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This work evaluates the resistance to chemical attack and thermal shock of refractory bricks made from local clays and natural sand from Burkina Faso for their validation in industrial use. The clay was extruded and then sintered at 1300 ° C with a 1 hour hold to produce chamotte. Bricks were made by pressing a mixture of raw clays and chamotte, or raw clays and sand, then sintered at different temperatures ranging from 1250 to 1400 ° with steps of 50 ° C and a level of 2 time. The results of the thermal shock test show that these two types of bricks have average strength. The test with the concentrated solutions of sulfuric acid and soda showed that these bricks are also resistant to acid and basic attacks. The results obtained qualify the bricks for industrial use. [ABSTRACT FROM AUTHOR]

Pendant longtemps, le psychotraumatisme est resté l'affaire des médecins militaires. Les derniers attentats sur le sol français et le nombre important de personnes ayant développé un trouble de stress post-traumatique ont depuis ouvert la voie à de nouvelles approches dans la prise en charge. Cet article étudie par quels processus et dans quelle mesure un atelier d'art-thérapie par l'argile peut aider les personnes ayant subi un traumatisme. Comment l'argile, en tant que médium malléable, peut-elle contribuer au processus de changement dans un cadre thérapeutique ? Peut-elle favoriser l'élaboration du vécu PTSD ? L'argile permettrait un premier temps une voie cathartique nécessaire, suivi d'un deuxième temps d'élaboration et d'un troisième de transformation. Ces trois étapes sont-elles garantes d'un pronostic positif lors d'un PTSD ? Ce travail prend en compte l'importance de l'alliance thérapeutique entre thérapeute et participant. Cette relation est construite autour d'un cadre contenant et structurant qui permet au processus de création de se mettre en place. The purpose of this paper was to review of the benefits of art therapy in the management of post-traumatic stress disorder (PTSD). Psychotrauma has long been the business of military doctors. However, the latest attacks on French soil have opened the door for new approaches in care. Research in clinical psychology and psychopathology underlines the effectiveness of art therapy in the treatment of PTSD. Our aim is to identify the extent to which and the processes through which clay may be of benefit to people having suffered trauma. As a malleable medium, can clay contribute to the process of change in a therapeutic setting? Can it help the patient confront trauma-related information in a therapeutic manner? Clay is a vehicle that allows for three steps in the therapeutic process. First, clay allows for a cathartic release of emotions. Second, it helps elaborate the traumatic experience. Third, it leads to transformation. Do these three steps guarantee a positive prognosis for PTSD? This work takes into account the importance of the patient-therapist therapeutic alliance. This relationship, built within a structured and containing therapeutic framework, allows the creative process to take place. Art therapy with clay helps reduce anxiety. The act of kneading, smoothing, touching, or moistening the clay, makes artistic creation a pleasant and relaxing activity. This induces relaxation and the reduction of cortisol levels, reducing stress and anxiety. This relaxation is comparable to that achieved through mindfulness. Clay makes the unconscious visible and thus creates possibilities for investigating emotions and cognition. This contributes to cognitive regulation. Varying instructions during the sessions allow the participant to learn to self-regulate through touch, and control physical reactions that trigger the cycle of stress. Work with clay provides distance, improved recall of trauma and easier access to emotions. The setting, instruction, and attitude of the therapist create a safe environment for the conscious expression of emotions and memories. This is similar to exposure, recall, and emotional distancing and allows for better regulation of emotion. Clay facilitates the association of ideas. It helps the patient open up to his therapist and their experience during the process of creating with clay can be deepened through conversation. After identifying and isolating negative thoughts, patients gain new skills on how to counteract them. Clay allows the elaboration of thought and improves the capacity for symbolization and imagination. The results presented in this article provide insight into the effectiveness of clay art therapy in trauma treatment. They highlight the urgent need for further research on art therapy and trauma treatment. [ABSTRACT FROM AUTHOR]

