• Title/Summary/Keyword: chloride ion

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Analytical study of the influence of crack width and depth on the penetration of chloride ion and the carbonation (균열 폭 및 깊이가 염소이온 침투 및 탄산화에 미치는 영향에 대한 해석적 연구)

  • Kim, Chin-Yong;Kim, Jin-Keun
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.05a
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    • pp.594-597
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    • 2006
  • Chloride ion penetration and carbonation are the most important factors in the durability problems of reinforced concrete structures. Most of the existing studies on those subjects are focused on the no-crack concrete, though the existence of crack may strongly affect the chloride ion penetration and carbonation. To evaluate the influence of crack on the chloride ion penetration and carbonation and to assess the service life of reinforced concrete more accurately, finite volume analyses (FVA) were performed based on the FV mesh containing the ideal crack whose width is uniform along the depth. Analytical results show that the influence of crack width and depth is much more pronounced for the chloride ion penetration than for the carbonation.

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Durability Estimation of Fire-Hit Concrete Structure to the Chloride Ion (화재의 영향을 받은 콘크리트 구조물의 염해내구성 예측에 관한 연구)

  • Park, Dong-Cheon;Kang, Byeung-Hee
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2010.05a
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    • pp.219-220
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    • 2010
  • The purpose of this study is to evaluate chloride ion attack durability of concrete structure having experienced the high temperature fire. Mechanical properties and anti chloride ion diffusivity of concrete specimens were measured which have experienced of 2 hours heating at $200{^{\circ}C},\;400{^{\circ}C},\;600{^{\circ}C},\;800{^{\circ}C}$. The coupling FE model of thermal transfer and chloride ion diffusion was built to predict the life expectancy of RC structure using the property values by a series of experiment.

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An experimental study on Influence of Permeability on corrosion of reinforced Concrete (철근콘크리트의 부식에 영향을 미치는 물질 투과성능에 관한 실험적 연구)

  • 김용로;김영덕;조봉석;장종호;권영진;김무한
    • Proceedings of the Korea Concrete Institute Conference
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    • 2003.11a
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    • pp.62-65
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    • 2003
  • In this study, to confirm corrosion of reinforced concrete affected by carbonation, chloride ion diffusion, absorption ratio, air permeability, measured carbonation velocity coefficient, chloride ion diffusion coefficient, absorption coefficient, air permeability coefficient. Corrosion velocity under environment of complex deterioration. And than compared corrosion velocity with these coefficients. As the results of this study, the correlation coefficient between chloride ion diffusion coefficients and absorption coefficient was revealed that it is very high. As well, an increase in carbonation, chloride ion diffusion also increases corrosion velocity. It showed that corrosion velocity was affected by the carbonation, chloride ion diffusion, absorption ratio, air permeability. Generally, data on the development of these coefficient made with none, organic B, organic A, inorganic B, and inorganic A is shown. It showed that coating of surface prevent steel bar from deteriorating.

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A study on the Effect of Curing time on the Chloride ion Diffusion Coefficient in Concrete with Portland Cement and Ground Granulated blast-furnace slag (고로슬래그미분말 혼입 콘크리트의 양생재령이 염소이온 확산계수에 미치는 영향에 관한 연구)

  • Lee, Woo-Jin;Lee, Han-Seung;Song, Soo-Sang
    • Proceedings of the Korea Concrete Institute Conference
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    • 2004.11a
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    • pp.249-252
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    • 2004
  • Chloride ion diffusion is the most important thing of occuring deterioration in RC structure. According to establish data, the curing time in concrete reduce the chloride ion diffusion coefficient. The purpose of this study is to make clear through experience on the effect of curing time on the chloride ion diffusion coefficient in concrete with Portland cement and ground granulated blast-furnance slag and a propose the standard of chloride ion diffusion coefficient in concrete.

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Analysis of Chloride ion Penetration of Marine Concrete Structure (해양 콘크리트 구조물의 염소이온 침투해석)

  • 한상훈;박우선;김동현
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.15 no.2
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    • pp.71-79
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    • 2003
  • The estimation functions were proposed for calculating diffusion coefficient, chloride binding, and evaporable water. The program estimating chloride ion penetration was developed on the basis of these functions and the effects of humidity, curing temperature, water-cement ratio, and $C_3$A on chloride penetration were analyzed. The relative humidity increases the depth of chloride ion penetration and the trend becomes greater with aging. On the contrary, the influence of curing temperature on chloride ion penetration decreases with aging. By the way, the rise of $C_3$A in cement increases total chloride concentration on the surface as the bound chloride concentration increases but it decreases total chloride concentration on the inner part as the diffusion velocity of free chloride decreases. The fall of water-cement ratio decreases the chloride penetration depth rapidly. Therefore, the reduction of water-cement ratio may be the most effective method for reducing of the steel corrosion by chloride penetration.

