The effect of macrocells between active and passive areas of steel reinforcements

The effects of macrocells formed between active (depassivated) and passive areas on the corrosion rate of steel reinforcements in concrete beams and slabs are studied. With a uniform distribution of current lines on the electrodes, the anodic current density (i.e. the corrosion rate) is a function of the difference in potential, ohmic resistance and polarization resistance. This case is approached when passive and active reinforcements are placed opposite each other. A coplanar location of the anode and cathode areas on the reinforcements results in a non-uniform distribution of the current. These cells are modelled by means of a transmission line circuit. A reasonable concordance is obtained between the theoretical predictions and the experimental data.