Abstract In the present work, we have investigated the adsorption capacities of natural raw clays originated from Tunisia, such as those from Tabarka (a mixture of kaolinite and illite) and from Fouchana (a mixture of smectite, kaolinite, and illite), a standard kaolinite (KGa-2), and a palygorskite (PFl-1) for the removal of a reactive red dye (RR 120) usually found in textile industry effluents. Thus, batch adsorption experiments were performed and were tuned by varying different parameters such as adsorption contact time, aqueous phase pH, ionic strength, and initial dye concentration. In addition, zeta potential measurements allowed the determination of the electrical charge and of the dye behavior at the clay–water interface. Despite the fact that palygorskite has higher porosity and specific surface values, the amount of dye adsorbed on this clay is low in comparison to that of the other solid samples, regardless of the values of pH and ionic strength of the aqueous phase. On the other hand, a higher amount of adsorbed dye was observed on KGa-2, having the lowest specific surface area value. This sample, in comparison to smectite and fibrous clays, was found to be more efficient in the removal the anionic dye, and thus it can be used as an adsorbent for the treatment of effluents in the textile industry. Graphical abstract Image 1 Highlights • The clay particles' efficiency in the dye removal from the textile effluents depends on the clay mineralogical composition. • Clay having largest specific surface area and porosity values has the lowest removal dye capacity. • Clay having lowest specific surface area and cationic exchange capacity values shows the highest removal dye capacity. • Dye adsorption on the clay results mainly from the electrostatic interaction occurring between the dye and the clay. • The adsorption process of the anionic dye on the clay is exothermic and more favourable at ambient temperature. [ABSTRACT FROM AUTHOR]

We measured organic-layer (OL) recovery and carbon stocks in dead woody debris a decade after wildfire in black spruce ( Picea mariana (Mill.) B.S.P.) forests of interior Alaska. Previous study at these research plots has shown the strong role that landscape position plays in governing the proportion of OL consumed during fire and revegetation after fire. Here, we show that landscape position likely influences fire dynamics in these stands through changes in mineral soil texture. The content of fine-textured materials in underlying mineral soils was positively related to OL depths measured 1 and 10 years after fire, and there was an interaction between soil texture and elevation in governing OL consumption and OL recovery a decade following fire. OL depths 10 years after fire were 2 cm greater than 1 year after fire, with a range of 19 cm of accumulation to 9 cm of subsidence. Subsidence was inversely related to the percentage of fine textures within the parent material. The most influential factor determining the accumulation of OL carbon stocks a decade following wildfire was the interaction between landscape position and the presence of fine-textured soil. As such, parent material texture interacted with biological processes to govern the recovery of soil organic layers. [ABSTRACT FROM AUTHOR]

Low-cost biosourced hybrid microporous adsorbents with improved affinity towards carbon dioxyde (CO2) were prepared through the incorporation of various amounts of glucosylated dendrimer into bentonite- and montmorillonite-rich composite materials. Characterization by nitrogen adsorption-desorption isotherms, surface specific and pore size analyses (BET and BJH), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) revealed changes in the interlayer spacing and textural structure of the materials. Thermal programmed desorption measurements (TPD) showed significant improvements of the retention capacity of CO2 (CRC) and water (WRC). This was explained in terms of enhancement of both surface basicity and hydrophilic character due to the incorporation of terminal polyhydroxyl groups. The CRC was found to vary according to the previous saturation time with CO2 and the carrier gas throughput. CO2 was totally released upon temperature not exceeding 80 °C or even at room temperature upon strong carrier gas stream, thus providing evidence that CO2 capture involves almost exclusively physical interaction with the OH groups of the dendrimer. This result opens promising prospects for the reversible capture of carbon dioxide with easy release without thermal regeneration, more particularly when extending this concept to biosourced dendrimers. [ABSTRACT FROM AUTHOR]

Researches for non-energy intensive construction products, that are durable and cheaper is today of global concern because of the limited resources (energy, financial, etc.). To address this issue, the present work presents the combination of the decoction of pods of Parkia Biglobosa (néré) that is rich in tannins compounds including gallic acid, epicatechin gallate and epigallocatechin, with a clay-sand mixture. The clay used is referenced KORO and contains montmorillonite, illite, quartz, albite, orthoclase, kaolinite and goethite. The study of the mechanical properties of geomaterials formulated from the mixture shows that they have values of mechanical resistance higher and that their behavior becomes viscoplastic. This is due to the formation of chemical complexes from carboxylic groups of tannins macromolecules with the iron oxy-hydroxide in the interlayer spacing of clay minerals. This process is enhanced by the sorption of tannins on the surface of clay minerals. [ABSTRACT FROM AUTHOR]

