• Title, Summary, Keyword: 염화물 침투깊이

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Chloride Ion Penetration Resistance of Slag-replaced Concrete and Cementless Slag Concrete by Marine Environmental Exposure (해양환경 폭로에 의한 슬래그 치환 콘크리트 및 슬래그 콘크리트의 염화물 이온 침투 저항성)

  • Lee, Bo-Kyeong;Kim, Gyu-Yong;Kim, Gyeong-Tae;Shin, Kyoung-Su;Nam, Jeong-Soo
    • Journal of the Korea Concrete Institute
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    • v.29 no.3
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    • pp.299-306
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    • 2017
  • In this research, it was examined chloride ion penetration resistance of slag-replaced concrete and cementless slag concrete considering marine environmental exposure conditions of splash zone, tidal zone and immersion zone. In the design strength of grade 24 MPa, the specimens were tested to determine their compressive strength, scanning electron microscopy images and chloride migration coefficient. Further, chloride ion penetration depth and carbonation depth of specimens exposed to marine environment were measured. Experimental results confirm that chloride migration coefficient of specimens tended to decrease with increasing the replacement ratio of ground granulated blast-furnace slag in accelerated laboratory test. In addition, the specimens exposed to the tidal zone were found to be the greatest chloride ion penetration depth compared to splash zone and immersion zone. On the other hand, the chloride ion penetration depth of the specimens exposed to splash zone tended to increase with increasing the replacement ratio of ground granulated blast-furnace slag in contrast with the results for the tidal zone and immersion zone.

Resistance In Chloride ion Penetration and Pore Structure of Concrete Containing Pozzolanic Admixtures (포졸란재 함유 콘크리트의 세공구조와 염화물이온 침투 저항성)

  • 소양섭;소형석
    • Journal of the Korea Concrete Institute
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    • v.14 no.1
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    • pp.100-109
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    • 2002
  • Significant damage to concrete results from the intrusion of corrosive solutions, for example, dissolved chlorides corrode reinforcing steel and cause spatting. Effectively blocks the penetration of these solutions will eliminate or greatly reduce this damage and lead to increased durability. This study is to investigate the effects of pozzolanic admixtures, fly ash and silica fume, and a blast furnace slag on the chloride ion penetration of concretes. The main experimental variables wore the water-cementitious material ratios, the types and amount of admixtures, and the curing time. And it is tested for the porosity and pore size distributions of cement paste, chloride ion permeability based on electrical conductance, and 180-day ponding test for chloride intrusion. The results show that the resistance of concrete to the penetration of chloride ions increases as the w/c was decreased, and the increasing of curing time. Also, concrete with pozzolans exhibited higher resistance to chloride ion penetration than the plain concrete. The significant reduction in chloride ion permeability(charge passed) of concrete with pozzolans due to formation of a discontinuous macro-pore system which inhibits flow. It is shown that there is a relationship between chloride ion permeability and depth of chloride ion penetration of concrete, based on the pore structure (porosity and pore size distributions) of cement paste.

Field Investigation of Chloride Penetration and Evaluation of Corrosion Characteristics for Deicer (염화물 침투 현장조사 및 제설제에 따른 부식특성)

  • Yang, Eun-Ik;Kim, Myung-Yu;Park, Hae-Geun
    • Journal of Korean Society of Hazard Mitigation
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    • v.8 no.6
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    • pp.47-52
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    • 2008
  • Deicer has been generally used for prevention of a road freezing in winter, and the usage amount is increasing every year. However, deicer may induce the decrease of bond strength, surface scaling, and environmental pollution. In this study, the field test was performed to investigate the deterioration of concrete road structures used for 17 years. And, the corrosion resistance characteristics were compared for the existing deicer and eco-friendly deicer. According to the field test results, the penetration depth of limit chloride amount was about 40mm, and the average concentration of chloride was $3.45kg/m^3$ at the surface of structures. On the contrary, the carbonation depth was slight. The penetration depth of eco-friendly deicer was less than the existing deicer, and the corrosion resistance of eco-friendly deicer was higher.

