scholarly journals Swelling pressure of a divalent-rich bentonite: Diffuse double-layer theory revisited

2009 ◽  
Vol 45 (5) ◽  
Author(s):  
Tom Schanz ◽  
Snehasis Tripathy
Keyword(s):  
Double Layer ◽  
Swelling Pressure ◽  
Diffuse Double Layer ◽  
Double Layer Theory

Swelling pressures of compacted bentonites from diffuse double layer theory

2004 ◽  
Vol 41 (3) ◽  
pp. 437-450 ◽  
Author(s):  
Snehasis Tripathy ◽  
Asuri Sridharan ◽  
Tom Schanz
Keyword(s):  
Radioactive Waste ◽  
Double Layer ◽  
Expansive Soils ◽  
Chemical Properties ◽  
Weighted Average ◽  
Swelling Pressure ◽  
Radioactive Waste Disposal ◽  
Diffuse Double Layer ◽  
Barrier Materials ◽  
Double Layer Theory

The swelling pressures of several compacted bentonites (MX80, Febex, and Montigel) proposed for use as barrier materials in storing high-level radioactive waste in many countries were determined from the Gouy–Chapman diffuse double layer theory. The swelling pressures thus determined were compared with the reported experimental swelling pressures. The study revealed that, in general, at low compaction dry densities of the bentonites, the experimental swelling pressures are less than their theoretical counterparts, with the reverse trend at high compaction dry densities. Based on the reported experimental results for the three bentonites, relationships between the nondimensional midplane potential function, u, and the nondimensional distance function, Kd, were established. New equations for the swelling pressure were proposed on the basis of the diffuse double layer theory and the reported experimental data to compute swelling pressures of compacted bentonites. The suitability of the new equations was also verified with additionally reported experimental swelling pressures from three other bentonites (Kunigel V1, Kunigel, and bentonite S-2) that have been also proposed for use as barrier materials. Very good agreement was found in all the cases between the experimental swelling pressures and the swelling pressures obtained using the proposed equations. The use of the proposed equations is based on the weighted average valency of the cations present in bentonites, since the valency of the cations present has a significant influence on the swelling pressure.Key words: clays, compressibility, swelling pressure, expansive soils, chemical properties, radioactive waste disposal.

scholarly journals Estimation of Compressibility and Permeability of Very Soft Clays by Means of the Diffuse Double Layer Theory

1991 ◽  
Vol 31 (3) ◽  
pp. 175-184 ◽  
Author(s):  
Hyeongjoo Kim ◽  
Hiroshi Yoshikuni ◽  
Kazuhiro Tsurugasaki
Keyword(s):  
Double Layer ◽  
Diffuse Double Layer ◽  
Soft Clays ◽  
Double Layer Theory

New equations for swelling characteristics of bentonite-based buffer materials

2003 ◽  
Vol 40 (2) ◽  
pp. 460-475 ◽  
Author(s):  
Hideo Komine ◽  
Nobuhide Ogata
Keyword(s):  
Double Layer ◽  
Nuclear Waste ◽  
Van Der Waals ◽  
Swelling Pressure ◽  
Van Der Waals Force ◽  
Diffuse Double Layer ◽  
Mass Ratio ◽  
Compacted Bentonite ◽  
Buffer Material ◽  
Swelling Characteristics

Compacted bentonite and sand–bentonite mixtures are attracting greater attention as buffer material for repositories of high-level nuclear waste. This buffer material is expected to fill up the space between the canisters containing the waste and the surrounding ground by swelling. To produce the specifications, such as dry density, sand–bentonite mass ratio, and dimensions, of the buffer material, the swelling characteristics of compacted bentonite and sand–bentonite mixtures must be evaluated quantitatively. New equations for evaluating the swelling behavior of compacted bentonite and sand–bentonite mixtures are presented that can accommodate the influences of the sand–bentonite mass ratio and the exchangeable-cation composition of bentonite. The new method for predicting swelling characteristics is presented by combining the new equations with the theoretical equations of the Gouy–Chapman diffuse double layer theory and of the van der Waals force, which can evaluate the repulsive and attractive forces of montmorillonite mineral (i.e., the swelling clay mineral in bentonite). Furthermore, the applicability of the new prediction method has been confirmed by comparing the predicted results with laboratory test results on the swelling deformation and swelling pressure of compacted bentonites and sand–bentonite mixtures.Key words: bentonite, diffuse double layer theory, van der Waals force, nuclear waste disposal, swelling deformation, swelling pressure.

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