Estimation of Chloride Diffusion Coefficent of Concrete Using Mineral Admixtures

It is well known that mineral admixtures, such as granulated blast-furnace slag and fly ash, control the ingress of chloride ions into concrete. However, the effects of the qualities and the replacement ratios of these admixtures on the diffusivity of chloride ions are not clear. Moreover, the micro-structure of concrete is changed by carbonation and change in microstructure affects mass transfer in concrete. This effect on the chloride diffusivity of concrete using mineral admixtures has not been clarified sufficiently. Therefore, in this study, the chloride ion diffusion coefficients of mortar specimens containing mineral admixtures were measured, and the influences of the kind of mineral admixture, replacement ratio, and carbonation on the chloride diffusion coefficient were estimated, and the relation between the microstructure and diffusion coefficient was studied. Furthermore, an estimation method of the diffusion coefficient using the pore volume and surface area of the pore system as parameters was proposed.