Thermal Conductivity of Bentonite Grout Containing Graphite or Chopped Carbon Fibers
Publication: Journal of Materials in Civil Engineering
Volume 26, Issue 7
Abstract
The effectiveness of chopped carbon fibers to enhance the thermal conductivity of bentonite-based grout was examined. Fibers of 3 mm and 150 μm in length were added to sodium bentonite and silica sand mixtures at different volumetric concentrations. The thermal conductivity of the resulting composite material was then measured using a non-steady-state needle probe technique. The conductivities of the fibrous materials were compared to bentonite and sand mixtures containing natural flake graphite and milled, compressed exfoliated graphite at corresponding volumetric concentrations. The resulting conductivities for all tested materials increased with the volumetric fraction of additive. However, the 3-mm carbon fibers were more effective as compared to either granular graphite; at a volume fraction of 0.68% the 3-mm fibers were approximately twice as effective as either form of graphite.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
This research was funded by the Natural Sciences and Engineering Research Council of Canada. The authors wish also to acknowledge the support of Mr. Peter Koudys in the development of the thermal needle probe and the experimental technique. Both the carbon fibers and the granular graphite used in this study were provided by Asbury Carbons.
References
Agari, Y., Ueda, A., and Nagai, S. (1991). “Thermal conductivity of polyethylene filled with disoriented short-cut carbon fibres.” J. Appl. Polym. Sci., 43(6), 1117–1124.
Allan, M. L., and Kukacka, L. E. (1995). “Permeability of microcracked fibre-reinforced containment barriers.” Waste Manage., 15(2), 171–177.
ASTM. (2008). “Standard test method for determination of thermal conductivity of soil and soft rock by thermal needle probe procedure.”, ASTM International, West Conshohocken, PA.
Bigg, D. M. (1979). “Mechanical, thermal, and electrical properties of metal fiber-filled polymer composites.” Polym. Eng. Sci., 19(16), 1189–1192.
Delaleux, F., Py, X., Olives, R., and Dominguez, A. (2012). “Enhancement of geothermal borehole heat exchangers performances by improvement of bentonite grouts conductivity.” Appl. Therm. Eng., 33–34, 92–99.
Demain, A., and Issi, J. P. (1993). “The effect of fiber concentration on the thermal conductivity of a polycarbonate/pitch-based carbon fiber composite.” J. Compos. Mater., 27(7), 668–683.
Fukai, J., Kanou, M., Kodama, Y., and Miyatake, O. (2000). “Thermal conductivity enhancement of energy storage media using carbon fibers.” Energy Convers. Manage., 41(14), 1543–1556.
Karaipekli, A., Sari, A., and Kaygusuz, K. (2007). “Thermal conductivity improvement of stearic acid using expanded graphite and carbon fiber for energy storage applications.” Renewable Energy, 32(13), 2201–2210.
Lee, C., Lee, K., Choi, H., and Choi, H. P. (2010). “Characteristics of thermally-enhanced bentonite grouts for geothermal heat exchanger in South Korea.” Sci. China E, 53(1), 123–128.
Lee, C., Park, M., Nguyen, T. B., Sohn, B., Choi, J. M., and Choi, H. (2012). “Performance evaluation of closed-loop vertical ground heat exchangers by conducting in-situ thermal response tests.” Renewable Energy, 42, 77–83.
Miller, C. J., and Rifai, S. (2004). “Fiber reinforcement for waste containment soil liners.” J. Environ. Eng., 891–895.
Nan, C. W., Shi, Z., and Lin, Y. (2003). “A simple model for thermal conductivity of carbon nanotube-based composites.” Chem. Phys. Lett., 375(5–6), 666–669.
Information & Authors
Information
Published In
Journal of Materials in Civil Engineering
Volume 26 • Issue 7 • July 2014
Copyright
© 2014 American Society of Civil Engineers.
History
Received: Mar 12, 2013
Accepted: Nov 7, 2013
Published online: Nov 9, 2013
Published in print: Jul 1, 2014
Discussion open until: Sep 9, 2014
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.