After oil sands separations, settling of clays from aqueous tailings can be promoted by additives such as Ca2+ salts. However, if the liberated water is then recycled, these same additives in the water interfere with bitumen recovery in the separator. Therefore, we have tested CO2-triggered switchable additives to see whether they can switch back and forth between a form that is suitable for the separation stage and a form that promotes tailings ponds settling. CO2-triggered switchable additives can reversibly change water chemistry merely by introduction and removal of CO2, a benign trigger. Here, the effects of CO2-mediated switchable additives on colloidal interactions found in model oil sands were studied by chemical force spectrometry. Self-assembled monolayers of 12-phenyldodecanethiol and 12-mercaptododecanoic acid were used to chemically modify gold-coated atomic force microscope tips. These were subsequently used to study the adhesion force between the modified tips and the minerals silica and mica. The adhesion between the tips and the mineral substrates was studied in aqueous solutions of varying pH and divalent cation concentration and in the presence of cationic switchable additives of varying surfactant potency, both in the presence and in the absence of CO2. In the presence of CO2, the best additive promotes attractive forces, while in the absence of CO2, the forces are repulsive. These results are discussed in the context of the mechanism of colloidal interactions in an oil sands system. [ABSTRACT FROM AUTHOR]

Background: Determinants of waterpipe use in adolescents are believed to differ from those for other tobacco products, but there is a lack of studies of possible social, cultural, or psychological aspects of waterpipe use in this population. This study applied a socioecological model to explore waterpipe use, and its relationship to other tobacco use in Swedish adolescents. Methods: A total of 106 adolescents who attended an urban high-school in northern Sweden responded to an anonymous questionnaire. Prevalence rates for waterpipe use were examined in relation to socio-demographics, peer pressure, sensation seeking behavior, harm perception, environmental factors, and depression. Results: Thirty-three percent reported ever having smoked waterpipe (ever use), with 30 % having done so during the last 30 days (current use). Among waterpipe ever users, 60 % had ever smoked cigarettes in comparison to 32 % of non-waterpipe smokers (95 % confidence interval 1.4-7.9). The odds of having ever smoked waterpipe were three times higher among male high school seniors as well as students with lower grades. Waterpipe ever users had three times higher odds of having higher levels of sensation-seeking (95 % confidence interval 1.2-9.5) and scored high on the depression scales (95 % confidence interval 1.6-6.8) than non-users. The odds of waterpipe ever use were four times higher for those who perceived waterpipe products to have pleasant smell compared to cigarettes (95 % confidence interval 1.7-9.8). Waterpipe ever users were twice as likely to have seen waterpipe use on television compared to non-users (95 % confidence interval 1.1-5.7). The odds of having friends who smoked regularly was eight times higher for waterpipe ever users than non-users (95 % confidence interval 2.1-31.2). Conclusion: The current study reports a high use of waterpipe in a select group of students in northern Sweden. The study adds the importance of looking at socioecological determinants of use, including peer pressure and exposure to media marketing, as well as mental health among users. [ABSTRACT FROM AUTHOR]

Background: Determinants of waterpipe use in adolescents are believed to differ from those for other tobacco products, but there is a lack of studies of possible social, cultural, or psychological aspects of waterpipe use in this population. This study applied a socioecological model to explore waterpipe use, and its relationship to other tobacco use in Swedish adolescents. Methods: A total of 106 adolescents who attended an urban high-school in northern Sweden responded to an anonymous questionnaire. Prevalence rates for waterpipe use were examined in relation to socio-demographics, peer pressure, sensation seeking behavior, harm perception, environmental factors, and depression. Results: Thirty-three percent reported ever having smoked waterpipe (ever use), with 30 % having done so during the last 30 days (current use). Among waterpipe ever users, 60 % had ever smoked cigarettes in comparison to 32 % of non-waterpipe smokers (95 % confidence interval 1.4–7.9). The odds of having ever smoked waterpipe were three times higher among male high school seniors as well as students with lower grades. Waterpipe ever users had three times higher odds of having higher levels of sensation-seeking (95 % confidence interval 1.2–9.5) and scored high on the depression scales (95 % confidence interval 1.6–6.8) than non-users. The odds of waterpipe ever use were four times higher for those who perceived waterpipe products to have pleasant smell compared to cigarettes (95 % confidence interval 1.7–9.8). Waterpipe ever users were twice as likely to have seen waterpipe use on television compared to non-users (95 % confidence interval 1.1–5.7). The odds of having friends who smoked regularly was eight times higher for waterpipe ever users than non-users (95 % confidence interval 2.1–31.2). Conclusion: The current study reports a high use of waterpipe in a select group of students in northern Sweden. The study adds the importance of looking at socioecological determinants of use, including peer pressure and exposure to media marketing, as well as mental health among users. [ABSTRACT FROM AUTHOR]