Experimental Study on the Time-dependent Property of Chloride Diffusivity of Concrete (콘크리트의 염소이온 확산계수의 시간의존성에 대한 실험적 고찰)

  • Choi, Doo Sun;Choi, Jae Jin
    • Journal of The Korean Society of Civil Engineers
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    • v.29 no.4A
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    • pp.365-371
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    • 2009
  • It is time-consuming to estimate chloride diffusivity of concrete by concentration difference test. For the reason chloride diffusivity of concrete is mainly tested by electrically accelerated method, which is accelerating the movement of chloride ion by potential difference. In this study, portland cement concrete and concrete containing with ground granulated blast-furnace slag (40 and 60% of cement by weight) with water-cementitious material ratio 40, 45, 50 and 60% were manufactured. To compare with chloride diffusivity calculated from the electrically accelerated test and immersed test in artifical seawater, chloride diffusivity tests were conducted. From the results of regression analysis, regression equation between accelerated chloride diffusivity and immersed chloride diffusivity was linear function. And the determinant coefficient was 0.96 for linear equation.

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Strength and Durability of Polymer-Modified Mortars Using Ground Granulated Blast-Furnace Slag (고로슬래그 미분말을 혼입한 폴리머 시멘트 모르타르의 강도 및 내구성)

  • 주명기;김남길;연규석
    • Journal of the Korea Concrete Institute
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    • v.14 no.2
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    • pp.164-170
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    • 2002
  • Effect of the polymer-binder ratio and slag content on the properties of combined wet/dry-cured polymer-modified mortars using granulated blast-furnace slag are examined. Results shows that the flexural and compressive strengths of polymer-modified mortar using the slag tend to increase with increasing slag content, and reaches a maximum at a slag content of 40 %, and is inclined to increase with increasing polymer-binder ratio. Water absorption, carbonation depth and chloride ion penetration depth tend to decrease with increasing polymer-binder ratio and slag content. Accordingly, the incorporation of slag into polymer-modified mortars at a slag content of 40% is recommended for a combined wet/dry curing regardless of the types of polymer.

A Study of the Effect of Mineral Admixtures on the Chloride Diffusion of the Concrete Immersed in Chloride Solution (무기질 혼화재가 염수침지한 콘크리트의 염화물 확산에 미치는 영향에 관한 연구)

  • Kim Dong-Seok;Yoo Jae-Kang;Park Sang-Joon;Won Cheol;Kim Young-Jin
    • Journal of the Korea Concrete Institute
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    • v.17 no.5
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    • pp.679-686
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    • 2005
  • The corrosion of reinforcement induced by chloride ingress is the main deterioration cause of coastal reinforced concrete structures. In this paper, an experimental study was executed to investigate the effect of the kinds and replacement ratios of mineral admixtures (fly-ash, ground granulated blast-furnace slag silica fume and meta-kaolin), W/B and curing time on chloride diffusion of concrete by long-time immersion test in chloride solution. According to the result, the use of mineral admixtures was effective in improving the resistant to chloride ingress. The chloride penetration depth and diffusion coefficient were decreased as replacement ratios of mineral admixture were increased. The kind and replacement ratio of the mineral admixture are more important than the W/B in reducing the chloride diffusion of concrete. Chloride binding capacity of mineral admixture, which was sequenced in the order of MK

Influence of Hydrostatic Pressure on Chloride Ion Penetration of Marine Concrete (정수압이 해양콘크리트의 염화물이온 침투에 미치는 영향)

  • Kim, Gyeong-Tae;Kim, Gyu-Yong;Nam, Jeong-Soo;Lee, Bo-Kyeong;Lim, Chang-Hyuck
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.23 no.1
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    • pp.78-84
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    • 2019
  • The Marine concrete that located at immersion zone receives an hydrostatic pressure of 1 atm as depth of the water increased by 10 m. And it could accelerate chloride ion penetration. In this study, to evaluate the influence of hydrostatic pressure on chloride ion penetration, concrete mixed by ordinary Portland cement and Portland blast-furnace slag cement was exposed to 1 and 6 atm and substitute ocean water. As a result, the surface chloride ion concentration of the concrete under 6 atm of hydrostatic pressure increased rapidly and the water-soluble chloride ion contents was increased by depth. In addition, the concrete under 6 atm of hydrostatic pressure showed the increase of capillary pores corresponding to 5~100 nm.

