Journal of the Korean Recycled Construction Resources Institute (한국건설순환자원학회논문집)

Korean Recycled Construction Resources Institute (한국건설순환자원학회)
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Corrosion Behavior and Ultrasonic Velocity in RC Beams with Various Cover Depth

다양한 피복두께를 가진 RC 보의 부식 거동 및 초음파 속도

  • Jin-Won Nam (Department of Civil and Environmental Engineering, Inha Techincal College) ;
  • Hyun-Min Yang (Division of Smart Convergence Engineering, Hanyang University ERICA) ;
  • Seung-Jun Kwon (Department of Civil and Environmental Engineering, Hannam University)
  • 남진원 (인하공업전문대학 건설환경공학과) ;
  • 양현민 (한양대학교 에리카 캠퍼스 스마트융합공학부 지속가능건축융합전공) ;
  • 권성준 (한남대학교 토목환경공학과)
  • Received : 2023.07.05
  • Accepted : 2023.07.28
  • Published : 2023.09.30
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Abstract

With increasing corrosion in RC (Reinforced Concrete) structures, cracks occurred due to corrosion products and bearing load resistance decreased. In this study, corrosion was induced through an accelerated corrosion test (ICM: Impressed Current Method) with 140 hours of duration, and changes in USV (Ultra-Sonic Velocity), flexural failure load, and corrosion weight were evaluated before and after corrosion test. Three levels of cover depth (20 mm, 30 mm, and 40 mm) were considered, and the initial cracking period increased and the rust around steel decreased with increasing cover depth. In addition, the USV linearly decreased with decreasing cover depth and increasing amount of corrosion. In the flexural loading test, the bending capacity decreased by more than 10% due to corrosion, but a clear correlation could not be obtained since the corrosion ratio was small, so that the effect of slip was greater than that of reduced cross-sectional area of steel due to corrosion. As cover depth increased, the produced corrosion amount and USV changed with a clear linear relationship, and the cracking period due to corrosion could be estimated by the gradient of the measured corrosion current.

철근 콘크리트 구조물은 부식이 증가함에 따라 부식생성물로 인한 균열이 발생하고 하중저항 능력이 감소한다. 본 연구에서는 140시간 동안 촉진염해시험(ICM)을 적용하여 부식을 유도하였으며 부식 전후의 초음파속도 변화, 휨파괴 하중, 부식생성물량을 평가하였다. 피복두께를 3수준(20 mm, 30 mm. 40 mm)으로 고려하였는데, 피복두께가 증가할수록 균열발생시기 및 부식생성량이 증가하였다. 또한 초음파 속도는 피복두께의 감소 및 부식생성량의 증가에 따라 뚜렷한 선형관계를 가지고 감소하였다. 휨파괴 하중의 경우 부식에 따라 10 % 이상 휨하중이 감소하였으나, 명확한 상관성을 도출할 수 없었는데, 이는 부식률이 작으므로 철근단면적의 감소 영향보다 슬립에 의한 영향이 크기 때문이다. 피복두께가 증가함에 따라 부식생성량 및 초음파 속도는 뚜렷한 선형관계를 가지고 변화하였으며, 부식으로 인한 균열발생 시간은 평가된 전류의 기울기를 분석하여 추측할 수 있었다.

Keywords

Acknowledgement

본 연구는 한남대학교 연구년(2022)에 대한 연구 결과로 저자는 이에 감사드립니다.

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