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Hydration of swelling clays: multi-scale sequence of hydration and determination of macroscopic energies from microscopic properties; Hydratation des argiles gonflantes : sequence d'hydratation multi-echelle determination des energies macroscopiques a partir des proprietes microscopiques.

Smectites have interesting properties which make them potential candidates for engineered barriers in deep geological nuclear waste repository: low permeability, swelling and cations retention. The subject of this thesis consists in the determination of the relationship between hydration properties, swelling properties and cations mobility in relation with confinement properties of clayey materials.

The aim is to understand and to predict the behaviour of water in smectites, following two research orientations: the mechanistic aspects and the energetic aspects of the hydration of smectites. We worked on the Na-Ca montmorillonite contained in the MX80 bentonite, with the exchanged homo ionic structure saturated with alkaline cations and calcium cations.

The approach crosses the various scales microscopic, mesoscopic and macroscopic and implied the study of the various components of the system layer-cation-water , by using original experimental methods thermo-poro-metry and electric conductivity for various relative humidities RH and electrostatic calculations. Initially, the dry state is defined by SCTA scanning calorimetry thermal analysis.

Then a classical characterization of the smectite porosity for the dry state is carried out using mercury intrusion and nitrogen adsorption. We evidenced the existence of a meso-porosity which radius varies from 2 to 10 nm depending on the compensating cation.

The thermo-poro-metry and conductivity experiments performed at various hydration states made it possible to follow the increase in the pore sizes and the cations mobility as a function of the hydration state. By combining the results of thermo-poro-metry, X-ray diffraction and electric conductivity, we are able to propose a complete hydration sequence for each cation, showing the crucial role of the compensating cation in the hydration of.

Fluid-Swelling Clays Interaction Interaction entre fluide et argile gonflante. Directory of Open Access Journals Sweden. Full Text Available The structural changes which occur during the swelling of Wyoming Na montmorillonite have been investigated by adsorption and desorption of water, simulation of XRD powder patterns, immersion microcalorimetry, and small-angle X-ray scattering in 10 to the power of -3 N NaCl solutions.

The progressive changes of the water concentration in the interlamellar space, and the mechanisms of water adsorption were followed from dry state to relative pressures up to 0.

The tactoids were found to consist of a few layers and the water was mainly located in the layers inside the tactoids. The formation of ferriargillans and densing processes were studied on a soil sequence over diabase situated in Piracicaba SP Brazil.

Morphological, micromorphological, scanning electron microscopic and microanalytical studies were performed on samples taken from three trenches within the sequence. The presence of illuvial ferriargillans was observed mainly in the argillic B horizons and the saprolite, which filled the mamelonar, polyconcave and planar voids which led to their densing.

Evidence of temporary hydromorphy suggested that this process would affect the stability of the iron oxide-clay interactions which would promote the mobilization and redistribution of iron and clay. Mineralogical association in the zone of argillic advanced alteration in a kaolin deposit of Patagonia Argentina.

This work is about the mineralogical and petrological relations of the para genetic association of advanced argillic zone in the kaolin deposit in Patagonia.

This study allowed to establish the sequence of events that took place in the deposit as well as the conditions under which they were generated. Hydration of swelling clay and bacteria interaction. An experimental in situ reaction study; Hydratation des argiles gonflantes et influence des bacteries.

Etude experimentale de reaction in situ. This study reports on the physical-chemical behaviour of swelling di-octahedral clays smectites and their interaction with aqueous solutions and bacteria Shewanella putrefaciens.

Experimental results are presented for compacted clays, hydrated under confined volume conditions, using a new type of reaction-cell the 'wet-cell' of Warr and Hoffman, that was designed for in situ X-ray diffraction XRD measurement. For comparison, dispersed clay systems were studied using standard batch solutions subjected to varying degrees of agitation. The combination of time-dependent in situ XRD measurements with gravimetric measurements and calculated diffraction patterns using the CALCMIX software Plancon and Drits, allowed to successful quantification of the dynamics of water uptake and storage.

This analytical procedure combined with published water vapour adsorption data enabled determination of the abundance of structured water layers, developed in the interlayer space, and the amount of water contained in different storage sites interlayers, surfaces and pore spaces. Qualitative information on surface area and textural organization was also estimated based on calculated changes in the average particle thickness and the organization of water layer structures ordering.

