scholarly journals Bentonite swelling characteristics with a hypersaline multi-component pore fluid

2021 ◽  
Vol 58 (3) ◽  
pp. 367-376
Author(s):  
R.W.I. Brachman ◽  
R.K. Rowe ◽  
A. Baral ◽  
M.S. Hosney ◽  
G. Su ◽  
...  
Keyword(s):  
Chemical Interaction ◽  
Total Dissolved Solids ◽  
Deionized Water ◽  
Pore Fluid ◽  
Dry Density ◽  
Michigan Basin ◽  
Volume Increase ◽  
Compacted Bentonite ◽  
Swelling Characteristics ◽  
Swell Pressure

Swelling characteristics of compacted bentonite when hydrated with a hypersaline pore fluid (332 g/L total dissolved solids; 6.6 mol/L ionic strength) are reported. The pore fluid mimics the multiple constituents and their concentrations found for the Cobourg limestone of the Michigan Basin and is dominated by sodium (25% mole fraction) with some potassium, calcium, and magnesium (10%, 5%, and 4% mole fractions). Measurements of swell pressure for two sodium bentonites when hydrated under conditions of zero volume increase are reported. Swell pressure reached a peak within 10–30 h from the onset of hydration, followed by a continual decrease over 1 year of testing from chemical interaction between the bentonite and pore fluid. After 1 year, the swell pressure of the MX-80 bentonite tested decreased by a factor of nine relative to the peak swell pressure with deionized water when the dry density was 1.6 Mg/m3. Swell pressures increased as dry density increased. However, chemical interactions appear to have more influence on swell pressure than density for the pore fluid examined as a swell pressure of just under 1200 kPa was measured for MX-80 after 1.8 years of hydration when compacted to the highest dry density of 1.8 Mg/m3 examined.

Experimental study on swelling characteristics of compacted bentonite

1994 ◽  
Vol 31 (4) ◽  
pp. 478-490 ◽  
Author(s):  
Hideo Komine ◽  
Nobuhide Ogata
Keyword(s):  
Water Content ◽  
Nuclear Waste ◽  
Volumetric Strain ◽  
Swelling Pressure ◽  
Dry Density ◽  
Initial Water Content ◽  
Initial Water ◽  
Compacted Bentonite ◽  
Swelling Characteristics ◽  
High Level

Compacted bentonites are attracting greater attention as back-filling (buffer) materials for repositories of high-level nuclear waste. However, since there are few studies about the swelling characteristics of compacted bentonites, it is first necessary to clarify the fundamental swelling characteristics in detail. For this purpose, various laboratory tests on the swelling deformation and swelling pressure of compacted bentonites were performed and the results analyzed. The following conclusions were drawn from the study. (i) The curve of swelling deformation versus time is strongly dependent on the initial dry density, vertical pressure, and initial water content. The maximum swelling deformation, however, is almost independent of initial water content, and the maximum swelling deformation increases in proportion to the initial dry density, (ii) The maximum swelling pressure increases exponentially with increasing initial dry density, whereas the maximum swelling pressure is almost independent of initial water content. (iii) The swelling mechanism of compacted bentonite was considered on the basis of the swelling behavior of swelling clay particles such as montmorillonite. Furthermore, a model of the swelling characteristics and a new parameter (swelling volumetric strain of montmorillonite), which were able to evaluate the swelling characteristics of compacted bentonite, were proposed. Key words : bentonite, laboratory test, nuclear waste disposal, swelling deformation, swelling pressure.

scholarly journals Response of compacted bentonite to hyperalkalinity and thermal history

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rohini C. Kale ◽  
Bhanwariwal Kapil ◽  
K. Ravi
Keyword(s):  
Thermal History ◽  
Dry Density ◽  
Distilled Water ◽  
Cement Concrete ◽  
Compacted Bentonite ◽  
Concrete Layer ◽  
Geological Repository ◽  
High Level Nuclear Waste ◽  
High Level ◽  
Swell Pressure

