AN INVESTIGATION OF GALVANOSTATIC TRANSIENT METHODS USED TO MONITOR THE CORROSION RATE OF STEEL IN CONCRETE

The sensitivity of the time constants describing galvanostatically induced potential-time transients to corrosion rate changes was examined on steel embedded in concrete. While it was noted that the shape of the transients changed significantly with changes in corrosion rate, the decay was not an exponential function which would be expected if it were determined by activation controlled reactions. Indeed the time constants resulting from an assumed exponential decay were insensitive to corrosion rate changes. However, a proposed empirical function, which fitted the transients more accurately, produced time constants that were inversely proportional to the corrosion rate of active steel. It may be noted that potential-time transients are expected to be insensitive to specimen area and this may prove to be an advantage when monitoring the corrosion rate of an unknown or variable steel area.