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Sample records for modeling clay based

  1. Thermo-mechanical constitutive modeling of unsaturated clays based on the critical state concepts

    OpenAIRE

    Tourchi, Saeed; Hamidi, Amir

    2015-01-01

    A thermo-mechanical constitutive model for unsaturated clays is constructed based on the existing model for saturated clays originally proposed by the authors. The saturated clays model was formulated in the framework of critical state soil mechanics and modified Cam-clay model. The existing model has been generalized to simulate the experimentally observed behavior of unsaturated clays by introducing Bishop's stress and suction as independent stress parameters and modifying the hardening rul...

  2. Validation of water sorption-based clay prediction models for calcareous soils

    DEFF Research Database (Denmark)

    Arthur, Emmanuel; Razzaghi, Fatemeh; Moosavi, Ali

    2017-01-01

    on prediction accuracy. The soils had clay content ranging from 9 to 61% and CaCO3 from 24 to 97%. The three water sorption models considered showed a reasonably fair prediction of the clay content from water sorption at 28% relative humidity (RMSE and ME values ranging from 10.6 to 12.1 and −8.1 to −4......Soil particle size distribution (PSD), particularly the active clay fraction, mediates soil engineering, agronomic and environmental functions. The tedious and costly nature of traditional methods of determining PSD prompted the development of water sorption-based models for determining the clay...... fraction. The applicability of such models to semi-arid soils with significant amounts of calcium carbonate and/or gypsum is unknown. The objective of this study was to validate three water sorption-based clay prediction models for 30 calcareous soils from Iran and identify the effect of CaCO3...

  3. Thermo-mechanical constitutive modeling of unsaturated clays based on the critical state concepts

    Directory of Open Access Journals (Sweden)

    Saeed Tourchi

    2015-04-01

    Full Text Available A thermo-mechanical constitutive model for unsaturated clays is constructed based on the existing model for saturated clays originally proposed by the authors. The saturated clays model was formulated in the framework of critical state soil mechanics and modified Cam-clay model. The existing model has been generalized to simulate the experimentally observed behavior of unsaturated clays by introducing Bishop's stress and suction as independent stress parameters and modifying the hardening rule and yield criterion to take into account the role of suction. Also, according to previous studies, an increase in temperature causes a reduction in specific volume. A reduction in suction (wetting for a given confining stress may induce an irreversible volumetric compression (collapse. Thus an increase in suction (drying raises a specific volume i.e. the movement of normal consolidation line (NCL to higher values of void ratio. However, some experimental data confirm the assumption that this reduction is dependent on the stress level of soil element. A generalized approach considering the effect of stress level on the magnitude of clays thermal dependency in compression plane is proposed in this study. The number of modeling parameters is kept to a minimum, and they all have clear physical interpretations, to facilitate the usefulness of model for practical applications. A step-by-step procedure used for parameter calibration is also described. The model is finally evaluated using a comprehensive set of experimental data for the thermo-mechanical behavior of unsaturated soils.

  4. Developments in modelling of thermohydro-geomechanical behaviour of Boom clay and clay-based buffer materials (volume 2)

    International Nuclear Information System (INIS)

    Baldi, G.; Hueckel, T.; Peano, A.; Pellegrini, R.

    1991-01-01

    This study is composed of two parts: The first part (Volume 1) lays the foundations of a comprehensive theoretical treatment of the interaction between water and soil skeleton during thermal dilatation. The second part (volume 2) is devoted to the development and the application of advance constitutive modelling of mechanical behaviour of clays taking into account the extensive tests of Boom clay reported in the first volume. The development concentrated on the improvement of prediction of the volumetric response of clay skeleton: (a) improving the dilatancy prediction at low to high overconsolidation ratios (Section 2). An elasto-plastic constitutive model has been developed to account for this effect (Section 3.2.); (b) modelling of swelling effects (Section 2.5). A preliminary interpretative model for swelling prediction has been developed (Section 2.5). The application part consisted in interpreting the experimental results obtained for Boom clay to calibrate a set of constants (Section 3) for performing numerical analyses (Section 4) for the thermomechanical model already calibrated for Boom clay (Appendix). Interpretation of the tests required an assessment of influence of the strong anisotropy effects revealed by Boom clay on the basis of an interpretative model characterized by a kinematic hardening plasticity and coupled elasticity (section 3)

  5. Developments in modelling of thermohydro-geomechanical behaviour of Boom clay and clay-based buffer materials (Volume 1)

    International Nuclear Information System (INIS)

    Baldi, G.; Hueckel, T.; Peano, A.; Pellegrini, R.

    1991-01-01

    The results of two years of research on thermomechanics of clays performed within CEC contract Fl1W/0150 are described herein. Previous studies (research contracts with CEC/WAS/380.83.7 l) performed by ISMES have evidenced the need for an improved modelling of the volumetric response of natural clays. In a coupled approach, this leads to an improved prediction of pore-pressure development and dissipation. This is crucial for assessing conditions of a possible local thermal failure as verified in laboratory tests done at ISMES. The first part of the study lays the foundations of a comprehensive theoretical treatment of the interaction between water and soil skeleton. It consists in: (a) developing a framework for inclusion of water/soil particle thermally induced interaction into a thermodynamically consistent mixture theory approach (Section 2); (b) studying possible modelling approaches of considering the effective thermal expansion coefficient of pore water dependency on pore water status (Section 2); (c) testing artificial clays to assess pore water thermal expansion dependence on temperature in the presence of different amounts of active clay minerals and also Boom clay (Section 3); (d) performing a laboratory test campaign on Boom clay with special attention to the response in the overconsolidated domain (Section 4). 89 figs., 18 tabs., 102 refs

  6. generalized constitutive model for stabilized quick clay

    African Journals Online (AJOL)

    QUICK CLAY. PANCRAS MUGISHAGWE BUJULU AND GUSTAV GRIMSTAD. ABSTRACT. An experimentally-based two yield surface constitutive model for cemented quick clay has been ... Clay Model, the Koiter Rule and two Mapping Rules. .... models, where a mobilization formulation is used, this is independent of q.

  7. Long-term modeling of glass waste in portland cement- and clay-based matrices

    International Nuclear Information System (INIS)

    Stockman, H.W.; Nagy, K.L.; Morris, C.E.

    1995-12-01

    A set of ''templates'' was developed for modeling waste glass interactions with cement-based and clay-based matrices. The templates consist of a modified thermodynamic database, and input files for the EQ3/6 reaction path code, containing embedded rate models and compositions for waste glass, cement, and several pozzolanic materials. Significant modifications were made in the thermodynamic data for Th, Pb, Ra, Ba, cement phases, and aqueous silica species. It was found that the cement-containing matrices could increase glass corrosion rates by several orders of magnitude (over matrixless or clay matrix systems), but they also offered the lowest overall solubility for Pb, Ra, Th and U. Addition of pozzolans to cement decreased calculated glass corrosion rates by up to a factor of 30. It is shown that with current modeling capabilities, the ''affinity effect'' cannot be trusted to passivate glass if nuclei are available for precipitation of secondary phases that reduce silica activity

  8. Acid-base properties of 2:1 clays. I. Modeling the role of electrostatics.

    Science.gov (United States)

    Delhorme, Maxime; Labbez, Christophe; Caillet, Céline; Thomas, Fabien

    2010-06-15

    We present a theoretical investigation of the titratable charge of clays with various structural charge (sigma(b)): pyrophyllite (sigma(b) = 0 e x nm(-2)), montmorillonite (sigma(b) = -0.7 e x nm(-2)) and illite (sigma(b) = -1.2 e x nm(-2)). The calculations were carried out using a Monte Carlo method in the Grand Canonical ensemble and in the framework of the primitive model. The clay particle was modeled as a perfect hexagonal platelet, with an "ideal" crystal structure. The only fitting parameters used are the intrinsic equilibrium constants (pK(0)) for the protonation/deprotonation reactions of the broken-bond sites on the lateral faces of the clay particles, silanol, =SiO(-) + H(+) --> =SiOH, and aluminol, =AlO(-1/2) + H(+) --> =AlOH(+1/2). Simulations are found to give a satisfactory description of the acid-base titration of montmorillonite without any additional fitting parameter. In particular, combining the electrostatics from the crystal substitutions with ionization constants, the simulations satisfactorily catch the shift in the titration curve of montmorillonite according to the ionic strength. Change in the ionic strength modulates the screening of the electrostatic interactions which results in this shift. Accordingly, the PZNPC is found to shift toward alkaline pH upon increasing the permanent basal charge. Unlike previous mean field model results, a significant decrease in PZNPC values is predicted in response to stack formation. Finally, the mean field approach is shown to be inappropriate to study the acid-base properties of clays.

  9. Synthesis and Characterization of the Hybrid Clay- Based Material Montmorillonite-Melanoidin: A Potential Soil Model

    Energy Technology Data Exchange (ETDEWEB)

    V Vilas; B Matthiasch; J Huth; J Kratz; S Rubert de la Rosa; P Michel; T Schäfer

    2011-12-31

    The study of the interactions among metals, minerals, and humic substances is essential in understanding the migration of inorganic pollutants in the geosphere. A considerable amount of organic matter in the environment is associated with clay minerals. To understand the role of organic matter in the environment and its association with clay minerals, a hybrid clay-based material (HCM), montmorillonite (STx-1)-melanoidin, was prepared from L-tyrosine and L-glutamic acid by the Maillard reaction. The HCM was characterized by elemental analysis, nuclear magnetic resonance, x-ray photoelectron spectroscopy (XPS), scanning transmission x-ray microscopy (STXM), and thermal analysis. The presence of organic materials on the surface was confirmed by XPS and STXM. The STXM results showed the presence of organic spots on the surface of the STx-1 and the characterization of the functional groups present in those spots. Thermal analysis confirmed the existence of organic materials in the montmorillonite interlayer, indicating the formation of a composite of melanoidin and montmorillonite. The melanoidin appeared to be located partially between the layers of montmorillonite and partially at the surface, forming a structure that resembles the way a cork sits on the top of a champagne bottle.

  10. Influence of clay mineralogy on clay based ceramic products

    International Nuclear Information System (INIS)

    Radzali Othman; Tuan Besar Tuan Sarif; Zainal Arifin Ahmad; Ahmad Fauzi Mohd Noor; Abu Bakar Aramjat

    1996-01-01

    Clay-based ceramic products can either be produced directly from a suitable clay source without the need further addition or such products can be produced from a ceramic body formulated by additions of other raw materials such as feldspar and silica sand. In either case, the mineralogical make-up of the clay component plays a dominating role in the fabrication and properties of the ceramic product. This study was sparked off by a peculiar result observed in one of five local ball clay samples that were used to reformulate a ceramic body. Initial characterisation tests conducted on the clays indicated that these clays can be classified as kaolinitic. However, one of these clays produced a ceramic body that is distinctively different in terms of whiteness, smoothness and density as compared to the other four clays. Careful re-examination of other characterisation data, such as particle size distribution and chemical analysis, failed to offer any plausible explanation. Consequently, the mineralogical analysis by x-ray diffraction was repeated by paying meticulous attention to specimen preparation. Diffraction data for the clay with anomalous behaviour indicated the presence of a ∼ 10A peak that diminished when the same specimen was re-tested after heating in an oven at 12O degree C whilst the other four clays only exhibit the characteristic kaolinite (Al sub 2 O sub 3. 2SiO sub 2. 2H sub 2 0) and muscovite peaks at ∼ 7A and ∼ 10A before and after heat treatment. This suggests the presence of the mineral halloysite (A1 sub 2 0 sub 3. 2SiO sub 2.4H sub 2 0) in that particular clay. This difference in mineralogy can be attributed to account for the variations in physical properties of the final product. Consequently, this paper reviews in general the precautionary measures that must be adhered to during any mineralogical investigation of clay minerals or clay-based materials. The common pitfalls during specimen preparation, machine settings and interpretation of

  11. Sectioning Clay Models Makes Anatomy & Development Tangible

    Science.gov (United States)

    Howell, Carina Endres; Howell, James Endres

    2010-01-01

    Clay models have proved to be useful teaching aids for many topics in biology that depend on three-dimensional reasoning. Students studying embryonic development struggle to mentally reconstruct the three-dimensional structure of embryos and larvae by observing prepared slides of cross-sectional slices. Students who build clay models of embryos…

  12. Multiscale Micromechanical Modeling of Polymer/Clay Nanocomposites and the Effective Clay Particle

    Science.gov (United States)

    Sheng, Nuo; Boyce, Mary C.; Parks, David M.; Manovitch, Oleg; Rutledge, Gregory C.; Lee, Hojun; McKinley, Gareth H.

