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

Korea Institute for Structural Maintenance Inspection (한국구조물진단유지관리공학회)
권호 표지
DOI QR코드

DOI QR Code

Analysis Technique for Chloride Penetration using Double-layer and Time-Dependent Chloride Diffusion in Concrete

콘크리트내의 이중구조와 시간의존성을 고려한 염화물 해석기법의 개발

  • 문진만 (한남대학교 건설시스템 공학과) ;
  • 김진영 (한국산업단지공단) ;
  • 김영준 (한남대학교 건설시스템 공학과) ;
  • 오경석 (한남대학교 건설시스템 공학과) ;
  • 권성준 (한남대학교 건설시스템 공학과)
  • Received : 2015.05.19
  • Accepted : 2015.07.21
  • Published : 2015.09.01
Download PDF
⟨ Previous Next ⟩

Abstract

With varying conditions of concrete surface, induced chloride contents are changed and this is a key parameter for steel corrosion and service life in RC (Reinforced Concrete) structures. Many surface enhancement techniques using impregnation have been developed, however the evaluation techniques for chloride behavior through doubly layered media and time-dependent diffusion are rarely proposed. This paper presents an analysis technique considering double-layer concrete and time-dependent diffusion behavior, and the results are compared with those from the previous test results through reverse analysis. The chloride profiles from the surface-impregnated concrete exposed to atmospheric, tidal, submerged zone for 2 years are adopted. Furthermore surface chloride contents and diffusion coefficients are obtained, and are compared with those from Life365. Through consideration of time effect, the relative error decreases from 0.28 to 0.20 in atmospheric, 0.29 to 0.11 in tidal, and 0.54 to 0.40 in submerged zone, respectively, which shows more reasonable results. Utilizing the diffusion coefficients from Life365, relative errors increases and it needs deeper penetration depth (e) and lower diffusion coefficient ratio ($D_1/D_2$) due to higher diffusion coefficient.

콘크리트 표면의 상태에 따라 염화물은 증가 또는 감소하게 되며 이는 철근부식 및 내구수명에 매우 중요한 인자가 된다. 콘크리트의 내구성 저하를 방지하기 위해 표면함침과 같이 많은 표면강화 기술이 개발되었으나 이중 콘크리트 구조와 확산계수의 시간의존성을 고려한 염화물 해석방법은 매우 제한적이다. 본 논문에서는 표면 강화된 이중구조 콘크리트에 대해 시간의존성 확산계수를 도입하여 염화물 해석기법을 제안하였으며, 역해석을 통하여 기존의 실험결과와 비교하였다. 2년간 비말대, 해수중, 조석대 상태에 노출된 표면 함침된 콘크리트 시편에 대해 표면염화물량과 확산계수를 도출하고 Life-365에서 제안한 확산계수 식과 비교 분석하였다. 시간의존성을 고려한 결과 비말대 시편의 오차는 0.28에서 0.20 수준으로, 조석대 시편은 0.29에서 0.11 수준으로, 해수중에서는 0.54에서 0.40 수준으로 오차가 감소함을 알 수 있었다. 또한 Life365에서 사용되는 확산계수식을 사용할 경우, 과다한 확산계수로 인해 상대오차가 커지고 높은 침투깊이(e)와 낮은 확산계수비($D_1/D_2$)를 필요로 함을 알 수 있다.

