Journal of the Korea Institute of Building Construction (한국건축시공학회지)

The Korean Institute of Building Construction (한국건축시공학회)
권호 표지
DOI QR코드

DOI QR Code

Variation of Critical Chloride Content of Rebar Embedded in Concrete with Admixture

혼화재 혼입에 따른 콘크리트에 매립된 철근의 부식 임계 염화물량의 변화

  • Park, Jang-Hyun (Department of Architectural Engineering, Hanyang University) ;
  • Lee, Yun-Su (Department of Architectural Engineering, Hanyang University) ;
  • Lee, Han-Seung (Department of Architecture & Architectural Engineering, Hanyang University ERICA)
  • Received : 2019.10.07
  • Accepted : 2019.11.26
  • Published : 2019.12.20
Download PDF
⟨ Previous Next ⟩

Abstract

The critical chloride content of rebar embedded in concrete was experimentally evaluated according to the admixture replacement ratio and admixture type. Four types of reinforced concrete were mixed OPC 100%, OPC 70% + GGBFS 30%, OPC 40% + GGBFS 60%, and OPC 40% + GGBFS 40% + FA 20%. NaCl solution was supplied to the specimens, and the open circuit potential of the embedded rebar was monitored. The specimens determined to initiate corrosion were cut at intervals of 5mm from the NaCl solution supply surface and conducted to chlorine ion profile. Corrosion initiation time of rebar embedded in concrete was delayed as the admixture replacement ratio increased. Looking at the critical chloride content of the types of reinforced concrete, it was highest in OPC 1.46kg/㎥, followed in order by S30 0.98kg/㎥, TBC 0.74kg/㎥, and S60 0.71kg/㎥.

혼화재 혼입에 따른 콘크리트의 철근부식 임계염화물량의 변화를 실험적으로 평가하였다. 콘크리트 배합조건은 OPC 100%, OPC 70% + GGBFS 30%, OPC 40% + GGBFS 60%, OPC 40% + GGBFS 40% + FA 20% 로 구분하여 4가지 배합의 철근 콘크리트 시험체를 제작하였다. 시험체에 NaCl 수용액을 공급하며, 매립된 철근의 자연전위를 모니터링 하였다. 부식이 발생한 것으로 판단된 시험체는 NaCl 수용액 공급면으로부터 5mm간격으로 절단하여 염소이온량 프로파일을 실시하였다. 콘크리트에 매립된 철근의 부식 개시시기는 시멘트를 혼화재로 치환하여 사용하는 경우 지연되는 것을 확인하였다. 하지만 콘크리트에 매립된 철근의 부식임계염화물량은 혼화재 혼입율 증가에 따라 감소하여, OPC 1.46kg/㎥, S30 0.98kg/㎥, TBC 0.74kg/㎥, S60 0.71kg/㎥ 순으로 높게 나타났다.

Keywords

References

  1. Bertolini L, Elsener B, Pedeferri P, Polder R. Corrosion of steel in concrete: Prevention, Diagnosis, Repair. Weinheim: WILEY-VCH; 2003. 392 p.
  2. Wallbank EJ. The performance of concrete in bridges. A survey of 200 highway bridges. London: HMSO; 1989. 96 p.
  3. Skalny J, Mindess S. Materials science of concrete. westerville: American Ceramic Society; 1999. p. 285-313.
  4. Hussain SE. Mechanisms of high durability performance of plain and blended cements [PhD Thesis]. [Dhaharan (Saudi Arabia)]; King Fahd University of Petroleum and Minerals; 1991. 367 p.
  5. Malhotra VM. Concrete technology for a sustainable development in the 21st century. Gjorv OE, Sakai K, editors. London: CRC Press; 1999 Dec. Chapter 19, Role of supplementary cementing materials in reducing greenhouse gas emissions; p. 226-35.
  6. Jung YB, Yang KH, Choi DU. Influence of fly ash on life-cycle environmental impact of concrete. Jounal of Korea Institute of Building Construction. 2014 Dec;14(6):515-22. https://doi.org/10.5345/JKIBC.2014.14.6.515
  7. Flower DJ, Sanjayan JG. Green house gas emissions due to concrete manufacture. The International Journal of Life Cycle Assessment. 2007 Jul;12(5):282-8. https://doi.org/10.1065/lca2007.05.327
  8. Berke NS. Resistance of microsilica concrete to steel corrosion erosion and chemical attack. American Concrete Institute Special Publication. 1989 May;114:861-86.
  9. Hussain SE, Rasheeduzzafar. Corrosion resistance performance of fly ash blended cement concrete. Materials Journal. 1994 May;91(3):264-72.
  10. Thomas M. Chloride thresholds in marine concrete. Cement and Concrete Research. 1996 Apr;26(4):513-9. https://doi.org/10.1016/0008-8846(96)00035-X
  11. Ryou JS, Ann KY. Variation in the chloride threshold level for steel corrosion in concrete arising from different chloride sources. Magazine of Concrete Research. 2008 Apr;60(3):177-87. https://doi.org/10.1680/macr.2008.60.3.177
  12. Yang SK, Kim DS, Um TS, Lee JR, Kono K. Study on the critical threshold chloride content for steel corrosion in concrete with various cement contents. Jounal of the Korea Concrete Institute. 2008 Aug;20(4):415-21. https://doi.org/10.4334/JKCI.2008.20.4.415
  13. Ministry of Land, Infrastructure and Transport (KOREA), Concrete Standard specification. 2016. 358 p.
  14. Jin CK, Kyoung EJ, Jeong JN. A study on the corrosion monitoring of multi-functional sensor for reinforced concrete structures: Part 1. Corrosion Science and Technology. 2012 Dec;11(6):270-4. https://doi.org/10.14773/cst.2012.11.6.270
  15. Parthiban T, Ravi R, Parthiban GT. Potential monitoring system for corrosion of steel in concrete. Advances in Engineering Software. 2006 Jun;37(6):375-81. https://doi.org/10.1016/j.advengsoft.2005.09.004
  16. ASTM Standard C876. Standard test method for half-cell potentials of uncoated reinforcing steel in concrete. American Society for Testing and Materials. 1991.
  17. KS L 5201. Portland Cement. Korean Agency for Technology and Standards. 2016.
  18. KS F 2563. Groung granulated blast-furnace slag for use in concrete. Korean Agency for Technology and Standards. 2009.
  19. KS L 5405. Fly ash. Korean Agency for Technology and Standards. 2018.
  20. Muralidharan S, Sarawathy V, Madhavamayandi A, Thangavel K, Palaniswamy N. Evaluation of embeddable potential sensor for corrosion monitoring in concrete structures. Electrochimica Acta. 2008 Oct;53(24):7248-54. https://doi.org/10.1016/j.electacta.2008.04.078
  21. KS F 2402. Standard test method for concrete slump. Korean Agency for Technology and Standards. 2017.
  22. KS F 2421. Standard test method for air content of fresh concrete bt the pressure method : air receiver method. Korean Agency for Technology and Standards. 2016.
  23. KS F 2403. Standard test method for making and curing concrete specimens. Korean Agency for Technology and Standards. 2014.
  24. KS F 2405. Standard test method for compressive strength of concrete. Korean Agency for Technology and Standards. 2010.
  25. KS F 2713. Standard test method for analysis of chloride in concrete and concrete raw materials. Korean Agency for Technology and Standards. 2017.