• Title/Summary/Keyword: chloride content

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Application of Electrochemical Accelerated Corrosion Technique to Detection of Reinforcing Corrosion in Concrete (전기화학적 부식촉진 기법을 이용한 철근 콘크리트 부식의 영향평가)

  • 이수열;이재봉;정영수
    • Proceedings of the Korea Concrete Institute Conference
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    • 1999.10a
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    • pp.675-678
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    • 1999
  • Rebar corrosion in concrete containing both chloride ions and calcium nitrite inhibitors were investigated by the various electrochemical methods. Rebar corrosion was accelerated by applying the impressed current to the rebar in concrete. Effect of chloride content and inhibitors on rebar corrosion were evaluated. Accelerated corrosion technique is the method to measure the time to the initiation of cracks of reinforced concretes, by applying constant voltage between rebar and the stainless steel cathedes. The increase of concentration of chloride ions in concrete result in the increase in anodic currents and the reduction of time to crack. However addition of inhibitors did not improve corrosion resistance of rebar in concrete. Rebar corrosion in concrete with chloride ions and inhibitors was also analyzed by the immersed tests though the mesurement of corrosion potentials.

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Study on the Properties of Steel Corrosion in Concrete (콘크리트 중의 철근 부식특성에 관한 연구)

  • Yang, Seung-Kyu;Um, Tai-Sun;Lee, Jong-Ryul;Yamada, Kazuo;Kono, Katsuya
    • Proceedings of the Korea Concrete Institute Conference
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    • 2006.05b
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    • pp.493-496
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    • 2006
  • Steel corrosion in concrete is aggravated with the increase of chloride content in concrete. So, there are regulations in the total amount of chloride ions in concrete in Korea and Japan. The purpose of this paper is to propose a resonable method to regulate the amount of chlorides in concrete. In this study, the experimental results showed that it is rather reasonable to regulate the amount of chloride ions in cement than the total amount of the chloride ions in concrete.

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Effects of Mepiquat Chloride and Trinexapac-Ethyl on Oil Composition, Seed Yield and Endogenous Gibberellins in Flax

  • Kim, Sang-Kuk;Lee, Hee-Dong;Choi, Hong-Jib
    • Korean Journal of Plant Resources
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    • v.24 no.6
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    • pp.696-701
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    • 2011
  • The aim of this field experiment was to investigate the possible effects of mepiquat chloride (TE) and trinexapac-ethyl (MC) on oil composition, seed yield and endogenous gibberellins content of flax cultivar. Foliar application of plant growth retardants mepiquat chloride (0.897, 1.794 and 2.691 kg a.i. $ha^{-1}$) and trinexapac-ethyl (0.756, 1.512 and 2.668 kg a.i. $ha^{-1}$) had significantly increased seeds ripening rate and seed yield. In contrast, plant height was decreased by foliar application of MC and TE. The application of MC significantly increased seed oil yield (730 kg $ha^{-1}$ by 27.0%) compared to the control. Seed and oil yield, and unsaturated fatty acids (oleic acid, linoleic acid and linolenic acid) were increased by foliar application of MC.

Effects of Lime Compounds on the Reduction of Ammonia Gas Formation and Nitrogen Loss During the Formation of Poultry Manure-Sawdust (가축분에 몇가지 석회 화합물 처리에 의한 질소손실 경감과 $NH_3$ 가스 발생 감소에 미치는 영향)

  • 박창규;양장석;조광래;원선이
    • Korean Journal of Organic Agriculture
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    • v.8 no.2
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    • pp.89-96
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    • 2000
  • To reduce loss of nitrogen and generation of ammonia gas during composting, poultry manure and sawdust were mixed at the equivalent ratio and calcium chloride, fused superphosphate and vermiculite were added. Ammonia and sulfurous gas during composting, and NH4-N and NO3-N contents of composts were periodically measured. With the treatments of 0.5∼3% calcium chloride and 3% fused superphosphate, ammonia and sulfurous gas during composting significantly decreased, and especially generation of gases sharply reduced and a increase of calcium chlorde. Extractable NH4-N content in composts treasted with calcium chloride and fused superphosphate were high but extractable NO3-N markedly decreased. In conclusion, the results suggest that it is necessary the additon of 1∼3% calcium chloride or 3% fused superphosphate to reduce loss of nirogen and generation of offensive odor during composting of poultry manure mixed with sawdust.

