Measurement of the steady and non-steady-state chloride diffusion coefficients in a migration test by means of monitoring the conductivity in the anolyte chamber. Comparison with natural diffusion tests

Abstract

The precise calculation of steady-state chloride diffusion coefficients is laborious, expensive, and time consuming due to the fact that it is necessary to take liquid samples for the chlorides to be analysed. In this paper, the concentration of chlorides is monitored by measuring the conductivity of the anolyte which initially is distilled water. Additionally, the calculation of Ds and Dns is made from the same test using the concept of “time-lag” and of the “equivalent time” between diffusion and migration experiments. The correlation between Ds and the conductivity has been done by testing 10 different cementitious matrixes (concrete and mortar) with different binders, and considering the influence of the type of solution that is the source of chloride ions as well as the variation of the electrodes and the effect of the kind of matrix. The results obtained have been compared with natural diffusion results in order to validate them. As a result, for the possibility of making it automatic, the calculation of Ds and Dns diffusion coefficients has been verified.