ABSTRACT
In the real reinforced concrete structures, macrocell current density (icorr-ma) of the current flowing between the actively corroding steel and the steel which was passive or had a lower corrosion rate usually cannot be measured directly due to the continuity and integrity of steel. The corrosion current density calculated by the Stern-Geary equation (icorr-SG) was widely used as the parameter to quantitatively evaluate the corrosion rate of steel. Technically, this corrosion current density was defined as microcell current density, because it was confined to a defined area under the counter electrode and was obtained based on the hypothesis that the oxidation current of an anode was equal to the reduction current of a cathode. Strictly speaking, this corrosion current density was not the real dissolution rate of steel, because it did not contain the macrocell current density (icorr-ma) of the current flowing from the measured area to another un-measured area. Therefore, in order
high performance concretes and concluded that the icorr-SG value was about 2 times greater than the icorr-ma value in ordinary concrete, while the icorr-ma in high performance concrete was between two and three orders of magnitude lower than the icorr-SG. Poursaee et al. (Poursaee, Laurent & Hansson, 2010) found that for the specimens exposed to NaCl and MgCl2 solutions, the icorr-SG values were higher than the icorr-ma values and this difference was greater for the specimens exposed to NaCl solution than for those exposed to MgCl2. The icorr-ma and icorr-SG values of the specimens exposed to CaCl2 were similar.
