A CRITICAL REAPPRAISAL OF ION DIFFUSION THROUGH CEMENT BASED MATERIALS .1. SAMPLE PREPARATION, MEASUREMENT TECHNIQUE AND INTERPRETATION OF RESULTS

This critical review of the literature on the diffusion of ions through cement based materials has revealed some uncertainties in the techniques of diffusion measurement and in the interpretation of the results. It has also revealed that the difference between the measured diffusion coefficients of alkali ions and chloride ions are due to a co-diffusion of calcium ions along with the alkali ions. This review indicated that a part of the measured beneficial effect of mineral addition, especially at early ages, is due to a reduction of the effective area of diffusion. For the evaluation of the intrinsic effect of mineral additives on the diffusion of ions some additional measurements have to be done.