Study on Chloride Ion Diffusion Model in Crack Zones of Saturated Concrete Structure

In order to accurately characterize the behavior of cracks in accelerating chloride ion transport on both sides of the concrete, the concept of effective influence distance of cracks was proposed, and the crack pores were non-uniformly distributed according to the distance perpendicular to the crack surface in the modified equivalent medium model. The expression of chloride ion diffusion coefficient in crack zones of concrete was established based on the principle of flux conservation. Based on the existing experimental data, the applicability of the modified equivalent chloride ion diffusion model established in this paper was verified. Finally, the characteristics of non-uniform acceleration of chloride ion transport on both sides of concrete by cracks were discussed, and the influence of crack spacing and number on chloride ion transport was explored. It finds that the results obtained by the modified equivalent chloride ion diffusion model are in good agreement with the experimental data. The parametric studies show that with the increase in the distance perpendicular to the crack surface, the chloride ion content continues to decrease, and the chloride ion content on both sides is only 19% of that at the crack center point at the same depth of effective influence distance of cracks. The number of cracks has a certain influence on chloride ion diffusion, and the maximum increase in chloride ion content in multi-crack areas is 2% and 17% compared with that of single cracks. In addition, with the increase in the number of cracks, the diffusion capacity of chloride ions first increases rapidly and then flattens. The crack spacing has a significant effect on the multi-crack area of concrete, and with the increase in crack spacing, the overall chloride ion content in the multi-crack area decreases rapidly, and the decrease is the most obvious in the central area.