• Title/Summary/Keyword: 염화물이온 침투 저항성

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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.

Characteristics of Chloride Penetration in Cracked Flexural Member using Durable Materials (고내구성 재료를 사용한 휨부재의 균열에 따른 염화물 침투 특성)

  • Jin, Sang-Ho;Kim, Il-Sun;Kim, Myung-Yu;Yang, Eun-Ik;Yi, Seong-Tae
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.11a
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    • pp.401-404
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    • 2008
  • Crack is a penetration path of harmful material such as chloride ion, and causes a serious deterioration in durability. So, the characteristics of chloride penetration are investigated for the cracked flexural concrete members using high-durable materials. For these, the flexural crack of beam specimen is introduced by transverse loading. And, Rapid Chloride Penetration Test (RCPT) and Long-term chloride penetration test are carried out to compare the chloride penetration depth. From test results when crack is happened, the chloride penetration resistance of the durable member was superior than that of the normal member. Blast furnace slag concrete member has a excellent chloride penetration resistance in long-term chloride penetration test.

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A Study on Resistance of Chloride Ion Penetration in Ground Granulated Blast-Furnace Slag Concrete (고로슬래그 미분말 콘크리트의 염화물 침투 저항성에 관한 연구)

  • Song, Ha-Won;Kwon, Seung-Jun;Lee, Suk-Won;Byun, Keun-Joo
    • Journal of the Korea Concrete Institute
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    • v.15 no.3
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    • pp.400-408
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    • 2003
  • Chloride ion inside concrete destroys the so-called passive film surrounding reinforcing bars inside concrete so that the so-called salt attack accelerates corrosion which is the most critical factor for durability as well as structural safety of reinforced concrete structures. Recently, as a solution of the salt attack, the ground granulated blast-furnace slag(GGBFS) have been used as binder or blended cement more extensively. In this paper, characteristics of chloride ion diffusion for the GGBFS concrete, which is known to possess better resistance to damage due to the chloride ion penetration than ordinary portland cement(OPC) concrete possesses, are analyzed and a chloride ion diffusion model for the GGBFS concrete is proposed by modifying an existing diffusion model for the OPC concrete. The proposed model is verified by comparing diffusion analysis results using the model accelerated chloride penetration test results for concrete specimens as well as field test results for an RC bridge pier. Then, an optimal resistance condition to chloride penetration for the GGBFS concrete is obtained according to degrees of fineness and replacement ratios of the GGBFS concrete. The result shows that the GGBFS concrete has better resistance to chloride ion penetration than OPC concrete has and the resistance is more affected by the replacement ratio than the degree of fineness of the GGBFS.

A Study on Prediction Model of Chloride ion Permeation of Cement Mortar by Steel Powder (염해환경에서의 염화물이온 침투 예측에 관한 연구)

  • Kim, Jeong-Jin;Park, Soon-Jeon;Ko, Joo-Hwan;Han, Cheon-Goo
    • Proceedings of the Korea Concrete Institute Conference
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    • 2008.04a
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    • pp.513-516
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    • 2008
  • In this study the prediction model of Chloride Ion progress rate of concrete using steel powder as an addition is developed, in which the reduction of not only the diffusion rate of $Cl^-$ but also the corrosion rate by replenishment of pore by corrosion products. The model is based on the diffusions of $Cl^-$ and its reaction with $Fe^{2+}$, in chloride attack progression region. The model can also explain the characteristics of chloride ion permeation resistance of concrete that the matrix is densified due to corrosion products. The prediction by the model agreed well the experimental data in which the concrete using steel powder, and it showed the lower rate in long-term age to Chloride Ion progress rate than the concrete without steel powder. Consequently the model can predict Chloride Ion progress rate of concrete exposed in the atmosphere regardless of the water-to-cement raito, the amount of the content of steel powder, etc.

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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.

Effect of Initial Flexural Crack on Resistance to Chloride Penetration into Reinforced Concrete Members (초기 휨균열이 철근콘크리트 부재의 염화물침투저항성에 미치는 영향)

  • Yang, Eun Ik;Jin, Sang Ho;Kim, Myung Yu;Choi, Yoon Suk;Han, Sang Hun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.15 no.2
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    • pp.79-87
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    • 2011
  • In this study, the chloride penetration tests were performed for the initially cracked reinforced concrete members. The chloride diffusion characteristics and the critical crack width are compared, and the properties of self-healing are investigated. According to the test results, the chloride penetration resistance was greatly reduced as the surface crack width increased. When the mineral admixtures are added, the chloride penetration resistance of uncracked specimens were effectively increased, however, in case of the blast furnace slag and fly ash, the cracked specimens showed the more reduced resistance than OPC case, inversely. Also, the critical width was $29{\mu}m$, on average, for immersion test. The crack width with $4{\sim}15{\mu}m$ was restored by self-healing, The parts restored by self-healing were seemed to be visually restored, however, the chloride penetration resistance was not restored, perfectly.

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 s.89
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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

The Diffusion Property of Chloride Ion into Concrete by Electrically Accelerated Method (전기적인 촉진시험에 의한 콘크리트의 염화물이온 확산특성)

  • Bae, Ju-Seong;Park, Gook-Joon
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.14 no.3
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    • pp.138-143
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    • 2010
  • Recently, as many big marine concrete structures increase, it is necessary that chloride ion diffusion coefficient of concrete shall be evaluated but it will take a long time to evaluate chloride ion diffusion coefficient of concrete. Accordingly, many test methods are suggested to evaluate chloride ion diffusion coefficient in a short period time by the promotion in electro chemical ways but the systematic study for this is insufficient. Therefore, this study evaluates chloride ion penetration and diffusion features by three representative electric promotion tests targeting for three different cements whose ingredients are different and analyzes the correlationship between them. As a result, diffusion features of chloride ion varied according to the cement ingredients and three ingredients cement in which blast furnace slag powder and fly ash are mixed in constant ratio, which shows the most excellent cement diffusion properties. For diffusion properties of chloride ion, the correlationship between test methods are good.

Compressive Strength and Chloride Ion Penetration Resistance of SHCC Coated by PDMS-based Penetrating Water Repellency (PDMS 흡수방지재를 적용한 SHCC의 압축강도 및 염화물이온 침투저항성)

  • Lee, Jun-Hee;Hyun, Jung-Hwan;Park, Su-Hyun;Kim, Yun-Yong
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.22 no.6
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    • pp.16-23
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    • 2018
  • In this study, Polydimethylsiloxane (PDMS) was applied to Strain Hardening Cement Composites (SHCC) for penetrating water repellency. The penetration depth of PDMS, strength of SHCC, and chloride ion penetration resistance of SHCC were investigated. As a result of measuring penetration depth of PDMS when applying different application method, it was confirmed that all methods satisfied the requirements of KS F 4930. Although the immersion method showed the largest penetration depth, the spray method was considered to be more appropriate considering the ease of field application. Compressive strength tests showed that the penetration depth of PDMS decreased as the compressive strength of SHCC increased. The compressive strength of M4-A and M4-B specimens with large PDMS penetration depths decreased by 9.6% and 8.0%, respectively, compared with those of M4 specimens produced without PDMS. Compressive strengths of the M1-A and M1-B specimens with small PDMS penetration depths were reduced by 4% and 2.2%, respectively, compared with the M1 specimen. As a result, it can be seen that the strength reduction rate of SHCC increases as the penetration depth of PDMS increases. The chlorine ion penetration tests showed that the chlorine ion penetration resistance increases with the penetration depth of PDMS.

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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