The rate of smectite hydration, as expected, was seen to be highly dependent on the type of interlayer cation enhanced for Ca as opposed to Na and the ionic strength of solution enhanced uptake rates with saline solutions, particularly as they infiltrate Na-smectite.

A range of dynamic changes in micro textural state occurred as a function of packing density. These changes explain the differences in hydration behaviour observed between Na- and Ca-smectite. The hydration mechanisms of compacted smectite occurring within a confined volume system are presented in a schematic model involving different scales, ranging from the Angstrom-scale of lattice layers to the bulk clay structure.

Whereas the nature of interlayer cation affects hydration on all scales, the ionic strength of the infiltrating solution primarily affects the bulk texture. The prolonged survival of bacteria in smectite suspensions compared to growth in culture medium is attributed to i a continuous and sustainable supply of cationic nutrients and Corg, ii the buffering capacity of the smectite clay and iii the large clay surface areas, which accumulate nutrients, serve as attachment sites and sorb toxic waste products.

The constantly depleted Ca is most likely stored in the abundant EPS exo-polymeric substance. In contrast, the Fe-poor, Na-smectite was not seen to be affected by bacterial activity in this way and the increased release of Al by acid leaching corresponds to only 1.

The presence of S. In confined volume conditions, the presence of bacteria in Na-smectite clay was seen to enhance both the uptake of interlayer water and the amount of externally stored surface and pore water. In this type of compacted smectite, an increase in the total thickness of water layer structures occurs due to bacterial enhancement of sample porosity as seen by combined X-ray diffraction study and CALCMIX profile calculations.

In the case of nontronite, additional water was stored as external water indicating a similar enhancement of porosity, but here, the rate of water inflow into the reaction cell decreased, most likely due to clogging of the pores by biofilm. With respect to the application of bentonites as a suitable backfill material in underground waste disposal sites, this study demonstrates that bacterial activity can modify both chemically and physically the properties of the smectite.

Even if bacteria are not likely to survive in a hydrated bentonite seal, their effects are considered to be long-term, especially due to bacterially produced substances such as EPS and organic ligands. Potentiality if Rb-Sr method for dating the argillous sedimentary rocks. The potentiality of application Rb-Sr method in argillous sediments, using samples from paleozoic and mesozoic formation in brazilian sedimentaries basin was tested.

Physical, chemistry and isotopic analysis of thirty eight samples were made in the laboratories of geochronology Research Center from the University of Sao Paulo. Four isochronic diagrams for the argillous sedimentary rocks were also proposed.

Mapping advanced argillic alteration at Cuprite, Nevada, using imaging spectroscopy. Swayze, Gregg A. Eric; Breit, George N. Distributions of Fe-bearing minerals, clays, micas, sulfates, and carbonates were mapped using the Tetracorder spectral-shape matching system.

The Al content of white micas increases toward altered areas and near intrusive rocks. Alunite composition varies from pure K to intimate mixtures of Na-K endmembers with subpixel occurrences of huangite, the Ca analogue of alunite.

Intimately mixed Na-K alunite marks areas of relatively lower alteration temperature, whereas co-occurring Na-alunite and dickite may delineate relict hydrothermal conduits. The presence of dickite, halloysite, and well-ordered kaolinite, but absence of disordered kaolinite, is consistent with acidic conditions during hydrothermal alteration.

Partial lichen cover on opal spectrally mimics chalcedony, limiting its detection to lichen-free areas. Pods of buddingtonite are remnants of initial quartz-adularia-smectite alteration. Thus, spectral maps provide a synoptic view of the surface mineralogy, and define a previously unrecognized early steam-heated hydrothermal event.

Faulting and episodes of hydrothermal alteration at Cuprite were intimately linked to upper plate movements above the Silver Peak-Lone Mountain detachment and growth, collapse, and resurgence of the nearby Stonewall Mountain volcanic complex between 8 and 5 Ma.

Isotopic dating indicates that hydrothermal activity started at least by 7. Spectral and stable isotope data suggest that Cuprite is a late Miocene low-sulfidation adularia-sericite type hot spring deposit overprinted by late-stage, steam-heated advanced argillic alteration formed along the margin of the Stonewall Mountain caldera.

The formation of argillic horizons in vertical soil profiles is mainly attributed to lessivage, namely the transport of clay from an upper E horizon to a deeper illuviated horizon.

