Abstract
The equivalent diffuse double layer (DDL) thickness in clay-electrolyte systems is a very useful parameter for analyzing the engineering behavior of clays under different environmental conditions. The equivalent DDL thickness is generally assumed to be equal to the characteristic (Debye) length. The present work examined critically the applicability of characteristic length to define equivalent DDL thickness under various clay-surface and pore-fluid conditions. A critical analysis is presented of the changes in the equivalent DDL thickness and characteristic length under the influence of different clay-surface and electrolyte properties. The equivalent DDL thickness was found to be smaller than the characteristic length for a wide range of surface and pore-fluid parameters normally encountered in engineering practice. An accurate and simple power relationship was developed to predict the equivalent DDL thickness from the characteristic length, which is applicable to a wide range of clay-electrolyte systems.
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References
Achari, G., Joshi, R., Bentley, L., and Chatterji, S. (1999) Prediction of the hydraulic conductivity of clays using the electric double layer theory. Canadian Geotechnical Journal, 36, 783–792.
Baille, W., Tripathy, S., and Schanz, T. (2010) Swelling pressures and one-dimensional compressibility behaviour of bentonite at large pressures. Applied Clay Science, 48, 324–333.
Bharat, T.V., Sivapullaiah, P.V., and Allam, M.M. (2013) Novel procedure for the estimation of swelling pressures of compacted bentonites based on diffuse double layer theory. Environmental Earth Sciences, 70, 303–314.
Chen, J. and Anadarajah, A. (1998) Influence of pore fluid composition on volume of sediments in kaolinite suspensions. Clays and Clay Minerals, 46, 145–152.
Fernandez, F. and Quigley, R.M. (1985) Hydraulic conductivity of natural clays permeated with simple liquid hydrocarbons. Canadian Geotechnical Journal, 22, 205–214.
Japan Nuclear Cycle Development Institute (JNCDI) (1999) H12: Project to Establish the Scientific and Technical Basis for HLW Disposal in Japan: Supporting Report 2 (Respiratory Design and Engineering Technology), Japan Nuclear Cycle Development Institute, Tokyo.
Kitazumi, Y., Shirai, O., Yamamoto, M., and Kano, K. (2013) Numerical simulation of diffuse double layer around microporous electrodes based on the Poisson-Boltzmann equation. Electrochimica Acta, 112, 171–175.
Lambe, W.T. and Whitman, R.V. (1979) Soil Mechanics. Wiley, New York.
Low, P.F. (1980) The swelling of clay. II. Montmorillonites. Soil Science Society of America Journal, 44, 667–676.
MATLAB 8.0 and Statistics Toolbox 8.1 (2012) The MathWorks, Inc., Natick, Massachusetts, USA.
McBride, M.B. (1997) A critique of diffuse double layer models applied to colloid and surface chemistry. Clays and Clay Minerals, 45, 598–608.
Mitchell, J.K. and Soga, K. (2005) Fundamentals of Soil Behavior. Wiley, New York.
Muhunthan, B. (1994) Liquid limit and surface area of clays. Geotechnique, 41, 135–138.
Poortinga, A.B., Bos, R., Norde, W., and Busscher, H.J. (2002) Electric double layer interaction in bacterial adhesion to surfaces. Surface Science Reports, 47, 1–32.
Prakash, K. and Sridharan, A. (2004) Free swell ratio and clay mineralogy of fine-grained soils. Geotechnical Testing Journal, 27, 220–225.
Schanz, T. and Tripathy, S. (2009) Swelling pressure of a divalent rich bentonite: Diffuse double-layer theory revisited. Water Resources Research, 45, 1–9.
Scruton, B. and Blott, B.H. (1973) A high resolution probe for scanning electrostatic potential profiles across surfaces. Journal of Physics E: Scientific Instruments, 6, 472–474.
Sellin, P. and Leupin, O.X. (2014) The use of clay as an engineered barrier in radioactive-waste management — a review. Clays and Clay Minerals, 61, 477–498.
Sridharan, A. and Prakash, K. (1999a) Influence of clay mineralogy and pore medium chemistry on clay sediment formation. Canadian Geotechnical Journal, 36, 961–966.
Sridharan, A. and Prakash, K. (1999b) Mechanisms controlling the undrained shear strength behaviour of clays. Canadian Geotechnical Journal, 36, 1030–1038.
Sridharan, A. and Choudhury, D. (2002) Swelling pressure of sodium montmorillonites. Geotechnique, 52, 459–462.
Sridharan, A., Rao, S.M., and Murthy, N.S. (1986) Liquid limit of montmorillonite soils. Geotechnical Testing Journal, 19, 156–164.
Tripathy, S., Sridharan, A., and Schanz, T. (2004) Swelling pressures of compacted bentonites from diffuse double layer theory. Canadian Geotechnical Journal, 41, 437–450.
van Olphen, H. (1977) An Introduction to Clay Colloid Chemistry. Interscience, New York.
Verwey, E.J.W. and Overbeek, J.T.G. (1948) Theory of the Stability of Lyophobic Colloids. Elsevier, Amsterdam.
Zheng, L., Samper, J., and Montenegro, L. (2011) A coupled THC model of the FEBEX in situ test with bentonite swelling and chemical and thermal osmosis. Journal of Contaminant Hydrology, 126, 45–60.
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Formerly Professor of Civil Engineering, Indian Institute of Science, Bangalore
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Bharat, T.V., Sridharan, A. A Critical Appraisal of Debye Length in Clay-Electrolyte Systems. Clays Clay Miner. 63, 43–50 (2015). https://doi.org/10.1346/CCMN.2015.0630104
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DOI: https://doi.org/10.1346/CCMN.2015.0630104