• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.973-976
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• 2008

Recently, it is increasingly reported that the deterioration of concrete structure under marine environments is due to diffusion and penetration of chloride ions. It is very important to estimate the diffusion coefficient of chloride ion in concrete. Estimation methods of chloride diffusivity by concentration difference is time-consuming. Therefore, chloride diffusivity of concrete is mainly conducted by electrically accelerated method, which is accelerating the movement of chloride ion by potential difference. However, there has not been any proper method for field quality control to closely determine the diffusion coefficient of chloride ion through accelerated tests using potential difference. In this paper, the various test methods for determination of chloride diffusion coefficient in concrete were investigated through comparison accelerated tests. From the results of estimated diffusion coefficient of chloride ion, relationship between the ponding test and acceleration test was examined.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2016.05a
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• pp.209-210
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• 2016

Mechanical properties and durability of recycled aggregate concrete was known to decrease due to the adhesive mortar of recycled aggregate. But in this study, As the result of chloride diffusion resistance of recycled fine aggregate mortar, the mechanical properties are reduced according to the increase of the substitute ratio of recycled fine aggregate. But the chloride diffusion coefficient was almost same with natural fine aggregate mortar.

• Journal of the Society of Disaster Information
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• v.11 no.4
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• pp.548-555
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• 2015

This paper aims to estimate the service life of the target bridge structures subjected to chloride ingress from de-icer, which is used for safety of vehicles in winter, by investigating the chloride ingress into concrete. In this study, the 10-year-old bridge structures were investigated by measuring the chloride along the depth from the exposed surface to derive the surface chloride concentration and the diffusion coefficient for the prediction of service life. The service life of each measured point on the structures were estimated with the surface chloride concentration and the diffusion coefficient by using Life-365 software. As a result, it was estimated for all measured points to have over 100-year service life. Furthermore, the diffusion coefficient and the service life from the measured data were compared to another method calculated with the concrete mix, considering the time dependency of diffusion coefficient.

• Journal of the Korea Concrete Institute
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• v.17 no.5 s.89
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• pp.735-742
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• 2005

The purpose of this study was to evaluate the salt water resistance of concrete depending on various types of cement. In this regard, 5 types of concrete were selected and their strength, void ratio and chloride ion diffusion characteristics were tested, and mutual correlation were analyzed. From the test results, the compressive strength and void ratio of concrete which using Type V cement was as good as Type I cement at long-term ages but the chloride diffusion coefficient of Type V cement was larger than Type I cement. And the concrete replacing some portion of the Type I cement with fly ash was superior in the cases of compressive strength, void ratio and the resistance of chloride ion permeation compared to the Type I cement with the lapse of ages. On the other hand, the compressive strength, the void ratio and the chloride diffusion coefficient of the concrete all indicated high levels of the correlation coefficient and the coefficient of determination regardless of the type of cement.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.5
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• pp.30-36
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• 2019

In order to evaluate service life of RC (Reinforced Concrete) structures exposed to chloride attack, chloride penetration analysis is required referred to the chloride diffusion coefficient from the actual mix proportions. In this work, accelerated diffusion coefficients are obtained from NT BUILD 492 and ASTM C 1202 and the related apparent diffusion coefficients are derived via the previously proposed relationship for RC structures near to sea shore. Considering the properties of the mix proportions and the most conservative analysis conditions like critical and surface chloride contents, service lifes in column and exterior wall member are evaluated through conventional program LIFE 365 ver.2. The different built-up period of 10 and 15 years has no significant effect on service life. The results from mix proportions with slag show longer than 75 years of service life with the help of higher time dependent parameter and lower initial diffusion coefficient.

• 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 Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.15-16
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• 2017

The properties of concrete damaged by fire change according to the temperature. Diffusion coefficient of chloride ion also can change which affect the life expectation under salt circumstance. Diffusion coefficient was measured by NT BUILD 492 using the concrete specimen damaged by high temperature. FEM analysis was performed to predict the life expectancy which can help to diagnose the concrete diagnose and to design maintenance strategy.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.2
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• pp.1-9
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• 2019

GGBFS(Ground Granulated Blast Furnace Slag), one of the representative concrete mineral admixtures, improves the long-term durability and engineering performance of concrete by latent hydraulic activity. In this study, considering 3 levels of W/B(0.37, 0.42, 0.47) and GGBFS replacement ratio(0 %, 30 %, 50 %), durability performances for chloride attack are evaluated, and equations which predict behavior of accelerated chloride diffusion are proposed. Also, the relationship between accelerated chloride diffusion coefficient and passed charge is evaluated. In target curing day, accelerated chloride diffusion tests(Tang's method, ASTM C 1202) and compressive strength(KS F 2405) are performed. In the 730 day's results of accelerated chloride diffusion coefficient, GGBFS concrete has up to 28 % of decreasing ratio compared to OPC concrete, and in those of passed charge, GGBFS concrete has up to 29 % of decreasing ratio compared to OPC concrete. Also, it is deemed that the impact of variation of W/B is less in GGBFS concrete than in OPC concrete. The equations which predict accelerated chloride diffusion coefficient and passed charge are drawn, based on the characteristics of mixture and test results. The equation which predicts passed charge shows slightly higher coefficient of determination than that which predicts accelerated chloride diffusion coefficient.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.4
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• pp.54-61
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• 2023

In this paper, the compressive strength, pore characteristics, and chloride diffusion coefficient were measured at 28 days of age in order to examine the influence of curing conditions for the chloride diffusion and pores in concrete cured under extreme condition. According to the test results, the compressive strength was improved as the relative humidity increased. Additionally, higher compressive strength was observed when the specimens were cured at 35℃. However, the compressive strength of specimens cured at 45℃ was decreased. Meanwhile, the chloride diffusion coefficient decreased with an increase in curing temperature and relative humidity, indicating a difference compared to the trend observed for compressive strength. On the other hand, the excellent correlation showed between compressive strength and chloride diffusion coefficient, porosity and chloride diffusion coefficient when the concrete cured under water. However, when the concrete cured under extreme condition, this correlation was significantly reduced compared to the water curing case. In contrast, it has been determined that there is no significant correlation between the average pore size and chloride diffusion coefficient, regardless of the curing conditions.

• Journal of the Korea institute for structural maintenance and inspection
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• v.28 no.4
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• pp.48-54
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• 2024

NPP (Nuclear power plant) structures have been constructed near to the sea shore line for cooling water and exposed to steel corrosion due to chloride attack. Regarding NPP structures built in the UAE, chloride transport may be more rapid than those in the other regions since the temperature near to the coast is high. In this study, concrete samples with 5,000psi (35MPa) design strength grade were manufactured with the materials and mix proportions, which were the same as used in the UAE NPP structures, then chloride diffusion coefficients were evaluated considering temperature and curing age. The compressive strength and the diffusion coefficient were evaluated and analyzed for the samples with 28 and 91 curing days. In addition, chloride diffusion tests for 91-day-cured condition were carried out in the range of 20℃ to 50℃. The activation energy was obtained through converting the temperature slope to a logarithmic function and it was compared with the previous studies. The proposed activation energy can be useful for a reasonable durability design by using actual temperature-dependent chloride diffusion coefficient.