    2003-03-01

    Polymer/clay nanocomposites have been observed to exhibit enhanced mechanical properties at low weight fractions (Wp) of clay. Continuum-based composite modeling reveals that the enhanced properties are strongly dependent on particular features of the second-phase ¡°particles¡+/-; in particular, the particle volume fraction (fp), the particle aspect ratio (L/t), and the ratio of particle mechanical properties to those of the matrix. However, these important aspects of as-processed nanoclay composites have yet to be consistently and accurately defined. A multiscale modeling strategy was developed to account for the hierarchical morphology of the nanocomposite: at a lengthscale of thousands of microns, the structure is one of high aspect ratio particles within a matrix; at the lengthscale of microns, the clay particle structure is either (a) exfoliated clay sheets of nanometer level thickness or (b) stacks of parallel clay sheets separated from one another by interlayer galleries of nanometer level height. Here, quantitative structural parameters extracted from XRD patterns and TEM micrographs are used to determine geometric features of the as-processed clay ¡°particles¡+/-, including L/t and the ratio of fp to Wp. These geometric features, together with estimates of silicate lamina stiffness obtained from molecular dynamics simulations, provide a basis for modeling effective mechanical properties of the clay particle. The structure-based predictions of the macroscopic elastic modulus of the nanocomposite as a function of clay weight fraction are in excellent agreement with experimental data. The adopted methodology offers promise for study of related properties in polymer/clay nanocomposites.

  13. Modeling of calcination of single kaolinitic clay particle

    DEFF Research Database (Denmark)

    Gebremariam, Abraham Teklay; Yin, Chungen; Rosendahl, Lasse

    The present work aims at modeling of the calcination (dehydroxylation) process of clay particles, specifically kaolinite, and its thermal transformation. For such purpose, 1D single particle calcination model was developed based on the concept of shrinking core model to assess the dehydroxylation...

  14. Modeling Coupled Processes in Clay Formations for Radioactive Waste Disposal

    International Nuclear Information System (INIS)

    Liu, Hui-Hai; Rutqvist, Jonny; Zheng, Liange; Sonnenthal, Eric; Houseworth, Jim; Birkholzer, Jens

    2010-01-01

    example, the excavation-damaged zone (EDZ) near repository tunnels can modify local permeability (resulting from induced fractures), potentially leading to less confinement capability (Tsang et al., 2005). Because of clay's swelling and shrinkage behavior (depending on whether the clay is in imbibition or drainage processes), fracture properties in the EDZ are quite dynamic and evolve over time as hydromechanical conditions change. To understand and model the coupled processes and their impact on repository performance is critical for the defensible performance assessment of a clay repository. Within the Natural Barrier System (NBS) group of the Used Fuel Disposition (UFD) Campaign at DOE's Office of Nuclear Energy, LBNL's research activities have focused on understanding and modeling such coupled processes. LBNL provided a report in this April on literature survey of studies on coupled processes in clay repositories and identification of technical issues and knowledge gaps (Tsang et al., 2010). This report will document other LBNL research activities within the natural system work package, including the development of constitutive relationships for elastic deformation of clay rock (Section 2), a THM modeling study (Section 3) and a THC modeling study (Section 4). The purpose of the THM and THC modeling studies is to demonstrate the current modeling capabilities in dealing with coupled processes in a potential clay repository. In Section 5, we discuss potential future R and D work based on the identified knowledge gaps. The linkage between these activities and related FEPs is presented in Section 6.

  15. Modeling Coupled Processes in Clay Formations for Radioactive Waste Disposal

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Hui-Hai; Rutqvist, Jonny; Zheng, Liange; Sonnenthal, Eric; Houseworth, Jim; Birkholzer, Jens

    2010-08-31

    example, the excavation-damaged zone (EDZ) near repository tunnels can modify local permeability (resulting from induced fractures), potentially leading to less confinement capability (Tsang et al., 2005). Because of clay's swelling and shrinkage behavior (depending on whether the clay is in imbibition or drainage processes), fracture properties in the EDZ are quite dynamic and evolve over time as hydromechanical conditions change. To understand and model the coupled processes and their impact on repository performance is critical for the defensible performance assessment of a clay repository. Within the Natural Barrier System (NBS) group of the Used Fuel Disposition (UFD) Campaign at DOE's Office of Nuclear Energy, LBNL's research activities have focused on understanding and modeling such coupled processes. LBNL provided a report in this April on literature survey of studies on coupled processes in clay repositories and identification of technical issues and knowledge gaps (Tsang et al., 2010). This report will document other LBNL research activities within the natural system work package, including the development of constitutive relationships for elastic deformation of clay rock (Section 2), a THM modeling study (Section 3) and a THC modeling study (Section 4). The purpose of the THM and THC modeling studies is to demonstrate the current modeling capabilities in dealing with coupled processes in a potential clay repository. In Section 5, we discuss potential future R&D work based on the identified knowledge gaps. The linkage between these activities and related FEPs is presented in Section 6.

  16. Clay-based geothermal drilling fluids

    Energy Technology Data Exchange (ETDEWEB)

    Guven, N.; Carney, L.L.; Lee, L.J.; Bernhard, R.P.

    1982-11-01

    The rheological properties of fluids based on fibrous clays such as sepiolite and attapulgite have been systematically examined under conditions similar to those of geothermal wells, i.e. at elevated temperatures and pressures in environments with concentrated brines. Attapulgite- and sepiolite-based fluids have been autoclaved at temperatures in the range from 70 to 800/sup 0/F with the addition of chlorides and hydroxides of Na, K, Ca, and Mg. The rheological properties (apparent and plastic viscosity, fluid loss, gel strength, yield point, and cake thickness) of the autoclaved fluids have been studied and correlated with the chemical and physical changes that occur in the clay minerals during the autoclaving process.

  17. Induced polarization of clay-sand mixtures: experiments and modeling

    International Nuclear Information System (INIS)

    Okay, G.; Leroy, P.; Tournassat, C.; Ghorbani, A.; Jougnot, D.; Cosenza, P.; Camerlynck, C.; Cabrera, J.; Florsch, N.; Revil, A.

    2012-01-01

    were performed with a cylindrical four-electrode sample-holder (cylinder made of PVC with 30 cm in length and 19 cm in diameter) associated with a SIP-Fuchs II impedance meter and non-polarizing Cu/CuSO 4 electrodes. These electrodes were installed at 10 cm from the base of the sample holder and regularly spaced (each 90 degree). The results illustrate the strong impact of the Cationic Exchange Capacity (CEC) of the clay minerals upon the complex conductivity. The amplitude of the in-phase conductivity of the kaolinite-clay samples is strongly dependent to saturating fluid salinity for all volumetric clay fractions, whereas the in-phase conductivity of the smectite-clay samples is quite independent on the salinity, except at the low clay content (5% and 1% of clay in volume). This is due to the strong and constant surface conductivity of smectite associated with its very high CEC. The quadrature conductivity increases steadily with the CEC and the clay content. We observe that the dependence on frequency of the quadrature conductivity of sand-kaolinite mixtures is more important than for sand-bentonite mixtures. For both types of clay, the quadrature conductivity seems to be fairly independent on the pore fluid salinity except at very low clay contents (1% in volume of kaolinite-clay). This is due to the constant surface site density of Na counter-ions in the Stern layer of clay materials. At the lowest clay content (1%), the magnitude of the quadrature conductivity increases with the salinity, as expected for silica sands. In this case, the surface site density of Na counter-ions in the Stern layer increases with salinity. The experimental data show good agreement with predicted values given by our Spectral Induced Polarization (SIP) model. This complex conductivity model considers the electrochemical polarization of the Stern layer coating the clay particles and the Maxwell-Wagner polarization. We use the differential effective medium theory to calculate the complex

  18. Modification of clay-based waste containment materials

    International Nuclear Information System (INIS)

    Adu-Wusu, K.; Whang, J.M.; McDevitt, M.F.

    1997-01-01

    Bentonite clays are used extensively for waste containment barriers to help impede the flow of water in the subsurface because of their low permeability characteristics. However, they do little to prevent diffusion of contaminants, which is the major transport mechanism at low water flows. A more effective way of minimizing contaminant migration in the subsurface is to modify the bentonite clay with highly sorptive materials. Batch sorption studies were conducted to evaluate the sorptive capabilities of organo-clays and humic- and iron-based materials. These materials proved to be effective sorbents for the organic contaminants 1,2,4-trichlorobenzene, nitrobenzene, and aniline in water, humic acid, and methanol solution media. The sorption capacities were several orders of magnitude greater than that of unmodified bentonite clay. Modeling results indicate that with small amounts of these materials used as additives in clay barriers, contaminant flux through walls could be kept very small for 100 years or more. The cost of such levels of additives can be small compared to overall construction costs

  19. Kaolinitic clay-based grouting demonstration

    International Nuclear Information System (INIS)

    McCloskey, A.L.; Barry, C.J.; Wilmoth, R.

    1997-01-01

    An innovative Kaolinitic Clay-Based Grouting Demonstration was performed under the Mine Waste Technology Program (MWTP), funded by the U.S. Environmental Protection Agency (EPA) and jointly administered by the EPA and the U.S. Department of Energy (DOE). The objective of the technology was to demonstrate the effectiveness of kaolinitic clay-based grouting in reducing/eliminating infiltration of surface and shallow groundwater through fractured bedrock into underground mine workings. In 1993, the Mike Horse Mine was selected as a demonstration site for the field implementation and evaluation of the grouting technology. The mine portal discharge ranged between 114 to 454 liters per minute (30 to 120 gpm) of water containing iron, zinc, manganese, and cadmium at levels exceeding the National Drinking Water Maximum Contaminant Levels. The grout formulation was designed by the developer Morrison Knudsen Corporation/Spetstamponazhgeologia (MK/STG), in May 1994. Grout injection was performed by Hayward Baker, Inc. under the directive of MSE Technology Applications, Inc. (MSE-TA) during fall of 1994. The grout was injected into directionally-drilled grout holes to form a grout curtain at the project site. Post grout observations suggest the grout was successful in reducing the infiltration of the surface and shallow groundwater from entering the underground mine workings. The proceeding paper describes the demonstration and technology used to form the subsurface barrier in the fracture system

  20. Stochastic modeling of filtrate alkalinity in water filtration devices: Transport through micro/nano porous clay based ceramic materials

    Science.gov (United States)

    Clay and plant materials such as wood are the raw materials used in manufacture of ceramic water filtration devices around the world. A step by step manufacturing procedure which includes initial mixing, molding and sintering is used. The manufactured ceramic filters have numerous pores which help i...

  1. Quantum-chemical modeling of smectite clays

    Science.gov (United States)

    Aronowitz, S.; Coyne, L.; Lawless, J.; Rishpon, J.

    1982-01-01

    A self-consistent charge extended Hueckel program is used in modeling isomorphic substitution of Al(3+) by Na(+), K(+), Mg(2+), Fe(2+), and Fe(3+) in the octahedral layer of a dioctahedral smectite clay, such as montmorillonite. Upon comparison of the energies involved in the isomorphic substitution, it is found that the order for successful substitution is as follows: Al(3+), Fe(3+), Mg(2+), Fe(2+), Na(+), which is equivalent to Ca(2+), and then K(+). This ordering is found to be consistent with experimental observation. The calculations also make it possible to determine the possible penetration of metal ions into the clay's 2:1 crystalline layer. For the cases studied, this type of penetration can occur at elevated temperatures into regions where isomorphic substitution has occurred with metal ions that bear a formal charge of less than 3+. The computed behavior of the electronic structure in the presence of isomorphic substitution is found to be similar to behavior associated with semiconductors.

