• Bulletin of the Korean Chemical Society
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• v.6 no.3
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• pp.128-131
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• 1985

A series of copolymer membranes of 2-hydroxyethylmethacrylate (HEMA) with selected hydrophobic monomers were prepared without crosslinking agents. The equilibrium water content, the partition coefficient, and the permeability of the solutes such as urea, methylurea, 1,3-di-methylurea, and acetamide via these membranes were measured. The partition coefficient data show that as the hydrophobicity of solutes increased, the partition of solutes were dictated by hydrophobic interaction between solute and polymer matrix. Diffusion coefficients obtained in these experiments decrease as the water content of polymer membrane decreases. This decrease is blunt as the excess heat capacities, ${\phi}C^0_p$ (excess) in aqueous solution at infinite dilution of solute increases. To investigate the relationship between water content and diffusion coefficient, the results of the diffusion experiments were examined in light of a free-volume model of diffusive transport. The remarkable increase of urea mobility in the polymer network containing relatively larger bulk water can be considered as water structure breaking effect.

• Journal of the Korea Concrete Institute
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• v.22 no.2
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• pp.255-262
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• 2010

The purpose of this study is to provide preliminary data on chloride diffusion of lightweight aggregate concrete containing crushed stone-powder. Accordingly, the study performed experiments using concrete aggregates of Crushed Aggregate (CG), Single-sized Lightweight Aggregate (SLG), Continuous Graded Lightweight Aggregate (CLG), and using water-binder ratio of 0.4, 0.5, 0.6, and using binder of FA and BFS. The chloride diffusion coefficient is calculated according to the NT BUILD 492. Diffusion coefficient of SLG and CLG were higher than that of CG concrete, but the difference was not significant. Also, chloride diffusion coefficient data indicated that it was highly affected by water-binder ratio, and it decreased with the decrease in waterbinder ratio. The admixture substitution of FA15% was effective in decreasing the diffusion coefficient only with water-binder ratio of 0.4 while admixture substitution of FA10+BFS20% was effective with all levels of water-binder ratio. The result of study shows lightweight aggregate concrete containing crushed stone-powder has slightly higher chloride diffusion coefficient than CG concrete, but the difference is not significant such that it can be overcome by adjusting water-binder ratio and admixture substitution. In addition, the data indicate the chloride diffusion coefficient of lightweight aggregate concrete can be estimated from the strength of lightweight aggregate.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05b
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• pp.185-188
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• 2005

This study selected three different specified concrete strength types of mixture which were applied to domestic seawater concrete structure and measured compressive strength and chloride diffusion coefficient and composed the formula of prediction model of chloride diffusion coefficient in order to provide the useful data for concrete mix decision of seawater structures. As a result, the formula of prediction model of chloride diffusion coefficient which set W/C and compressive strength as parameters and performed multiplex regression analysis which was based on the mathematical theory was confirmed more reliable than the formula of prediction which was composed existing water-cement ratio function.

• Journal of The Korean Society of Agricultural Engineers
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• v.50 no.6
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• pp.49-60
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• 2008

This study were predicted the corrosion threshold reached at steel reinforcement in latex modified concrete(LMC) which were applied the agricultural hydraulic concrete structures. Accelerated testing was accomplished to the evaluate the diffusion coefficient of LMC mix, and the time dependent constants of diffusion. Also, the average chloride diffusion coefficient was estimated. From the average chloride ion diffusion coefficient, the time which critical chloride contents at depth of reinforcement steel was estimated. Test results indicated that the corrosion threshold reached at reinforcement in LMC were effected on the mix proportion factor including cement contents, latex content, and water-cement ratio. Especially, the average chloride diffusion coefficient, the corrosion threshold reached at reinforcement in LMC were affected by the all mix proportion factor.