Kinetics of methane hydrate formation with different ratios of silica sand and clay and different water saturations were studied. At suitable temperature and methane gas pressure, water in the void spaces of silica sand packing and intercalated area of clay were converted into hydrate. It was observed that the rate of hydrate formation increases with higher void space in the packing, and addition of clay in test sediment decreases water to hydrate conversion as well as rate of hydrate formation. Maximum water to hydrate conversion of 60.0% was achieved in pure silica sand bed at 75% water saturation. Presence of fine clay particles is expected to reduce the void spaces and thus may hinder effective mass transfer of hydrate forming gases in the bed. However, it is also possible that the bentonite clay used in this work may actually inhibit hydrate growth. Additional experiments in stirred tank reactor were carried out to understand the inhibiting effect of bentonite clay for hydrate formation. [ABSTRACT FROM AUTHOR]

Fossil-bearing shale specimens that include sulfides in their compositions are chemically reactive and sometimes also mechanically fragile. This decay is often related to iron sulfate efflorescence resulting from the oxidation of sulfide compounds. The processes underlying these degradations are poorly known, thus impeding the elaboration of curative or preventive treatments. The present contribution aims to identify the origin of museum specimen alterations. It focuses on the Flouest collection housed at the Muséum national d’Histoire naturelle (MNHN, Paris, France) and originating from the Autun Basin (Saône-et-Loire, France; Permian). To evaluate the alteration of MNHN specimens, it appeared necessary to compare their composition with that of unaltered shale so as to identify chemical changes occurring during ageing. Therefore new material was collected in the Autun Basin, among others on the locality of Muse that corresponds to the same lithostratigraphic unit than that of the MNHN specimens. The present article focuses on the combined use of X-ray diffraction and Mössbauer spectrometry for characterizing the speciation and reactivity of iron within the shale matrix. Crystalline pyrite was evidenced by X-ray diffraction (XRD) on one sample only and elemental analysis showed that iron is present in large excess with respect to sulfur. Iron sulfide, if present, involves a minor fraction of iron. A more complete characterization of iron-bearing phases was achieved with Mössbauer measurements, showing that a great part of iron, between approx. 25% and 65%, corresponds to iron(II) incorporated in clay minerals (illite and vermiculite were detected by XRD). Similar percentages of these iron(II) signatures were found for MNHN specimens and new shale samples, suggesting that iron(II) present in clays is not affected by ageing. This point is complementary highlighted by porosity and permeability measurements showing that the pore size distribution of the samples originating from Muse is mostly unimodal and narrow (average radius below 10 nm). As a result, the shale is poorly permeable to water and almost fully impermeable to oxygen. This might explain the poor reactivity of iron(II) during ageing. Iron(III)-bearing phases were also identified. On new shale samples, they exclusively involve clay minerals. On MNHN specimens, poorly crystallized iron(III) sulfates are additionally observed. The presence of iron(III) oxyhydroxides appeared unlikely. The change of iron speciation provoked by the alteration of the matrix also mainly corresponds to the emergence of more or less crystallized iron(III) sulfates probably formed though iron sulfide oxidation. These phases however remain in the inner part of shale and cannot account for the large efflorescence of iron(II) sulfates observed nearby the fossil. [ABSTRACT FROM AUTHOR]

