Journal of the Korean Recycled Construction Resources Institute (한국건설순환자원학회논문집)

Korean Recycled Construction Resources Institute (한국건설순환자원학회)
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Service Life Variation Considering Increasing Initial Chloride Content and Characteristics of Mix Proportions and Design Parameters

초기 염화물량의 증가와 배합 및 설계 변수 특성을 고려한 콘크리트 내구수명의 변동성

  • Park, Sun-Kyung (Department of Civil and Environment Engineering, Hannam University) ;
  • Kwon, Seung-Jun (Department of Civil and Environment Engineering, Hannam University)
  • 박선경 (한남대학교 건설시스템공학과) ;
  • 권성준 (한남대학교 건설시스템공학과)
  • Received : 2021.05.18
  • Accepted : 2021.09.13
  • Published : 2021.09.30
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Abstract

It is very important for structure designer to understand the service life variation since a wide range of service life is evaluated with changing exposure conditions and design parameters. Recently, for zero-carbon, waste plastic has been used for fuel for clinker production and this yields increase in chloride content in cement. This study is for evaluation of changing service life in the concrete with increasing initial chloride content due to usage of plastic-SRF(Solid Refuse Fuel) considering various exposure conditions and design parameters. For this, 4 levels of initial chloride content were assumed, and the service life was assessed using LIFE 365 program considering various environmental conditions including 3 levels of surface chloride content. As for analysis parameters, critical/initial chloride content, blast furnace slag powder replacement ratio, W/B(Water to Binder) ratio, cover depth, and unit mass for binder are adopted. Service life decreases with increasing initial chloride content and a significant reduction of service life is not evaluated permitting up to 1,000ppm of initial chloride content. With increasing slag replacement ratio, a longer service life can be secured since blast furnace slag powder has the effect of reducing the diffusion of external chloride ions and fixing the free chloride. It is thought that increasing initial chloride content up to European standard is helpful for enhancing sustainability and reducing carbon emission. Though the reduction in service life due to an increase in the initial chloride content is not significant in slag-concrete with low surface chloride content, careful consideration for mixing design should be paid for the exposure environment with high surface chloride content.

노출 환경 및 설계 변수의 변화에 따라 내구수명은 큰 범위를 가지고 변화하게 되므로 설계자 입장에서는 내구수명의 변동성을 이해하는 것은 중요하다. 최근 들어 탄소 중립을 위하여 플라스틱 혼소재가 클링커 생산 시 원료로 사용되고 있는데, 이러한 경우, 시멘트의 염화물 함유량은 증가하게 된다. 본 연구의 목적은 플라스틱 혼소재를 사용하여 초기 염화물량이 증가할 경우, 다양한 노출 환경과 설계 변수를 고려하여 내구수명이 어떤 수준으로 변화하는지에 대한 연구이다. 이를 위해 4 수준의 초기 염화물량을 설정하였으며, 3 수준의 표면 염화물량을 포함한 다양한 환경 조건에 따라 내구수명을 LIFE 365 프로그램을 이용하여 평가하였다. 해석 변수로서 임계 염화물량, 고로슬래그 미분말 치환 혼입율, 물-결합재 비, 피복두께, 단위 결합재량, 초기 염화물량을 설정하였다. 초기 염화물량이 증가함에 따라 내구수명은 감소하는 경향을 보이지만 이 값을 1,000ppm까지 허용해도 내구수명의 큰 감소는 나타나지 않았다. 또한 슬래그 치환율을 증가시킬 경우 더 높은 내구수명을 확보할 수 있는데, 이는 고로슬래그 미분말이 외부 염화물 이온의 확산 저감과 동시에 자유 염화물을 고정시키는 효과가 있기 때문이다. 초기 염화물량의 허용 농도를 유럽기준과 같이 증가시키는 것도 지속가능성 향상과 탄소량을 저감시키는 데 도움이 될 것으로 판단된다. 또한 표면 염화물량이 낮고 혼화재(슬래그)를 사용한 경우, 초기 염화물량의 영향은 상대적으로 낮았지만 표면염화물량이 높은 경우, 노출환경을 고려한 신중한 배합설계가 필요하다.