Because of the long timescales involved in this phenomenon, quantitative modeling is useful to explore the role of clay lessivage on soil formation and sub-surface clay accumulation. The limitations of detailed models of colloidal transport to short timescales make it necessary to resort to simple models. Here, we present a parsimonious model of clay transport in which lessivage is interpreted stochastically. Clay particles approach the soil surface at a speed equal to the erosion rate and are intermittently transported to deeper soil layers when percolation events occur or removed by erosion.

Along with the evolution of clay particles trajectories, the model predicts the vertical clay profile, the depth of the B horizon, and the mean time to erosion. Dimensional analysis reveals the two dimensionless parameters governing the dynamics, leading to a new classification of soil types based on erosion rates and intensity of lessivage.

Itataia's phosphorous-uraniferous deposit - Alteration and argilization influence in physical processing of the mineralized lithologies. This study was developed by NUCLEBRAS, firstly defining the quality and quantity of the Itataia ore body untill the m level of the future pit, considering the lithological types, the P 2 O 5 and U 3 O 8 contents and the alteration and argillization of the rocks.

Finally it was compared the results of these two stages with the results of the pilot treatment, related to the gangue in the phosphoric acid concentrate. Through this charaterization it was defined three types of material related to the degree of alteration and argillization : Type I fresh or pratically fresh and little or monargillized material ; Type II partially altered and argillized material.

The new geological syntesis and iformation, together with seismic parameters allowed to a material classification according to the scarificability, and important factor in the costs of an open pit mine.

The spectral signatures of some alteration clay minerals, such as dickite and alunite, have similar absorption features; thus separating them using multispectral satellite images is a complex challenge. However, Hyperion with its fine spectral bands has potential for good separability of features. The Spectral Angle Mapper algorithm was used in this study to map three advanced argillic alteration minerals alunite, kaolinite, and dickite in a known alteration zone in the Peruvian Andes.

Controls and occurance of interflow over a restrictive argillic horizon in a low gradient hillslope. Interflow throughflow or lateral flow , is shallow lateral subsurface flow that moves over a horizon that restricts percolation. Interflow is important for a number of reasons. First, rapid saturated interflow through macropores can travel to streams and alluvial aquifers with high celerity. Also, experimental studies have shown that interflow can be an important source of baseflow and stormflow.

Because interflow travels through a biologically active region of soil with roots and relatively high OM content, the final outcome is the potential contamination of surface water bodies from subsurface water.

Many of the soils in the southeastern US are characterized by an argillic , or clay horizon, that largely parallels the soil surface at depths ranging from a few centimeters to hundreds of centimeters. The degree to which these argillic horizons alter subsurface movement of infiltrated water is not well known. Hydro-mechanical coupling and permeability of an unsaturated swelling clay under hydrous and thermal stress: sorption curve and water permeability; Couplage hydromecanique et permeabilite d'une argile gonflante non saturee sous sollicitations hydriques et thermiques: courbe de sorption et permeabilite a l'eau.

The use of swelling clay for engineered safety barriers of radioactive waste disposal require the understanding of its thermal-hydro-mechanical behaviour. This work concerns particularly the characterization and the modelling of the behaviour of one of these clays: the FoCa7 clay. The characteristics of the studied material are: the sorption desorption curve and the water permeability.

For each of them, new experiments have allowed to acquire data in fields still few explored: in temperature between 20 and 80 C for the sorption curve and in the unsaturated field for the water permeability.

The analysis of these results and of bibliographic data has allowed in one hand to estimate the importance of the hysteresis phenomenon and the temperature influence on the sorption curve and in another hand, to establish the requirement to introduce in the modelling of the sorption curve, a plastic parameter due to the irreversible deformations occurring during the compaction.

Moreover, the tests carried out for data acquirement have been used too to give validation elements to the non linear behaviour laws proposed by O. Coussy and P.

Dangla for the non saturated porous media. The particularity of these laws is to suppose the existence of an effective constraint in the non saturated field, this shows the importance of the validation elements presented here.

Full Text Available Northwest of Shir-Kuh batholith, a number of leucocratic granitic and granodioritic plutons have intruded sedimentary hosts including shale-sandstone Triassic-Jurassic and sandstone-conglomerate Lower Cretaceous. Contact metamorphism and hydrothermal alterations are widespread.


Translation of "argiles gonflantes" in English



Minéral argileux




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