Journal of the Korea institute for structural maintenance and inspection (한국구조물진단유지관리공학회 논문집)

Korea Institute for Structural Maintenance Inspection (한국구조물진단유지관리공학회)
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Modeling on Chloride Diffusivity in Concrete with Isotropic and Anisotropic Crack

등방성 및 이방성 균열을 가진 콘크리트의 염화물 확산계수 모델링

  • 이학수 (한남대학교 건설시스템공학과) ;
  • 배상운 (다산컬설턴트) ;
  • 권성준 (한남대학교 건설시스템공학과)
  • Received : 2013.07.10
  • Accepted : 2013.07.31
  • Published : 2013.11.30
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Abstract

Deterioration is accelerated due to additional intrusion of chloride ion in crack width in cracked concrete. In this paper, modeling on equivalent diffusion coefficient in cracked concrete is performed for 1-D (Anisotropic) and 2-D (Isotropic) diffusion based on steady state condition. In the previous research, rectangular shape of crack was considered but the shape was modified to wedge shape with torturity. For verification of the proposed model, crack is induced in concrete sample and migration test in steady state is performed for 1-D diffusion. For 2-D diffusion, previous test results are adopted for verification. Through considering wedge shape of crack with torturity, diffusion coefficients in 1-D and 2-D diffusion are reduced, and the more reasonable prediction is obtained. The results from the proposed model with torturity of 0.10~0.15 are shown to be in the best agreement with the test results.

균열을 가진 콘크리트에서는 균열폭으로 유입되는 염화물 이온에 의해 열화가 가속화된다. 본 연구는 균열을 가진 콘크리트의 염화물 확산에 대한 모델링으로, 정상상태를 가정하여 1차원 (이방성) 및 2차원 (등방성) 균열 모델링을 수행하였다. 기존의 균열 모델링에서는 직사각형 균열패턴으로 모델링을 수행하였으나, 본 연구에서는 조도를 가진 쐐기형 형태로 균열을 모델링하였다. 검증을 위하여 1차원 유입에 대해서는 콘크리트 시편에 균열을 유입하여 염화물 영동실험을 수행하였으며, 2차원 유입에 대해서는 기존의 실험결과를 이용하여 검증을 수행하였다. 모든 경우에서 균열형태를 쐐기형으로 고려하여 염화물 확산성이 감소되었으며, 조도를 고려함으로서 합리적인 결과가 도출되었다. 특히 0.10~0.15의 조도계수를 고려할 때, 실험값에 가장 근접한 결과를 나타내었다.

