The Sealing Mechanisms of a Fracture in Opalinus Clay as Revealed by in situ Synchrotron X-Ray Micro-Tomography

X-ray micro-tomography has been applied recently in a wide range of research fields (damage in materials, solidification …). Thanks to the high flux of synchrotrons and specific cameras the total time to acquire a scan was considerably reduced. The use of a specific camera based on CMOS technology allows dividing the acquisition time for a complete scan by a factor of 100. Therefore we have been able to perform in situ solidification of aluminium-copper alloys at high cooling rates (between 1 and 10°C/s) and we will show results concerning the evolution of the microstructure in 3D in the early stage of solidification, in particular the morphology of the solid phase and the kinetics of growth.

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Catastrophic failure: how and when? Insights from 4D in-situ x-ray micro-tomography

10.1002/essoar.10503361.1 ◽

2020 ◽

Author(s):

Alexis Cartwright-Taylor ◽

Ian G Main ◽

Ian B Butler ◽

Florian Fusseis ◽

Michael Flynn ◽

...

Keyword(s):

Catastrophic Failure ◽

X Ray ◽

Micro Tomography

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Fast in-situ X-ray micro tomography characterisation of microstructural evolution and strain-induced damage in alloys at various temperatures

International Journal of Materials Research (formerly Zeitschrift fuer Metallkunde) ◽

10.3139/146.110386 ◽

2010 ◽

Vol 101 (9) ◽

pp. 1080-1088 ◽

Cited By ~ 12

Author(s):

Michel Suéry ◽

Jérôme Adrien ◽

Caroline Landron ◽

Sofiane Terzi ◽

Eric Maire ◽

...

Keyword(s):

Microstructural Evolution ◽

X Ray ◽

Micro Tomography

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Synchrotron X-ray micro-tomography at the Advanced Light Source: Developments in high-temperature in-situ mechanical testing

Journal of Physics Conference Series ◽

10.1088/1742-6596/849/1/012043 ◽

2017 ◽

Vol 849 ◽

pp. 012043 ◽

Cited By ~ 2

Author(s):

Harold S. Barnard ◽

A.A. MacDowell ◽

D.Y. Parkinson ◽

P. Mandal ◽

M. Czabaj ◽

...

Keyword(s):

High Temperature ◽

Mechanical Testing ◽

Light Source ◽

X Ray ◽

Advanced Light Source ◽

In Situ Mechanical Testing ◽

Micro Tomography

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In Situ Measurements of the Hydration Behavior of Compacted Milos (SD80) Bentonite by Wet-Cell X-ray Diffraction in an Opalinus Clay Pore Water and a Diluted Cap Rock Brine

Minerals ◽

10.3390/min11101082 ◽

2021 ◽

Vol 11 (10) ◽

pp. 1082

Author(s):

Tobias Manzel ◽

Carolin Podlech ◽

Georg Grathoff ◽

Stephan Kaufhold ◽

Laurence N. Warr

Keyword(s):

Pore Water ◽

Packing Density ◽

In Situ Monitoring ◽

Opalinus Clay ◽

X Ray Diffraction ◽

Interlayer Water ◽

Steady State Condition ◽

X Ray ◽

Cap Rock

Compacted bentonite is currently being considered as a suitable backfill material for sealing underground repositories for radioactive waste as part of a multi-barrier concept. Although showing favorable properties for this purpose (swelling capability, low permeability, and high adsorption capacity), the best choice of material remains unclear. The goal of this study was to examine and compare the hydration behavior of a Milos (Greek) Ca-bentonite sample (SD80) in two types of simulated ground water: i) Opalinus clay pore water, and ii) a diluted saline cap rock brine using a confined volume, flow-through reaction cell adapted for in situ monitoring by X-ray diffraction. Based on wet-cell X-ray diffractometry (XRD) and calculations with the software CALCMIX of the smectite d(001) reflection, it was possible to quantify the abundance of water layers (WL) in the interlayer spaces and the amount of non-interlayer water uptake during hydration using the two types of solutions. This was done by varying WL distributions to fit the CALCMIX-simulated XRD model to the observed data. Hydrating SD80 bentonite with Opalinus clay pore water resulted in the formation of a dominant mixture of 3- and 4-WLs. The preservation of ca. 10% 1-WLs and the apparent disappearance of 2-WLs in this hydrated sample are attributed to small quantities of interlayer K (ca. 8% of exchangeable cations). The SD80 bentonite of equivalent packing density that was hydrated in diluted cap rock brine also contained ca. 15% 1-WLs, associated with a slightly higher concentration of interlayer K. However, this sample showed notable suppression of WL thickness with 2- and 3-WLs dominating in the steady-state condition. This effect is to be expected for the higher salt content of the brine but the observed generation of CO2 gas in this experiment, derived from enhanced dissolution of calcite, may have contributed to the suppression of WL thickness. Based on a comparison with all published wet-cell bentonite hydration experiments, the ratio of packing density to the total layer charge of smectite is suggested as a useful proxy for predicting the relative amounts of interlayer and non-interlayer water incorporated during hydration. Such information is important for assessing the subsequent rates of chemical transport through the bentonite barrier.

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Pore formation during dehydration of a polycrystalline gypsum sample observed and quantified in a time-series synchrotron X-ray micro-tomography experiment

Solid Earth ◽

10.5194/se-3-71-2012 ◽

2012 ◽

Vol 3 (1) ◽

pp. 71-86 ◽

Cited By ~ 31

Author(s):

F. Fusseis ◽

C. Schrank ◽

J. Liu ◽

A. Karrech ◽

S. Llana-Fúnez ◽

...

Keyword(s):

Time Series ◽

Pore Space ◽

Three Dimensional ◽

Internal Stresses ◽

Micro Computed Tomography ◽

X Ray ◽

Computer Codes ◽

Micro Tomography ◽

Effective Drainage

Abstract. We conducted an in-situ X-ray micro-computed tomography heating experiment at the Advanced Photon Source (USA) to dehydrate an unconfined 2.3 mm diameter cylinder of Volterra Gypsum. We used a purpose-built X-ray transparent furnace to heat the sample to 388 K for a total of 310 min to acquire a three-dimensional time-series tomography dataset comprising nine time steps. The voxel size of 2.2 μm3 proved sufficient to pinpoint reaction initiation and the organization of drainage architecture in space and time. We observed that dehydration commences across a narrow front, which propagates from the margins to the centre of the sample in more than four hours. The advance of this front can be fitted with a square-root function, implying that the initiation of the reaction in the sample can be described as a diffusion process. Novel parallelized computer codes allow quantifying the geometry of the porosity and the drainage architecture from the very large tomographic datasets (20483 voxels) in unprecedented detail. We determined position, volume, shape and orientation of each resolvable pore and tracked these properties over the duration of the experiment. We found that the pore-size distribution follows a power law. Pores tend to be anisotropic but rarely crack-shaped and have a preferred orientation, likely controlled by a pre-existing fabric in the sample. With on-going dehydration, pores coalesce into a single interconnected pore cluster that is connected to the surface of the sample cylinder and provides an effective drainage pathway. Our observations can be summarized in a model in which gypsum is stabilized by thermal expansion stresses and locally increased pore fluid pressures until the dehydration front approaches to within about 100 μm. Then, the internal stresses are released and dehydration happens efficiently, resulting in new pore space. Pressure release, the production of pores and the advance of the front are coupled in a feedback loop.

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