• Title/Summary/Keyword: chloride ion

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Analysis of Chloride Ion Penetration for Harbor Concrete Structure with In-situation Environment (항만 콘크리트 구조물의 현장환경변화에 따른 염소이온 침투해석)

  • Han, Sang-Hun;Jang, In-Sung
    • Proceedings of the Korea Concrete Institute Conference
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    • 2004.11a
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    • pp.225-228
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    • 2004
  • In order to estimate the chloride ion penetration, the model, which considers diffusion and sorption, is proposed on the basis of Finite Element Method (FEM). The FEM program provides the estimation of chloride concentration according to cyclic humidity and sorption. After the humidity diffusion analysis is carried out, the chloride ion diffusion and sorption analysis are conducted on the basis of the preestimated humidity data in each element. Each element has different analysis variables at different ages and locations. At early ages and constant outer humidity, the difference between inner and outer relative humidity causes the chloride ion penetration by sorption. As the humidity diffusion reduces the difference with age, the effect of sorption on the chloride ion penetration decreases. By the way, the cyclic humidity increases the effect of sorption on the chloride ion penetration at early ages, and the quantity of chloride ion around steel at later ages. Therefore, the in-situ analysis of chloride ion penetration for marine concrete structures must be performed considering the cyclic humidity condition and the long term sorption.

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An Electrochemical Study on the Effect of Salt Affecting to Corrosion Behavior of Concrete Reinforced Steel in Natural Sea Water (천연해수에 침지된 콘크리트 내부의 철근부식거동에 미치는 염분의 영향에 관한 전기화학적 연구)

  • 김광근;류보현;점성종;김기준;문경만
    • Journal of Ocean Engineering and Technology
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    • v.14 no.4
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    • pp.23-29
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    • 2000
  • When the concrete structures were being made with sand containing chloride ion it was knows that corrosion rate of reinforced steel embedded in concrete with chloride ion was higher than that of concrete with on chloride ion. In this study, the operation of Friedel salts affecting the corrosion behavior of reinforced steel embedded in cement mortar was investigated with electrochemical view. Corrosion potential of reinforced steel embedded in cement mortar with sand containing chloride ion was shifted noble direction than that of cement mortar with no chloride ion after immersed 5 month in natural sea water and also corrosion current density decreased with shifting corrosion potential to noble direction. However Friedel salts appeared from surface to 2.5cm of inside direction of mortar specimen, which is located at 11.5$\circ$(2$\theta$) in XRD analysis and the amount of Ca(OH)2 by SEM photograph in cement mortar with chloride ion was larger than that of cement mortar with mo chloride ion. Eventually it is suggested that Friedel salts was resulted from chloride ion and it acted as the corrosion inhibitor.

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Experimental Study of Chloride Binding in Concrete with Mneral Amixtures (혼화재를 혼입한 콘크리트의 염화물 고정화에 관한 실험적 연구)

  • 박정준;고경택;김도겸;김성욱;하진규
    • Proceedings of the Korea Concrete Institute Conference
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    • 2001.11a
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    • pp.787-792
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    • 2001
  • The chloride ion penetrating into concrete is classified as the fixed chloride ion being bound in reacting to cement hydrate and the free chloride ion having a direct effect on rebar corrosion because being in solution inside porosity of concrete. Therefore, in order to study the diffusion properties of chloride ion, it is needed to evaluate binding chloride ion in concrete. In this study, we tried to give a fundamental information on diffusion of chloride ion in concrete with mineral admixtures through analysis of micro-structure transformations in concrete and effects on binding of chloride ion in cement paste when mixed with fly-ash, blast furnace slag, silica fume etc. which are used to improve durability and permeability of concrete

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Analysis of Chloride Ion Penetraion for Marine Concrete Structure with Cyclic Humidity Environment (건습이 반복되는 환경하의 해양콘크리트 구조물에 대한 염소이온 침투 해석)

  • Han, Sang-Hun
    • Ocean and Polar Research
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    • v.26 no.1
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    • pp.43-50
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    • 2004
  • The diffusion model, which considers diffusion and sorption, is proposed. The FEM program developed on the basis of the diffusion model provides the estimation of chloride concentration according to cyclic humidity and sorption. After the humidity diffusion analysis is carried out, the chloride ion diffusion and sorption analysis are conducted on the basis of the preestimated humidity data in each element. Each element has different analysis variables at different ages and locations. At early ages, the difference between inner and outer relative humidity causes the chloride ion penetration by sorption. As the humidity diffusion reduces the difference with age, the effect of sorption on the chloride ion penetration decreases. By the way, the cyclic humidity increases the effect of sorption on the chloride ion penetration at early ages, and the quantity of chloride ion around steel at later ages. Therefore, the in situ analysis of chloride ion penetration for marine concrete structures must be performed considering the cyclic humidity condition and the long term sorption.

