Evaluation of labile ionic pool in cement-based matrix

Abstract: The realization of a diffusive sampling probe, suitable for the assessment of ion mobility in a cement-based matrix, is presented. Laboratory tests have been performed with the purpose of investigating the probe performance and correlating the dynamically induced flux with the ions release obtained under equilibrium condition from leaching test realized in parallel. The diffusion fluxes were induced by an ionic exchange resin from the mortar through a thin diffusion chamber full of water. The resin acts as a sink, thus causing a re-supply from the labile ionic pool of the solid phase. This re-supply is dependent on the amount of labile ions adsorbed on the solid phase and on the rate of exchange between solid and solution phase. This model simulates and assumes the probe deployment based on the first Fick's laws. The time evolution of the accumulated mass of non adsorbed species (nitrate) was used to calculate the re-supply due to diffusion only. In situ diffusion deployment may potentially provide reliable information and it may represent a support for the assessment of both environment impact of the porous material and its durability.