KSCE Journal of Civil and Environmental Engineering Research (대한토목학회논문집)

Korean Society of Civil Engeneers (대한토목학회)
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An Experimental Study on the Durability Characterization using Porosity

시멘트 모르타르의 공극률과 내구특성과의 관계에 대한 실험적 연구

  • Received : 2008.12.01
  • Accepted : 2009.03.02
  • Published : 2009.03.31
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Abstract

The porosity in porous media like concrete can be considered as a durability index since it may be a routine for the intrusion of harmful ions and room for the keeping moisture. Recently, modeling and analysis techniques for deterioration are provided based on the pore structure with the significance of durability and the relationship between porosity and durability characteristics is an important issue. In this paper, a series of mortar samples with five water to cement ratios are prepared and tests for durability performance are carried out including porosity measurement. The durability test covers those for compressive strength, air permeability, chloride diffusion coefficient, absorption, and moisture diffusion coefficient. They are compared with water to cement ratios and porosity. From the normalized data, when porosity increases to 1.45 times, air permeability, chloride diffusion coefficient, absorption, and moisture diffusion coefficient decrease to 2.3 times, 2.1 times, 5.5 times and 3.7 times, respectively, while compressive strength decreases to 0.6 times. It was evaluated that these are linearly changed with porosity showing high corelation factors. Additionally, intended durability performances are established from the test results and literature studies and a porosity for durable concrete is proposed based on them.

콘크리트의 공극률은 유해인자의 주된 이동통로가 될 뿐 아니라, 수분을 보유할 수 있는 역할을 하게 되므로, 열화물질 이동 저항성을 평가할 수 있는 주된 지표가 되고 있다. 내구성에 대한 연구가 중요해짐에 따라, 공극구조를 기본으로 하는 열화모델이 최근 들어 개발되고 있으며, 공극구조와 내구특성간의 관계는 매우 중요하게 평가되고 있다. 본 연구는 5가지의 다른 물-시멘트비(40%, 45%, 50%, 55%, 60%)를 가진 시멘트 모르타르를 제조하여, 공극률을 포함한 다양한 내구성 실험을 수행하였다. 내구특성 실험은 기본적인 압축강도 실험을 포함하여, 투기성 실험, 염화물 확산계수 실험, 흡수율 및 수분 확산계수 실험 등이 수행되었다. 평가된 내구성 실험결과는 물-시멘트비와 공극률에 따라 분석되었다. 공극률이 1.45 배 높아질수록, 강도는 0.6배 수준으로 감소하였으며, 투기성, 염화물 확산계수, 흡수율, 수분확산계수는 각각 2.3배, 2.1배, 5.5배, 그리고 3.7배 수준으로 증가하였다. 이러한 내구특성 변화율은 높은 상관성을 보이며, 공극률에 따라 선형적으로 변화함을 알 수 있었다. 한편, 실험결과와 문헌분석을 통하여, 목표내구성능을 설정하였으며, 이에 따라서 고내구성 콘크리트를 위한 공극를을 제안하였다.

