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물-시멘트비에 따른 경량콘크리트 및 일반콘크리트의 수축과 습도와의 관계

Relation Between Shrinkage and Humidity on Lightweight Concrete and Normal Concrete by Water-Cement Ratio

  • 이창수 (서울시립대학교 토목공학과) ;
  • 박종혁 (서울시립대학교 토목공학과) ;
  • 정봉조 (서울시립대학교 토목공학과) ;
  • 최영준 (서울시립대학교 토목공학과)
  • 투고 : 2009.02.18
  • 심사 : 2009.05.15
  • 발행 : 2009.07.31

초록

콘크리트 수축과 습도를 측정하고 기존 연구 결과와의 비교를 통해 다공성 경량골재의 사전흡수수에 따른 콘크리트의 수축과 콘크리트 내 상대습도와의 관계를 파악하였다. 물-결합재비 0.3에서 경량 콘크리트의 수축 저감효과는 7일 초기재령에서 36%, 6개월 장기재령에서 25%를 나타내었으며, 물-결합재비 0.4는 7일 초기재령에서 19%, 6개월 장기재령에서 16%의 수축 저감률을 그리고 물-결합재비 0.5에서는 각각 37%, 32%를 나타내었다. 물-결합재비에 관계없이 경량골재 사전흡수수의 습도 공급 효과는 7~10일 이내의 초기 재령에서 두드러지게 나타났다. 콘크리트 내 습도와 수축과의 관계는 물-결합재비 0.3의 경우 기존 모델식 적용 종류에 상관없이 습도 변화 전체 구간에 대하여 수축이 과소평가되었으며, 물-결합재비 0.4, 0.5의 경우 비교적 기존 모델식과 측정값이 유사한 경향을 나타내었다. 습도감소와 수축 변형률간의 관계를 고차 다항식으로 회귀분석할 수 있었으며, 콘크리트의 수분이동 해석을 통해 시간에 따른 상대습도를 고려할 경우 수분이동 해석과 부등수축 해석을 연관할 수 있는 매개변수로 적용할 수 있는 결과를 도출하였다.

This study grasped the relationship between relative humidity in concrete and concrete shrinkage followed by pre-absorbed water of porous lightweight aggregates through measurements of concrete shrinkage and humidity and comparisons with established research results. It was showed that shrinkage reduction effect of lightweight concrete is 36% at 7 days early ages and 25% at 180 days long-term ages when water-binder ratio is 0.3. It also showed that shrinkage reduction effect is 19% at 7 days and 16% at 180 days when water-binder ratio is 0.4 and 37%, 32% when water-binder ratio is 0.5. The moisture supply effect of lightweight aggregates was remarkable at early age within 7~10 days irrespective of water-binder ratio. In case of waterbinder ratio is 0.3, the relationship between shrinkage and internal humidity of concrete has been underestimated regardless of applied existing model type and in case of water-binder ratio is 0.4, 0.5, measurement values are relatively similar with existing model equations. Finally this study did regression analyses about the relation among the humidity change and the shrinkage strain as a high-degree polynomial and derived parameters that can connect moisture movement analysis with differential shrinkage analysis in case of considering relative humidity at the time by moisture movement analysis of concrete.

키워드

참고문헌

  1. 곽효경, 하수준(2004) 철근콘크리트 벽체의 초기재령 거동 해석, 대한토목학회 논문집, 대한토목학회, 제24권 제1A호, pp. 35-47.
  2. 이창수, 박종혁(2008) 공극 내 상대습도, 모세관압력, 표면에너지 변화에 따른 콘크리트 자기수축, 한국콘크리트학회 논문집, 한국콘크리트학회, 제20권 2호, pp. 131-138. https://doi.org/10.4334/JKCI.2008.20.2.131
  3. 이칠성(1998) 콘크리트의 수분확산과 부등건조수축에 관한 연구, 박사학위논문, 한국과학기술원.
  4. 한국콘크리트학회(2007) 콘크리트 구조설계기준해설, 기문당.
  5. Ala, M.S. and Hadidi, R. (2002) Cause and Control of Transverse Cracking in Concrete Bridge Decks, FHWA-NJ-2002-019, Department of Civil and Environmental Engineering New Jersey Institute of Technology, Newark.
  6. Bazant, Z.P. and Raftshol, W.J. (1982) Effect of Cracking in Drying and Shrinkage Specimens, Cement and Concrete Research, Vol. 12, pp. 209-226. https://doi.org/10.1016/0008-8846(82)90008-4
  7. Bazant, Z.P. and Murphy, W.P. (1995) Creep and shrinkage prediction model for analysis and design of concrete structures-model B3, Materials and Structures, Vol 28, pp. 357-365. https://doi.org/10.1007/BF02473152
  8. CEB-FIP (1990) CEB-FIP Model Code 90 for Concrete Structures, Comite Euro-International du Beton, Lausanne, 1990.
  9. Haluk, A., Fu, G., and Dekelbab, W. (2003) Investigate Causes and Develop Methods to Minimize Early-Age Deck Cracking on Michigan Bridge Decks, Research Report RC-1437, Michigan Department of Transportation, Detroit.
  10. Jensen, O.M. and Lura, P. (2006) Techniques and materials for internal water curing of concrete, Materials and Structures, Vol. 39, pp. 817-825. https://doi.org/10.1617/s11527-006-9136-6
  11. Lura, P. (2003) Autogenous Deformation and Internal Curing of Concrete, Ph.D thesis, Deft University of Technology.
  12. Lura, P., Jensen, O.M., and Igarashi, S.I. (2006) Experimental observation of internal water curing of concrete, Materials and Structures, Vol. 40, pp. 211-220. https://doi.org/10.1617/s11527-006-9132-x
  13. Ribeiro, A.B., Goncalves, A., and Carrajora, A. (2006) Effect of shrinkage reducing admixtures on the pore structures properties of mortars, Materials and Structures, Vol. 39, pp. 159-166.
  14. Tazawa, E. and Miyazawa, S. (1993) Autogenous shrinkage of Concrete and Its Importance in Concrete Technology, Creep and Shrinkage of Concrete, edited by Bazant, Z. P. E&FN Spon, pp. 105-133.
  15. Weiss, W.J. and Shah, S.P. (2002) Restrained shrinkage cracking : the role of shrinkage reducing admixtures and specimen geometry, Materials and Structures, Vol. 35, pp. 85-91. https://doi.org/10.1617/13799
  16. Whiting, D. and Detwiler, R. (1998) Silica Fume Concrete for Bridge Decks, NCHRP Report 410, Transportation Reaearch Borad, Washinton D.C.
  17. Will, D.L., David, D., and Joann, P.B. (2005) Cracking and Chloride Contents in Reinforced Concrete Bridge Decks, SM Report No. 78, Kansas Department of Transportation, Lawrence, Kansas.
  18. Xi, Y., Shing, B., and Suwito, A. (2003) Assesment of Cracking Problems in Newly Constructed Bridge Decks in Colorado, CDOT-DTD-R-2003-3, Colorado Department of Transportation, Denver.
  19. Zachary, C.G., David, A.L., and Matthew, D.D. (2006) Internal relative humidity and drying stress gradients in concrete, Materials and Structures, Vol. 39, pp. 901-909. https://doi.org/10.1617/s11527-006-9090-3