Keywords

Acknowledgement

이 논문은 2015년도 정부(미래창조과학부)의 재원으로 한국연구재단의 지원을 받아 수행된 기초연구사업임(No. 2015R1A5A1037548).

References

  1. Architectural Institute of Japan. (2016). Recommendations for Durability Design and Construction Practice of Reinforced Concrete Buildings - 2nd ed., Architectural Institute of Japan, Tokyo, Japan, 129-130.
  2. Alonso, C., Castellote, M., Andrade, C. (2002). Chloride threshold dependence of pitting potential of reinforcements, Electrochimica Acta, 47(21), 3469-3481. https://doi.org/10.1016/S0013-4686(02)00283-9
  3. Angst, U., Elsener, B., Larsen, C.K., Vennesland, O. (2009). Critical chloride content in reinforced concrete-a review, Cement and Concrete Research, 39(12), 1122-1138. https://doi.org/10.1016/j.cemconres.2009.08.006
  4. Ann, K.Y., Song, H.W. (2007). Chloride threshold level for corrosion of steel in concrete, Corrosion Science, 49(11), 4113-4133. https://doi.org/10.1016/j.corsci.2007.05.007
  5. Bamforth, P.B. (1999). The derivation of input data for modelling chloride ingress from eight-year UK coastal exposure trials, Magazine of Concrete Research, 51(2), 87-96. https://doi.org/10.1680/macr.1999.51.2.87
  6. Broomfield, J.P. (1997). Corrosion of Steel in Concrete: Understanding, Investigation and Repair, E&FN, London, 1-15.
  7. Cao, Y., Gehlen, C., Angst, U., Wang, L., Wang, Z., Yao, Y. (2019). Critical chloride content in reinforced concrete-an updated review considering Chinese experience, Cement and Concrete Research, 117, 58-68. https://doi.org/10.1016/j.cemconres.2018.11.020
  8. CEMBUREAU. (2020). Cementing the European Green Deal: Reaching Climate Neutrality along the Cement and Concrete Value Chain by 2050, The European Cement Association, Brussels, Belgium, 22-25.
  9. CEN. (2004). Eurocode 2: Design of Concrete Structure; EN-1992-1-1; European Committee for Standardization(Comite Europeen de Normalisation, CEN), Brussels, Belgium.
  10. Erdem, T.K., Kirca, O. (2008). Use of binary and ternary blends in high strength concrete, Construction and Building Materials, 22(7), 1477-1483. https://doi.org/10.1016/j.conbuildmat.2007.03.026
  11. Hannsson, C.M., Sorensen, B. (1990). The Threshold Concentration of Chloride in Concrete for the Initiation of Reinforcement Corrosion, ASTM International, Philadelphia, PA, USA, 3-16.
  12. Hussain, S.E., Al-Musallam, A., Al-Gahtani, A.S. (1995). Factors affecting threshold chloride for reinforcement corrosion in concrete, Cement and Concrete Research, 25(7), 1543-1555. https://doi.org/10.1016/0008-8846(95)00148-6
  13. Jau, W.C., Tsay, D.S. (1998). A study of the basic engineering properties of slag cement concrete and its resistance to seawater corrosion, Cement and Concrete Research, 28(10), 1363-1371. https://doi.org/10.1016/S0008-8846(98)00117-3
  14. JCI. (2018). Report on the Changes in Portland Cement Quality, Japan Concrete Institute.
  15. JSCE. (2007a). Standard Specification for Concrete Structures-Design; JSCE Guidelines for Concrete 15, Japan Society of Civil Engineering(JSCE), Tokyo, Japan.
  16. JSCE. (2007b). Standard Specification for Concrete Structures-Materials and Construction; JSCE-Guidelines for Concrete 16, Japan Society of Civil Engineering(JSCE), Tokyo, Japan.
  17. KCI. (2021). KDS 14 20 40 - Design Standard for Durability of Concrete Structure, Korea Concrete Institute [in Korean].
  18. Ministry of Land, Infrastructure and Transport. (2009). Concrete Standard Specification for Republic of Korea, 324 [in Korean].