AbstractThe use of compacted bentonite around the high-level nuclear waste canister (HLW) inside the deep geological repository (DGR) ensures the prevention of entry of active radionuclides in the atmosphere due to its noteworthy large swelling ability. In the eventual repository, the waste canister has a high (100 °C–200 °C) temperature initially, and it reduces over a vast period, which induces a thermal history over the compacted bentonite layer. The cement/concrete layer is constructed as a bulkhead or in the vaults or to support the access of galleries between a buffer and the host rock, and it degrades over the period. The hyperalkaline fluid is created when it percolates through the cement/concrete layer and comes in contact with the compacted bentonite. The contact of hyperalkaline fluid to compacted bentonite induced with thermal history can hamper the swell pressure characteristic of the bentonite. Therefore to determine the combined effect of hyperalkalinity to the thermal history induced compacted bentonite, swell pressure testing has been conducted on two compacted Barmer bentonites (B1 and B2) specimens with an initial dry density of 1.5 Mg/m3, 1.75 Mg/m3, and 2.0 Mg/m3 and saturated with distilled water as well as with hyperalkaline cement water (W/C = 1 und pH = 12.5) and heated to 110 °C and 200 °C. When the specimens were saturated with hyperalkaline cement water, the swell pressure exerted by both bentonites was noticeably reduced compared to specimens saturated with distilled water. Nevertheless, the time taken to full saturation was longer than distilled water for samples saturated with hyperalkaline cement water. Also, the decrease in swell pressure was observed in the samples subjected to thermal history than samples, which were tested without inducing thermal history in both the cases of hyperalkaline cement water and distilled water. The microstructural observations through XRD, FESEM and EDX revealed the clogging of pores due to the presence of non-swelling minerals.

Swelling Pressures of Compacted Bentonite/Sand Mixtures

1984 ◽  
Vol 44 ◽  
Author(s):  
M. N. Gray ◽  
S. C. H. Cheung ◽  
D. A. Dixon
Keyword(s):  
Threshold Value ◽  
Deionized Water ◽  
Silica Sand ◽  
Dry Density ◽  
Sodium Bentonite ◽  
Compacted Bentonite ◽  
Bentonitic Clay ◽  
Soil Fabric ◽  
Nuclear Fuel Waste ◽  
Limiting Value

AbstractCompacted bentonitic clay/sand mixtures are being considered for use as buffer materials in the Canadian concept for nuclear fuel waste disposal. This paper describes a laboratory study of the swelling pressures that develop in statically compacted, air-dry specimens of mixtures of sodium bentonite and silica sand as they are saturated with double-distilled, deionized water. The results are interpreted with the aid of scanning electron microscope observations of the soils' structures.It is shown that the sand acts as an inert filler material, and swelling pressures are controlled by a parameter termed the effective clay dry density, γC, defined as the ratio of the mass of clay to the combined volume of the claq plus voids in the mixture. A threshold value of γC exists below which swelling pressures can be expected to be isotropic. Above the threshold value of γC, pressures parallel to the axis of compaction can be expected to be greatgr than those perpendicular to it. This is related to a change in soil fabric as γC is increased above the threshold value. For the Canadian disposal concept, γC would probably be below the limiting value and swelling pressures of 2.5 MPS or less are expected. The swelling pressures are likely to be isotropic within a saturated buffer mass.

Migration Behaviour of Lanthanides in Compacted Bentonite with Iron Corrosion Product Using Electrochemical Method

2012 ◽  
Vol 1475 ◽  
Author(s):  
Kazuya Idemitsu ◽  
Daisuke Akiyama ◽  
Yoshihiko Matsuki ◽  
Yusuke Irie ◽  
Yaohiro Inagaki ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Dispersion Coefficient ◽  
Reference Electrode ◽  
High Level Waste ◽  
Dry Density ◽  
Migration Behavior ◽  
Iron Corrosion ◽  
Compacted Bentonite ◽  
Steel Coupon ◽  
Best Fit

ABSTRACTAfter the closure of a high-level waste repository, corrosion of the carbon steel overpack will occur. The corrosion products can then migrate into bentonite and affect the migration behavior of radionuclides in bentonite. Therefore, electrochemical experiments, with Fe2+ supplied by anodic corrosion of carbon steel, were carried out to study trivalent lanthanides in compacted bentonite. The interface between a carbon steel coupon and bentonite (dry density, 1.5 Mg/m3) was spiked with a tracer solution containing Nd(NO3)3, Eu(NO3)3, Dy(NO3)3, and Er(NO3)3. The carbon steel coupon was connected as the working electrode to a potentiostat and held at a constant potential between -550 and 0 mV (vs. Ag/AgCl reference electrode) for 7 days. A model using dispersion and electromigration could explain the measured profiles in the bentonite specimens. The best-fit electromigration velocity was related to the applied electric potential and was 1.0–3.8 nm/s for Nd, Eu, Dy, and Er ions. For these lanthanides, the best-fit dispersion coefficient was also related to the applied potential and was 0.8–1.6 μm2/s, and the dispersion length was calculated as 0.2 mm from the linear relationship between the dispersion coefficient and electromigration velocity. Finally, the apparent diffusion coefficient for these lanthanides was estimated as 0.6–0.9 μm2/s.

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.