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Chloride Ion Penetration Properties of Normal Strength High-Fluidity Concrete Using Lime Stone Powder (석회석 미분말을 활용한 보통강도 고유동 콘크리트의 염소이온 침투특성)

  • Choi, Yun-Wang;Moon, Jae-Heum;Eom, Joo-Han
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.14 no.4
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    • pp.160-168
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    • 2010
  • Recently, there are a lot of researches related to the high-fluidity concrete (HFC) with field applications. However, most applications and studies are with concretes with high strength level so there are little studies about durability evaluations such as chloride ion penetration properties with normal strength concrete. Therefore, to evaluate the durability of HFC with normal strength level, this study performed the chloride ion penetration test and observed the micro pore distribution with normal strength HFC which contains limestone powder. Experimental results showed that most micro-pores have diameters between 0.005 to 0.05 ${\mu}m$ with HFCs using limestone powder and the average diameter becomes larger with the increase of limestone powder content. Also, it was shown that, with the increase of the limestone powder content, penetration depth and diffusion coefficient of chloride ion increased and diffusion coefficient had good relationships with compressive strength and average pore diameter with the coefficient of determination over 0.90.

A Compound Deterioration Assessment of Concrete Subjected In Freezing-Thawing and Chloride Attack (동결융해와 염해의 복합작용을 받는 콘크리트의 내구성능 저하 평가)

  • 고경택;김도겸;김성욱;조명석;송영철
    • Journal of the Korea Concrete Institute
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    • v.13 no.4
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    • pp.397-405
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    • 2001
  • In clod weather regions, a strong seasonal wind brings sea salts to the land. In addition to it, recently, the spreading amount of deicing salts has increased numerously for purpose of removing snow and ice. Thus the salts environment around concrete structures becomes so severe that various damages of concrete due to applied salts will be brought up. Much of countries such as America, Europe etc. is carried out study for effects of deicing salts on concrete. However, there are not test methods for deterioration of concrete subjected to both freezing-thawing and chloride in Korea. In this study, we carried out test for the compound deterioration subjected to both freezing-thawing and chloride attack, to investigate the effects of sodium chloride on the deterioration of concrete. The test was performed to investigate the effects of cement type, strength and air content on the scaling deterioration of concrete. As a result, the scaling deterioration was accelerated in the presence of salts. And the resistance to scaling was strongly influenced by the type of cement, the strength and air content of concrete.

A Study on Corrosion Resistance of CA2-Mixed Paste (CA2 혼입 페이스트의 부식저항성에 관한 연구)

  • Kim, Jae-Don;Jang, Il-Young
    • Journal of the Korean Society of Industry Convergence
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    • v.25 no.2_2
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    • pp.289-297
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    • 2022
  • Deterioration in durability of structures due to the steel corrosion is difficult to determine whether or not corrosion is initiated and how much propagated, and moreover, repair and maintenance are not easy to deal with. Therefore, preventive treatments can be the best option to avoid the deterioration. Various methods for preventing corrosion of steel, such as electrochemical treatments, anti-corrosion agents and steel surface coatings, are being developed, but economic and environmental aspects make it difficult to apply them to in-situ field. Thus, the purpose of this study was to improve corrosion resistance by using CA-based clinker that are relatively simple and expected to be economically profitable Existing CA-based clinkers had problems such as flash setting and low strength development during the initial hydration process, but in order to solve this problem, CA clinker with low initial reactivity were used as binder in this study. The cement paste used in the experiments was replaced with CA2 clinker for 0%, 10%, 20%, and 30% in OPC. And the mixture used in the chloride binding test for the extraction of water-soluble chloride was intermixed with Cl- 0.5%, 1%, 2%, and 3% by weight of binder content. To evaluate characteristic of hydration heat evolution, calorimetry analysis was performed and simultaneously chloride binding capacity and acid neutralization capacity were carried out. The identification of hydration products with curing ages was verified by X-ray diffraction analysis. The free chloride extraction test showed that the chlorine ion holding ability improved in order OC 10 > OC 30 > OC 20 > OC 0 and the pH drop resistance test showed that the resistance capability in pH 12 was OC 0 > OA 10 > OA 20 > OA 30. The XRD analyses showed that AFm phase, which can affect the ability to hold chlorine ions, tended to increase when CA2 was mixed, and that in pH12 the content of calcium hydroxide (Ca(OH)2), which indicates pH-low resistance, decreased as CA2 was mixed

