AC impedance spectroscopy is a powerful technique, and has been widely applied to measure microstructure and electrochemical properties of cement-based materials. This paper reviews the equivalent circuit models proposed by researchers to study the chloride related issues, including microstructure based models and electrical circuit models corresponding to ion migration and steel corrosion. The determination of the chloride induced corrosion parameters such as chloride diffusion coefficient, chloride concentration threshold and corrosion rate, and the microstructural modification of cement-based materials due to the chloride penetration in chloride migration test are all introduced. The inhomogeneous structure of cement-based materials make it difficult to determine an appropriate equivalent circuit model. An systemic and instructive methodology for the determination of equivalent circuit for AC impedance spectroscopy analysis is needed.
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