51314-4090-Electrochemical Characteristics and Equivalent Circuit Representation of Steel-Coating-Mortar by EIS

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Product Number: 51314-4090-SG

ISBN: 4090 2014 CP

Author: Fujian Tang

Publication Date: 2014

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Corrosion behavior of steel in concrete is generally investigated by applying a small electrical perturbation on the concrete-steel system at the equilibrium state (around open-circuit potential) and simultaneously recording the system response to the perturbation. The electrochemical properties of the concrete-steel system can be determined by analyzing the relationship between the input and the output electrical signals which is usually represented by an equivalent electrical circuit. The circuitry elements such as resistor capacitor constant phase element diffusion impedance and so on can quantitatively reveal the underlying electrochemical behavior of the system under investigation. In our previous studies coating has been considered as an effective way to protect steel reinforcement from corrosion. In this study however coating serves as an insert layer between the concrete and steel to create a concrete-coating-steel system. By changing the dielectric properties and microstructures of various coating layers the electrochemical property of the concrete-steel system can be understood with additional insights and depths. This study experimentally investigates the electrochemical characteristics of mortar-coating-steel systems with different coating materials and proposed a generalized equivalent electric circuit to represent them. Mortar cylinders with uncoated (iron oxide layer) porcelain enamel-coated (inorganic coating layer) and fusion bonded epoxy-coated (organic coating layer) steel bars were investigated in 3.5 wt.% NaCl solution up to 244 days. The effects of water cement ratio and exposure condition are also considered. Experimental results indicated that the electrochemical characteristics and equivalent circuit representation of mortar-coating-steel interfaces depended on the properties of mortar cover coating layer and the state of steel surface.