Electrochemical Characteristics and Equivalent Circuit Representation of Mortar-Coating-Steel Systems by EIS
This paper summarizes an experimental study on the electrochemical characteristics of various mortarcoating-steel systems and on the equivalent electrical circuit modeling for their representative behaviors. Mortar cylinders with uncoated, enamel-coated, and fusion bonded epoxy (FBE)-coated steel bars were investigated in 3.5 wt.% NaCl solution up to 244 days using electrochemical impedance spectroscopy (EIS). The microstructure of a mortar-coating-steel system was examined using scanning electron microscopy (SEM), and the effects of water cement ratio and exposure condition were considered. SEM images showed a thin porous mill scale on the surface of uncoated steel bars, a 150 μm thick coating with air bubbles of enamel-coated bars, and a 300 μm thick coating with air bubbles distributed near the FBE-coated steel bars. EIS results indicated that the frequency ranges of mortar/coating matrix, passive film, and solution-steel interface can be completely separated for specimens with uncoated steel bars, and but not for specimens with enamel and FBE-coated steel bars. Moreover, the mortar-coating-steel systems can be modeled by an electrical circuit that consists of a series of components representing different material layers. The effect of water cement ratio on the evolution of impedance spectra was less significant than the effect of exposure conditions.
F. Tang et al., "Electrochemical Characteristics and Equivalent Circuit Representation of Mortar-Coating-Steel Systems by EIS," NACE - International Corrosion Conference Series, National Association of Corrosion Engineers International, Mar 2014.
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Civil, Architectural and Environmental Engineering
Materials Science and Engineering
Keywords and Phrases
Scanning electron microscopy, Electrochemical characteristics; Equivalent electrical circuits; Steel-concrete interface; Electrochemical impedance spectroscopy
International Standard Serial Number (ISSN)
Article - Conference proceedings
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01 Mar 2014