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    Calculation of Extended Counter Electrode Polarization Effects on the Electrochemical Impedance Response of Steel in Concrete

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    Electrochemical impedance spectroscopy (EIS) measurements of corroding reinforcing steel in concrete are complicated by the formation of corrosion macrocells with associated potential gradients through the electrolyte. The measurements often require placing macroscopic counter electrodes in contact with the external concrete surface. This paper presents computations of the extent of current pattern changes and associated EIS response variations due to placement of counter electrodes. A model cylindrical reinforced concrete system was used, in which the rebar had a central active spot where both anodic and cathodic reactions took place. The rest of the bar surface was considered to be passive and supporting only cathodic reactions. The predicted impedance spectra yielded apparent polarization resistances that tended to underestimate the corrosion current. This was ascribed to nonuniformity of the excitation current distribution. Generally, current distribution effects overshadowed variations in the impedance response due to counter electrode placement or polarizability.


    concrete, corrosion, electrochemical impedance, macrocells, measurement, counter electrode, polarizability, current distribution, computation

    Author Information:

    Kranc, SC
    Professors, University of South Florida, Tampa, FL

    Sagüés, AA
    Professors, University of South Florida, Tampa, FL

    Committee/Subcommittee: G01.11

    DOI: 10.1520/STP18080S