Basic Half Cell System for Locating Areas of Rebar Corrosion
Caltech Engineering Services offer Rebar Corrosion Tester is complete economical kit for identifying concrete rebar corrosion as per ASTM C876 or rebar corrosion detection. A STM C876 standard describes procedure for half cell potential of reinforced concrete structure.
Accurate measurement of the rebar corrosion rate is necessary for estimating the remaining service life of concrete structures, scheduling repair or maintenance operation using half cell potential test procedure. This is the best corrosion measurement technique for rebar corrosion using half cell potential.
Rebar Corrosion Tester detector 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-201F) and specially made highly electrical conductive despensing sponge on the concrete surface where a measurement can be made for the half-cell potential or half cell corrosion mapping. This test method applies to members regardless of their size or the depth of concrete cover over the reinforcing steel. Concrete cover in excess of 3 in. (75 mm) can result in an averaging of adjacent reinforcement corrosion potentials that can result in a loss of the ability to discriminate variation in relative corrosion activity. 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.
Rebar Corrosion Tester complete kit contents following:
- Easy to use
- Detachable electrode extension pieces facilitate measurements in hard to reach locations - Optional
- High impedance digital meter is designed for tough field conditions
- Electrode is designed for use on horizontal, vertical and inverted positions
- Conforms to ASTM C-876
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. When using Rebar Corrosion Kit, the potential measurements should be interpreted by engineers or technical specialists experienced in the fields of concrete materials and corrosion testing. It is often necessary to use other data such as chloride contents, depth of carbonation, delamination survey findings, rate of corrosion results, and environmental exposure conditions, in addition to corrosion potential measurements, to formulate conclusions concerning corrosion activity of embedded steel and its probable effect on the service life of a structure.
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 rebar corrosion tester 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:
- For potentials of 350mV and greater there is a 95% chance of active steel corrosion
- For potentials 200 to 350mV there is a 50% chance of active steel corrosion
- For potentials less than 200mV there is only 5% chance of active steel corrosion
- Bridge Decks
- Parking Garages
- Concrete Piers & Docks
- Tunnel Lining
|DV-05||Rebar Corrosion Tester Kit|
|Fontana-101F||Half Cell Reference Electrode|
|DV-05CR||Cable reel with 100 ft. (32 meters) cable|
|DV-05 V||Half Cell CP Voltmeter|