Australian National Drag Racing Association

About: Australian National Drag Racing Association is a based out in . It is known for research contribution in the topics: Corrosion & Radioactive waste. The organization has 1014 authors who have published 1572 publications receiving 31390 citations.

Investigation of smectite hydration properties by modeling experimental X-ray diffraction patterns: Part I. Montmorillonite hydration properties

Abstract: Hydration of the <1 μm size fraction of SWy-1 source clay (low-charge montmorillonite) was studied by modeling of X-ray diffraction (XRD) patterns recorded under controlled relative humidity (RH) conditions on Li-, Na-, K-, Mg-, Ca-, and Sr-saturated specimens. The quantitative description of smectite hydration, based on the relative proportions of different layer types derived from the fitting of experimental XRD patterns, was consistent with previous reports of smectite hydration. However, the coexistence of smectite layer types exhibiting contrasting hydration states was systematically observed, and heterogeneity rather than homogeneity seems to be the rule for smectite hydration. This heterogeneity can be characterized qualitatively using the standard deviation of the departure from rationality of the 00 l reflection series (ξ), which is systematically larger than 0.4 A when the prevailing layer type accounts for ~70% or less of the total layers (~25% of XRD patterns examined). In addition, hydration heterogeneities are not distributed randomly within smectite crystallites, and models describing these complex structures involve two distinct contributions, each containing different layer types that are interstratifed randomly. As a result, the different layer types are partially segregated in the sample. However, these two contributions do not imply the actual presence of two populations of particles in the sample. XRD profile modeling also has allowed the refinement of structural parameters, such as the location of interlayer species and the layer thickness corresponding to the different layer types, for all interlayer cations and RH values. From the observed dependence of the latter parameter on the cation ionic potential ( v / r; v = cation valency and r = ionic radius) and on RH, the following equations were derived: \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \[Layer\ thickness\ (1W)\ =\ 12.556\ +\ 0.3525\ {\times}\ ({ u}/\mathit{r}\ {-}\ 0.241)\ {\times}\ ({ u}\ {\times}\ RH\ {-}\ 0.979)\] \end{document} \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \[Layer\ thickness\ (2W)\ =\ 15.592\ +\ 0.6472\ {\times}\ ({ u}/\mathit{r}\ {-}\ 0.839)\ {\times}\ ({ u}\ {\times}\ RH\ {-}\ 1.412)\] \end{document} which allow the quantification of the increase of layer thickness with increasing RH for both 1W (one water) and 2W (two water) layers. In addition, for 2W layers, interlayer H2O molecules are probably distributed as a unique plane on each side of the central interlayer cation. This plane of H2O molecules is located at ~1.20 A from the central interlayer cation along the c* axis.

Volumetric Digital Image Correlation Applied to X-ray Microtomography Images from Triaxial Compression Tests on Argillaceous Rock

Abstract: A set of triaxial compression tests on specimens of argillaceous rock were performed under tomographic monitoring at the European Synchrotron Radiation Facility in Grenoble, France, using an original experimental set-up developed at Laboratoire 3S, Grenoble Complete 3D images of the specimens were recorded throughout each test using X-ray microtomography Such images were subsequently analysed using a Volumetric Digital Image Correlation software developed at the Laboratoire de Me?canique des Solides in Palaiseau, France Full-field incremental strain measurements were obtained, which allow to detect the onset of shear strain localisation and to characterise its development in a 3D complex pattern Volumetric Digital Image Correlation revealed patterns which could not be directly observed from the original tomographic images, because the deformation process in the zones of localised deformation was essentially isochoric (ie without volumetric strain), hence not associated to density changes

ANDRA underground research laboratory: interpretation of the mineralogical and geochemical data acquired in the Callovian-Oxfordian formation by investigative drilling