Resistance to Corrosion of Reinforcing Steel and Critical Chloride Content of High Volume Fly Ash Concrete (하이볼륨 플라이애시 콘크리트의 철근부식 저항성 및 임계 염화물량)

  • Lee, Hyun-Jin;Bae, Su-Ho;Jung, Sang-Hwa
    • Journal of the Korean Recycled Construction Resources Institute
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    • v.5 no.4
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    • pp.375-381
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    • 2017
  • Recently, due to the increasing of interest about the eco-friendly concrete, it is being increased to use concretes containing by-products of industry such as fly ash, ground granulated blast furnace slag, silica fume, and etc. Especially, these are well known for improving the resistance to reinforcement corrosion in concrete and decreasing chloride ion penetration. The purpose of this experimental research is to evaluate the resistance to corrosion of reinforcement and critical chloride content of high volume fly ash concrete(HVFAC) which is replaced with fly ash for approximately 50% cement content. For this purpose, corrosion monitoring of reinforcement by half cell potential method was carried out for the cylindrical test specimens that the upper of reinforcement in concrete was exposed to detect the time of corrosion initiation for reinforcement. It was observed from the test result that the the time of corrosion initiation for reinforcement of HVFAC by the accelerated corrosion tests increased 1.2~1.3 times than plain concrete and the critical chloride contents of plain concrete and HVFAC were found to range $0.80{\sim}1.20kg/m^3$, $0.89{\sim}1.60kg/m^3$, respectively.

The Effect of Entrained Air Contents on the Properties of Freeze-thaw Deterioration and Chloride Migration in Marine Concrete (연행 공기량이 해양콘크리트의 동결융해 및 염화물 확산특성에 미치는 영향)

  • Park, Sang-Joon
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.12 no.5
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    • pp.161-168
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    • 2008
  • The freeze-thaw deterioration and chloride attack, which are the typical degradation factors for durability of marine concrete, are significantly affected by pore structures in terms of penetration and diffusion. These pore structures of concrete are closely related to the types and amount of AE agent, used to guarantee the resistance of freeze-thaw deterioration, and the elapsed time before concrete pouring. This paper evaluates the durability of concrete based on the results of tests on cylinder specimens and core specimens from mock-up members with different air content of 4~6% and 8~10%, respectively. According to the test results, the air content of hardened concrete is 2.5~5.2% at 7 days and 2.4~5.1% at 28 days. These air contents are about half of the initial values just after the concrete mixing. Judging from the amount of scale after the freeze-thaw test completed, air content of 8~10% is slightly more beneficial against the deterioration of concrete than air content of 4~6%. Meanwhile, the core specimens from mock-up members exhibit somewhat unfavorable freeze-thaw deterioration and chloride migration characteristic compared with the cylinder specimens tested in the laboratory under the same mixing condition, as to show 106% in freeze-thaw test and 160% in chloride diffusion coefficient test, respectively.

A Study on Synthetic Method and Material Characteristics of Magnesium Ammine Chloride as Ammonia Transport Materials for Solid SCR (Solid SCR용 암모니아 저장물질인 Magnesium Ammine Chloride의 합성방법 및 물질특성 연구)

  • Shin, Jong Kook;Yoon, Cheon Seog;Kim, Hongsuk
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.39 no.11
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    • pp.843-851
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    • 2015
  • Among various ammonium salts and metal ammine chlorides used as solid materials for the sources of ammonia with solid SCR for lean NOx reduction, magnesium ammine chloride was taken up for study in this paper because of its ease of handling and safety. Lab-scale synthetic method of magnesium ammine chloride were studied for different durations, temperatures, and pressures with proper ammonia gas charged, as a respect of ammonia gas adsorption rate(%). To understand material characteristics for lab-made magnesium ammine chloride, DA, IC, FT-IR, XRD and SDT analyses were performed using the published data available in literature. From the analytical results, the water content in the lab-made magnesium ammine chloride can be determined. A new test procedure for water removal was proposed, by which the adsorption rate of lab-made sample was found to be approximately 100%.