Uses of Half Cell Potential Field Measurement Equipment

Corrosion potential mapping is used to identify rebar spots that are undergoing corrosion. It is a non-destructive technique carried out on concrete structures in order to determine corrosion status related to the identified corrosion potential value. The contours and measurements obtained by using plotting potential corrosion values are also significant in delineating corroding portions of structures from "healthy" non-corroding portions.

The half-cell, open circuit potential test method is a more frequently used technique for potential corrosion mapping, although double-probing is also applicable. The half cell testing method is suitable for on-site (in-situ) evaluation as well as for research and development work. It applies to concrete members regardless of size or depth of covers over reinforcing steel.  Half-cell circuit potential testing and measurement can also be used any time during the lifespan of a concrete member. It is an inexpensive test method that is simple and quick to perform and analyse, even when surveying an entire structure.

Half-cell potential field measurement requires proper selection of test points, depending on the type of the concrete member being investigated as well as the intended end use of the resulting measurements. On large structures like bridge decks, testing should start with an initial spacing of about 1 meter. Sections should then be resurveyed with 300mm spacing where the potential difference between adjacent readings has exceeded 100 mV. 300 mm is becoming a more accepted standard for initial spacing, reducing to 100 mm over high-ingredient sections.

Under certain conditions, concrete surface or overlaying materials should be pre-wetted using a specific solution to make contact of concrete with the reference electrode more efficient and reduce the circuit's electrical resistance. Test measurements can be presented using one of two ways, including a cumulative frequency diagram and an equipotential contour map, which provides a graphical delineation of areas where corrosion may be occurring.