STP1065

    Quantitative Measurement of the Corrosion Rate Using a Small Counter Electrode in the Boundary of Passive and Corroded Zones of a Long Concrete Beam

    Published: Jan 1990


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    Abstract

    Recently, in CORROSION-87, one paper was presented which, assuming the electrical model of the “transmission line” to represent the nonuniform distribution of the current in a concrete beam, demonstrated the calculation of the instantaneous corrosion rate by unit of length of the rebar through mathematical equations.

    In the present contribution those equations are used in order to determine whether the equations enable distinction between the corroded zones of a rebar and those which remain passive. A concrete beam was fabricated, half of it by mixing chlorides with the cement (and therefore inducing a corrosion in the rebars) and the other half without admixtures (passivated zones of the rebars). The apparent polarization resistance was measured along the beam using a small counter electrode. Through the equations previously proposed, the corrosion rate was calculated.

    The results obtained confirm that the boundary between corroded and passivated zones can be clearly identified using these formulae. Finally, some comments are given on the relative activity of galvanic macrocells compared with the corrosion microcells.

    Keywords:

    steel in concrete, polarization resistance measurements, on-site corrosion rate, macrocell action, steels, corrosion, concrete


    Author Information:

    Andrade, C
    Researchers, Institute of Construction and Cement “Eduardo Torroja,” CSIC, Madrid,

    Macias, A
    Researchers, Institute of Construction and Cement “Eduardo Torroja,” CSIC, Madrid,

    Feliu, S
    Researchers, National Center of Metallurgical Research, CSIC, Madrid,

    Escudero, ML
    Researchers, National Center of Metallurgical Research, CSIC, Madrid,

    González, JA
    Researchers, National Center of Metallurgical Research, CSIC, Madrid,


    Paper ID: STP25020S

    Committee/Subcommittee: G01.07

    DOI: 10.1520/STP25020S


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