Electrochemical impedance study on steel corrosion in the simulated concrete system with a novel self-healing microcapsule

• A microcapsule is designed for chemical self-healing target in concrete environment.
• An electrochemical model is proposed to state the property of microcapsule inhibitor.
• The microcapsule shows excellent protection against steel bar corrosion.

Based on microcapsule technology, a new type of self-healing system for concrete materials was created, which mainly focuses on the corrosion protection of steel bars. In this paper, the performance of the system is characterized by means of the electrochemical impedance spectroscopy (EIS) of steel bar immersed in a simulated concrete environment. The experimental results demonstrate strong inhibition of chloride-induced corrosion when microcapsules are added to the water solution with sodium chloride by different mass fractions. A novel equivalent circuit model, which takes into account the inductive effect arising from the generation of corrosion products on the steel bar surface, is proposed to explain the protection performance of the microcapsules against the corrosion of a steel rebar in a concrete.