Rebar Corrosion Voltmeter

Basic Half Cell System for Locating Areas of Rebar Corrosion

Caltech Engineering Services offer DV-05 rebar corrosion voltmeter kit complete economical kit for identifying areas of rebar corrosion in concrete as per ASTM C876. This standard describes procedure for Half-Cell Potentials of Uncoated Reinforcing Steel in Concrete

DV-05 rebar corrosion voltmeter kit includes half cell and voltmeter integrated with a high impedance and long earth cable and despensing damp sponge. When rebar corrosion voltmeter DV-05 is connected between the reinforcing steel, Cu-CuSO4 reference half cell electrode (Fontana-101F) and specially made highly electrical conductive despensing sponge on the concrete surface where a measurement can be made for the half-cell potential. This gives measurement of the probability of corrosion activity. By testing at a fixed distance apart, a grid of half-cell potentials can be developed and areas delineated. This test method covers the estimation of the electrical half-cell potential of uncoated reinforcing steel in field and laboratory concrete, for the purpose of determining the corrosion activity of the reinforcing steel.

Corrosion, which is an electrochemical process, occurs in concrete when oxygen and moisture are present. The actual corrosion is an exchange of energy within different sections of the uncoated reinforcing steel. The relative energy levels can be determined in relation to a reference electrode with a stable electrochemical potential.
By connecting a high impedance voltmeter between the reinforcing steel and a reference electrode placed on the concrete surface, a measurement can be made for the half cell potential at the location of the reference cell. This then is a measurement of the probability of corrosion activity in the steel in the vicinity of the reference cell. This is used to locate corroding steel reinforcement

The reference half cell is copper in a copper sulphate solution. By taking half cell potential measurements a fixed distance apart a grid of half cell potentials can be quickly made and thus areas delineated with a high probability of corrosion of the reinforcing steel.
To analyze the results, the measurements made with DV-05 rebar corrosion voltmeter can be plotted on a grid and lines of equipotential contours drawn, highlighting areas of possible corrosion activity.

For example the following guide is listed in ASTM C876 ( half cell potentials of uncoated reinforcing steel in concrete) using a copper/copper sulphate half cell:

The method is particularly useful for:

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