It was also observed that the macro-cell anodic and cathodic reactions periodically change their overall electrochemical behavior from anodic to cathodic or cathodic to anodic. It is proposed that the time dependent variation of macro-cell corrosion occurs due to the spatial variation of oxygen and moisture concentrations caused by an ongoing corrosion process that is briefly explained in this paper.