Résumé La position et le contenu systématique de la famille des Mecochiridae sont brièvement revus. Meyeria houdardi (Van Straelen, 1936) des argiles de faciès Gault de l’Albien de l’est du bassin de Paris et du Pays de Bray est décrit de manière détaillée. Les structures suivantes, jusque-là inconnues, sont décrites : rostre, sillon hépatique, endopleurites, somites abdominaux postérieurs et éventail caudal. Un ? Meyeria sp. du Cénomanien basal de Charente-Maritime est décrit. Ces deux espèces étaient vraisemblablement fouisseuses, déposivores et suspensivores, et vivaient sur des fonds sédimentaires abrités, calmes, à sédimentation argileuse, en domaine marin. The systematic placement and content of the family Mecochiridae are briefly reviewed. Meyeria houdardi (Van Straelen, 1936) (Gault facies, Albian, East of the Paris Basin and Pays de Bray) is revisited and described in detail. Previously unknown rostrum, hepatic furrow, endopleurites, posterior abdominal somites and caudal fan are described. A ? Meyeria sp. (lowermost Cenomanian, Charente-Maritime) is described. Both species were seemingly burrowers, deposit and suspension feeders and lived on sheltered, quiet, clayey sedimentary bottom, in marine domain. [ABSTRACT FROM AUTHOR]

This paper presents the case study of the Ampurdán tunnel that suffered an unexpected partial collapse during construction due to the weathering of the claystone groundmass after excavation and wetting by infiltration water. To overcome the problems encountered, a finite elements model was used to understand the behaviour of the tunnel and surrounding ground to determine the geotechnical properties that lead to failure, allowing engineers to choose suitable procedures for the construction of the tunnel. The parametric study performed simulated the deformations measured in situ and related to the tunnel collapse. The geotechnical parameters used for the weathered claystone, when compared with the intact portion, correspond to a wide range of reductions between 8 % in the apparent density and in the effective friction angle, up to 40 % in the effective cohesion and 56 % in the Young modulus. [ABSTRACT FROM AUTHOR]

The objective of this research is to provide a better understanding of the relation between the macroscopic and microscopic behaviours of two clayey materials, a kaolinite and a mixture of kaolinite and montmorillonite. At the macroscopic scale, the approach consists of measuring the water content, void ratio and degree of saturation versus suction (s) during drying, which allows to specify the relationship between shrinkage and desaturation and highlights the characteristic phases of behaviour. At the microscopic scale, study of the orientation of the clay particles is carried out by scanning electron microscope (SEM) picture analysis under different suctions. On drying paths, the observations show an isotropy of the microfabric. The evolution of the porosity derived from mercury intrusion porosimetry tests is confirmed by SEM photograph observations. [ABSTRACT FROM AUTHOR]

Instrumental neutron activation analysis was used to determine nine rare earth elements ( REE), Sc and five high field-strength elements ( HFSE) in the Multani Mitti ( MM) clay. Chondrite-normalised rare earth element patterns for the MM clay compared with those for the Post-Archaean Australian Shale ( PAAS), Upper Continental Crust ( UCC) and North American Shale Composite ( NASC) showed enrichment of light REEs and depletion of heavy REEs with a slight negative Eu anomaly. The Multani Mitti clay showed close resemblance to PAAS and NASC in its average REE and HFSE contents. Positive correlations between La/Ce, La/Sm, La/Yb, Zr/Hf, Th/U and Th/Ta ratios predict enrichment of LREEs, Zr and Th and depletion of HREEs. A parent source of felsic origin for the MM clay is also endorsed through the high La/Th and low Th/Sc ratios observed. [ABSTRACT FROM AUTHOR]

A permeability test in a monitoring well (MW) is used to assess the hydraulic conductivity, k, of clay. To interpret the test data, the piezometric level (PL) during the test must be known. A previous paper has concluded that due to a long time lag, the water level in the pipe is never a PL and any extrapolation of water level versus time gives an unreliable prediction of the PL. As a result, an incorrect PL yields an incorrect k value. This paper shows that a variable-head permeability test can provide a fair estimate of both the PL and the k value when it is interpreted using the central portion of the velocity graph. The first portion of the graph, when the head difference and the gradients are high, is curved by the expansion of the injection zone (undrained and drained wall displacement with eventually some creep), and thus cannot be used. The last portion of the graph primarily reflects, with some time lag, the natural variations of hydraulic heads in adjacent aquifers, and thus must not be used. [ABSTRACT FROM AUTHOR]