Keywords

References

  1. Andrade, C., "Calculation of chloride diffusion coefficients in concrete from ionic migration measurement", Cement and Concrete Research, Vol. 23, No. 3, 1993, pp.724-742. https://doi.org/10.1016/0008-8846(93)90023-3
  2. Gerard, B., Marchand, J., "Influence of cracking on the diffusion properties of cement-based materials Part I: Influence of continuous cracks on the steady-state regime", Cement and Concrete Research, Vol. 30, No. 2, pp.37-43. https://doi.org/10.1016/S0008-8846(99)00201-X
  3. Ishida, T., Maekawa, K., "Modeling of PH profile in pore water based on mass transport and chemical equilibrium theory", Concrete Library of JSCE, Vol. 37, No. 1, 2001, pp.151-166.
  4. Jacobsen, S., Marchand, J., Boisvert, L., "Effect of cracking and healing on chloride transport in OPC concrete", Cement and Concrete Research, Vol. 26, No. 6, 1996, pp.869-881. https://doi.org/10.1016/0008-8846(96)00072-5
  5. JSCE - Concrete Committee. Standard Specification for Concrete Structures, 2002.
  6. Korea Concrete Institute. Concrete standard specification -Durability Part, 2004 (in Korean).
  7. Kwon, S. J., Lee, H. S., Park, S. G., "Effect of additional water on durability and pore size distribution in cement mortar", Journal of the Korea Institute for Structural Maintenance and Inspection, Vol. 3, No. 3, 2012, pp.75-83. https://doi.org/10.11112/jksmi.2012.16.3.075
  8. Kwon, S. J., Na, U. J., Park, S. S., Jung, S. H., "Service life prediction of concrete wharves with early-aged crack : Probabilistic approach for chloride diffusion", Structural Safety, Vol. 31, No.1, 2009, pp.75-83. https://doi.org/10.1016/j.strusafe.2008.03.004
  9. Maekawa, K., Ishida, T., Kishi, T., Multi-Scale Modeling of Structural Performance, Taylor & Francis, 2009, pp.322-325.
  10. Park, S. S., Kwon, S. J., Jung, S. H., "Analysis technique for chloride penetration in cracked concrete using equivalent diffusion and permeation", Construction and Building Materials, Vol. 29, No. 2, 2012b, pp.183-192. https://doi.org/10.1016/j.conbuildmat.2011.09.019
  11. Park, S. S., Kwon, S. J., Jung, S. H., Lee, S. W., "Modeling of water permeability in early aged concrete with cracks based on micro pore structure", Construction and Building Materials, Vol. 27, No. 1, 2012a, pp.597-604. https://doi.org/10.1016/j.conbuildmat.2011.07.002
  12. Park, S. S., Song, H. W., Byun, K. J., "Model for chloride diffusivity and water permeability in cracked concrete", J. of KSCE, Vol. 21, No. 6-B, 2001, pp.925-924 (in Korean).
  13. Song, H. W., Cho, H. J., Park, S. S., Byun, K. J,. Maekawa, K., "Early-age cracking resistance evaluation of concrete structure", Concrete Science Engineering, Vol. 3, No. 1, 2001, pp.62-72.
  14. Song, H. W., Kim, H. J., Kwon, S. J., Lee, C. H., Byun, K. J., Park, C. K., "Prediction of service life in cracked reinforced concrete structures subjected to chloride attack and carbonation", 6th International Congress Global Construction: Ultimate Concrete Opportunities, Dundee, Scotland, 5-7 July, Vol. Cement Combinations for Durable Concrete, 2005b, pp.767-776.
  15. Song, H. W., Kwon, S. J., Byun, K. J., Park, C. K., "Predicting carbonation in early-aged cracked concrete", Cement and Concrete Research, Vol. 36, No. 5, 2006, pp.979-989. https://doi.org/10.1016/j.cemconres.2005.12.019
  16. Song, H. W., Kwon, S. J., Byun, K. J., Park. C. K., "A Study on analytical technique of chloride diffusion considering characteristics of mixture design for high performance concrete using mineral admixture", Journal of KSCE, Vol. 25, No. 1A., 2005a, pp.213-223 (in Korean).
  17. Song, H. W., Pack, S. W., Lee, C. H., Kwon, S. J., "Service life Prediction of concrete structures under marine environment considering coupled deterioration", J. of Restoration of Buildings and Monuments, Vol. 12, No. 4, 2006, pp.265-284.
  18. Thomas, M. D. A., Bamforth, P. B., "Modeling chloride diffusion in concrete: Effect of fly ash and slag", Cement and Concrete Research, Vol. 29, No. 4, 1999, pp.487-495. https://doi.org/10.1016/S0008-8846(98)00192-6
  19. Win, P. P., Watanabe, M., Machida, A., "Penetration profile of chloride ion in cracked reinforced concrete", Cement and Concrete Research, Vol. 34, No. 2, 2004, pp.1073-1079. https://doi.org/10.1016/j.cemconres.2003.11.020
  20. Yokozeki, K., Okada, K., Tsutsumi, T., Watanabe, K., "Prediction of the service life of RC with crack exposed to chloride attack", Japan Symposium of Rehabilitation of Concrete Structure, Vol. 10. No. 1, 1998, pp.1-6.