  19. KCI. (2004). Concrete Standard Specification Durability Edition, 10 [in Korean].
  20. KICET. (2020). Investigation on Eco-Friendly Cement Manufacturing Technology and Industrial Status, Korea Institute of Ceramic Engineering & Technology, 1-13 [in Korean].
  21. Kouloumbi, N., Batis, G., Malami, C. (1994). The anticorrosive effect of fly ash, slag and a Greek pozzolan in reinforced concrete, Cement and Concrete Composites, 16(4), 253-260. https://doi.org/10.1016/0958-9465(94)90037-X
  22. Kwon, S.J., Na, U.J., Park, S.S., Jung, S.H. (2009), Service life prediction of concrete wharves with early-aged crack: Probabilistic approach for chloride diffusion, Structural Safety, 31(1), 75-83. https://doi.org/10.1016/j.strusafe.2008.03.004
  23. Noguchi, T., Kanematsu, M., Fukuyama, T. (2016). Revision of the "Recommendations for durability design and construction practice of reinforced concrete buildings" of the Architectural Institute of Japan, Concrete Journal, 54(11), 1091-1096. https://doi.org/10.3151/coj.54.11_1091
  24. Park, S.S., Kwon, S.J., Song, H.W. (2011). Analysis technique for restrained shrinkage of concrete containing chlorides, Materials and Structures, 44(2), 475-486. https://doi.org/10.1617/s11527-010-9642-4
  25. Pettersson, K. (1993). Chloride Threshold Value and Corrosion Rate in Reinforcement Concrete, E&FN Spon, London, UK, 461-471.
  26. Song, H.W., Cho, H.J., Park, S.S., Byun, K.J., Maekawa, K. (2001). Early-age cracking resistance evaluation of concrete structures, Concrete Science and Engineering, 3(10), 62-72.
  27. Sudret, B., Defaux, G., Pendola, M. (2005). Time-variant finite element reliability analysis-application to the durability of cooling towers, Structural Safety, 27(2), 93-112. https://doi.org/10.1016/j.strusafe.2004.05.001
  28. Thomas, M. (1996). Chloride thresholds in marine concrete, Cement and Concrete Research, 26(4), 513-519. https://doi.org/10.1016/0008-8846(96)00035-X
  29. Tomosawa, F. (2018). "Changes in durability standards for reinforced concrete", International Conference on the Durability Improvement of Cement and Concrete, Architectural Institute of Japan.
  30. Tuutti, K. (1993). Effect of Cement Type and Different Additions on Service Live, Concrete 2000, 1285-1295.
  31. Vassie, P., TRRL. (1984). Reinforcement corrosion and the durability of concrete bridges, Proceedings of the Institution of Civil Engineers, 76(3), 713-723. https://doi.org/10.1680/iicep.1984.1207
  32. Yang, T., Guan, B., Liu, G., Li, J., Pan, Y., Jia, Y., Zhao, Y. (2019). Service life prediction of chloride-corrosive concrete under fatigue load, Advances in Concrete Construction, 8(1), 55-64. https://doi.org/10.12989/ACC.2019.8.1.055
  33. Yoon, Y.S. (2021). Evaluation of Service Life for RC Girder under Chloride Ingress with Probabilistic Analysis Considering Stress and Cold Joint Effect, Ph.D Thesis, Hannam University, 87-90 [in Korean].
  34. Yoon, Y.S., Ryu, H.S., Lim, H.S., Koh, K.T., Kim, J.S., Kwon, S.J. (2018). Effect of grout conditions and tendon location on corrosion pattern in PS tendon in grout, Construction and Building Materials, 186, 1005-1015. https://doi.org/10.1016/j.conbuildmat.2018.08.023
  35. Zhou, S. (2014). Modeling chloride diffusion in concrete with linear increase of surface chloride, ACI Materials Journal, 111(5), 483. https://doi.org/10.14359/51686989