Abstract: Clay materials, montmorillonite from Maghniya deposits (Algeria), were used as an acidic catalyst in toluene conversion. Toluene disproportionation reaction in gaseous phase was used. These clays were modified by ion exchange with uranyl ions UO2 2+. The surface acidity of catalysts was determined by the stepwise desorption technique (STD) of probe molecules using butylamine and ammonia. Thus, total acidity and distribution of the acidity strength were determined. The results show that materials presented an appreciable total acidity and catalytic activity in studied reaction. The acidity strength of catalysts due to UO2 2+ ions was kept at a temperature of 550°C. A relationship was found between the catalytic activity and acidity strength generated by the introduction of uranyl ions in the clay structure. [Copyright &y& Elsevier]

Pollution and nitrates fate in soils are a major environmental problem and concern. Good choice of treatment process and aims to achieve, may avoid the risk. The electrokinetic technique used here has proven its effectiveness in several cases. In this study this technique has been used in order to follow nitrates transport and retention in an Algerian clayey soil. Three electrokinetic trials have been carried out at laboratory scale at an imposed current of 0.050, 0.750 and 0.125 A. All results obtained show the efficient transport of nitrates from the cathode to the anode and their retention in the clayey soil. The two mechanisms involved in this transport are the electro-migration and the electro-osmosis. The low calculated energy consumption (150 Wh/kg), compared with those found in the literature, gives an incentive to the experimentation of this electrokinetic technique on a large scale. [ABSTRACT FROM AUTHOR]

Small angle neutron scattering (SANS) data are reported from a system that models the contamination of a clay - organic matter soil from a fuel spillage. The soil was represented as an aqueous dispersion of the synthetic clay mineral Laponite coated with lysine, and the contaminant was a representative jet fuel, quadricyclane, mixed with the detergent cetyltrimethylammonium bromide (CTAB). The adsorbed surface coverage on the clay was estimated. It is shown that the presence of adsorbed lysine considerably enhances the subsequent adsorption of both CTAB and quadricyclane. It is demonstrated that the SANS technique can contribute to the general problem of environmental remediation and retention by probing the interactions of pollutants and clay surfaces. [ABSTRACT FROM AUTHOR]

Abstract: Acoustic P and S wave propagation in the argillaceous sediments is related to the media porosity as well as on clay-mineral composition. The propagation-velocity prediction of these waves thus requires knowledge of these two parameters and their impact on the velocities. Porosity decreasing with effective pressure increasing, due to the burial, follows an exponential law. We will limit our analysis to the three clays: kaolinite, illite and montmorillonite. The variations of porosity between various clays are strongly reduced with the increase in effective pressure, which tends to minimize the impact of mineralogy with the burial. By integrating these equations in a model of Reuss and Voigt, in which we consider an association mineral argillaceous/fluid, we extract a law of evolution for bulk and shear moduli of clay according to the pressure, for each type of clay. By associating clay moduli calculation results to qualitative and quantitative predictions from spectral nuclear-radiations tools and X-ray-diffraction measurements on cores, it is possible to predict sonic velocities in clays with a given effective pressure. An example of P and S velocity modelling is presented on a well in the deep offshore-turbiditic environment. [Copyright &y& Elsevier]

The fine granular structure and surface activity of clay minerals increase the amount of mixing water needed to provide workability in concrete. Even when the microfine material percentage in fine aggregate is low, the methylene blue value of the fine aggregate increases when materials of clay origin are present. In this study, methylene blue values were determined in fine aggregate samples used to produce ready-mixed concrete. Samples were taken from four different aggregate quarries, and relationships between methylene blue values of the concrete samples produced with these aggregates and some of their properties were investigated. Tests were done to determine the quality of microfine material (i.e., passing 0.063 mm sieve). Slump, ultrasonic pulse velocity, compressive strength, and surface abrasion resistance tests were performed on concretes made with these aggregate fines. It is shown that clay content, as indicated by the methylene blue value test, affects the concrete properties, but the microfine material percentage does not give any hint about clay content. [ABSTRACT FROM AUTHOR]

The optimization of the production of fired clay brick is essential for the sustainability of the clay brick industry. While there exist areas for improvement of these bricks’ properties when they are used in severe climates, concerns — including nonrenewable resource depletion, increasing energy costs, and waste management — have become increasingly important in Canadian and global industries. One strategy to address these concerns is to use waste additives as fluxing agents in bricks. Use of these additives can decrease the dependency of the industry on nonrenewable resources and can improve brick strength and durability. The effect nonrecycled waste glass additives have on fired brick durability and mechanical and transport properties was investigated in this study. The variables studied were waste glass particle size and percentage added by mass. Microstructure was investigated using mercury intrusion porosimetry to determine the effect on pore structure. The results yielded an optimal percentage addition of waste glass. [ABSTRACT FROM AUTHOR]

