Shear strength of unsaturated bentonite buffer material

Compacted bentonite materials are often considered as a buffer material in the geological radioactive waste disposal. This bentonite is expected to fill up the space between the waste and the surrounding ground by swelling. Therefore, understanding the surrounding ground, i.e., groundwater behavior in bentonite, as a buffer material, is essential in order to evaluate the bentonite buffer performance and guarantee long-term safety. The monitoring system of the water saturation level in compacted bentonite is required because water content in buffer material may influence its elastic properties. In this study, the correlation between water content and elasticity in unsaturated compressed bentonite was experimentally evaluated. The evaluation was done by measuring the sound velocity of both longitudinal wave and transverse wave. As a result, it can be confirmed that ultrasonic velocities could evaluate a degree of saturation and bulk modulus of compacted bentonite.

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An assessment of strontium sorption onto bentonite buffer material in waste repository

Environmental Science and Pollution Research ◽

10.1007/s11356-017-8536-1 ◽

2017 ◽

Vol 24 (9) ◽

pp. 8825-8836 ◽

Cited By ~ 20

Author(s):

Pankaj Pathak

Keyword(s):

Bentonite Buffer ◽

Buffer Material ◽

Waste Repository ◽

Strontium Sorption

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Model for the Microbiological Corrosion of Copper Containers in a Deep Geologic Repository

MRS Proceedings ◽

10.1557/proc-807-811 ◽

2003 ◽

Vol 807 ◽

Cited By ~ 8

Author(s):

Fraser King ◽

Miroslav Kolar ◽

Simcha Stroes-Gascoyne ◽

Peter Maak

Keyword(s):

Microbial Activity ◽

Corrosion Behaviour ◽

Geologic Repository ◽

Microbiological Corrosion ◽

Microbiological Processes ◽

Bentonite Buffer ◽

Buffer Material ◽

The Impact ◽

Aerobic And Anaerobic

ABSTRACTA model has been developed to predict the impact of microbiological processes on the long-term corrosion behaviour of copper containers in a deep geologic repository. The model accounts for a range of aerobic and anaerobic microbial processes. Various factors expected to limit the extent of microbial activity in the repository, such as the lack of water, evolving redox conditions, and the nutrient-poor environment, are taken into account in the model. Amongst other effects, the model predicts that microbial activity will not occur close to the container in the presence of highly compacted bentonite buffer material.

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Laboratory gas injection tests of compacted bentonite buffer material for TRU waste disposal

Geological Society London Special Publications ◽

10.1144/sp400.27 ◽

2014 ◽

Vol 400 (1) ◽

pp. 521-529 ◽

Cited By ~ 3

Author(s):

Kazuto Namiki ◽

Hidekazu Asano ◽

Shinichi Takahashi ◽

Tomoyuki Shimura ◽

Ken Hirota

Keyword(s):

Waste Disposal ◽

Gas Injection ◽

Compacted Bentonite ◽

Bentonite Buffer ◽

Buffer Material

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Isothermal modeling of sand–bentonite mixtures at elevated temperatures

Canadian Geotechnical Journal ◽

10.1139/t95-006 ◽

1995 ◽

Vol 32 (1) ◽

pp. 78-88 ◽

Cited By ~ 36

Author(s):

B.E. Lingnau ◽

J. Graham ◽

N. Tanaka

Keyword(s):

Shear Strength ◽

Elevated Temperatures ◽

Triaxial Compression ◽

Friction Angle ◽

Compression Tests ◽

Strain Behavior ◽

Bentonite Buffer ◽

State Boundary ◽

Increasing Temperature ◽

Triaxial Compression Tests

Two models are proposed for describing the stress–strain behavior of sand–bentonite (buffer) mixtures at elevated temperatures: (1) isothermal pseudoelasticity and (2) isothermal elastic-plasticity. Data to support the models come from consolidated undrained triaxial compression tests performed on dense saturated buffer specimens at effective confining stresses up to 9.0 MPa and temperatures of 26°, 65°, and 100 °C. Measurements indicate that volumes decrease with increasing temperature if the tests are carried out under drained conditions. These trends can be modelled by a family of hardening lines in semilog compression space. Power law relationships are presented for undrained shear-strength envelopes that increase in size with an increase in temperature. The slopes of unload-reload lines, κ, in semilog compression space vary with temperature and can be related to systematic variation in the friction angle [Formula: see text]. The shear modulus G50 at 50% peak strength also depends on temperature. Several plotting techniques are used to show the existence of different state boundary surfaces for each test temperature. Key words : sand–bentonite, buffer, compression, shear strength, temperature, modelling.

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Study Of Factors Affecting The Thermal Conductivity Of Iraqi Bentonite

Baghdad Science Journal ◽

10.21123/bsj.9.3.548-553 ◽

2012 ◽

Vol 9 (3) ◽

pp. 548-553

Author(s):

Baghdad Science Journal

Keyword(s):

Experimental Data ◽

Thermal Conductivity ◽

Volume Fraction ◽

Dry Density ◽

Factors Affecting ◽

Compacted Bentonite ◽

Bentonite Buffer ◽

Buffer Material ◽

Major Factors ◽

Water Contents

Thermal conductivity of compacted bentonite is one of the most important properties where this type of clay is proposed for use as a buffer material. In this study, Lee's disc method was used to measure the thermal conductivity of compacted bentonite specimens. The experimental results have been analyzed to observe the three major factors affecting the thermal conductivity of bentonite buffer material. While the clay density reaches to a target value, the measurement is taken to evaluate the thermal conductivity. By repeating this procedure, a relationship between clay dry density and thermal conductivity has been established in specimens after adjusting the water contents of the bentonite by placing its specimens in a drying oven for different periods. So relationships of thermal conductivity with each of these major factors (clay density, water content, and sand volume fraction) are established in this study. The relevance of these relationships be analyzed together using experimental data on many compacted bentonites.

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