Numerical study of macro-cell corrosion on reinforced concrete induced by chloride attack

Uneven distribution of chloride ions will cause macro-cell corrosion, which is typical but much more severe to reinforced concrete (RC) structures compared to micro-cell corrosion. In order to evaluate the electro-chemical characteristics of such macro-cell corrosion happening in actual RC structures, an integrated numerical platform including the coupled electric and chemical analysis has been developed. The platform had been successfully validated through an artificial electric field induced by external charge to obtain the accelerated macro-cell corrosion within a short period. In this paper, the application of integrated platform is conducted to chloride induced macro-cell corrosion with verification by long-term laboratory tests and in-service infrastructures in terms of the time-dependent chloride profile and corrosion characteristics. In addition, parametric analysis is conducted to further study the influence of chloride distribution as well as oxygen concentration on macro-cell effect. Results show that the uniformity of micro-cell corrosion even within a single rebar is found broken in either laboratory test or actual infrastructures. The polarization creates anode and cathode along the cross section of rebar, which is qualitatively captured by the numerical analysis. Meanwhile, the impact of adjacent rebars on the macro-cell corrosion of certain rebar, as well as the macro-cell properties within one rebar under the effect of single or multiple cover concrete cracks are also discussed in detail.