• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.787-790
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• 1999

To estimate durability of reinforced concrete structures located in or nearby seawater, many different kinds of accelerated tests for evaluation of chloride ion permeation in concrete were proposed. At present the only standardized test is the ASTM C 1202(RCP test). This test method is used to estimate the concrete's resistivity of the chloride penetration in concrete by using the total charges passed and sometimes used to calculate the chloride diffusion coefficients. However, this test may lead to an erroneous chloride diffusion coefficient. So this test method was compared with the modified Dhir's test and the traditional concentration diffusion test. Experimental results showed that the diffusion coefficients determined the RCP test and the PD Index gave wrongous values, but the diffusion coefficient acquired by considering a migration term was nearly the same to the CD Test.

• 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.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.409-412
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• 2000

Many researchers have been trying to evaluate the diffusion coefficient of chloride ion in concrete by using qualitative and quantitative electro-migration tests. Up to now, however, there has been no sufficient method to closely determine the diffusion coefficient of chloride ion through electro-migration test. In this paper, the diffusion coefficient of chloride ion in concrete was investigated through an electro-migration test, that is, AASHTO T 277, Dhir's method, Tang's method and Andrade's method. And the results of these test were compared with each other.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.3
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• pp.138-143
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• 2010

Recently, as many big marine concrete structures increase, it is necessary that chloride ion diffusion coefficient of concrete shall be evaluated but it will take a long time to evaluate chloride ion diffusion coefficient of concrete. Accordingly, many test methods are suggested to evaluate chloride ion diffusion coefficient in a short period time by the promotion in electro chemical ways but the systematic study for this is insufficient. Therefore, this study evaluates chloride ion penetration and diffusion features by three representative electric promotion tests targeting for three different cements whose ingredients are different and analyzes the correlationship between them. As a result, diffusion features of chloride ion varied according to the cement ingredients and three ingredients cement in which blast furnace slag powder and fly ash are mixed in constant ratio, which shows the most excellent cement diffusion properties. For diffusion properties of chloride ion, the correlationship between test methods are good.

• Computers and Concrete
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• v.10 no.5
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• pp.523-539
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• 2012

Silica fume has long been used as a mineral admixture to improve the durability and produce high strength and high performance concrete. And in marine and coastal environments, penetration of chloride ions is one of the main mechanisms causing concrete reinforcement corrosion. In this paper, we proposed a numerical procedure to predict the chloride diffusion in a hydrating silica fume blended concrete. This numerical procedure includes two parts: a hydration model and a chloride diffusion model. The hydration model starts with mix proportions of silica fume blended concrete and considers Portland cement hydration and silica fume reaction respectively. By using the hydration model, the evolution of properties of silica fume blended concrete is predicted as a function of curing age and these properties are adopted as input parameters for the chloride penetration model. Furthermore, based on the modeling of physicochemical processes of diffusion of chloride ion into concrete, the chloride distribution in silica fume blended concrete is evaluated. The prediction results agree well with experiment results of chloride ion concentrations in the hydrating concrete incorporating silica fume.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4A
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• pp.753-759
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• 2006

To predict service life of concrete structures exposed to chloride attack, surface chloride concentration, diffusion coefficient of chloride ion, and chloride corrosion threshold value in concrete, are used as important factors. Of these, as the diffusion coefficient of chloride ion for concrete is strongly influenced by concrete quality and environmental conditions of structures and may significantly change the service life of structures, it is considered as the most important factor for service life prediction. The qualitative factors affecting the penetration and diffusion of chloride ion into concrete are water-cement (W/C) ratio, age, curing conditions, chloride ion concentration of given environment, wet and dry conditions, etc. In this paper the influence of W/C ratio and curing conditions on the diffusion characteristics of chloride ion in concrete was investigated through the chloride ion diffusion test. In the test, the voltages passing through the diffusion cell were measured by accelerated test method using potential difference, and then with the consideration of IR drop ratio the diffusion coefficient of chloride ion for concrete with different W/C ratios were estimated by Andrade's model. Furthermore, under different curing conditions formulas for the estimation of the diffusion coefficient of chloride ion have been proposed by the regression analysis considering the effect of W/C ratio and age.

• Computers and Concrete
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• v.20 no.2
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• pp.185-196
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• 2017

Durability problems initiated from steel corrosion are unseen but critical issues, so that many researches are focused on chloride penetration evaluation. Even if RC (Reinforced Concrete) structures are exposed to normal environment, chloride ingress varies with concrete surface conditions and exposed period. This paper presents an analysis technique for chloride behavior evaluation considering time effect on diffusion and surface conditions assumed as double-layered system. For evaluation of deteriorated surface condition, field investigation was performed for concrete pavement exposed to deicing agent for 18 years. In order to consider enhanced surface concrete, chloride profiles in surface-impregnated concretes exposed to chloride attack for 2 years from previous research were investigated. Through reverse analysis, effectively deteriorated/enhanced depth of surface and the related reduced/enlarged diffusion coefficient in the depth are simulated. The proposed analysis technique was evaluated to handle the chloride behavior more accurately considering changes of chloride ingress within surface layer and decreased diffusion coefficient with time. For the concrete surface exposed to deicing agent, the deteriorated depth and enlarged diffusion coefficient are evaluated to be 12.5~15.0 mm and 200% increasing diffusion coefficient, respectively. The results in concrete containing enhanced cover show 10.0~12.5 mm of impregnated depth and 85% reduction of chloride diffusion in tidal and submerged conditions.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.515-518
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• 2005

In recent years, many research works have been carried out in order to obtain a more controlled durability and long-term performance of concrete structures exposed to chloride environments. In particular, the development of new procedures for probability-based durability analysis and design has been proved to be very valuable. To carry out the procedures described above, the statistical properties of design valuables such as diffusion coefficient of chloride ion, surface chloride concentration, and chloride threshold value etc. should be known. For this purpose, this paper presents the statistical properties of the diffusion coefficient of chloride ion such as mean value and standard deviation with water-cement(w/c) ratio and curing conditions, respectively. It was observed from the test that the standard deviation for the diffusion coefficient of chloride ion was found to be small with decrease in the w/c ratio irrespective of curing conditions and that of standard curing was found to be smaller than that of field curing.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.17-22
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• 2002

Chloride ions have a tendency to penetrate into concrete and proceed the corrosion by depassivating rebar surface. Thus the deteriorated concrete is subject to experience severe degrading of durability under marine environment. Physical properties of mortar, such as, compressive strength and penetration depth of chloride ion were investigated. And to investigate the effect of containing SG, FA in mortar, the diffusion coefficient of chloride was measured through an electro - migration test. The diffusion coefficient of chloride was decreased with the increase of replacement ratio of SG compared with plain specimen.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.775-778
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• 1999

Accelerated chloride diffusion tests were carried out to estimate the chloride diffusion coefficient of concrete using ordinary portland cement, low heat belite-rich portland cement, and sulphate resistant portland cement. Concrete using low heat belite-rich portland cement showed a high diffusion coefficient due to delayed hydration of low heat belite rich portland cement, while the diffusion coefficients of concrete using sulphate resistant portland cement and ordinary portland cement were low.