The corrosion of steel in concrete is an electro-chemical process which creates a current flow causing metal to dissolve so that it is possible to assess the probability of reinforcement corrosion by evaluating the electrical resistance of the concrete.
The factor is measured in terms of resistivity and expressed in Ohm.The resistivity of concrete varies over a complete structure due to a variety of changing site conditions from day to day so that other methods, like half-cell potential or impact testing, should be combined to ensure the data. Generally, the probability of the steel corrosion increases, the concrete resistivity deceases.
One of the practical problem of concrete resistivity testing is to ensure the good electrical contact between the electrodes and concrete surface. In Resitest-400M, Sponge insert type sensor is used for good electrical contact.
Resitest-400M is supplied with Wenner sensor, carrying pouch, reference block, connection cable, AC adaptor, sensor cleaning bottle, insert sponge, aluminium bag and instruction manual.