Effects Of Surface Coating And Penetration Direction On The Diffusion Of Chloride Ions Into Concrete

Chloride ion penetration is the predominant causal factor in the premature degradation of reinforced concrete structures located in a chloride-ladden environment. The chloride ions penetrated into concrete destroy the passive film on bar, induce corrosion of reinforcement, and cause structural failure. Therefore, it is particularly important to effectively prevent chloride ions into concrete by various means. The intention of this thesis is to quantify the effects of the water/cement ratio, curing age, surface coating, penetration direction, and penetration time on the chloride diffusion of ions by experiment.The experimental results showed that the chloride diffusivity of concrete decreases with the increase of the curing age. When the water/cement ratio is 0.4,0.5, and 0.6, the chloride diffusivity of concrete at the curing age of 28 days is smaller than that at the curing age of 7 days by 37%,34%, and 29%, respectively. The chloride diffusivity of concrete increases by increasing the water/cement ratio. When the curing age is 7 days,14 days, and 28 days, the chloride diffusivity of concrete at a water/cement ratio of 0.6 is larger than that at a water/cement ratio of 0.4 by 22%,48%, and 39%, respectively. The chloride diffusivity of concrete coated with epoxy resin, acrylate, and JSA polymer is smaller than that without coating by 73.37%,22.10%, and 13.77%, respectively. When the water/cement ratio is larger and/or the curing age is shorter, a better result is achieved by surface coating. The chloride content in concrete varies with the penetration direction. At a distance of 5 mm from the concrete surface, the chloride content in concrete subjected to chloride penetration from the top surface is larger than those from the lateral and bottom surfaces by 115% and 421%, respectively.