  2. Clay intercalation and influence on crystallinity of EVA-based clay nanocomposites

    International Nuclear Information System (INIS)

    Chaudhary, D.S.; Prasad, R.; Gupta, R.K.; Bhattacharya, S.N.

    2005-01-01

    Various polymer clay nanocomposites (PCNs) were prepared from ethylene vinyl acetate copolymer (EVA) with 9, 18 and 28% vinyl acetate (VA) content filled with different wt.% (2.5, 5 and 7.5) of a Montmorillonite-based organo-modified clay (Cloisite[reg] C15A and C30B). The PCNs were prepared using melt blending techniques. Morphological information regarding intercalation and exfoliation were determined by using wide-angle X-ray scattering (WAXS) and transmission electron microscopy (TEM). WAXS and TEM confirmed that increasing the VA content was necessary to achieve greater clay-polymer interaction as seen from the comparatively higher intercalation of clay platelets with 28% VA. The effect of addition of clay on the development and the modification of crystalline morphology in EVA matrix was also studied using WAXS and temperature-modulated differential scanning calorimetry (MDSC). Results are presented showing that the addition of clay platelets does not increase the matrix crystallinity but the morphology was significantly modified such that there was an increase in the 'rigid' amorphous phase. Mechanical properties were also evaluated against the respective morphological information for each specimen and there are indications that the level of clay-polymer interaction plays a significant role in such morphological modification, and in such a way that affects the final PCN mechanical properties which has wide and significant applications in the packaging industries

  3. Composites Based on Fly Ash and Clay

    International Nuclear Information System (INIS)

    Fidancevska, E.; Jovanov, V.; Angusheva, B.; Srebrenkoska, V.

    2014-01-01

    Fly ash is a waste generated from the coal combustion during the production of electricity in the thermal power plants. It presents industrial by-product containing Technologically Enhanced Natural Occurring Radioactive Materials (TENORM) with the great potential for valorisation. Fly ash is successfully utilized in cement and concrete industry, also in ceramics industry as component for manufacturing bricks and tiles, and recently there are many investigations for production of glass-ceramics from fly ash. Although the utilization of fly ash in construction and civil engineering is dominant, the development of new alternative application for its further exploitation into new products is needed. This work presents the possibility for fly ash utilization for fabricating dense composites based on clay and fly ash with the potential to be used in construction industry

  4. Reconstruction of a digital core containing clay minerals based on a clustering algorithm

    Science.gov (United States)

    He, Yanlong; Pu, Chunsheng; Jing, Cheng; Gu, Xiaoyu; Chen, Qingdong; Liu, Hongzhi; Khan, Nasir; Dong, Qiaoling

    2017-10-01

    It is difficult to obtain a core sample and information for digital core reconstruction of mature sandstone reservoirs around the world, especially for an unconsolidated sandstone reservoir. Meanwhile, reconstruction and division of clay minerals play a vital role in the reconstruction of the digital cores, although the two-dimensional data-based reconstruction methods are specifically applicable as the microstructure reservoir simulation methods for the sandstone reservoir. However, reconstruction of clay minerals is still challenging from a research viewpoint for the better reconstruction of various clay minerals in the digital cores. In the present work, the content of clay minerals was considered on the basis of two-dimensional information about the reservoir. After application of the hybrid method, and compared with the model reconstructed by the process-based method, the digital core containing clay clusters without the labels of the clusters' number, size, and texture were the output. The statistics and geometry of the reconstruction model were similar to the reference model. In addition, the Hoshen-Kopelman algorithm was used to label various connected unclassified clay clusters in the initial model and then the number and size of clay clusters were recorded. At the same time, the K -means clustering algorithm was applied to divide the labeled, large connecting clusters into smaller clusters on the basis of difference in the clusters' characteristics. According to the clay minerals' characteristics, such as types, textures, and distributions, the digital core containing clay minerals was reconstructed by means of the clustering algorithm and the clay clusters' structure judgment. The distributions and textures of the clay minerals of the digital core were reasonable. The clustering algorithm improved the digital core reconstruction and provided an alternative method for the simulation of different clay minerals in the digital cores.

  5. Reconstruction of a digital core containing clay minerals based on a clustering algorithm.

    Science.gov (United States)

    He, Yanlong; Pu, Chunsheng; Jing, Cheng; Gu, Xiaoyu; Chen, Qingdong; Liu, Hongzhi; Khan, Nasir; Dong, Qiaoling

    2017-10-01

    It is difficult to obtain a core sample and information for digital core reconstruction of mature sandstone reservoirs around the world, especially for an unconsolidated sandstone reservoir. Meanwhile, reconstruction and division of clay minerals play a vital role in the reconstruction of the digital cores, although the two-dimensional data-based reconstruction methods are specifically applicable as the microstructure reservoir simulation methods for the sandstone reservoir. However, reconstruction of clay minerals is still challenging from a research viewpoint for the better reconstruction of various clay minerals in the digital cores. In the present work, the content of clay minerals was considered on the basis of two-dimensional information about the reservoir. After application of the hybrid method, and compared with the model reconstructed by the process-based method, the digital core containing clay clusters without the labels of the clusters' number, size, and texture were the output. The statistics and geometry of the reconstruction model were similar to the reference model. In addition, the Hoshen-Kopelman algorithm was used to label various connected unclassified clay clusters in the initial model and then the number and size of clay clusters were recorded. At the same time, the K-means clustering algorithm was applied to divide the labeled, large connecting clusters into smaller clusters on the basis of difference in the clusters' characteristics. According to the clay minerals' characteristics, such as types, textures, and distributions, the digital core containing clay minerals was reconstructed by means of the clustering algorithm and the clay clusters' structure judgment. The distributions and textures of the clay minerals of the digital core were reasonable. The clustering algorithm improved the digital core reconstruction and provided an alternative method for the simulation of different clay minerals in the digital cores.

  6. Loess clay based copolymer for removing Pb(II) ions

    International Nuclear Information System (INIS)

    He, Yu-Feng; Zhang, Ling; Wang, Rong-Min; Li, Hui-Ru; Wang, Yan

    2012-01-01

    Highlights: ► The loess clay based copolymer was prepared using functional monomers. ► Characterization of the polymer adsorbent and the raw material were carried out. ► The adsorption behavior of the complex for Pb(II) ions was evaluated. ► The removal rate of Pb(II) got to 99% and the adsorption capacity got to 356.9 mg/g. - Abstract: Functional monomers, such as acrylic acid and 2-hydroxyethyl methacrylate were supported into loess clay in situ polymerization, which afforded loess clay based copolymer (LC/PAAHM), a new kind of polymer adsorbent for removing Pb(II) ions from aqueous solution. Characterization of the polymer adsorbent was carried out by different sophisticated methods, such as Fourier transformation infrared spectrometry (FTIR), scanning electron microscopy (SEM), X-ray diffractometry (XRD), thermogravimetric analysis (TGA), and Zetasizer. Batch experiments were carried out to evaluate the factors affecting the removal efficiency, in which the pH, the adsorbent dosage, temperature and initial Pb(II) concentration all found in positive relevance to the increase of Pb(II) removal efficiency. The removal rate of Pb(II) got to 99% at room temperature and the adsorption capacity got to 356.9 mg/g. The pseudo-first-order and pseudo-second-order kinetic models were applied to test the experimental data, and Langmuir and Freundlich models have been applied to study the adsorption equilibrium, respectively.

  7. Learning of Cross-Sectional Anatomy Using Clay Models

    Science.gov (United States)

    Oh, Chang-Seok; Kim, Ji-Young; Choe, Yeon Hyeon

    2009-01-01

    We incorporated clay modeling into gross anatomy and neuro-anatomy courses to help students understand cross-sectional anatomy. By making clay models, cutting them and comparing cut surfaces to CT and MR images, students learned how cross-sectional two-dimensional images were created from three-dimensional structure of human organs. Most students…

  8. Evaluation of kaolinite clays of Moa for the production of cement based clinker-calcined clay-limestone (LC3

    Directory of Open Access Journals (Sweden)

    Roger S. Almenares-Reyes

    2016-12-01

    Full Text Available Clay materials from two outcrops of the Moa region were analyzed to determine their potential use as supplementary cementitious material in the production of ternary cements based on limestone-calcined clay. The clays were characterized by atomic absorption spectroscopy (EAA, X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR and thermogravimetric analysis (ATG. These methods revealed high aluminum in clays, moderate kaolinite content, a disordered structure and the presence of impurities. The solubility of aluminum and silicon in alkali and the compressive strength of LC3 systems is proportional to their content in clay, being higher for the one with higher kaolinite content and greater structural disorder (outcrop D1, although the clay of both outcrops may constitute supplementary cementitious materials in the production of ternary cements based clinker-calcined clay-limestone. The suitable thermal activation range for both clays is between 650 ° C and 850 ° C.

  9. Centrifuge modelling of rigid piles in soft clay

    DEFF Research Database (Denmark)

    Klinkvort, R.T.; Poder, M.; Truong, P.

    2016-01-01

    of this study is to employ centrifuge modelling in order to derive experimental p-y curves for rigid piles embedded in over-consolidated soft clay. A kaolin clay sample was prepared and pre-consolidated by applying a constant pressure at the soil surface, while different over-consolidation ratios were achieved...

  10. Gassmann Modeling of Acoustic Properties of Sand-clay Mixtures

    Science.gov (United States)

    Gurevich, B.; Carcione, J. M.

    The feasibility of modeling elastic properties of a fluid-saturated sand-clay mixture rock is analyzed by assuming that the rock is composed of macroscopic regions of sand and clay. The elastic properties of such a composite rock are computed using two alternative schemes.The first scheme, which we call the composite Gassmann (CG) scheme, uses Gassmann equations to compute elastic moduli of the saturated sand and clay from their respective dry moduli. The effective elastic moduli of the fluid-saturated composite rock are then computed by applying one of the mixing laws commonly used to estimate elastic properties of composite materials.In the second scheme which we call the Berryman-Milton scheme, the elastic moduli of the dry composite rock matrix are computed from the moduli of dry sand and clay matrices using the same composite mixing law used in the first scheme. Next, the saturated composite rock moduli are computed using the equations of Brown and Korringa, which, together with the expressions for the coefficients derived by Berryman and Milton, provide an extension of Gassmann equations to rocks with a heterogeneous solid matrix.For both schemes, the moduli of the dry homogeneous sand and clay matrices are assumed to obey the Krief's velocity-porosity relationship. As a mixing law we use the self-consistent coherent potential approximation proposed by Berryman.The calculated dependence of compressional and shear velocities on porosity and clay content for a given set of parameters using the two schemes depends on the distribution of total porosity between the sand and clay regions. If the distribution of total porosity between sand and clay is relatively uniform, the predictions of the two schemes in the porosity range up to 0.3 are very similar to each other. For higher porosities and medium-to-large clay content the elastic moduli predicted by CG scheme are significantly higher than those predicted by the BM scheme.This difference is explained by the fact

  11. Integrated modelling of the glass-iron-clay system

    Energy Technology Data Exchange (ETDEWEB)

    Bildstein, O

    2007-01-15

    This report summarizes the results of integrated calculations on the near-field evolution in the VHLW/steel/bentonite/clay system. The calculations of the near-field evolution include different components: the vitrified waste packages, the steel container, the bentonite-based EBS (optional), the EDZ and the geological medium. Coupled reaction-transport (X-T) is used to simulate the corrosion of the steel canister and the glass alteration phase in presence of corrosion products (CPs), looking at mass transfer for chemical elements, especially iron and silica, pH, and porosity change. Calculations as performed give actual parameters for PA calculations: rate of glass alteration (through the calculated pH) as a function of time, extension of altered zone for iron-clay interactions with their own transport parameters, nature of CPs, effect on porosity distribution. According to the operational model currently used at the CEA and the calculations performed on the glass-iron-clay system, the alteration rate of glass and the evolution of the system strongly depend on the timing of CPs saturation with respect to silica sorption. The fate of silica which can be sorbed or precipitate is crucial to the lifetime of glass and to the overall evolution of the system. The other process that might influence the glass is the porosity decrease due to the precipitation of CPs and silica rich phases. However, it is difficult to assign a safety functions to clogging. It is scarcely observed in experiments, either because the conditions are not met for clogging or because the timescale of experiments does not allow for observable clogging. Moreover, the effect of mechanical stress in the NF has to be accounted for in the assessment of the effect of porosity changes. (author)

  12. Integrated modelling of the glass-iron-clay system

    International Nuclear Information System (INIS)

    Bildstein, O.

