| The durability of concrete structures has attracted extraordinary concern from thefield of civil engineering. In practical engineering, concrete often suffered different degreeof damage from various physical, chemical and mechanical factors, and the durability ofconcrete was declined by damages. When the concrete is used in chloride environment,damage accelerated chloride diffusion velocity. Which leads to the corrosion damage ofconcrete structures. This topic in the concrete resistance to chloride ion permeability werestudied based on the different damage degree of concrete resistance to chloride ionpermeability.Taking the influence factors of chloride binding capacity, time dependence ofchloride diffusion and damage degree of concrete into consideration, a diffusion equationfor damaged concrete is formulated based on Fick's second law. The chemical analyticalmethod was used to determine total chloride and free chloride contents of damagedconcretes (damage degree:0.00,0.04,0.08,0.14,0.18,0.24) in3.5%NaCl solutionexposed prescribed days(15d,30d,45d,60d,90d,120d,180d,240d). The resultsshowed that: under the same soaking period and depth, the concentration of chloride ion inconcrete increases gradually with the damage degree increases. The effects of damagedegree on the resistance performance of concrete to chloride ion penetration werediscussed. The results show that the influence of damage degree on chloride diffusioncoefficient is significant, which was expressed by degradation indexK i. TheK iis quitesmall when damage degree under0.1, When the damage degree is0.08,K iis1.27.however,K igrow sharply in case that damage degree excees0.1. When the damagedegree is as big as0.24,K igrows up to2.37.Study on the damage degree of concrete resistance to chloride ion penetration effectrule, this will have on the damaged concrete structures in chloride environment assessmentof durability, service life prediction and reinforcement are of guiding significance. |
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