Effect of Current Distribution on Corrosion Rate Measurements in Reinforced Concrete

The effect of current distribution on corrosion rate measurements was studied for the case of reinforcing bars (rebar) in concrete. The manner in which the current that is applied during electrochemical determination is distributed around the rebar circumference was considered theoretically and by using an electrical analyzer. The ratio between the maximum and minimum current density (i_max and i_min, respectively) at opposite points on the surface of the cylindrical electrode indicated the lack of uniformity in the current distribution. This index first was estimated for the primary distribution of the current, which represented a situation of less uniformity. Subsequently, an electrical resistance model was used to determine the additional effect of polarization on the secondary distribution. Finally, an attempt was made to quantify the influence of a nonuniform current distribution around the rebar circumference on corrosion rate values obtained from the Stern-Geary equation.