    2007-01-01

    This report summarizes the results of integrated calculations on the near-field evolution in the VHLW/steel/bentonite/clay system. The calculations of the near-field evolution include different components: the vitrified waste packages, the steel container, the bentonite-based EBS (optional), the EDZ and the geological medium. Coupled reaction-transport (X-T) is used to simulate the corrosion of the steel canister and the glass alteration phase in presence of corrosion products (CPs), looking at mass transfer for chemical elements, especially iron and silica, pH, and porosity change. Calculations as performed give actual parameters for PA calculations: rate of glass alteration (through the calculated pH) as a function of time, extension of altered zone for iron-clay interactions with their own transport parameters, nature of CPs, effect on porosity distribution. According to the operational model currently used at the CEA and the calculations performed on the glass-iron-clay system, the alteration rate of glass and the evolution of the system strongly depend on the timing of CPs saturation with respect to silica sorption. The fate of silica which can be sorbed or precipitate is crucial to the lifetime of glass and to the overall evolution of the system. The other process that might influence the glass is the porosity decrease due to the precipitation of CPs and silica rich phases. However, it is difficult to assign a safety functions to clogging. It is scarcely observed in experiments, either because the conditions are not met for clogging or because the timescale of experiments does not allow for observable clogging. Moreover, the effect of mechanical stress in the NF has to be accounted for in the assessment of the effect of porosity changes. (author)

  13. Numerical Analysis of Diaphragm Wall Model Executed in Poznań Clay Formation Applying Selected Fem Codes

    Directory of Open Access Journals (Sweden)

    Superczyńska M.

    2016-09-01

    Full Text Available The paper presents results of numerical calculations of a diaphragm wall model executed in Poznań clay formation. Two selected FEM codes were applied, Plaxis and Abaqus. Geological description of Poznań clay formation in Poland as well as geotechnical conditions on construction site in Warsaw city area were presented. The constitutive models of clay implemented both in Plaxis and Abaqus were discussed. The parameters of the Poznań clay constitutive models were assumed based on authors’ experimental tests. The results of numerical analysis were compared taking into account the measured values of horizontal displacements.

  14. Poro-elasto-plastic behaviour of dry compacted Fo-Ca clay: experiment and modelling. Application to the re-saturation of an engineered clay barrier

    International Nuclear Information System (INIS)

    Lassabatere, Th.; Imbert, Ch.; Etile, M.A.

    1999-01-01

    Many projects of underground repositories for high level radioactive waste involve an engineered clay barrier, placed between the waste canister and the surrounding rock. When hydrated, this barrier seals the gap and provides a good watertightness. The natural clay powder, dried and compacted, exhibits hydro-mechanical couplings during the hydration. Such a coupled behaviour, interesting for the industrial application, has been clearly demonstrated by many studies and laboratory experiments. But the modelling of this behaviour, in order to predict the hydration of the clay barrier, is difficult. A coupled modelling, based, at a macroscopic scale, on the thermodynamics of unsaturated porous media, is proposed. This thermodynamical model founds a general framework for non linear poro-elastic and poro-elasto-plastic coupled behaviours. The symmetries of this coupling, induced by this thermodynamical framework, let us take into account the often neglected influence of the mechanical state on the hydraulic problem of the re-saturation of the clay. The complete resolution of the flow problem, coupled with the mechanical behaviour, leads us to study the influence of the rheological behaviour chosen for the clay (elastic - linear or no linear -, or elastoplastic) on the evaluation of the duration of the re-saturation of the clay barrier). (authors)

  15. Processing, Characterization, and Modeling of Polymer/Clay Nanocomposite Foams

    Science.gov (United States)

    Jo, Choonghee; Naguib, Hani E.

    2007-04-01

    The effects of the material parameters and processing conditions on the foam morphologies, and mechanical properties of polymer/clay nanocomposite foams were studied. Microcellular closed-cell nanocomposite foams were manufactured with poly(methylmethacrylate) (PMMA) and high density polyethylene (HDPE), where the nanoclay loadings of 0.5, 1.0, and 2.0 wt% were used. The effect of clay contents and foaming conditions on the volume expansion ratio, cell size, elastic modulus, tensile strength, and elongation at break were investigated and compared between amorphous and semicrystalline polymers. An elastic modulus model for tensile behavior of foams was proposed by using the micromechanics theory. The model was expressed in terms of microstructural properties of polymer and physical properties of the foams. The tensile experimental data of the foams were compared with those predicted by the theoretical model.

  16. Hydromechanical modeling of clay rock including fracture damage

    Science.gov (United States)

    Asahina, D.; Houseworth, J. E.; Birkholzer, J. T.

    2012-12-01

    Argillaceous rock typically acts as a flow barrier, but under certain conditions significant and potentially conductive fractures may be present. Fracture formation is well-known to occur in the vicinity of underground excavations in a region known as the excavation disturbed zone. Such problems are of particular importance for low-permeability, mechanically weak rock such as clays and shales because fractures can be relatively transient as a result of fracture self-sealing processes. Perhaps not as well appreciated is the fact that natural fractures can form in argillaceous rock as a result of hydraulic overpressure caused by phenomena such as disequlibrium compaction, changes in tectonic stress, and mineral dehydration. Overpressure conditions can cause hydraulic fracturing if the fluid pressure leads to tensile effective stresses that exceed the tensile strength of the material. Quantitative modeling of this type of process requires coupling between hydrogeologic processes and geomechanical processes including fracture initiation and propagation. Here we present a computational method for three-dimensional, hydromechanical coupled processes including fracture damage. Fractures are represented as discrete features in a fracture network that interact with a porous rock matrix. Fracture configurations are mapped onto an unstructured, three-dimensonal, Voronoi grid, which is based on a random set of spatial points. Discrete fracture networks (DFN) are represented by the connections of the edges of a Voronoi cells. This methodology has the advantage that fractures can be more easily introduced in response to coupled hydro-mechanical processes and generally eliminates several potential issues associated with the geometry of DFN and numerical gridding. A geomechanical and fracture-damage model is developed here using the Rigid-Body-Spring-Network (RBSN) numerical method. The hydrogelogic and geomechanical models share the same geometrical information from a 3D Voronoi

  17. Potentials for the Modified Cam-Clay model

    OpenAIRE

    Zouain , Nestor; Pontes , Ivaldo; Vaunat , Jean

    2009-01-01

    Abstract Energy and dissipation pseudo-potentials are employed to derive constitutive relationships, in the context of thermodynamic concepts, for the widely used Modified Cam-Clay (MCC) model for soil mechanics. A variational formulation of the MCC evolution equations is proposed in this paper. Since plastic collapse of MCC soils cannot be embedded in the classical limit analysis theory, finding the critical amplification of the load that produces plastic collapse is formulated in...

  18. Vegetable Oil-Based Hyperbranched Thermosetting Polyurethane/Clay Nanocomposites

    Directory of Open Access Journals (Sweden)

    Deka Harekrishna

    2009-01-01

    Full Text Available Abstract The highly branched polyurethanes and vegetable oil-based polymer nanocomposites have been showing fruitful advantages across a spectrum of potential field of applications.Mesua ferreaL. seed oil-based hyperbranched polyurethane (HBPU/clay nanocomposites were prepared at different dose levels by in situ polymerization technique. The performances of epoxy-cured thermosetting nanocomposites are reported for the first time. The partially exfoliated structure of clay layers was confirmed by XRD and TEM. FTIR spectra indicate the presence of H bonding between nanoclay and the polymer matrix. The present investigation outlines the significant improvement of tensile strength, scratch hardness, thermostability, water vapor permeability, and adhesive strength without much influencing impact resistance, bending, and elongation at break of the nanocomposites compared to pristine HBPU thermoset. An increment of two times the tensile strength, 6 °C of melting point, and 111 °C of thermo-stability were achieved by the formation of nanocomposites. An excellent shape recovery of about 96–99% was observed for the nanocomposites. Thus, the formation of partially exfoliated clay/vegetable oil-based hyperbranched polyurethane nanocomposites significantly improved the performance.

  19. Vegetable Oil-Based Hyperbranched Thermosetting Polyurethane/Clay Nanocomposites.

    Science.gov (United States)

    Deka, Harekrishna; Karak, Niranjan

    2009-04-25

    The highly branched polyurethanes and vegetable oil-based polymer nanocomposites have been showing fruitful advantages across a spectrum of potential field of applications. Mesua ferrea L. seed oil-based hyperbranched polyurethane (HBPU)/clay nanocomposites were prepared at different dose levels by in situ polymerization technique. The performances of epoxy-cured thermosetting nanocomposites are reported for the first time. The partially exfoliated structure of clay layers was confirmed by XRD and TEM. FTIR spectra indicate the presence of H bonding between nanoclay and the polymer matrix. The present investigation outlines the significant improvement of tensile strength, scratch hardness, thermostability, water vapor permeability, and adhesive strength without much influencing impact resistance, bending, and elongation at break of the nanocomposites compared to pristine HBPU thermoset. An increment of two times the tensile strength, 6 degrees C of melting point, and 111 degrees C of thermo-stability were achieved by the formation of nanocomposites. An excellent shape recovery of about 96-99% was observed for the nanocomposites. Thus, the formation of partially exfoliated clay/vegetable oil-based hyperbranched polyurethane nanocomposites significantly improved the performance.

  20. Thermal characterization of a new effective building material based on clay and olive waste

    Directory of Open Access Journals (Sweden)

    Mohamed Lamrani

    2018-01-01

    Full Text Available The influence of thermophysical properties of wall materials on energy performance and comfort in traditional building was investigated. The clay is the most commonly used sustainable building material. The study looked at the effects of the addition of pomace olive on the thermophysical properties of clay bricks to improve the energy efficiency of this ecological material. An experimental measurement of thermal properties of clay mixed with pomace olive was carried out by using the transient and steady state hot-plate and flash methods. The experimental methods are applied to measure the thermal properties of the composite material. The estimation of these thermal characteristics is based on a one dimensional model and the experimental errors are found less than 3%. The composite samples were prepared with different granular classes and mass fractions of the pomace olive in the mixture. The results show that the density of the new material was not substantially influenced by the size of the pomace olive. However, the thermal conductivity and diffusivity decrease from 0.65 W.m-1.K-1 and 4.21×10-7 m2.s-1 to 0.29 W.m-1.K-1 and 2.47×10-7m2.s-1, respectively, according to the variation of the volume fraction of pomace olive from 0 (pure clay to 71% showing that the olive pomace can be used as effective secondary raw materials in the making of clay bricks.

  1. Modelling aqueous solubility of sodium chloride in clays at thermodynamic conditions of hydraulic fracturing by molecular simulations.

    Science.gov (United States)

    Moučka, Filip; Svoboda, Martin; Lísal, Martin

    2017-06-28

    To address the high salinity of flow-back water during hydraulic fracturing, we have studied the equilibrium partitioning of NaCl and water between the bulk phase and clay pores. In shale rocks, such a partitioning can occur between fractures with a bulk-like phase and clay pores. We use an advanced Grand Canonical Monte Carlo (GCMC) technique based on fractional exchanges of dissolved ions and water molecules. We consider a typical shale gas reservoir condition of a temperature of 365 K and pressure of 275 bar, and we represent clay pores by pyrophyllite and Na-montmorillonite slits of a width ranging from about 7 to 28 Å, covering clay pores from dry clay to clay pores with a bulk-like layer in the middle of the pore. We employ the Joung-Cheatham model for ions, SPC/E model for water and CLAYFF for the clay pores. We first determine the chemical potentials for NaCl and water in the bulk phase using Osmotic Ensemble Monte Carlo simulations. The chemical potentials are then used in GCMC to simulate the adsorption of ions and water molecules in the clay pores, and in turn to predict the salt solubility in confined solutions. Besides the thermodynamic properties, we evaluate the structure and in-plane diffusion of the adsorbed fluids, and ion conductivities.

