Determinate Chloride Diffusion Coefficient and Corrosion Initiation on Self-consolidating Concrete

The use of supplementary cementitious materials (SCMs) such as silica fume (SF), metakaolin (MK), fly ash (FA), and slag (SL) can significantly extend concrete life, especially for those exposed to coastal environments. An essential part of estimating the service life of the reinforced concrete (RC) structures is estimating the time when the corrosion begins. The diffusion coefficient that leads to the concentration of chloride ions in concrete is one of the most important parameters for evaluating the corrosion initiation time. This study determined the chloride diffusion coefficient by preparing samples containing different admixtures based on the Nord-test accelerated migration test. The samples are placed in two environmental conditions, submerged and dry and wet cycles for 180 days. The Charged System Search (CSS) meta-exploration algorithm based on the Hesofer-Lind-Rakowitz-Fissler (HL-RF) method evaluated corrosion and chloride diffusion coefficient initiation time. Test results and numerical models showed that in a sample with admixture, its corrosion resistance was almost two times that of the ordinary concrete and the initial corrosion time. If several types of admixture are used, the corrosion time becomes twice as long as when only one admixture is utilized. The best performance for the durability of concrete belonged to the samples with three admixtures. Using additives, MK, SF, and SL, with concrete results in the probability of corrosion to decrease by about 40% after 25 years, and at 50 years, this value becomes about 50%.