Evaluation of Chloride Ion Binding Capacity of Hardened Portland Cement Paste Containing Hydrotalcite (경화된 하이드로탈사이트 혼입 포틀랜드 시멘트 페이스트의 염소이온 고정능력 평가)

  • Han, Jae-Do;Lee, Yun-Su;Lee, Han-Seung
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2018.05a
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    • pp.27-28
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    • 2018
  • Deterioration of reinforced concrete structures due to salt corrosion is a phenomenon that can be easily seen, and the main reason for deterioration is chloride ion. Therefore, researches are actively conducted to control chlorine ion penetration worldwide. The purpose of this study is to evaluate the chloride ion fixation capacity of Portland cement paste containing Hydrotalcite. For this purpose, cement paste containing 0%, 2.5%, and 5% of Hydrotalcite was sealed and cured for 28 days, and the cured cement paste was crushed. Chloride ion solution was prepared at a concentration of 0.5M using NaCl, and the powdered cement paste was reacted for a specific time in aqueous chloride ion solution. After the reaction, the concentration of the chloride ion aqueous solution was measured using a silver nitrate potentiometric titrator, and the reacted cement paste was analyzed using XRD and FT-IR.

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Research on chloride ion diffusivity of concrete subjected to CO2 environment

  • Zhang, Shiping;Zhao, Binghua
    • Computers and Concrete
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    • v.10 no.3
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    • pp.219-229
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    • 2012
  • Carbonation is a widespread degradation of concrete and may be coupled with more severe degradations. An experimental investigation was carried out to study the effect of carbonation on chloride ion diffusion of concrete. The characteristic of concrete after carbonation was measured, such as carbonation depth, strength and pore structure. Results indicated that carbonation depth has a good linear relation with square root of carbonate time, and carbonation can improve compressive strength, but lower flexural strength. Results about pore structure of concrete before and after carbonation have shown that carbonation could cause a redistribution of the pore sizes and increase the proportion of small pores. It also can decrease porosities, most probable pore size and average pore diameters. Chloride ion diffusion of concrete after carbonation was studied through natural diffusion method and steady state migration testing method respectively. It is supposed that the chloride ion concentration of carbonation region is higher than that of the sound region because of the separation of fixed salts, and chloride ion diffusion coefficient was increased due to carbonation action evidently.

Evaluation of Chloride Ion Penetration Resistance of Coal Gasification Slag Replaced Concrete (석탄가스화 용융 슬래그 치환 콘크리트의 염화이온 침투 저항성 검토)

  • Cho, Hyeon-Seo;Kim, Min-Hyouck;Lee, Gun-Cheol
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2019.11a
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    • pp.166-167
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    • 2019
  • In this study, to test the performance of concrete used as a concrete admixture as a recycling method of CGS, gypsum was mixed and the chloride ion penetration resistance test of CGS and BFS substituted concrete was conducted. As a result, it was found that without gypsum type test specimen, the CGS sustituted test specimens had lower chloride ion penetration resistance than the BFS substituted specimens. When gypsum was added, it was confirmed that the chloride ion penetration resistance was poor regardless of the type of admixture. In addition, it was confirmed that both admixtures were less resistant to chloride ion penetration than OPC, regardless of the presence of gypsum. However, considering the uneven quality variation of coal, which greatly affects the quality of CGS, further research is needed.

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Evaluation of Chloride Ion Penetration Characteristics for Concrete Structures at Coastal Area (해안지역 콘크리트 구조물의 염소이온침투특성 평가)

  • Han, Sang-Hun;Yi, Jin-Hak;Park, Woo-Sun
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.23 no.1
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    • pp.11-17
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    • 2011
  • A major source of durability problems in concrete structures is the corrosion of steel by the damage of passivity layer around steel bars. As chloride ion penetration is major cause of the destruction of passivity layer, evaluation of depth and concentration profile of chloride ion is the essential factor for the service-life estimation of concrete structure. To estimate chloride ion penetration characteristics, this paper on the basis of in-situ experimental data investigated the depth and concentration profile of chloride ion penetration. The core specimens are obtained at air-zone, splash zone, and tidal zone in Wando, Masan, Incheon, Gwangyang, and donghae harbors. Colorimentric method measured the chloride ion penetration depth and ASTM C 114 evaluated the concentration profile of chloride ion. Based on experimental data, the influence of harbor location and exposure condition on chloride ion penetration is evaluated.

Influence of Cement Type on the Diffusion Characteristics of Chloride Ion in Concrete (콘크리트의 염소이온 확산특성에 미치는 시멘트 종류의 영향)

  • Park, Jae-Im;Bae, Su-Ho;Lee, Kwang-Myong;Kim, Jee-Sang;Cha, Soo-Won
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.11a
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    • pp.573-576
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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-binder(W/B) ratio, age, cement type and constituents, chloride ion concentration of given environment, wet and dry conditions, etc. In this paper the influence of cement type on the diffusion characteristics of chloride ion in concrete was investigated through the chloride ion diffusion test. For this purpose, the diffusion characteristics in concrete with cement type such as ordinary portland cement(OPC), binary blended cement(BBC), and ternary blended cement(TBC) were estimated for the concrete with W/B ratios of 32% and 38%, respectively. It was observed from the test that the difussion characteristics of BBC containing OPC and ground granulated blast-furnace slag was found to be most excellent of the cement type used in this study.

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Chloride Ion Penetration Resistance of Mortars including Expanded Vermiculite Immobilizing Bacteria (박테리아 흡착 팽창질석을 혼입한 모르타르의 염소이온 침투 저항성)

  • Jung, Seung-Bae;Yang, Keun-Hyeok
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2017.11a
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    • pp.151-152
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    • 2017
  • This tests examined the effectiveness of bacteria slime on the chloride ion penetration resistance of cement mortar. Test results exhibited that the chloride ion penetration depth of mortars including 5% expanded vermiculite immobilizing bacteria was 17% smaller than that of the control mortar without expanded vermiculite.

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