  2. Chloride Ingress in Chemically Activated Calcined Clay-Based Cement

    Directory of Open Access Journals (Sweden)

    Joseph Mwiti Marangu

    2018-01-01

    Full Text Available Chloride-laden environments pose serious durability concerns in cement based materials. This paper presents the findings of chloride ingress in chemically activated calcined Clay-Ordinary Portland Cement blended mortars. Results are also presented for compressive strength development and porosity tests. Sampled clays were incinerated at a temperature of 800°C for 4 hours. The resultant calcined clay was blended with Ordinary Portland Cement (OPC at replacement level of 35% by mass of OPC to make test cement labeled PCC35. Mortar prisms measuring 40 mm × 40 mm × 160 mm were cast using PCC35 with 0.5 M Na2SO4 solution as a chemical activator instead of water. Compressive strength was determined at 28th day of curing. As a control, OPC, Portland Pozzolana Cement (PPC, and PCC35 were similarly investigated without use of activator. After the 28th day of curing, mortar specimens were subjected to accelerated chloride ingress, porosity, compressive strength tests, and chloride profiling. Subsequently, apparent diffusion coefficients (Dapp were estimated from solutions to Fick’s second law of diffusion. Compressive strength increased after exposure to the chloride rich media in all cement categories. Chemically activated PCC35 exhibited higher compressive strength compared to nonactivated PCC35. However, chemically activated PCC35 had the least gain in compressive strength, lower porosity, and lower chloride ingress in terms of Dapp, compared to OPC, PPC, and nonactivated PCC35.

  3. A new coupled elastoplastic damage model for clay-stone and its parameter identification

    International Nuclear Information System (INIS)

    Jia, S.P.; Chen, W.Z.; Yu, H.D.; Li, X.L.; Sillen, X.

    2010-01-01

    Document available in extended abstract form only. In Belgium, the Boom Clay is considered as a potential host rock for the geological disposal of the high level nuclear waste and is intensively studied from hydro-mechanical point of view. Laboratory tests on Boom clay shown that the Boom clay presents very complex stress strain behaviour. Undrained triaxial tests indicated often a hardening behaviour at small deformation and softening at larger deformation. It is not easy to give an explicit function to describe the stress-strain behaviour under triaxial stress state. The mechanical characteristics are obviously affected by the porosity, fractures growth, water content, and stress, etc., four stages can be usually distinguished from the stress-strain curve of Boom Clay, named as OA, AB, BC and CD. 1) Stage OA, the relation between stress and strain is linear. This stage is elastic state, and point A is called as yield strength σ c0 . 2) Stage AB, the weak fractures in the rock appear, develop and cumulate gradually. Point B is called peak strength σ cu . 3) Stage BC, peak strength is reached and stress reduces with the increasing of strain, up to the residual strength. This stage is called strain softening and point C is the residual strength σ cr . The axial pressure causes the fracture developing and strength reducing. 4) Stage CD, the final strength doesn't reduce obviously with the development of plastic deformation. This stage is called plastic flow. Obviously, The conventional elasto-plastic constitutive model can not describe the mechanical behaviours of Boom Clay. Based on damage mechanics theory, an new elasto-plastic damage constitutive model is put forward and applied to Boom Clay, which can describe the complex stress-strain behaviour of clay. It is described as follows: stage OA with an elastic model, stage AB with elastic damage model, stage BC and stage CD with plastic damage model. The complete process curve of stress-strain can be divided

  4. Modelling of the thermomechanical behaviour of saturated clays: application to the radioactive wastes disposal

    International Nuclear Information System (INIS)

    Rahbaoui, A.

    1995-01-01

    During the waste disposal of containers, the clay barriers of backfill and the confining medium, which is essentially composed of clay, are submitted to heavy thermal stresses which induce volume change and can result in material failure. The clay, composed of solid skeleton, adsorbed water, and free water, is submitted to physico-chemical interactions which influence its thermomechanical behaviour, itself quits different from granular media such as sand. The principal factor responsible for this response is the effect of temperature on the clays water. Thus, the loss of special structure of adsorbed water and the increase in thickness of the diffused double-layer provoke microstructural rearrangement mechanisms of particles. Those mechanisms are strongly correlated with the mechanical state of material. When it is highly over-consolidated, an irreversible swelling occurs during thermal cycle, accompanied by a breaking up of the particles and a permanent expansion of meso-pores. The greater the OCR, the more important the thermal swelling. When the material is normally consolidated, the particles settle during heating under the external stress, which results in a denser rearrangement of the material. With a slight over-consolidated material, all the intermediate stages between the above mechanisms can be reached. However, cooling produces only a weak reversible compression characterising the thermal contraction of the components. Those microscopic phenomena have been used to elaborate a macroscopic thermomechanical model based on the Cam-Clay and the Hujeux Models. The model formulation includes a thermal softening, on one hand, by the reduction of the mechanical yield surface f c and the translation of the thermal yield surface f T (PTL), and, on the other hand, an irreversible thermal expansive volumetric strain. This approach of the problem was tested along various thermomechanical paths and especially on the laboratory tests, on the expansive and non expansive

  5. Analysis of the `Biarez Favre' and `Burland' models for the compressibility of remoulded clays

    Science.gov (United States)

    Favre, Jean-Louis; Hattab, Mahdia

    2008-01-01

    This study aims at comparing the prediction by the Biarez and Favre model as well as by the more recent Burland one, established for reconstituted normally consolidated clays submitted to oedometric loading. The former, proposed in the 1970s, uses the liquidity index IL, and while the latter introduces a parameter, Iv, which is a normalised void index based on two characteristic void ratios ( e100* and e1000*) corresponding to the oedometric curve of σv=100 kPa and σv=1000 kPa. The aim of these models is to predict the compressibility parameters based on the identification of parameters represented by the Atterberg limits ( wL, wP, Ip) as well as of other physical parameters such as the void ratio e or the natural water content wnat, taking into account the effective overburden pressure σv. These models, which represent the intrinsic properties of clays under compression, are compared with two experimental curves, the first one representing remoulded and reconstituted clay, and the other one a deepwater clay sediment taken from the Gulf of Guinea at a depth of 700 m.

  6. Intensified Pozzolanic Reaction on Kaolinite Clay-Based Mortar

    Directory of Open Access Journals (Sweden)

    Yang-Hee Kwon

    2017-05-01

    Full Text Available The objective of this study is to develop and characterize kaolinite clay-based structural mortar. The pozzolanic reaction induced from two mineral additives, i.e., calcium hydroxide and silica fume (SF, and the physical filling effect from SF, were found to be effective on the enhancement of structural properties. Based on several preliminary experiments, 7:3 ratio of kaolinite clay/calcium hydroxide was selected as a basic binder. Then, the amount of SF was chosen as 0%, 7.5%, and 15% of the total binder to consider both the chemical and physical effects. The results showed that compressive strengths of samples with 7.5% and 15% SF are significantly increased by approximately 200% and 350%, respectively, at 28 days compared to the sample without SF. However, based on the results of the sample with 15% SF, it is found that excessive addition of SF causes long-term strength loss, possibly owing to micro cracks. With the careful consideration on this long-term behavior, this suggested new mix design can be further extended to develop sustainable structural materials using natural minerals or waste materials with nonbinding properties.

  7. Predictive modelling of an excavation test in indurated clay

    International Nuclear Information System (INIS)

    Garitte, B.; Vaunat, J.; Gens, A.; Vietor, T.

    2010-01-01

    Document available in extended abstract form only. This Abstract presents the predictive hydro-mechanical (HM) modelling of an excavation performed in Opalinus clay in the Mont Terri underground laboratory. Niche 2 was excavated in the shaly facies of Opalinus clay from gallery 08. The area surrounding the gallery was intensively instrumented. The geology of Mont Terri is described in Thury and Bosssart (1999) and the parameters used in the analysis were taken from Bock (2009). The stress state is derived from Martin and Lanyion (2003). Gallery 08 is horseshoe shaped and has a mean radius of 2.25 m. It was excavated with a road header at a mean velocity of 1 m/day starting on January 30, 2008 (Gallery chainage 43.8) and ending on June 30, 2008 (Gallery chainage 123.8) with a stop from March 18, to April 24, to instrument the area of niche 2. Niche 2 was excavated by successive blastings 1.3 m deep until reaching a distance of 24 m from the gallery 08 wall. Advance was continuous from October 13, to November 7 with the exception of three stops of 3, 5 and 4 days. The niche has an average diameter of 4.5 m and has a slight upward slope of 0.98%. The excavation of gallery 08 from chainage 43.8 to chainage 123.8 and of the niche was simulated by relaxing the normal total stress and water pressure from the value before excavation to 0. The gallery advance rate was simulated in an approximate manner by applying successively the excavation procedure to 9 m long gallery sections. In the case of the niche, the blasting scheme and the application of the shotcrete was closely reproduced. The three dimensional geometry used in the simulation is shown. The coupled hydro-mechanical formulation used for the analysis is based on the simultaneous solution of the balance equation for solid mass, water mass and momentum (equilibrium). In accordance with field observations, it has been assumed that the medium remains saturated throughout. The formulation was completed with a number of

  8. Multi-scale modeling of the behaviour of water and ions clays

    International Nuclear Information System (INIS)

    Rotenberg, B.

    2007-10-01

    Predicting the fate of radioactive waste stored in a clay formation requires a good understanding of the transport properties of water and ions in clays. Their diffusion in this charged porous medium is described by empirical parameters such as their partitioning coefficient Kd which accounts for the interactions with the mineral surfaces. The present work deals with the relevance of this concept and its definition based on microscopic grounds. We have first modeled the ionic contribution to the dielectric properties of clays and suggested an experimental determination of Kd from dielectric spectroscopy measurements. Using microscopic simulations (Monte-Carlo and Molecular Dynamics), we then have computed the Gibbs free energy and enthalpy for ionic exchange in the case of alkaline cations. They control the value of Kd and its evolution with the temperature. The results for cesium are in good agreement with both microcalorimetric measurements and the determination of Kd at different temperatures. We have participated in the development of a new lattice simulation method (Lattice Fokker-Planck), which we have then used to link explicitly the microscopic dynamics of ions to the diffusion-reaction model underlying the definition of Kd. Finally, we have used Molecular Dynamics to investigate the kinetics of exchange of water and ions between clay particles (interlayer) and the extra-particle porosity. The results confirm the generally admitted idea that water and ions can explore the whole porosity, whereas anions are excluded from the interlayers. (author)

  9. Development of new baked bricks based on clay and sawdust

    Directory of Open Access Journals (Sweden)

    Benjeddou Omrane

    2018-01-01

    Full Text Available Current research in the field of building materials is oriented towards the recovery of waste to ensure the lightening of certain building elements and energy saving. The objective of this study is to produce a new bricks by adding sawdust to clay mixtures. The first part of this experimental work consists on detremining the proper manufacturing process and cooking diagram for these new bricks. In the second part, the effect of the maximum cooking temperature, the firing phase time's of the bricks and the sawdust prportion on the physical and mechanical properties of the new bricks have been studied. The studied properties are the absorption ratio, the unit weight and the compressive strength. The results showed that the addition of an increasing amount of sawdust tends to modify the physical and mechanical properties of the cooked samples. The presence of sawdust reduces the number of connections between the clay grains and produces a lighter, more absorbent and less resistant material. Finally, the results showed that the manufacture of bricks based on sawdust is possible.