Abstract: The safety analysis of geological disposal of nuclear waste relies on a comprehensive understanding of the structural and dynamic properties of the geological medium hosting the repository. In this context, a vast research program has been undertaken on the migration of radionuclides (mainly ions) in clays, under the supervision of ANDRA. In parallel to the experimental determination of empirical parameters describing the transport at the macroscopic scale, some theoretical efforts have been made to base such a description on a microscopic view of the transport mechanisms. We review here some of the theoretical approaches developed up to now in our research group, with a particular focus on their complementarity. [Copyright &y& Elsevier]

Abstract: The sorption of europium(III) species from EuCl3 solution at pH=5.4 onto dickite particles is investigated using spectroscopic methods. Thanks to the neutrality of phyllosilicate sheets of dickite, cation exchange is prevented. X-ray photoelectron spectroscopy reveals that chloride atoms probably remain in the ligand sphere of the europium(III) cation. The edge site-specific reactivity is evidenced by epifluorescence microscopy and Raman spectroscopy. Comparison between dickite/europium(III) samples rinsed or not with distilled water shows that the surface processes not only involve inner-sphere complex formation, but also either outer-sphere complex or surface precipitation. Raman spectra also indicate that europium(III) surface complexes are preferentially localised at the edge of tetrahedral silica sheets. [Copyright &y& Elsevier]

Abstract: Potential geological nuclear waste disposals must be properly sealed to prevent contamination of the biosphere by radionuclides. In the framework of the RESEAL project, the performance of a bentonite shaft seal is currently studied at Mol (Belgium). This paper focuses on the hydro-mechanical physical behavior of centimetric, unsaturated samples of the backfilling material – a mixture of FoCa-clay powder and pellets – during oedometer tests. The hydro-mechanical response of the samples is observed experimentally, and then compared to numerical simulations performed by our Cast3M Finite Element code. The generalized Darcy’s law and the Barcelona Basic Model mechanical model formed the physical basis of the numerical model and the interpretation. They are widely used in engineered barriers modeling. Vertical swelling pressure and water intake were measured throughout the test. Although water income presents a monotonous increase, the swelling pressure evolution is marked by a peak, and then a local minimum before increasing again to an asymptotic value. This unexpected behavior is explained by yielding rather than by heterogeneity. It is satisfactorily reproduced by the model after parameter calibration. Several samples with different heights ranging from 5 to 12cm show the same hydro-mechanical response, apart from a dilatation of the time scale. The interest of the characterization of centimetric samples to predicting the efficiency of a metric sealing is discussed. [Copyright &y& Elsevier]

Abstract: To make an approach of the caesium-137 (137Cs) profile in undisturbed soils and of its behaviour from soil characteristics, we have used a model unifying the compartment model and the diffusion–convection model, in which two 137Cs states are considered: free and bound. In order to calculate the concentration ratio for each one of the soil layers, we have developed a numerical program running under Visual Fortran, based on the finite-difference method. The experimental profile and the modelled one allow us to find out the model parameters for different types of undisturbed soil, and to establish the relation linking K, the transfer ratio from free state to bound state in these soils, and the clay content. Therefore, the application of this model to eight types of soil proves that it is applicable to any type of undisturbed soil. [Copyright &y& Elsevier]

