Non-uniform rust expansion for chloride-induced pitting corrosion in RC structures

[Display omitted] •Coupled micro- and macro-cell corrosion process is numerically simulated.•Pitting shape evolution is examined through electrochemical corrosion analysis.•Macrocell corrosion controls non-uniform rust expansion around rebar circumference. Steel corrosion normally takes pitting pattern in chloride contaminated RC structures. This paper examines the localized corrosion rust accumulation process through electrochemical analysis. The coupled micro- and macro-cell corrosion process involved in typical chloride-induced corrosion is numerically simulated by employing the Finite Element Method (FEM). The modeling results show that macrocell corrosion rate may decrease drastically while microcell corrosion rate may not change so much during the gradual initiation process of corrosion around reinforcing steel. The non-uniform rust distribution around steel–concrete interface is found to be mainly caused by macrocell corrosion circulating between upper active and lower passive rebar surface.