Keywords

References

  1. Andrade, C., Diez, J. M., and Alonso, C. (1997), Mathematical Modeling of a Concrete Surface "Skin Effect" on Diffusion in Chloride Contaminated Media, Advanced Cement Based Materials, 6(2), 39-44. https://doi.org/10.1016/S1065-7355(97)00002-3
  2. Broomfield, J. P. (1997), Corrosion of Steel in Concrete: Understanding, Investigation and Repair, E&FN, London, 1-15.
  3. Kim, K. H., and Cha, S. W. (2010), Reliability-Based Service Life Estimation of Concrete in Marine Environment, Journal of the Korea Concrete Institute, 22(4), 595-603. https://doi.org/10.4334/JKCI.2010.22.4.595
  4. Kim, K. H., Jang, S. Y., Cha, S. W., and Chang, S. P. (2008), Development of Chloride Penetration Analysis Program Considering Environmental Conditions, Journal of the Korean Society of Civil Engineers, 28(5), 709-718.
  5. Kim, W. C., Kim, J. J., Park, B. W., Park, T. S., Song, M. S., Lee, S. Y., Lee, Y. J. (2006), Introductory Statics, Youngji Publisher, Korea.
  6. Kwon, S. J., Na, U. J., Park, S. S., and 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
  7. Kwon, S. J., Park, S. J., and Lho B. C. (2008), Durability Evaluation of Inorganic-Impregnated Concrete Exposed to Long-Term Chloride Exposure Test, Journal of the Korea Concrete Institute, 20(3), 283-290. https://doi.org/10.4334/JKCI.2008.20.3.283
  8. Kwon, S. J., Park, S. S., Lee, S. M., and Kim, J. H. (2007), A Study on Durability Improvement for Concrete Structures Using Surface Impregnant, Journal of the Korea Institute for Structural Maintenance Inspection, 11(4), 79-88.
  9. Koo, H. B., Kim, E. T., and Lee, K. M. (2003), Modeling of Chloride Ingress in Reinforced Concrete Structures, Journal of the Korea Concrete Institute, 15(16), 25-34. https://doi.org/10.4334/JKCI.2003.15.1.025
  10. Lee S. H., and Kwon S. J. (2012), Experimental Study on the Relationship between Time-Dependent Chloride Diffusion Coefficient and Compressive Strength, Journal of Korea Concrete Institute, 24(6), 715-726. https://doi.org/10.4334/JKCI.2012.24.6.715
  11. Park, S. S., Kim, Y. Y., Lee, B. J., and Kwon, S. J. (2014), Evaluation of Concrete Durability Performance with Sodium Silicate Impregnants, Advance in Materials Science and Engineering, 2014, 1-11.
  12. Park, S. S., Lee, S. K., and Lee, S. M. (2004), Development of a Sealer for the Durable-Performance Improvement of the Nuclear Concrete, Journal of the Korea Concrete Institute, 16(2), 821-824.
  13. Poulsen, E. (1993), On a Model of Chloride Ingress into Concrete, Nordic Mini Seminar-Chloride Transport, Department of Building Materials, Gothenburg.
  14. RILEM. (1994), Durability Design of Concrete Structures, Report of RILEM Technical Committee 130-CSL, E&FN, 28-52.
  15. Sam Sung Construction (2003), Evaluation of chloride diffusion coefficient in High Performance Concrete, Technical Report, 18-28.
  16. Tang, L., and Joost, G. (2007), On the Mathematics of Time- Dependent Apparent Chloride Diffusion Coefficient in Concrete, Cement and Concrete Research, 37(4), 589-595. https://doi.org/10.1016/j.cemconres.2007.01.006
  17. Thomas, M. D. A., and Bamforth, P. B. (1999), Modeling Chloride Diffusion in Concrete: Effect of Fly Ash and Slag, Cement and Concrete Research, 29(4), 487-495. https://doi.org/10.1016/S0008-8846(98)00192-6
  18. Thomas, M. D. A., and Bentz, E. C. (2002), Computer Program for Predicting the Service Life and Life-Cycle Costs of Reinforced Concrete Exposed to Chlorides, Life365 Manual, SFA, 12-56.
  19. Yang E. I., Kim, M. Y., Kim, B. C., and Kim, J. H. (2006), Evaluation on Resistance of Chloride Attack and Freezing and Thawing of Concrete with Surface Penetration Sealer, Journal of the Korea Concrete Institute, 18(1), 65-71. https://doi.org/10.4334/JKCI.2006.18.1.065

Cited by

  1. 다층구조확산을 고려한 제설제에 노출된 콘크리트의 염화물 해석 vol.16, pp.4, 2016, https://doi.org/10.5392/jkca.2016.16.04.114