  10. Clay Generic Disposal System Model - Sensitivity Analysis for 32 PWR Assembly Canisters (+2 associated model files).

    Energy Technology Data Exchange (ETDEWEB)

    Morris, Edgar [Argonne National Lab. (ANL), Argonne, IL (United States)

    2014-10-01

    The Used Fuel Disposition Campaign (UFDC), as part of the DOE Office of Nuclear Energy’s (DOE-NE) Fuel Cycle Technology program (FCT) is investigating the disposal of high level radioactive waste (HLW) and spent nuclear fuela (SNF) in a variety of geologic media. The feasibility of disposing SNF and HLW in clay media has been investigated and has been shown to be promising [Ref. 1]. In addition the disposal of these wastes in clay media is being investigated in Belgium, France, and Switzerland. Thus, Argillaceous media is one of the environments being considered by UFDC. As identified by researchers at Sandia National Laboratory, potentially suitable formations that may exist in the U.S. include mudstone, clay, shale, and argillite formations [Ref. 1]. These formations encompass a broad range of material properties. In this report, reference to clay media is intended to cover the full range of material properties. This report presents the status of the development of a simulation model for evaluating the performance of generic clay media. The clay Generic Disposal System Model (GDSM) repository performance simulation tool has been developed with the flexibility to evaluate not only different properties, but different waste streams/forms and different repository designs and engineered barrier configurations/ materials that could be used to dispose of these wastes.

  11. Anatomical Knowledge Gain through a Clay-Modeling Exercise Compared to Live and Video Observations

    Science.gov (United States)

    Kooloos, Jan G. M.; Schepens-Franke, Annelieke N.; Bergman, Esther M.; Donders, Rogier A. R. T.; Vorstenbosch, Marc A. T. M.

    2014-01-01

    Clay modeling is increasingly used as a teaching method other than dissection. The haptic experience during clay modeling is supposed to correspond to the learning effect of manipulations during exercises in the dissection room involving tissues and organs. We questioned this assumption in two pretest-post-test experiments. In these experiments,…

  12. Clay Modeling as a Method to Learn Human Muscles: A Community College Study

    Science.gov (United States)

    Motoike, Howard K.; O'Kane, Robyn L.; Lenchner, Erez; Haspel, Carol

    2009-01-01

    The efficacy of clay modeling compared with cat dissection for human muscle identification was examined over two semesters at LaGuardia Community College in Queens, NY. The 181 students in 10 sections in this study were randomly distributed into control (cat dissection) and experimental (clay modeling) groups, and the results of the muscle…

  13. A remediation performance model for enhanced metabolic reductive dechlorination of chloroethenes in fractured clay till

    DEFF Research Database (Denmark)

    Manoli, Gabriele; Chambon, Julie C.; Bjerg, Poul L.

    2012-01-01

    A numerical model of metabolic reductive dechlorination is used to describe the performance of enhanced bioremediation in fractured clay till. The model is developed to simulate field observations of a full scale bioremediation scheme in a fractured clay till and thereby to assess remediation...

  14. Performance of polymeric films based thermoplastic starch and organophilic clay

    International Nuclear Information System (INIS)

    Cipriano, P.B.; Costa, A.N.M.; Araujo, S.S.; Araujo, A.R.A.; Canedo, E.L.; Carvalho, L.H.

    2010-01-01

    The aim of this work was the development and investigation of the properties of flat films of LDPE/corn thermoplastic starch (TPS). A bentonite clay (Argel) was organophilized and characterized by XRD. This clay (1%) in both pristine and organophilic forms was added to the matrix (LDPE) and to LDPE/TPS systems with TPS contents varying from 5-20% w/w. The films manufactured (LDPE, LDPE/Clay, LDPE/TPS, LDPE/TPS/Clay) were characterized. Results indicate that water vapor permeability is dependent and increases with TPS content which was attributed to the higher affinity of water by TPS. TPS and Clay addition to LDPE led to significant changes in film properties with respect to the neat LDPE. In general,tensile and perforation forces increased with clay and TPS contents; the strength of thermo sealed films lowered with natural clay addition and increased with TPS and organoclay incorporation and, in general, dynamic friction coefficient decrease with organoclay and TPS addition. Best overall properties were obtained for the systems containing the organoclay and optimal properties were achieved for the 5%TPS10 LDPE1% ANO system. (author)

  15. The brush model - a new approach to numerical modeling of matrix diffusion in fractured clay stone

    International Nuclear Information System (INIS)

    Lege, T.; Shao, H.

    1998-01-01

    A special approach for numerical modeling of contaminant transport in fractured clay stone is presented. The rock matrix and the fractures are simulated with individual formulations for FE grids and transport, coupled into a single model. The capacity of the rock matrix to take up contaminants is taken into consideration with a discrete simulation of matrix diffusion. Thus, the natural process of retardation due to matrix diffusion can be better simulated than by a standard introduction of an empirical parameter into the transport equation. Transport in groundwater in fractured clay stone can be simulated using a model called a 'brush model'. The 'brush handle' is discretized by 2-D finite elements. Advective-dispersive transport in groundwater in the fractures is assumed. The contaminant diffuses into 1D finite elements perpendicular to the fractures, i.e., the 'bristles of the brush'. The conclusion is drawn that matrix diffusion is an important property of fractured clay stone for contaminant retardation. (author)

  16. Modeling of flash calcination process during clay activation

    International Nuclear Information System (INIS)

    Borrajo Perez, Ruben; Gonzalez Bayon, Juan Jose; Sanchez Rodriguez, Andy A.

    2011-01-01

    Pozzolanic activity in some materials can be increased by means of different processes, among them, thermal activation is one of the most promising. The activation process, occurring at high temperatures and velocities produces a material with better characteristics. In the last few years, high reactivity pozzolan during cure's early days has been produced. Temperature is an important parameter in the activation process and as a consequence, the activation units must consider temperature variation to allow the use of different raw materials, each one of them with different characteristics. Considering the high prices of Kaolin in the market, new materials are being tested, the clayey soil, which after a sedimentation process produces a clay that has turned out to be a suitable raw material, when the kinetics of the pozzolanic reaction is considered. Additionally, other material with higher levels of kaolin are being used with good results. This paper is about the modeling of thermal, hydrodynamics and dehydroxilation processes suffering for solids particles exposed to a hot gas stream. The models employed are discussed; the velocity and temperature of particles are obtained as a function of carrier gas parameters. The calculation include the heat losses and finally the model predict the residence time needed for finish the activation process. (author)

  17. Improvement of a force field to model the edges of clay particles

    International Nuclear Information System (INIS)

    Pouvreau, Maxime

    2016-01-01

    The CLAYFF force field is widely used to model the interfaces of clay minerals - and related layered materials - with an aqueous phase. In the simulations, clay particles are typically represented by semi-infinite layers, i.e. only surfaces parallel to the layer plane (basal surfaces) are considered. This simplification is acceptable to a certain extent, but clay layers are really nano sized and terminated by lateral surfaces or edges. These surfaces can not only adsorb solvated species but are also subject to proton transfers, and all physico-chemical processes related to the aqueous phase acidity predominantly occur at the edges. By adding to the CLAYFF force field a Metal-O-H angle bending term whose parameters are correctly adjusted, the simulations of edge interfaces become possible.The parameters of Al-O-H and Mg-O-H terms were obtained from DFT calculations on bulk, basal surface and edge structural models of gibbsite Al(OH) 3 and brucite Mg(OH) 2 , whose layers can be considered as the backbones of clay minerals and related materials. In addition, the Si-O-H term was parametrized from an edge model of kaolinite Al 2 Si 2 O 5 (OH) 4 . Molecular dynamics simulations based on DFT and on CLAYFF with and without Metal-O-H term were performed. The modified force field clearly improves the description of hydroxylated surfaces: the orientation and the vibrational dynamics of the hydroxyl groups, the hydrogen bonding, and the coordination of metal atoms belonging to the edge are all closer to reality [fr

  18. Reactive transport modelling of a heating and radiation experiment in the Boom clay (Belgium)

    International Nuclear Information System (INIS)

    Montenegro, L.; Samper, J.; Delgado, J.

    2003-01-01

    Most countries around the world consider Deep Geological Repositories (DGR) as the most safe option for the final disposal of high level radioactive waste (HLW). DGR is based on adopting a system of multiple barriers between the HLW and the biosphere. Underground laboratories provide information about the behaviour of these barriers at real conditions. Here we present a reactive transport model for the CERBERUS experiment performed at the HADES underground laboratory at Mol (Belgium) in order to characterize the thermal (T), hydrodynamic (H) and geochemical (G) behaviour of the Boon clay. This experiment is unique because it addresses the combined effect of heat and radiation produced by the storage of HLW in a DGR. Reactive transport models which are solved with CORE, are used to perform quantitative predictions of Boom clay thermo-hydro-geochemical (THG) behaviour. Numerical results indicate that heat and radiation cause a slight oxidation near of the radioactive source, pyrite dissolution, a pH decrease and slight changes in the pore water chemical composition of the Boom clay. (Author) 33 refs

  19. Microanalysis of clay-based pigments in painted artworks by the means of Raman spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Košařová, V.; Hradil, David; Němec, I.; Bezdička, Petr; Kanický, V.

    2013-01-01

    Roč. 44, č. 11 (2013), s. 1570-1577 ISSN 0377-0486 Institutional support: RVO:61388980 Keywords : Raman spectroscopy * clay-based pigments * clay minerals * iron oxides * microanalysis of paintings Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 2.519, year: 2013

  20. Solar assisted liquid desiccant cooling using clay based membranes

    Directory of Open Access Journals (Sweden)

    Priya S. Shanmuga

    2018-01-01

    Full Text Available The environmental concerns have led to the urge of the usage of non-conventional energy resources like solar, wind, thermal, geothermal etc. which provide enormous source of energy without causing any further diminution of the environment. Instead of the conventional HVAC systems that cause colossal environmental perils, usage of liquid desiccants in coming in vogue whereby reducing ecological threats. Moreover, solar assisted systems provide further impulse to such systems. This paper discusses about the various comparisons between liquid desiccants: Lithium chloride, Potassium formate and Calcium chloride and concludes that potassium formate is the best desiccant to be used among the three. Potassium formate (HCOOK is used which is cheaper and less corrosive as compared to the other aqueous salts, and has a negative crystallization temperature. Potassium formate is a new liquid desiccant and thus, not much research is available currently. The weather conditions of Manipal provide an appropriate condition for the experimentations of solar aided liquid desiccant evaporative cooling systems due to its humid climate and intense solar radiation obtained. The small scale experimentation also encounters the problem of liquid desiccant carryover by the air flow, with the help of clay based membranes which are again cheap, environmentally benign and obtained in a facile way. The projected system takes complete advantage of pure solar energy aimed at the regeneration of liquid desiccant.

  1. Clay based superior aggregate for making light construction

    International Nuclear Information System (INIS)

    Sumarnadi, Eko Tri; Sudaryanto; Zulkarnain, Iskandar

    2002-01-01

    Aggregate is defined as material consisting of solid minerals with grain size ranging from sand to gravel. This material is usually used for filling components of concrete. Clay based aggregate has special properties that can be useful for making light construction in wet environment. Concrete build using the aggregate is not impermeable, but it can adsorb water in significant amount, so that is very useful to be used as paving block for walker zone (trotoir) and zone surrounding swimming pool. Laboratory test results show that the aggregate has grain size in zone 1 type with specific gravity between 1360 - 1840 kg/cm 3. Its abrasive factor about 35.32 % in average and it can be used as building material for light construction. Concrete with mixing ratio cement/aggregate of 1 to 6 with slump condition 3 to 6 cm and curing time of 28 days indicates compressive strength of 10 N/cm 3. Qualitative cost analysis reflected that the paving block production cost is relatively low and it will be more profitable if they are product from failed pentile having fail between 10 to 30 %

  2. Anatomical knowledge gain through a clay-modeling exercise compared to live and video observations.

    Science.gov (United States)

    Kooloos, Jan G M; Schepens-Franke, Annelieke N; Bergman, Esther M; Donders, Rogier A R T; Vorstenbosch, Marc A T M

    2014-01-01

    Clay modeling is increasingly used as a teaching method other than dissection. The haptic experience during clay modeling is supposed to correspond to the learning effect of manipulations during exercises in the dissection room involving tissues and organs. We questioned this assumption in two pretest-post-test experiments. In these experiments, the learning effects of clay modeling were compared to either live observations (Experiment I) or video observations (Experiment II) of the clay-modeling exercise. The effects of learning were measured with multiple choice questions, extended matching questions, and recognition of structures on illustrations of cross-sections. Analysis of covariance with pretest scores as the covariate was used to elaborate the results. Experiment I showed a significantly higher post-test score for the observers, whereas Experiment II showed a significantly higher post-test score for the clay modelers. This study shows that (1) students who perform clay-modeling exercises show less gain in anatomical knowledge than students who attentively observe the same exercise being carried out and (2) performing a clay-modeling exercise is better in anatomical knowledge gain compared to the study of a video of the recorded exercise. The most important learning effect seems to be the engagement in the exercise, focusing attention and stimulating time on task. © 2014 American Association of Anatomists.

