KSCE Journal of Civil and Environmental Engineering Research (대한토목학회논문집)

Korean Society of Civil Engeneers (대한토목학회)
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Characteristics of Compressive Strength of Concrete due to Form Curing Condition

거푸집 양생 조건에 따른 콘크리트의 압축강도 특성

  • Received : 2017.09.22
  • Accepted : 2017.12.14
  • Published : 2018.02.01
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Abstract

The time for form removal is an important factor for ensuring the safety and economical efficiency of concrete structures, because it affects the quality, period, and cost of construction. Although local specifications suggest the form curing time, there is a problem of low quality of concrete due to early removing of form. This is because they do not fully understand effect of curing condition, and they want to shorten construction period in the field. Therefore, this research evaluates the effect of curing condition according to the time for form removal by testing specimen. As a result, the concrete compressive strength at the age of 28 days decreased about 40% in the condition of form removal after 12 hours, while the strength in the condition of form removal after 28 days decreased about 7%. Finally, this paper suggests an estimating equation for the concrete compressive strength due to the time for form removal considering various curing temperatures as equivalent ages. The proposed equation can be used in the field for evaluating the strength after form removal.

거푸집의 탈형 시기는 콘크리트 구조물의 품질과 공사기간, 공사비에 영향을 주는 직접적인 요인으로 콘크리트 구조물의 안전성과 경제성을 확보하는데 중요한 요소이다. 국내 규정에서 거푸집 존치에 대한 규정을 제시하고 있으나 조기에 거푸집을 해체하여 콘크리트의 품질이 저하되고 있다. 이는 양생조건에 대한 이해가 부족하고 공사기간이 단축되길 원하기 때문이다. 따라서 본 연구에서는 콘크리트의 거푸집 탈형시기에 따른 양생조건이 압축강도에 미치는 영향을 시험을 통하여 평가하였다. 연구 결과 거푸집의 12시간 후 조기 탈형은 콘크리트의 28일 압축강도를 최대 약 40% 정도까지 저하시켰으며, 거푸집을 28일 동안 장기간 존치할 경우에는 28일 표준압축강도 대비 약 7%의 강도저하를 가져왔다. 결론으로 본 논문에서는 양생온도를 등가재령으로 고려하여 거푸집 해체 시기에 따른 콘크리트의 압축강도 추정식을 제안하였다. 이 제안식은 현장에서 거푸집 제거 후의 콘크리트 압축강도 평가에 활용될 수 있다.

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References

  1. ACI Committee 209 (2008). Guide for modeling and calculating shrinkage and creep in hardened concrete, ACI 209.2R-08, American Concrete Institute, Michigan.
  2. Bartlett, F. M. and MacGregor, J. G. (1994). "Effect of moisture condition on concrete core strength." ACI Materials Journal, Americal Concrete Institute, Vol. 91, No. 3, pp. 227-236.
  3. British Standard (1983). Testing concrete, BS 1881, British Standards Institution, London.
  4. British Standard (2000). Testing hardened concrete, BS EN 12390, British Standards Institution, London.
  5. Burg, R. G. (1996). The influence of casting and curing temperature on the properties of fresh and hardened concrete, Research and Development Bulletin RD113, Portland Cement Association, Chicago.
  6. Cho, H. D. and Jaung, J. D. (2008). "A study on the strength properties of high-strength concrete under various curing conditions." Proc. of 2008 Korea Concrete Institute Autumn Conference, KCI, Goyang, Korea, pp. 965-968 (in Korean).
  7. Gonnerman, H.F. (1930). "Study of methods of curing concrete." Journal of the American Concrete Institute-Proceedins, ACI, Vol. 26, pp. 359-396.
  8. Han, C. G. and Han, M. C. (2004). "Determination of removal time of the side form in high strength concrete." Journal of the Korea Concrete Institute, KCI, Vol. 16, No. 3, pp. 327-334 (in Korean). https://doi.org/10.4334/JKCI.2004.16.3.327
  9. Han, C. G., Hwang, Y. S. and Sin, B. H. (2002). "Determination of removal time of the forms according to the strength development of concrete at early age." Journal of the Architectural Institute of Korea Structure & Construction, AIOK, Vol. 18, No. 9, pp. 157-162 (in Korean).
  10. Hansen, P. F. and Pedersen, E. J. (1977). "Maturity Computer for Controlled Curing and Hardening of Concrete", Journal of the Nordic Concrete Federation, No.1, pp.21-25 (in Danish).
  11. Klieger, P. (1958). Effect of Mixing and Curing Temperature on Concrete Strength, Research Department Bulletin RX103, Portland Cement Association, Chicago.
  12. Korean Standard (2010). Standard test method for compressive strength of concrete, KS F 2405, Korean Standards Association (in Korean).
  13. Ministry of Land, Infrastructure and Transport (MOLIT) (2015). Building construction standard specification, Architectural Institute of Korea (in Korean).
  14. Ministry of Land, Infrastructure and Transport (MOLIT) (2016). Standard specification of concrete, Korea Concrete Institute (in Korean).
  15. Moon, Y. H. (1999). Prediction of concrete strength with different curing temperature and time, Ph.D. Dissertation, Korea Advanced Institute of Science and Technology (in Korean).
  16. Park, S. W., Cho, H. D. and Jaung, J. D. (2009a). "A study on the strength properties of high-strength concrete under various curing conditions (2)." Proc. of 2009 Korea Concrete Institute Spring Conference, KCI, Busan, Korea, pp. 273-274 (in Korean).
  17. Park, S. W., Yu, M. H., Cho, H. D. and Jaung, J. D. (2009b). "A study on the strength properties of high-strength concrete under various curing conditions (3)." Proc. of 2009 Korea Concrete Institute Autumn Conference, KCI, Yongin, Korea, pp. 465-466 (in Korean).
  18. Popovics, S. (1986). "Effect of curing method and final moisture condition on compressive strength of concrete." ACI Journal, ACI, Vol. 83, No. 4, pp. 650-657.
  19. Price, W. H. (1951). "Factors influencing concrete strength." Journal of American Concrete Institute, No. 47-31, pp. 417-432.
  20. Rastrup, E. (1954). "Heat of hydration in concrete", Magazine of Concrete Research, Vol. 6, No. 17, pp.79-92. https://doi.org/10.1680/macr.1954.6.17.79
  21. Yoon, G. W., Lee, Y. E. and Baek, D. H. (2002). "Determination of removal time of form." Proc. of 2002 Korea Concrete Institute Autumn Conference, KCI, Seoul, Korea, pp. 101-116 (in Korean).