Abstract: A set of regularly spaced specimens, made up of dark-coloured calcareous argillites, were collected from borehole-cores from the Early Callovian up to the Middle Oxfordian, in the eastern Paris Basin. These specimens have been studied for their magnetic susceptibility, natural and artificial remanence, and for their anisotropy of magnetic susceptibility. Compared with sulfate, carbonate and iron contents, these magnetic properties provide information on both the nature and the relative amounts of the constitutive minerals. To a first approximation, these data outline the main end-members of these argillites, namely (i) carbonate-enriched and less susceptible, (ii) clay-enriched and more susceptible, and (iii) more remanent and partly due to the silt fraction. The middle of the Callovo-Oxfordian formation, called the maximum clay zone, is marked by the highest recorded susceptibility, mainly due to the paramagnetic iron-bearing clay minerals, and by a rather low remanence. The anisotropy of susceptibility provides information on the petrofabric of mostly the clay fraction. The fabric is highly planar, in agreement with the subhorizontal preferred orientation of the clay platelets, but the always present linear anisotropy of the argillites, although modest in strength, points to ∼north–south trending directions throughout most of the formation. These directions agree with the detrital fractions coming from the northern Rhineland, Bohemian and London–Brabant massifs. To cite this article: L. Esteban et al., C. R. Geoscience 338 (2006). [Copyright &y& Elsevier]

Abstract: The Ordovician clays of Jbel Kharrou (Rehamna, Morocco) have been studied for their use in ceramic industry. The realised studies were carried out on two samples B1 and B2, the most representative, taken from a clay dominated formation that outcrops 25 km east of the Skhour Rehamna city. The chemical analyses, mineralogical studies and advanced technological tests undertaken on the two samples indicate that these clays can be considered as non-refractory material, so they can be used to the manufacturing of ceramic products: soil and wall tiles, sanitary, pottery, etc. The tested briquettes, cooked at 1040 °C, remain flat, without deformation or defects; they are of cream white dye. These briquettes show a high mechanical resistance to the flexion, the loss in weight remains tolerable with cooking, lightly elevated (12% ); it can be corrected by the addition of a grease-remover. To cite this article: N. El Yakoubi et al., C. R. Geoscience 338 (2006). [Copyright &y& Elsevier]

Abstract: The solid phase of the porous material considered in this Note is made up of lamellar particles. The influence of interaction forces between platelets on the macroscopic behavior is addressed. The results provide a micromechanical basis to the modelling of the behavior of clays of the smectite group, for which repulsive forces arise from the electrical interaction between the solid platelets and the interstitial fluid. To cite this article: L. Dormieux et al., C. R. Mecanique 334 (2006). [Copyright &y& Elsevier]

This paper presents an analytical approach for predicting the length limits of integral bridges built on cohesive soils based on the flexural strength of the abutments and the low cycle fatigue performance of the steel H-piles at the abutments under cyclic thermal loading. First, H-piles that can accommodate large inelastic deformations are determined considering their local buckling instability. Then, a damage model is used to determine the maximum cyclic deformations that such piles can sustain. Next, nonlinear static pushover analyses of typical integral bridges subjected to cyclic thermal variations are conducted to study the effect of various geometric, structural, and geotechnical parameters on their performance. Equations are derived by using the analyses results to determine the maximum length limits of integral bridges built on cohesive soils. It is found that the maximum length limits of integral bridges is affected by the stiffness of the deck, height of the abutment, properties, and orientation of the piles as well as stiffness of the cohesive soils. [ABSTRACT FROM AUTHOR]

Ce travail présente une nouvelle méthode de mesure des limites d''Atterberg par dessiccation dynamique. En effet, pour certaines argiles polluées ou des mélanges d''argiles, les méthodes classiques ne peuvent pas être mises en œuvre. Le principe de détermination des limites de liquidité et plasticité par cette méthode de dessiccation est présenté. Les valeurs des limites d''Atterberg obtenues sur des argiles courantes se révèlent peu différentes de celles déterminées par la méthode de Casagrande. Ces résultats permettent de considérer cette méthode comme une caractérisation physique des boues argileuses. Pour citer cet article : C. Proust et al., C. R. Geoscience 336 (2004). [Copyright 2004 Elsevier]

We have studied the clay assemblages found in the different palaeogeographic domains located at the several Tunisian margin basins, ranging in age from Palaeozoic to Neogene. This study has allowed us to characterize and highlight the relationship between the clay distribution in time and space and the geodynamic and eustatic events. Marine regressions, with the intensification of erosion, seem to be responsible for illite increases, whereas transgressions, in concordance with a warm and dry climate, coincide with the smectite dominance. The minimum marine level coincides with the abundance of palygorskite. Mineralogic changes in the clay assemblages as well as in the proportion of the different clay minerals will tentatively be related to erosive tectonic events and/or to subsiding and rifting events, marked by the inheritance or the neoformation of the several clays. [Copyright &y& Elsevier]