Applicability of Colormetric Method for Estimation of Chloride Penetration in Concrete Structures (콘크리트 구조물의 염화물 침투 특성 파악을 위한 변색법의 적용성)

  • Yang Eun-Ik;Kim Myung-Yu;Leem Young-Moon;Park Hae-Geun
    • Journal of the Korea Concrete Institute
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    • v.17 no.6
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    • pp.931-938
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    • 2005
  • When concrete structures are exposed under marine condition for a long time, the steel in concrete is corroded due to the ingression of chlorides in the seawater. Because the damages of corrosion resulting from the chloride ion are very serious, many researches have been performed. Silver nitrate colormetric method that can measure easily penetration depth of chloride ion has been executed, recent)y. However, characteristics of silver nitrate colormetric method were not fully examined. Therefore, the objective of this paper Is to study the applicability of colormetric method. For the purpose of this, effect factors and reaction mechanism of colormetric method were investigated, and the colormetric method is applied for marine concrete structures. According to the results of silver nitrate colored method, two reactions such as white reaction of AgCl and brown reaction of AgOH were shown when $AgNO_3$ was sprayed in splited section. And velocity constant ratio(K) of two reactions appeared that white reaction, AgCl reacts with the fast speed by 3240. When the colormetric method was applied in concrete, it is reasonable that $AgNO_3$ solution more than 0.05N concentration was sprayed. It is confirmed that the colormetric method is useful tool for estimating the chloride of concrete structures in situ. The average chloride amount of colored parts indicates $0.9kg/m^3$ per concrete unit weight.

The Estimation of Surface Chloride Content and Durability of the Marine Concrete Bridges in South Coast (남해안 해상 콘크리트 교량의 표면염화물이온농도 및 내구성 평가)

  • Jung, Dae-Jin;Choi, Ik-Chang
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.20 no.6
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    • pp.730-737
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    • 2014
  • In this study, chloride content of marine concrete bridge at the south coast in 5~34years was calculated based on the measured data and the validity of the proposed value was evaluated. Also, correlation of existence of salt injury prevention coating, chloride content, carbonation depth and the compressive strength of marine concrete bridges were derived and relationship of the four was evaluated. According to the research results, surface chloride content value in the tidal zone proposed form KCI 2009 and value in the splash zone and atmospheric zone proposed form Cheong et al.(2005) was the most valid. Also, salt injury prevention coating of marine concrete bridges had the outstanding effect of preventing chloride content penetration, carbonation depth and reduction in the compressive strength. Compressive strength of concrete was reduced by the increase of carbonation depth and chloride content.

Durability of High-fluidity Polymer-Modified Mortar Using Redispersible Polymer Powder (재유화형 분말수지 혼입 고유동 폴리머 시멘트 모르타르의 내구성)

  • Joo Myung-Ki;Lee Youn-Su;Youn Do-Yong;Jung In-Su
    • Journal of the Korea Concrete Institute
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    • v.17 no.5
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    • pp.703-708
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    • 2005
  • The effects of polymer-cement ratio and antifoamer content on the setting time and durability of high-fluidity polymer-modified mortars using redispersible polymer powder are examined. As the result, the setting time of the polymer-modified mortars using redispersible polymer powder tends to be delayed with increasing polymer-cement ratio, regardless of the antifoamer content. The water absorption, chloride ion penetration depth and carbonation depth of the high-fluidity polymer-modified mortars using redispersible polymer powder decrease with increasing polymer-cement ratio and antifoamer content. The resistance of freezing and thawing and chemicals improvement is attributed to the improved bond between cement hydrates and aggregates because of the incorporation of redispersible polymer powder