Study On The Chloride Ion Diffusion Mechanism Of Fly Ash And Slag Concrete

More and more people pay attention to its integrated durability in recent years. The diffusion of concrete is one of the most important factors affecting the durability of concrete. Through a variety of mix design, this article research and analyze different factors on the concrete diffusion properties and pore structure features, such as water-binder ratio, curing age and admixture replace content.Using electric flux method and the rapid transition method (RCM) to test and analyze the diffusion properties of concrete. Measured the electric flux and chloride diffusion coefficient under different curing period of concrete, compared electric flux and chloride diffusion coefficient of consistency and relevance, and examined the influence of curing period, mineral content and other parameters on diffusion properties of concrete. The results show that the use of mineral admixtures can significantly improve resistance to chloride ion diffusion properties of concrete, especially in the case of a longer curing period. Considering mineral admixtures need a certain process to perform their activities, it is recommended that using 90d age to evaluate the diffusion properties of mixed concrete is more reasonable.Mercury intrusion porosimetry was adopted when testing the pore structure feature of concrete and get the microscopic pore structure parameters. Date analysis focused on the influence of mineral admixtures on pore structure distribution, average pore size and the most probable pore size. The results show that mineral admixtures can significantly improve the distribution of the pore structure of concrete and increase the proportion of harmless pores and less harmful pores. The mineral admixtures also can reduce the average pore size and the most probable pore size. These pore structure changes enormously promoted the development of concrete resistance to chloride ion diffusivity.This paper studies the microscopic diffusion mechanism of concrete and the correlation between the average pore diameter and chloride ion diffusion coefficient. The result shows that evaluation of diffusion of concrete with average pore size is quite feasible. With the increase of the average pore diameter, chloride ion diffusion coefficient increases. Under the same water-binder ratio, both have quadratic term function relationship with the different proportion and quadratic polynomial correlation coefficient up to 0.9468.This paper studies the correlation between the average pore diameter and mineral admixtures content and curing age and uses average pore size of the intermediate variables to get the relationship of chloride diffusion coefficient and mineral admixtures content and curing age. The result shows that the measured value and the theoretical value of the chloride ion difiusion coefficient is very close, and the trend. is same.