Abstract: Under the ANDRA Meuse/Haute Marne underground research laboratory scientific programme, two boreholes (EST204 and EST205) were drilled to a depth of 510 m for the purposes of scientific characterisation. Twenty-nine core samples were taken in borehole EST205 every 3 m between 422 and 504 m depth. Physical property measurements (water content, porosity, density, specific surface), geochemical analyses (major and trace elements, cation exchange capacity [CEC] and surface cation occupancy, leaching anions, redox state, organic matter concentration), and a semi-quantitative mineralogical study were conducted on the samples. As the rocks are in a reduced state, the core samples were stored under nitrogen immediately after drilling. All the steps of the sampling and of the characterisation are done with a research of limitation of the oxidation to obtain representative samples of the in situ conditions. The top of the formation is more carbonate-rich, with interbedded clayey layers and carbonate rock. The formation is more homogeneous in its central section with a clay mineral concentration of 45-50%, which corresponds to a maximum of flooding within the area. In the upper part of this section, micas and mixed-layer illite/smectite R0 dominate, whereas in the lower part of the section we find an abrupt transition to mixed-layer illite/smectite R1 associated with kaolinite. A statistical analysis, including the data of major and trace elements with the semi-quantitative mineralogy, enabled the identification of some mineralogical traps for trace elements. The values of cation occupancy at the surface of the clay minerals provided a good image of the pore water chemistry; pore water is in equilibrium with the clay surfaces. Leaching experiments revealed the pore water salinity and provided profiles of Cl and Br concentrations. Cl/Br values in the centre of the formation are close to the present-day seawater ratio, which could indicate a seawater origin of the pore water. Some measurements of total reduced capacity, provide quantified results of the reduced state of the rock. Processing the data on water content, helium and petroleum pycnometry enabled calculation of total rock porosity and gave an uncertainty range for this value. Finally, the high BET(N-2) specific surfaces are consistent with the clayey nature of the rock.

Geological and hydraulic characterisation of the excavation disturbed zone in the Opalinus Clay of the Mont Terri Rock Laboratory

Abstract: The fracture network in the excavation disturbed zone (EDZ) of an argillaceous formation, the Opalinus Clay in the Mont Terri Rock Laboratory in northwest Switzerland, is characterised using structural and hydrogeological techniques. Sampling of unloading fractures is done by analysing resin-injected overcores taken from the EDZ, resulting in a structural data set of fracture orientations, frequencies and extent of the EDZ. These parameters are derived in tunnel sections, which were excavated by blasting, pneumatic hammering and road header techniques. Pneumatic and hydrogeological tests are subsequently carried out to derive hydraulic parameters such as permeability and transmissivity distributions of the fracture network. Synthesis of the structural and hydrogeological data led to a conceptual model of the EDZ in the Mont Terri Rock Laboratory, which is defined by a 2-m plastically deformed zone around the tunnel. This plastic zone is further divided into an inner 1 m zone consisting of an air-filled fracture network and an outer zone with mostly saturated and isolated fractures. Transmissivities in the inner zone are orders of magnitude higher than those of the undisturbed Opalinus Clay. Finally, a methodology is proposed for the structural and hydrogeological characterisation of the EDZ. This methodology is not site-specific and is thus applicable at any argillaceous underground facility.

A critical review of thermodynamic data for selenium species at 25°C

Abstract: The accuracy of published selenium thermodynamic data was evaluated to obtain a reliable basis for modelling Se migration behaviour in contaminated areas The Modified Bromley's Methodology was used to correct equilibrium constant to the standard state (zero ionic strength, 25°C and 1 bar pressure) Since redox reactions control the migration of selenium, equilibria between the various Se oxidation states and the associated reactions — acid–base, precipitation, and complexation — were studied Although pKa values for H2SeO3 and H2SeO4 acid–base reactions are well known, an ambiguity exists for the second dissociation of H2Se A value of 14 appears to be more suitable than a value close to 115 The most adequate standard potentials for the redox reactions of selenium are proposed Because of the very low solubility of metal-selenides, most of their solubility product constants are derived from combination of formation thermodynamic data selected in the literature or extrapolated from those of the corresponding sulfides Several values are reported for Se(IV) and Se(VI), but they are not always in agreement In generally, few values have been determined recently and noticeable differences can be observed between old and recent values For complexation reactions, there is a lack of data and for many equilibria only one constant is available