Microstructure and anisotropic swelling behaviour of compacted bentonite/sand mixture

Saba, Simona; Barnichon, Jean-Dominique; Cui, Yu‐Jun; Tang, Anh Minh; Delage, Pierre

doi:10.1016/j.jrmge.2014.01.006

Cited by 115 publications

(40 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is also well established that bentonite displays a high swelling characteristic that is a function of the aforesaid physicochemical properties related to the montmorillonite mineral [3,[11][12][13][14]. The high swelling capacity provides an effective mechanism for the barrier to retard and adsorb radionuclides as well as the ability to self-heal to ensure fissure closure.…”

Section: Introductionmentioning

confidence: 99%

Physicochemical and Geotechnical Alterations to MX-80 Bentonite at the Waste Canister Interface in an Engineered Barrier System

Davies¹,

Davie

Edward

et al. 2017

Geosciences

View full text Add to dashboard Cite

Abstract:The study investigated the basic geomechanical and mineralogical evolution of the bentonite barrier under various experimental boundary conditions which replicated the near-field Thermo-Hydro-Chemico (THC) conditions in a repository. The relationships between the physicochemical alterations and changes in the geotechnical properties have seldom been studied, especially on a consistent dataset. This paper attempts to link the physicochemical properties of Na-bentonite (MX-80) to the macro-scale engineering functionality of the bentonite post THC exposure. Experiments investigated the impact of THC variables on the engineering and physicochemical functionality of the bentonite with respect to its application within a High-Level Waste (HLW) engineered barrier system. Intrinsic alterations to the MX-80 bentonite under relatively short-term exposure to hydrothermal and chemical conditions were measured. Additionally, two long-term tests were conducted under ambient conditions to consider the impact of exposure duration. The intrinsic measurements were then related to the overall performance of the bentonite as a candidate barrier material for application in a UK geological disposal facility. Findings indicate that exposure to thermo-saline-corrosion conditions (i.e., corrosion products derived from structural grade 275 carbon steel) inhibits the free swell capacity and plasticity of the bentonite. However, the measured values remained above the design limits set out for the Swedish multi-barrier concept, from which the UK concept may take a lead. Corrosion alone does not appear to significantly affect the geotechnical measurements compared with the influence of thermal loading and high saline pore water after relatively short-term exposure. Thermal and corrosion exposure displayed no impact on the intrinsic swelling of the smectite component, indicating that no significant structural alteration had occurred. However, when exploring more complex saline solutions i.e., mixed Na, K and Ca, rather than the reference NaCl, divalent cation replacement was observed within the interlayer exchange site. This was accelerated in higher thermal loading conditions.

show abstract

Section: Introductionmentioning

confidence: 99%

Physicochemical and Geotechnical Alterations to MX-80 Bentonite at the Waste Canister Interface in an Engineered Barrier System

Davies¹,

Davie

Edward

et al. 2017

Geosciences

View full text Add to dashboard Cite

show abstract

“…The kinetics of relative humidity was found to be similar to the swelling pressure kinetics observed in the present work. Saba et al (2014a) investigated the anisotropy on the swelling pressure of the same material and found that the axial swelling pressure is slightly higher than the lateral one. In the present work, the final value of axial swelling pressure is also higher than the final values of radial ones.…”

Section: Discussionmentioning

confidence: 99%

Infiltration Column for Studying the Lateral Swell Behavior of Expansive Clay

Saba

Cui

Barnichon

et al. 2016

Geotechnical Testing Journal

Self Cite

View full text Add to dashboard Cite

International audienceInfiltration column is usually used to investigate the hydro-mechanical processes in unsaturated expansive clay. In this test, the moisture transfer is often monitored along the column during water infiltration using suction or water content probes. Nevertheless, the lateral swelling pressure developed is rarely considered. This paper describes an infiltration column for studying the lateral swell behavior of expansive clay. The column consists of a rigid cell ensuring the constant-volume condition and a hydraulic system enabling the water intake of the hosted sample. It is equipped with three types of sensors: pressure sensors, force transducers, and displacement transducers to, respectively, monitor the radial and axial swelling pressure of the sample at different positions and to check whether any axial displacement is taking place. A detailed description of the different parts of the cell is first presented. Second, analysis on the results of a test on a compacted bentonite/sand mixture allows the pertinence of such a device to be evaluated

show abstract

“…These bentonite particles swell anisotropically upon water uptake. This anisotropic swelling can be attributed to the difference in axial and radial stresses acting upon bentonite particles (Lee et al 2012;Saba et al 2014). Thus it is expected that the pore structure and distribution of pores in the bentonite reorganise upon hydration (Börgesson 1985;Katsumi et al 2008;Pusch 1982;Wang et al 2012), depending on the amount and types of stresses experienced.…”

Section: Page 12 Of 46mentioning

confidence: 99%

Thermal conductivity of geosynthetic clay liners

et al. 2016

View full text Add to dashboard Cite

The thermal conductivities of powdered and granular bentonite based needle punched GCLs were investigated at different gravimetric water contents under 25, 50, 75 and 100 kPa vertical stresses, respectively. Both types of GCLs exhibited an increase in thermal conductivity with increasing vertical stress at all water contents. The effect of vertical stresses was more pronounced for the specimens hydrated at lower gravimetricwater contents and this was attributed to their high initial volumetric air content. The variability of water distribution in partially hydrated GCLs has been identified as a factor which may affect their thermal conductivity. The forms of bentonites (i.e., powder or granular) affected their thermal conductivities; however, this effect was less apparent at higher gravimetric water contents due to the reduced air content and gel formation in the bentonites.Finally, the GCL thermal conductivity, calculated from the measured thermal conductivities of its various constituents (i.e geotextile and bentonite) components, differed from the measured values.This was attributed to the non-uniform water distribution across the GCL specimen and change in material properties when components of GCL were disassembled.

show abstract

Microstructure and anisotropic swelling behaviour of compacted bentonite/sand mixture

Cited by 115 publications

References 25 publications

Physicochemical and Geotechnical Alterations to MX-80 Bentonite at the Waste Canister Interface in an Engineered Barrier System

Physicochemical and Geotechnical Alterations to MX-80 Bentonite at the Waste Canister Interface in an Engineered Barrier System

Infiltration Column for Studying the Lateral Swell Behavior of Expansive Clay

Thermal conductivity of geosynthetic clay liners

Contact Info

Product

Resources

About