Mechanical Properties of Cement Material for Energy-Foundation (EF) Structures

DOI QR코드

DOI QR Code

Park, Yong-Boo;Choi, Hang-Seok;Sohn, Jeong-Rak;Sim, Young-Jong;Lee, Chul-Ho

  • 투고 : 2012.01.02
  • 심사 : 2012.01.19
  • 발행 : 2012.01.30

초록

In this study, physical characteristics of cement and/or concrete materials that are typically used for energy-foundation (EF) structures have been studied. The thermal conductivity and structural integrity of the cement-based materials were examined, which are commonly encountered in backfilling a vertical ground heat exchangers, cast-in-place concrete piles and concrete lining in tunnel. For this purpose the thermal conductivity and unconfined compression strength of cement-based materials with various curing conditions were experimentally estimated and compared. Hydration heat generated from massive concrete in the cast-in-place concrete energy pile was observed for 4 weeks to estimate its dissipation time in the underground. The hydration heat may mask the in-situ thermal response test (TRT) result performed in the cast-in-place concrete energy pile. It is concluded that at least two weeks are needed to dissipate the hydration heat in this case. In addition, a series of numerical analysis was performed to compare the effect of thermal property of the concrete material on the cast-in-place pile.

키워드

Energy Foundation;Thermal Conductivity;Structural Integrity;Hydration Heat;Unconfined Compression Strength

참고문헌

  1. Allan, M. L. and A. J. Philippacopoulos (1999), "Properties and performance of cement-based grouts for geothermal heat pump application", U.S. Department of Energy.
  2. Gao, J., X. Zhang, J. Liu, K. Li, and J. Yang (2008), "Numerical and experimental assessment of thermal performance of vertical energy pile: An application", Applied Energy, 85:901-910. https://doi.org/10.1016/j.apenergy.2008.02.010
  3. Jun, L., X. Zhang, J. Gao, and J. Yang (2009), "Evaluation of heat exchange rate of GHW in geothermal heat pump system", Renewable Energy, 34: 2898-2904. https://doi.org/10.1016/j.renene.2009.04.009
  4. Lee, C., M. Park, S. Min, H. Choi, and B. Sohn (2010), "Evaluation of performance of grouts and pipe sections for close-loop vertical ground heat exchanger by in-situ thermal response test", Journal of Korean Geotechnical Society, 26(7): 93-106, In Korean.
  5. Man, L., H. Yang, N. Diao, J. Liu, and J. Fang (2010), "A new model and analytical solutions for borehole and pile ground heat exchangers", International Journal of Heat and Mass Transfer, 53: 2593-2061. https://doi.org/10.1016/j.ijheatmasstransfer.2010.03.001
  6. Nam, Y., R. Ooka, and S. Hwang (2005), "Development of a numerical model to predict heat exchange rate for a groune source heat pump system", Energy and Building, 40: 2113-2140.
  7. Nam, Y. and R. Ooka (2011), "Development of potential map for ground and groundwater heat pump systems and application to Tokyo", Energy and Building, 43: 677-685. https://doi.org/10.1016/j.enbuild.2010.11.011
  8. Pahud, D. and M. Hubbuck (2007), "Measured thermal performances of the energy pile system of the Duck Midfield at Zurick Airport", Proceedings European Geothermal Congress, Unterhaching, Germany.
  9. PCA (1997), "Portland cement, concrete and heat of hydration", Concrete Technology Today, Portland Cement Association, 18(2).
  10. Takegoshi, E., S. Imura, Y. Hirasawa, and T. Takenaka (1982), "A method of measuring the thermal conductivity of solid materials by transient hot wire method of comparison", Bulletin of the Japan Society of Mechanical Engineers, 25(201): 395-402. https://doi.org/10.1299/jsme1958.25.395
  11. Yavuzturk, C., J. D. Spitler, and S. J. Rees (1999), "A transient two-dimensional finite volume model for simulation of vertical U-tube ground heat exchanger", ASHRAE Transactions, 105(2): 465-474.