  3. Clay-based materials for engineered barriers: a review

    International Nuclear Information System (INIS)

    Lajudie, A.; Raynal, J.; Petit, J.C.; Toulhoat, P.

    1994-01-01

    The potential importance of backfilling and plugging in underground radioactive waste repositories has led different research institutions to carry out extensive studies of swelling clay materials for the development of engineered barriers in underground conditions. These materials should combine a variety of hydro-thermo-mechanical and geochemical properties: impermeability, swelling ability in order to fill all void space, heat transfer and retention capacity for the most noxious radionuclides. Smectite clays best exhibit these properties and most of the research effort has been devoted to this type of materials. In this paper, mineralogical composition, sodium or calcium content, thermo-hydro-mechanical properties, swelling pressure, hydraulic and thermal conductivity, and chemical properties of five smectite clays selected by five major nuclear countries are reviewed: Avonseal montmorillonite (Canada), MX 80 montmorillonite (Sweden), Montigel montmorillonite (Switzerland), S-2 montmorillonite (Spain), and Fo-Ca inter stratified kaolinite/beidellite (France). (J.S.). 29 refs., 5 figs., 3 tabs

  4. Modelling of natural organic matter-linked radionuclide transport in Boom clay

    International Nuclear Information System (INIS)

    Govaerts, J.; Maes, N.

    2012-01-01

    Document available in extended abstract form only. In the framework of the Belgian research program on long term management of high-level and/or long-lived radioactive wastes coordinated by ONDRAF/NIRAS, Boom Clay is investigated for its potential to host a deep geological disposal repository. In order to demonstrate the suitability of the Boom Clay as a host rock, the mobility of critical radionuclides in this clay layer has been the subject of research during many years. As actinides, lanthanides and transition metals are known to form strong complexes with organic substances, the influence of the Natural Organic Matter (NOM) present in Boom Clay on the mobility of these critical radionuclides is of crucial importance. Interaction of radionuclides with OM present in Boom Clay could on the one hand retard the migration due to complexation/colloid interaction with the immobile OM, and on the other hand the mobility and solubility of the radionuclide can be enhanced by the formation of complexes/colloids with the mobile OM. The conceptual understanding (and its numerical modelling) of the kinetic stability and transport of these complexes/colloids is therefore regarded as highly important for the the long-term safety assesment of the geological disposal. This can be broken down into two subproblems: 1. Describing the transport behaviour of mobile OM in Boom Clay; 2. Describing the interaction of RN with mobile OM and the transport behaviour of the resulting complexes in Boom Clay. The first part of this paper revolves around the first subproblem, where a robust model for the description of the migration behaviour of Natural Organic Matter (NOM) is derived based on data from column migration experiments using 14 C-labelled NOM Tracer solution, obtained in the framework of the EC TRANCOM-II project. Clay plugs of different lengths and different Darcy velocities were used. Inverse modelling with the MATLAB and COMSOL numerical code was done in order to identify the

  5. Epoxy based nanocomposites with fully exfoliated unmodified clay: mechanical and thermal properties.

    Science.gov (United States)

    Li, Binghai; Zhang, Xiaohong; Gao, Jianming; Song, Zhihai; Qi, Guicun; Liu, Yiqun; Qiao, Jinliang

    2010-09-01

    The unmodified clay has been fully exfoliated in epoxy resin with the aid of a novel ultrafine full-vulcanized powdered rubber. Epoxy/rubber/clay nanocomposites with exfoliated morphology have been successfully prepared. The microstructures of the nanocomposites were characterized by means of X-ray diffraction and transmission electron microscopy. It was found that the unmodified clay was fully exfoliated and uniformly dispersed in the resulting nanocomposite. Characterizations of mechanical properties revealed that the impact strength of this special epoxy/rubber/clay nanocomposite increased up 107% over the neat epoxy resin. Thermal analyses showed that thermal stability of the nanocomposite was much better than that of epoxy nanocomposite based on organically modified clay.

  6. Slow diuron release formulations based on clay-phosphatidylcholine complexes

    Czech Academy of Sciences Publication Activity Database

    Undabeytia, T.; Recio, E.; Maqueda, C.; Sanchez-Verdejo, T.; Balek, Vladimír

    2012-01-01

    Roč. 55, JAN (2012), s. 53-61 ISSN 0169-1317 R&D Projects: GA MŠk(CZ) LC523 Institutional support: RVO:61388980 Keywords : Diuron * Phosphatidylcholine * Clay mineral * Leaching * Bioactivity * Slow release Subject RIV: CA - Inorganic Chemistry OBOR OECD: Inorganic and nuclear chemistry Impact factor: 2.342, year: 2012

  7. A 'putty-practically-clay' vintage model with R and D driven biases in energy-saving technical change

    International Nuclear Information System (INIS)

    Van Zon, A.; Lontzek, T.

    2005-01-01

    This paper deals with the problem of tackling the adverse effect of output growth on environmental quality. For this purpose we use an intermediate sector that builds 'putty-practically-clay' capital consisting of an energy-raw capital amalgam used for final goods production. The putty-practically-clay model is a strongly simplified version of a full putty-clay model, that mimics all the relevant behaviour of a full puttyclay model, but that does not entail the administrative hassle of a full putty-clay vintage model. In addition to this, we introduce an R and D sector that develops renewable- and conventional energy-based technologies. The allocation of R and D activities over these two uses of R and D gives rise to an induced bias in technical change. In the context of our model, this implies that technological progress is primarily driven by the desire to counteract the upward pressure on production cost implied by a continuing price increase of conventional energy resources. Hotelling's rule suggests that this price rise is unavoidable in the face of the ongoing depletion of conventional energy reserves. By means of some illustrative model simulations we study the effects of energy policy on the dynamics of the model for alternative policy options aimed at achieving GHG emission reductions. We identify the conditions under which energy policy might partly backfire and present some non-standard policy implications

  8. Interaction between clay-based shaft seal components and crystalline host rock

    International Nuclear Information System (INIS)

    Priyanto, D.; Dixon, D.; Man, A.

    2010-01-01

    Document available in extended abstract form only. The Government of Canada has accepted the Nuclear Waste Management Organization's (NWMO) recommendation of Adaptive Phased Management (APM) as the long-term management approach for Canada's used nuclear fuel. APM ultimately involves the isolation and containment of used nuclear fuel deep in a Deep Geological Repository (DGR). On completion of waste emplacement operation and during repository closure, shaft seals, comprising clay-based shaft seal components, will be installed at strategic locations, such as where significant fracture zones (FZs) are located. The primary function of a shaft seal is to limit and prevent short-circuiting of the groundwater flow regime via the shaft. Currently, at Atomic Energy of Canada Limited's Underground Research Laboratory (URL) a full-scale shaft seal is being constructed at the intersection of a low dipping thrust fault called FZ 2 as part of the overall URL decommissioning activities. Both crystalline rock and sedimentary rock are considered potentially suitable host rocks formations for a DGR. This paper presents the results of numerical simulation of a shaft seal installed in moderately to sparsely fractured crystalline rock (MFR). The shape and thickness of the shaft seal modelled for a DGR in this exercise are similar to the shaft seal at the URL, but in the modelling exercise it is given a larger diameter (i.e. 7.30 m) equal to the assumed diameter of a production shaft of a repository. The seal consists of a blended bentonite-sand (BS) component that is constrained between two massive concrete seals. Dense backfill (DBF) materials are installed above and below the concrete seals (CS). The concrete seals are keyed into the access shaft to better anchor the concrete units in place and in order to restrain the swelling of the bentonite-sand component of the seal as it hydrates. The reference geosphere in the proposed work is MFR similar to the rock conditions

  9. Flocculation of Clay Colloids Induced by Model Polyelectrolytes: Effects of Relative Charge Density and Size.

    Science.gov (United States)

    Sakhawoth, Yasine; Michot, Laurent J; Levitz, Pierre; Malikova, Natalie

    2017-10-06

    Flocculation and its tuning are of utmost importance in the optimization of several industrial protocols in areas such as purification of waste water and civil engineering. Herein, we studied the polyelectrolyte-induced flocculation of clay colloids on a model system consisting of purified clay colloids of well-defined size fractions and ionene polyelectrolytes presenting regular and tunable chain charge density. To characterize ionene-induced clay flocculation, we turned to the combination of light absorbance (turbidity) and ζ-potential measurements, as well as adsorption isotherms. Our model system allowed us to identify the exact ratio of positive and negative charges in clay-ionene mixtures, the (c+/c-) ratio. For all samples studied, the onset of efficient flocculation occurred consistently at c+/c- ratios significantly below 1, which indicated the formation of highly ionene-deficient aggregates. At the same time, the ζ-potential measurements indicated an apparent zero charge on such aggregates. Thus, the ζ-potential values could not provide the stoichiometry inside the clay-ionene aggregates. The early onset of flocculation in clay-ionene mixtures is reminiscent of the behavior of multivalent salts and contrasts that of monovalent salts, for which a large excess amount of ions is necessary to achieve flocculation. Clear differences in the flocculation behavior are visible as a function of the ionene charge density, which governs the conformation of the ionene chains on the clay surface. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Spectroscopic characterization of schiff base-copper complexes immobilized in smectite clays

    Directory of Open Access Journals (Sweden)

    Patrícia M. Dias

    2010-01-01

    Full Text Available Herein, the immobilization of some Schiff base-copper(II complexes in smectite clays is described as a strategy for the heterogenization of homogeneous catalysts. The obtained materials were characterized by spectroscopic techniques, mostly UV/Vis, EPR, XANES and luminescence spectroscopy. SWy-2 and synthetic Laponite clays were used for the immobilization of two different complexes that have previously shown catalytic activity in the dismutation of superoxide radicals, and disproportionation of hydrogen peroxide. The obtained results indicated the occurrence of an intriguing intramolecular redox process involving copper and the imine ligand at the surface of the clays. These studies are supported by computational calculations.