A study on effects of water-cement ratio and crack width on chloride ion transmission rate in concrete

  • Li, Yue;Chen, Xiaohan;Zhang, Guosheng
    • Computers and Concrete
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    • v.19 no.4
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    • pp.387-394
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    • 2017
  • To study the effects of water-cement ratio changes and cracks on chloride ion transmission rate in cracked concrete, RCM method was adopted to accelerate the diffusion of chloride ion in cracked concrete, and the changes in chloride ion concentration and around the cracks are inferred by finite-element method. The test results show that as far as prefabricated cracks on concrete components are concerned, the width thresholds of two cracks on the concrete specimens with a water-cement ratio of 0.5 and 0.6 are 0.05 mm and 0.1 mm respectively, the width threshold of two cracks on the concrete specimens with a water-cement ratio of 0.4 is 0.05 mm and 0.2 mm respectively; and the results of numerical simulation show that the smaller the water-cement ratio is, the more significant effects of cracks on chloride ion transmission rate are. As a result, more attention shall be paid to the crack prevention, repairing and strengthening for high-strength concrete.

Influence of Carbonation and Freezing-thawing on the Chloride Diffusion in Concrete (탄산화 및 동결융해 현상이 콘크리트 중의 염소이온 확산에 미치는 영향 연구)

  • Kim, Dong-Baek;Kwon, Ki-Jun;Jung, Sang-Hwa;Bok, Hoon
    • Journal of the Korean Society of Safety
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    • v.22 no.3 s.81
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    • pp.57-64
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    • 2007
  • Recently, the corrosion of concrete structures has received great attention related with the deterioration of sea-side structures, such as new airport, bridges, and nuclear power plants. In this regards, many studies have been done on the chloride attack in concrete structures. However, those studies were confined mostly to the single deterioration due to chloride only, although actual environment is rather of combined type. The purpose of the present study is, therefore, to explore the influences of carbonation and freezing-thawing action to chloride attack in concrete structures. The test results indicate that the chloride penetration is more pronounced than the case of single chloride attack when the carbonation process is combined with the chloride attack. It is supposed that the chloride ion concentration of carbonation region is higher than the sound region because of the separation of fixed salts. Though the use of fly ash pronounces the chloride ion concentration in surface, amounts of chloride ion penetration into deep region decreases with the use of fly ash. The small reduction of relative dynamic elastic modulus induced from freezing-thawing increases the chloride ion penetration depths much. The present study allows more realistic assessment of durability for such concrete structures which are subjected to combined attacks of both chlorides and carbonation or freezing-thawing but the future studies for combined environment will assure the precise assessment.

A Study on the $Cl^-$ ion property of antiwashout concrete using the superplasticizer agent (고유동화재를 사용한 수중불분리콘크리트의 Cl 이온 특성고찰)

  • 김동석;최재웅;구본창;하재담;엄태형;신연식
    • Proceedings of the Korea Concrete Institute Conference
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    • 1999.04a
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    • pp.117-122
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    • 1999
  • The antiwashout concrete which is a type of specific concrete is manufactured by using a plenty of superplasticizer with the non-dispersible underwater concrete admixture, and the application of it on construction site is being increased. But when we measure choride ion content by using the potentiographic tester, because it is over total chloride ion content(0.3kg/㎥ under) of Korean Concrete Specification, the claim of construction site is being presented on the quality of antiwashout concrete. Accordingly, hte aim of this study is to verify actual chloride ion content of antiwashout concrete by chloride ion analysis due to chemical admixtures by performance of antiwashout concrete. In conclusion the actual chloride ion content of antiwashout concrete is overestimated by anion($OH^-, SO4^{-2}, S^{-2}, etc) of chemical admixtures, and is proved to be as low as that of ordinary concrete.

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Electrochemical Acceletated Test for Evaluation of Chloride Diffusion in Concrete (콘크리트 중의 염화물 확산평가를 위한 전기화학적 촉진시험법)

  • 문한영;김홍삼;이승태;정호섭;최두선
    • 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.

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A Study on the Binding Ratio of Chloride Ion in Cement Pastes (시멘트 경화체 내에서의 염화물 이온 고정화율에 관한 연구)

  • 문소현;소승영;소양섭
    • Proceedings of the Korea Concrete Institute Conference
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    • 1997.04a
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    • pp.186-190
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    • 1997
  • Corrosion of steel reinforcement is the most significant factor of deterioration in reinforced concrete structures. It breaks down the passive film and allows the steel to be corroded severely at a high rate. The main object of this study is to determine the critical chloride ion concentrations in the pore solutions and chloride binding effect of cement pastes. It is found that binding chloride ion ratio of cement is between 0.04% and 0.3% and Cl/OH in pore solution under 0.3.

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