Numerical simulation of steel corrosion in chloride environment based on random aggregate concrete microstructure model

•Meso numerical cross-section of reinforced concrete with random polygonal coarse aggregates is built.•The coarse aggregate causes irregular corroded section shape of the steel bar.•The coarse aggregate can suppress the steel corrosion. The corrosion of steel bar in concrete structure under chloride environment is simulated considering the influence of concrete coarse aggregate. Firstly, the random polygonal coarse aggregate is generated, and the meso numerical cross-section of reinforced concrete is obtained. Then, based on Butler-Volmer equation, considering the coupling effect of diffusion and electrochemical corrosion, an electrochemical corrosion model of steel bar is established. Next, the accuracy of the model is verified by existing experimental data. Finally, the relationships between the volume fraction of coarse aggregate and corrosion morphology, steel corrosion quantity and corrosion process are gotten. The results show that the coarse aggregate causes irregular corroded section shape of the steel bar, and there are convexities and concavities on the corroded surface. The coarse aggregate can suppress the steel corrosion. As the volume fraction of coarse aggregate increases, the durations of the non-corrosive stage and the corrosion expansion stage extend.