• Journal of the Korea Institute of Building Construction
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• v.19 no.5
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• pp.421-429
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• 2019

The changes in the resistance to chloride ingress of concrete using a ground granulated blast furnace slag (GGBFS) according to curing conditions were examined. The curing conditions were divided in air-dry curing and under-water curing. Three concrete mixures with the GGBFS replacement ratio of 0%(control), 30%, and 60% were prepared. For tests, evaluations of concrete compressive strength, and chloride ion diffusion coefficient were performed. As the GGBFS replacement ratio increased, the concrete compressive strength of the in air-dry cured specimens decreased compared to under-water cured specimens. When the chloride ion diffusion coefficient was measured, the chloride ion diffusion coefficient decreased as the GGBFS replacement ratio increased. However, the diffusion coefficient of the in air-dry cured specimen was increased up to 111% compared with the under-water cured specimen.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.11a
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• pp.297-300
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• 2003

A chloride is an important deteriorating factor which governs the durability of the reinforced-concrete structures under marine environments. Also, the main penetration mechanism of chloride ion into concrete is a diffusion phenomenon. In this study, It is evaluated the diffusion coefficient of chloride ion in non-steady state by Fick's second law. Submergence method in salt water carried out in this experiment. Two types of cement which is different in mineral composition were used. In addition, the effect of mineral admixtures of blast-furnace slag and meta-kaolin was studied. In conclusion, the diffusion coefficient of chloride ion is much affected according to cement type and mineral admixtures, also, it is proved that meta-kaolin as well as blast-furnace slag is effective in preventing penetration of chloride ion.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.2
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• pp.18-27
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• 2022

In this study, the time-dependent chloride ingress behavior in GGBFS concrete was evaluated considering marine exposure conditions and the properties of concrete mixtures. The concrete mixture for this study had 3 levels of water to binder ratio and the substitution rate of GGBFS, and outdoor exposure tests were performed considering submerged area, tidal area, and splash area. According to the evaluation results of diffusion coefficient considering properties of concrete mixtures, as the substitution rate of GGBFS increased, the decreasing rate of the diffusion coefficient decreased based on exposure periods of 730 days(2 years). As the evaluation result of the diffusion behavior according to the marine exposure conditions, the diffusion coefficient was evaluated in the order of submerged area, tidal area, and splash area. In tidal area, a relatively high diffusion coefficient was evaluated due to the repetition of wet and dry seawater. In this study, the effects of GGBFS substitution rate on the decreasing behavior of apparent chloride diffusion coefficient was analyzed in consideration of exposure conditions and periods. Linear regression analysis was performed with apparent chloride diffusion coefficient as output value and GGBFS substitution rate as input value. After 730 days of exposure, the effect of GGBFS on diffusion coefficient was significantly reduced. Even for OPC concrete, after 730 days, the diffusion coefficient was as low as that of GGBFS concrete, so the gradient of the regression equation decreased significantly. It is thought that improved durability performance for chloride ingress can be secured before 730 days through the use of GGBFS.

• Ocean Systems Engineering
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• v.2 no.4
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• pp.289-295
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• 2012

Assume fluid eddy viscosity in the vertical direction is parabolic. Sediment particles diffuse with the given fluid eddy viscosity. However, when the vertical diffusion coefficient profile is computed from the suspended sediment concentration profile, the coefficient shows lager values than the fluid mixing coefficient values. This trend was explained by using two sizes of sediment particles. When fine sediment particles like wash load are added in water column the sediment mixing coefficient looks much larger than the fluid mixing coefficient.

• Journal of the Korea Institute of Building Construction
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• v.11 no.4
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• pp.371-378
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• 2011

Concrete is affected by various deterioration factors, such as $CO_2$ and chloride ions from the sea, which cause carbonation and salt attack on concrete. These deterioration phenomena cause steel corrosion in RC structures. Although a great deal of research has been carried out in this area thus far, it is difficult to know the point at which corrosion will occur to a reinforced bar. As the diffusion of deterioration factors depends on the water content in concrete, it is imperative to assess the condition of absorbed water content. A mass measuring method was applied to calculate the absorbed water diffusion coefficient, as well as non-linear finite element method(FEM) analysis. As a result, it was found that W/C and unit water content in concrete mixture affect the diffusion coefficient decision.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.673-678
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• 2002

There are various methods for the electrochemical techniques to estimate diffusion coefficient of chloride ions in concrete, such as ASTM C 1202 test method, Andrade's method, Dhir's method, Tang's method, and etc. In the case of estimating diffusion coefficient of chloride ions in concrete by using these methods, applied voltage and resistivity nay exercise some influence on the characteristics of chloride ions diffusion. Thus. in this study, effect of applied voltage and resistivity on the characteristics of chloride ions diffusion in concrete were researched by applying voltage in 12V, 30V, and 60V, and by using resistivity in 0.2Ω and 1.0Ω, respectively. It can be concluded that diffusion coefficient of chloride ions are found to be increasing as the individual applied voltage and resistivity decrease, when water-cement ratio is constant.