Keywords

References

  1. 권성준, 송하원, 변근주(2007) 인공신경망을 통한 확산계수 도출과 공극구조 변화를 고려한 콘크리트 탄산화 해석, 대한토목학회 논문집, 대한토목학회, 제27권 제1A호, pp. 107-116.
  2. 권성준, 송하원, 변근주, 박찬규(2007) 신경망 이론과 마이크로 모델링을 통한 혼화재를 사용한 콘크리트의 염화물 침투해석, 대한토목학회 논문집, 대한토목학회, 제27권 제1A호, pp. 117-129.
  3. 권성준, 송하원, 변근주, 이승훈(2004) 균열을 가진 초기재령 콘크리트의 탄산화 해석, 대한토목학회 논문집, 대한토목학회, 제24권 제5A호, pp. 1011-1022.
  4. 김태상, 정상화, 채성태, 이봉춘, 우영제, 송하원(2008) MIP를 통한 혼합시멘트계 재료의 미세구조 특성에 관한 실험적 연구, 2008년 콘크리트학회 봄학술발표회, 한국콘크리트학회, pp. 533-536.
  5. 소형석, 소양섭(2003) 포졸란재 함유 콘크리트 및 투기성과 염화물 이온 투과성, 대한건축학회 논문집, 대한건축학회, 제19권 제11호, pp. 117-124.
  6. 송하원, 권성준, 변근주, 박찬규(2005) 혼화재를 사용한 고성능 콘크리트의 배합특성을 고려한 염화물 확산 해석기법에 관한 연구. 대한토목학회 논문집, 대한토목학회, 제25권 제1A호. pp. 213-223.
  7. 오병환, 정상화, 이명규(2003) 공극률을 고려한 콘크리트중의 이산화탄소 확산특성에 대한 연구, 한국콘크리트학회 논문집, 한국콘크리트학회, Vol. 15, No. 3, pp. 443-453.
  8. Bamforth, P.B. (1987) The relationship between permeability coefficient for concrete obtained using liquid and gas, Magazine of Concrete Research, Vol. 39, No. 138, pp. 3-11. https://doi.org/10.1680/macr.1987.39.138.3
  9. Bassat, M.B., Nixon, P.J., and Hardcastle, J. (1990) The effect of differences in the composition of Portland cement on the properties of hardened concrete, Magazine of Concrete Research, Vol. 42, No. 151, pp. 59-66. https://doi.org/10.1680/macr.1990.42.151.59
  10. Ishida, T. and Maekawa, K. (2003) Modeling of durability performance of cementitious materials and structures based on thermo-hygro physics, Rilem Proceeding PRO 29, Life Prediction and Aging Management of Concrete Structures, pp. 39-49.
  11. Ishida, T. and Maekawa, K. (2001) Modeling of PH profile in pore water based on mass transport and chemical equilibrium theory, Concrete Library of JSCE, No. 37, pp. 151-166.
  12. Ishida, T., Maekawa, K., and Kishi, T. (2007) Enhanced modeling of moisture equilibrium and transport in cementitious materials under arbitrary temperature and relative humidity history, Cement and Concrete Research, Vol. 37, pp. 565-578. https://doi.org/10.1016/j.cemconres.2006.11.015
  13. Ishida, T., Soltani, M., and Maekawa, K. (2004) Influential parameters on the theoretical prediction of concrete carbonation process, Proceedings 4th International Conference on Concrete Under Severe Conditions, Seoul, Korea, pp. 205-212.
  14. Mabrouk, R., Ishida, T., and Maekawa, K. (2004) A unified solidification model of hardening concrete composite for predicting the young age behavior of concrete, Cement and Concrete Composites, Vol. 26, pp. 453-461. https://doi.org/10.1016/S0958-9465(03)00073-8
  15. Maekawa, K., Ishida, T., and Kishi, T. (2003) Multi-scale modeling of concrete performance, Journal of Advanced Concrete Technology, Vol. 1, No. 2 pp. 91-126. https://doi.org/10.3151/jact.1.91
  16. Maekawa, K., Chaube, R., and Kishi, T. (1999) Modeling of Concrete Performance: Hydration, Microstructure Formation and Mass Transport, Routledge, London and New York.
  17. Mangat, P.S. and Molly, B.T. (1994) Prediction of free chloride concentration in concrete using routine inspection data, Magazine of Concrete Research, Vol. 46, No. 169, pp. 279-287. https://doi.org/10.1680/macr.1994.46.169.279
  18. Metha, K. and Monteiro, P.J.M. (1993), Concrete: Structure, Properties, and Materials, Vol. 2, Prentice Hall, New Jersy.
  19. Narayanan Neithalath (2006), Analysis of moisture transport in mortar and concrete using sorption-diffusion approach, ACI Materials Journal, 103M24, pp. 209-217.
  20. Neville, A. (1996) Properties of Concrete, Longman (revised).
  21. Ngala, V.T. and Page, C.L. (1997) Effects of carbonation on pore structure and diffusional properties of hydrated cement paste, Cement and Concrete ResCement and Concrete Researchearch, Vol. 27, pp. 995-1007. https://doi.org/10.1016/S0008-8846(97)00102-6
  22. NORDTEST (1999) Chloride Migration Coefficient from Non-Steady-State Migration Experiments, NT BUILD 492.
  23. Papadakis, V.G., Vayenas,C.G., and Fardis, M.N. (1991) Fundamental modeling and experimental investigation of concrete carbonation, ACI Materials Journal, Vol. 88, No. 4, pp. 363-373.
  24. Song, H.-W., Cho, H.-J., Park, S.-S., Byun, K.J., and Maekawa, K. (2001) Early-age cracking resistance evaluation of concrete structure, Concrete Science and Engineering, Vol. 3, pp. 62-72.
  25. Song H.-W. and Kwon, S.-J. (2007) Permeability characteristics of carbonated concrete considering capillary pore structure, Cement and Concrete Research, Vol. 37, Issue 6, pp. 909-915. https://doi.org/10.1016/j.cemconres.2007.03.011
  26. Song, H.-W., Pack, S.-W., Lee, C.-H., and Kwon, S.-J. (2006) Service life prediction of concrete structures under marine environment considering coupled deterioration, J. of Restoration of Buildings and Monuments, Vol. 12, No. 4, pp. 265-284.
  27. Tang, L. and Nilsson, L.O. (1992) A study of the quantitative relationship between permeability and pore size distribution of hardened cement pastes, Cement and Concrete Research, Vol. 22, pp. 541-550. https://doi.org/10.1016/0008-8846(92)90004-F
  28. Tang, L. and Nilsson, L.O. (1993) Chloride binding capacity and binding isotherms of OPC paste and mortar, Cement and Concrete Research, Vol. 23, pp. 347-353. https://doi.org/10.1016/0008-8846(93)90100-N