한국건축시공학회지 (Journal of the Korea Institute of Building Construction)

  • 제22권6호
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  • Pages.651-662
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  • 2022
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  • 1598-2033(pISSN)
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  • 2233-5706(eISSN)
한국건축시공학회 (The Korean Institute of Building Construction)
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EIS를 활용한 철근 부식에 따른 콘크리트 손상 모니터링

Monitoring of Concrete Deterioration Caused by Steel Corrosion using Electrochemical Impedance Spectroscopy(EIS)

  • Woo, Seong-Yeop (Department of ICT Integrated Ocean Smart Cities Engineering, Dong-A University) ;
  • Kim, Je-Kyoung (National Core Research Center for Disaster-free and Safe Ocean Cities Construction, Dong-A University) ;
  • Yee, Jurng-Jae (ICT integrated Ocean Smart Cities Engineering, Dong-A University) ;
  • Kee, Seong-Hoon (ICT integrated Ocean Smart Cities Engineering, Dong-A University)
  • 투고 : 2022.09.26
  • 심사 : 2022.11.14
  • 발행 : 2022.12.20
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초록

이 연구에서는 전기화학적 임피던스분광법(Electrochemical Impedance Spectroscopy, EIS)을 활용하여 콘크리트 속 철근 부식의 개시, 전파 및 이로 인한 콘크리트의 손상을 관찰하기 위한 실험을 수행하였다. 먼저, 직경 25mm, 높이 70mm 원주형 콘크리트 실험체 중심에 지름 5mm의 탄소강봉을 매입한 실험체를 제작하였다. 실험체에 사용된 콘크리트는 물-시멘트 비 0.4, 0.5, 0.6을 갖는 세 가지 배합을 제작하였다. 촉진부식시험을 수행하여 위하여 철근 콘크리트 실험체는 0.5M NaCl 수용액에 침지한 후 0C, 13C, 65C, 130C의 네 가지 수준의 전하량을 인가하였다. 이 연구에서는 부식촉진 및 이 과정에서 EIS의 주기적 모니터링을 자동화하여 실험의 효율을 향상시켰다. 이 연구의 실험 결과를 통하여 EIS 주요 특성인자를 활용하여 콘크리트 속 철근의 부식상태를 효과적으로 평가할 수 있음을 확인하였다. 전하이동저항(Rc)값은 전하인가량이 0C에서 13C로 증가함에 따라 급격히 감소하여 대략 10kΩcm2 값을 나타내었다. 하지만 부식개시 이후 전하인가량을 13C에서 130C로 증가하였을 때 Rc값의 민감도는 현저히 감소하는 것을 확인하였다. 한편 이중층용량값(Cdl)값은 전하인가량이 0C에서 130C로 증가함에 따라 대략 50×10-6μF/cm2 에서 250×10-6μF/cm2 수준으로 선형비례관계를 보였다. 이러한 결과는 Cdl 모니터링을 통하여 부식물질에 팽창에 따라 유발된 콘크리트 내부 손상의 진전을 효과적으로 평가할 수 있음을 보여준다. 이 연구의 결과는 EIS를 활용하여 콘크리트 속 철근 부식의 확산 및 이에 따른 콘크리트 손상의 실시간 모니터링을 위한 매입형 센서 및 EIS 신호 분석방법의 고도화를 위한 기본 데이터를 제공하는데 의미가 있다.

The electrochemical impedance spectroscopy(EIS) method was used to evaluate the concrete deterioration process related to chloride-induced steel corrosion with various corrosion levels(initiation, rust propagation and acceleration periods). The impressed current technique, with four total current levels of 0C, 13C, 65C and 130C, was used to accelerate steel corrosion in concrete cylinder samples with w/c ratio of 0.4, 0.5, and 0.6, immersed in a 0.5M NaCl solution. A series of EIS measurements was performed to monitor concrete deterioration during the accelerated corrosion test in this study. Some critical parameters of the equivalent circuit were obtained through the EIS analysis. It was observed that the charge transfer resistance(Rc) dropped sharply as the impressed current increased from 0C to 13C, indicating a value of approximately 10kΩcm2. However, the sensitivity of Rc significantly decreased when the impressed current was further increased from 13C to 130C after corrosion of steel had been initiated. Meanwhile, the double-layer capacitance value(Cdl) linearly increased from 50×10-6μF/cm2 to 250×10-6μF/cm2 as the impressed current in creased from 0C to 130C. The results in this study showed that monitoring Cdl is an effective measurement parameter for evaluating the progress of internal concrete damages(de-bonding between steel and concrete, micro-cracks, and surface-breaking cracks) induced by steel corrosion. The findings of this study provide a fundamental basis for developing an embedded sensor and signal interpretation method for monitoring concrete deterioration due to steel corrosion at various corrosion levels.

키워드

과제정보

This work was supported by the Korea Agency for Infrastructure Technology Advancement(KAIA) grant funded by the Ministry of Land, Infrastructure, and Transport(Grant 21CTAP-C163815-01).

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