STP713

    Improved Test Methods for Determining Corrosion Inhibition by Calcium Nitrite in Concrete

    Published: Jan 1980


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    Abstract

    The use of open-circuit potential measurements for determining the extent of corrosion suffers from the inability to assign a corrosion rating with confidence to an observed voltage taken at a given location on a given substrate. We have attacked the problem by using a microprocessor to accumulate multiple readings on a given deck. The solid-state electronics reads, converts, and stores the data faster and with more reliability than is possible with completely manual operation.

    One problem in field applications is attachment to the rebar mat in order to measure the voltage. We report the usefulness of a two-probe method, which can be used without connecting to the metal framework of the bridge. An area large enough to contain active and passive regions must be surveyed.

    A new series of reinforced concrete decks has been cast with and without calcium nitrite inhibitor to confirm earlier findings that corrosion can be controlled at an addition rate of 2 percent by weight of cement. Also, the results from the construction of the first highway bridge built with calcium nitrite are reported here.

    Keywords:

    corrosion, concretes, reinforcing steels, admixtures, alkali-aggregate reactions, inhibitors, portland cement, strength of materials


    Author Information:

    Gaidis, JM
    Senior research chemist, research manager, and applied mathematician, W. R. Grace & Co., Columbia, Md.

    Rosenberg, AM
    Senior research chemist, research manager, and applied mathematician, W. R. Grace & Co., Columbia, Md.

    Saleh, I
    Senior research chemist, research manager, and applied mathematician, W. R. Grace & Co., Columbia, Md.


    Paper ID: STP27469S

    Committee/Subcommittee: G01.14

    DOI: 10.1520/STP27469S


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