Potential field measurement for assessing corrosion processes

The purpose of non-destructive electro-chemical potential measurement is to assess corrosion processes on reinforcement of reinforced concrete and prestressed concrete components. The tension between a reference electrode that is placed on the concrete surface, and whose potential is known, and the reinforcement is measured in this method, to obtain information about the likelihood of corrosion on reinforcement in multi-storey and underground carparks and tunnel structures on a large scale.

Corrosion of the steel can occur, if the steel surface in the concrete is depassivated through chlorine penetration. Anodic (active) and cathodic (passive) areas will form on the steel surface in this process. The corrosion current that is present in all corrosion cells causes a polarisation of the anodes and cathodes, and the resulting mixed potential that can be measured on the concrete surface is changed depending on the position. The likelihood of corrosion increases in line with negative potential values, and high potential gradients indicate a greater likelihood of corrosion.

Potential field measurement allows for qualitative statements regarding the existence of areas with active corrosion. The absolute values of potential measurements are influenced by the characteristics of the concrete, its level of conductivity, the concrete cover of the reinforcement and other ambient conditions. This is why they must be assessed in connection with other criteria and the potential gradient in particular.

We perform potential field measurements using the Canin+ device (by Proceq). A wheel or rod electrode is used, depending on the requirements.

For illustration purposes, the potential field measurement data is presented graphically. Based on the analysis, low-destruction sampling sites can be selected in a targeted manner.