The CorroMap™ system is designed for the evaluation of reinforcement corrosion rate and half-cell potentials. The system works by inducing a short duration anodic current pulse into the reinforcement galvanostatically from a counter electrode placed on the concrete surface together with a reference electrode.
In order to do the testing, access to the reinforcement is required. In addition, the half-cell potential and the electrical resistance of the cover layer are measured, all in one operation.
Estimating the Corrosion Rate
By utilizing the ohmic resistance (electrical resistance), the DC polarization resistance over time, and the applied current, the corrosion current can be estimated with the Stern Geary equation.
Method
To be able to measure the corrosion rate the electrode of the CorroMap™ has a “Guard Ring” to confine the current to an area equivalent to the central counter electrode. The Guard Ring in indispensable for the system in order to measure the effective polarization resistance and covert this to a corrosion rate. Without the Guard Ring the area of the counter electrode would be much smaller than that of the working electrode (the reinforcement) and the electrical signal would have a tendency to vanish with increasing distance (cover).