Assessment of ionic diffusivity in cementitious materials using electrical conductivity

This work aims to present an alternative method to verify the metal ion diffusivity in cementitious materials waste. The method was developed to simplify the calculation of inorganic elements diffusion in porous media. It was based on the electrolytic conduction theory and on Archie's law. Cylindrical samples of mortars were cast with Portland cement type V, and contaminated with lead and chromium in the proportion of 1000 mg/kg in relation to the cement mass. The leached solution was obtained and assessed from the immersion test, or Tank Test (NEN 7375:2004). The electrical conductivity of the solid sample was measured at each change of the solvent extract, in the saturated condition of dry surface. The results show that the correlations between the equivalent conductivity obtained in the leached solution and in the solid sample enable both an estimate of availability of components to leaching and the coefficient of diffusivity of heavy metals, without chemical analyzes.