Research on the Swelling Characteristics of Expansive Soil

2011 ◽  
Vol 250-253 ◽  
pp. 1761-1764
Author(s):  
Wei Fu ◽  
Wan Ping Wu ◽  
Sha Wu ◽  
Bin He ◽  
Yan Bin Ruan
Keyword(s):  
Initial Conditions ◽  
Three Dimensional ◽  
Expansive Soil ◽  
Quantitative Relationship ◽  
Dry Density ◽  
Time Interval ◽  
Initial Water Content ◽  
Initial Water ◽  
Overburden Pressure ◽  
Swelling Characteristics

Swelling tests of remolded expansive soil with water immersing are carried out by use of the simple consolidometers. The swelling characteristics of the expansive soil under the different initial conditions are studied. The Dose Response model is used to fit the rules of swelling time interval for expansive soil with water immersing. The quantitative relationship among the swelling and initial overburden pressure, initial water content and initial dry density is attained by use of the three dimensional regression analyses. The important index obtained could be provided to the engineering design, construction and stability evaluation of expansive soil slopes.

Distribution Coefficients and Apparent Diffusion Coefficients of Cesium in Compacted Bentonites

1999 ◽  
Vol 556 ◽  
Author(s):  
Akiko Okamoto ◽  
Kazuya Idemitsu ◽  
Hirotaka Furuya ◽  
Yaohiro Inagaki ◽  
Tatsumi Arima
Keyword(s):  
Diffusion Coefficients ◽  
Distribution Coefficients ◽  
Dry Density ◽  
Apparent Diffusion Coefficients ◽  
Compacted Bentonite ◽  
Apparent Diffusion ◽  
Tracer Solution ◽  
Cesium Concentration ◽  
Penetration Profile ◽  
Very High

AbstractDistribution coefficients and apparent diffusion coefficients of cesium in some compacted bentonites were determined by the penetration profile method. Cylindrical compacted bentonites with the dry density of 0.8 to 1.6 Mg/m3 were contacted with tracer solutions containing 1000, 100 or 10 ppm of cesium. The apparent diffusion coefficients were obtained from the concentration profiles of cesium in compacted bentonites. The distribution coefficients were obtained concurrently by dividing the intercepts of the profiles by the concentration of the tracer solution. The apparent diffusion coefficients of cesium in compacted bentonite were obtained in the range of 0.42 to 9.6· 10−12 m2/s. The apparent diffusion coefficients in the compacted bentonite contacted with three different concentrations of cesium tended to decrease with increasing dry density of the specimen; but, they had no dependence on cesium concentration within a factor of 3 at the same dry density. The distribution coefficient of cesium for the specimens contacted with three different concentrations of cesium were obtained in the range of 0.3 to 90 L/kg and had little dependence on dry density. The distribution coefficients obtained in the compacted bentonites were dependent on pH of the solution rather than concentration of cesium. These distribution coefficients obtained in the compacted bentonites were 10 to 1000 times smaller than those obtained by batch experiments. The data suggest that not all sorption sites for cesium are available in highly compacted bentonite. It is necessary to consider surface diffusion as a significant migration mechanism of cesium through the compacted bentonites at very high pH condition such as 12.

scholarly journals Characterization of Biofluid-Based Coolant-Mix Produced From Emulsified Groundnut Oils

2019 ◽  
Vol 11 (3) ◽  
pp. 285-292
Author(s):  
T. A. Yusuf ◽  
O. Orihu ◽  
T. D. Ipilakyaa
Keyword(s):  
Heat Transfer ◽  
Specific Gravity ◽  
Base Fluid ◽  
Water Extract ◽  
Total Dissolved Solids ◽  
Deionized Water ◽  
Cutting Fluids ◽  
Heat Transfer Fluids ◽  
Engine Cooling

Coolants are generally heat transfer fluids used as cutting fluids for machining or engine cooling. They are generally mixture of various constituents and their chemistry is responsible for their performance, acceptability and shelf lives. With much known about the merit of agro-based materials, this study proposes the use of bio-waters in coolant-mix as a substitute for ordinary water commonly used as base fluids. Water extract from fermented ground maize (WEFGM) employed as bio-water was emulsified in bio-oils (groundnut oils) to form a complete bio-fluid based for the coolant to which other additives are added to form the test solutions. Replicate samples were formulated with similar standards using deionized WEFGM and deionized water for comparison at 5 and 10%vol of additives. Following various analytical tests, the developed coolant samples have concentration 2.33-2.58mg/L, total dissolved solids 31.2-73.2 g/L, pH 1.85-2.50, specific gravity 1.29-1.31 and viscosity 8.12-11.44 cSt. At both additive concentrations, the biofluid-based samples have proven better in terms of all these properties than water which is generally considered as the most suitable and being currently used as base fluid in most heat transfer applications.

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