EVALUATION OF CHLORIDE DIFFUSION IN CARBONATED CONCRETE INCLUDING SILICA FUME

The purpose of this paper is to provide a model for predicting the corrosion process in concrete. This model is defined based on the simultaneous infiltration of chloride ions and the phenomenon of carbonation of concrete under certain environmental conditions. For this purpose, the simultaneous effect of chloride ion diffusion and carbonation phenomenon was studied using experiments on the fabricated samples. For this reason, in the first case, the samples are exposed to carbon dioxide once and then to chloride ions. In the latter case, only samples under the influence of chloride infiltration are examined. To make the samples, which include 9 mixing designs, three water-to-cement ratios of 0.35, 0.4 and 0.5 and three percent of 0%, 7% and 10% silica fume have been used. In this study, accelerated chloride ion (RCPT) penetration, capillary adsorption, pressurized water penetration and compressive strength tests of concrete were performed on the samples. Also in control and carbonate samples, the results of long-term experiments including chloride ion penetration and determination of chloride ion profile and determination of chloride ion diffusion coefficient have been investigated. The results of permeability tests show that carbonation has a direct effect on reducing the flow rate in the chloride ion permeation test and also reducing the capillary adsorption coefficient in the water capillary adsorption test. While increasing the ratio of water to cementations materials, the effect of carbonation on reducing the flow rate and also the capillary absorption coefficient of water increases, it should be noted that increasing the percentage of soot silica reduces this effect. Using linear fitting models on the results of long-term experiments, the amount of changes in chloride ion diffusion coefficient due to carbonation of concrete and determination of chloride ion concentration in concrete is presented.