  11. Numerical analysis of thermo-hydro-mechanical (THM) processes in the clay based material

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xuerui

    2016-10-06

    Clay formations are investigated worldwide as potential host rock for the deep geological disposal of high-level radioactive waste (HLW). Usually bentonite is preferred as the buffer and backfill material in the disposal system. In the disposal of HLW, heat emission is one of the most important issues as it can generate a series of complex thermo-hydro-mechanical (THM) processes in the surrounding materials and thus change the material properties. In the context of safety assessment, it is important to understand the thermally induced THM interactions and the associated change in material properties. In this work, the thermally induced coupled THM behaviours in the clay host rock and in the bentonite buffer as well as the corresponding coupling effects among the relevant material properties are numerically analysed. A coupled non-isothermal Richards flow mechanical model and a non-isothermal multiphase flow model were developed based on the scientific computer codes OpenGeoSys (OGS). Heat transfer in the porous media is governed by thermal conduction and advective flow of the pore fluids. Within the hydraulic processes, evaporation, vapour diffusion, and the unsaturated flow field are considered. Darcy's law is used to describe the advective flux of gas and liquid phases. The relative permeability of each phase is considered. The elastic deformation process is modelled by the generalized Hooke's law complemented with additional strain caused by swelling/shrinkage behaviour and by temperature change. In this study, special attention has been paid to the analysis of the thermally induced changes in material properties. The strong mechanical and hydraulic anisotropic properties of clay rock are described by a transversely isotropic mechanical model and by a transversely isotropic permeability tensor, respectively. The thermal anisotropy is described by adoption of the bedding-orientation-dependent thermal conductivity. The dependency of the thermal

  12. Numerical analysis of thermo-hydro-mechanical (THM) processes in the clay based material

    International Nuclear Information System (INIS)

    Wang, Xuerui

    2016-01-01

    Clay formations are investigated worldwide as potential host rock for the deep geological disposal of high-level radioactive waste (HLW). Usually bentonite is preferred as the buffer and backfill material in the disposal system. In the disposal of HLW, heat emission is one of the most important issues as it can generate a series of complex thermo-hydro-mechanical (THM) processes in the surrounding materials and thus change the material properties. In the context of safety assessment, it is important to understand the thermally induced THM interactions and the associated change in material properties. In this work, the thermally induced coupled THM behaviours in the clay host rock and in the bentonite buffer as well as the corresponding coupling effects among the relevant material properties are numerically analysed. A coupled non-isothermal Richards flow mechanical model and a non-isothermal multiphase flow model were developed based on the scientific computer codes OpenGeoSys (OGS). Heat transfer in the porous media is governed by thermal conduction and advective flow of the pore fluids. Within the hydraulic processes, evaporation, vapour diffusion, and the unsaturated flow field are considered. Darcy's law is used to describe the advective flux of gas and liquid phases. The relative permeability of each phase is considered. The elastic deformation process is modelled by the generalized Hooke's law complemented with additional strain caused by swelling/shrinkage behaviour and by temperature change. In this study, special attention has been paid to the analysis of the thermally induced changes in material properties. The strong mechanical and hydraulic anisotropic properties of clay rock are described by a transversely isotropic mechanical model and by a transversely isotropic permeability tensor, respectively. The thermal anisotropy is described by adoption of the bedding-orientation-dependent thermal conductivity. The dependency of the thermal

  13. Clay based polymeric composites: Preparation and quality characterization

    International Nuclear Information System (INIS)

    Aloisi, G.G.; Elisei, F.; Nocchetti, M.; Camino, G.; Frache, A.; Costantino, U.; Latterini, L.

    2010-01-01

    Commercial clays Cloisites Na + , 30B and 20A were labelled with the fluorescent dye Rhodamine B and used as fillers of polypropylene in order to prepare composites to be studied with confocal fluorescence microscopy. The dye uptake by clays was monitored by X-ray powder diffraction and spectroscopic analyses and clear evidences of intercalated dye in the organically modified montmorillonites Clo30B and Clo20A were obtained. Clay-Rhodamine B hybrids were investigated by steady-state absorption and emission spectroscopy to explore the effect of dye arrangement on the optical properties. The obtained information was used to rationalize fluorescence behaviour of composites. Confocal fluorescence imaging gave rise to bright fluorescent images of Cloisite aggregated labelled with the dye allowing to easily and directly visualize the 3-D dispersion of the labelled fillers in the polymer matrix in a non-invasive manner. The images were analyzed in terms of size distribution of the fluorescence grains to quantify the dispersion degree. The data indicate that Clo20A is able to homogeneously distribute in the polymer matrix forming a composite material.

  14. Effect of addition of organo clay on mechanical properties and dynamic-mechanical based TPV

    International Nuclear Information System (INIS)

    Honorato, Luciana R.; Silva, Adriana A.; Soares, Bluma G.; Soares, Ketly P.

    2011-01-01

    The effect of organophilic clay on the mechanical and dynamical-mechanical properties of thermoplastic elastomers based on polypropylene (PP) and nitrile rubber (NBR) was investigated. The addition of clay was performed from a master batch prepared by a solution intercalation of NBR inside the clay galleries. Since the PP/NBR blend is highly incompatible, PP functionalized with maleic anhydride (PP-g-MA) and carboxylated NBR (XNBR) were employed as compatibilizing system together with triethylene-tetramine (TETA) used as coupling agent. The addition of Clay inside the elastomeric phase of the TPV resulted in a significant decrease of the elongation at break without changes on the tensile strength. The presence of clay also promoted a slight increase of the storage modulus and the glass transition temperature. The small angle X ray scattering confirmed the high dispersion of clay inside the TPV. Analysis of light scattering small angle (SAXS) confirmed the high dispersion of clay in the matrix of the TPV. (author)

  15. Investigation of the overconsolidation and structural behavior of Shanghai clays by element testing and constitutive modeling

    Directory of Open Access Journals (Sweden)

    Guan-lin Ye

    2016-09-01

    Full Text Available The mechanical properties and constitutive modeling of Shanghai clays are very important for numerical analysis on geotechnical engineering in Shanghai, where continuous layers of soft clays run 30–40 m deep. The clays are divided into 5 major layers. A series of laboratory tests are carried out to investigate their mechanical properties. The top and bottom layers are overconsolidated hard clays, and the middle layers are normally consolidated or lightly overconsolidated sensitive marine clays. A constitutive model, which can describe the overconsolidation and structure of soils using only 8 parameters, is modified to simulate the test results. A rational procedure to determine the values of the material parameters and initial conditions is also proposed. The model is able to effectively reproduce both one-dimensional (1D consolidation and drained/undrained triaxial test results of Shanghai clays, with one set of parameters for each layer. From element testing and constitutive modeling, two findings are obtained. First, the decay rates of overconsolidation are smaller in overconsolidated layers than in normally consolidated layers. Second, the natural microstructure of layer 4 is relatively stable, that is, a large degree of structure is still maintained in the specimen even after 1D consolidation and drained triaxial tests. The modified model and obtained parameter values can be used for numerical analysis of geotechnical projects in Shanghai.

  16. Sealing Clay Text Segmentation Based on Radon-Like Features and Adaptive Enhancement Filters

    Directory of Open Access Journals (Sweden)

    Xia Zheng

    2015-01-01

    Full Text Available Text extraction is a key issue in sealing clay research. The traditional method based on rubbings increases the risk of sealing clay damage and is unfavorable to sealing clay protection. Therefore, using digital image of sealing clay, a new method for text segmentation based on Radon-like features and adaptive enhancement filters is proposed in this paper. First, adaptive enhancement LM filter bank is used to get the maximum energy image; second, the edge image of the maximum energy image is calculated; finally, Radon-like feature images are generated by combining maximum energy image and its edge image. The average image of Radon-like feature images is segmented by the image thresholding method. Compared with 2D Otsu, GA, and FastFCM, the experiment result shows that this method can perform better in terms of accuracy and completeness of the text.

  17. Modeling of Cation Binding in Hydrated 2:1 Clay Minerals - Final Report

    International Nuclear Information System (INIS)

    Smith, David E.

    2000-01-01

    Hydrated 2:1 clay minerals are high surface area, layered silicates that play a unique role in determining the fate of radionuclides in the environment. This project consisted of developing and implementing computer simulation methods for molecular characterization of the swelling and ion exchange properties of Hydrated 2:1 clay minerals, and the subsequent analysis and theoretical modeling with a view toward improving contaminant transport modeling as well as soil remediation and radionuclide containment strategies. Project results included the (a) development of simulation methods to treat clays under environmentally relevant conditions of variable water vapor pressure; (b) calculation of clay swelling thermodynamics as a function of interlayer ion size and charge (calculated quantities include immersion energies, free energies, and entropies of swelling); and (c) calculation of ion exchange free energies, including contributions from changing interlayer water contents and layer spacing

  18. State boundary surface of a hypoplastic model for clays

    Czech Academy of Sciences Publication Activity Database

    Mašín, David; Herle, Ivo

    2005-01-01

    Roč. 32, č. 6 (2005), s. 400-410 ISSN 0266-352X R&D Projects: GA ČR(CZ) GA103/04/0672 Grant - others:Evropská komise SSPI-CT-2003-501837 Institutional research plan: CEZ:AV0Z20710524 Keywords : hypoplasticity * clay * limit state Subject RIV: JM - Building Engineering Impact factor: 0.562, year: 2005

  19. Experimental Support for a Predictive Osmotic Model of Clay Membranes

    International Nuclear Information System (INIS)

    Fritz, S.J.

    2001-01-01

    Osmosis has been cited as a mechanism for explaining anomalously high fluid pressures in the subsurface. Clays and shales act as membranes, and osmotic flux across these units may result in pressures sufficiently high to explain these anomalies. The theoretical osmotic pressures as calculated solely from solution properties can be quite large; however, it is not yet resolved whether these geologic membranes are sufficiently ideal to generate such pressures

  20. Surface modification of montmorillonite on surface Acid-base characteristics of clay and thermal stability of epoxy/clay nanocomposites.

    Science.gov (United States)

    Park, Soo-Jin; Seo, Dong-Il; Lee, Jae-Rock

    2002-07-01

    In this work, the effect of surface treatments on smectitic clay was investigated in surface energetics and thermal behaviors of epoxy/clay nanocomposites. The pH values, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR) were used to analyze the effect of cation exchange on clay surface and the exfoliation phenomenon of clay interlayer. The surface energetics of clay and thermal properties of epoxy/clay nanocomposites were investigated in contact angles and thermogravimetric analysis (TGA), respectively. From the experimental results, the surface modification of clay by dodecylammonium chloride led to the increases in both distance between silicate layers of about 8 A and surface acid values, as well as in the electron acceptor component (gamma(+)(s)) of surface free energy, resulting in improved interfacial adhesion between basic (or electron donor) epoxy resins and acidic (electron acceptor) clay interlayers. Also, the thermal stability of nanocomposites was highly superior to pure epoxy resin due to the presence of the well-dispersed clay nanolayer, which has a barrier property in a composite system.

  1. Retention of radiocaesium traces in clay: a dynamic semi-empirical modelling

    International Nuclear Information System (INIS)

    Lewyckyi, N.

    2001-01-01

    The contribution consists of an abstract of a PhD thesis. After deposition, Cs + bioavailability in soil is a key parameter with regard to public exposure after a severe nuclear accident.The objective of the PhD thesis was to understand and model the interaction of Cs + and 2:1 clay minerals. This interaction was characterised through Cs + sorption-desorption experiments carried out on seven 2:1 clay minerals (four smectite types, illite, biotite and vermiculite)

  2. Aqueous dispersion of red clay-based ceramic powder with the addition of starch

    Directory of Open Access Journals (Sweden)

    Maria Victoria Alcantar Umaran

    2013-04-01

    Full Text Available The optimum dispersion and rheological properties of red clay-based ceramic suspension loaded with unary and binary starch were investigated in aqueous medium. The aqueous ceramic suspension was prepared consisting of red clay, quartz, feldspar, and distilled water. Using a polyelectrolyte dispersant (Darvan 821A, the ternary ceramic powder was initially optimized to give the smallest average particle size at 0.8 wt. (% dispersant dosage as supported by sedimentation test. This resulted into an optimum high solid loading of 55 wt. (%. The addition of either unary or binary starches to the optimized ceramic slurry increased the viscosity but maintained an acceptable fluidity. The mechanism of such viscosity increase was found to be due to an adsorption of starch granules onto ceramic surfaces causing tolerable agglomeration. Correspondingly, the rheological evaluations showed that the flow behaviors of all starch-loaded ceramic slurries can be described using Herschel-Bulkley model. The parameters from this model indicated that all ceramic slurries loaded with starch are shear thinning that is required for direct casting process.

  3. Sealing performance of fractured claystone and clay-based materials. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Chun-Liang

    2017-03-15

    The geological disposal concepts for radioactive waste are generally based on a multibarrier system comprising the natural geological formations and engineered barriers. After waste emplacement, disposal cells, access drifts and shafts will be backfilled and sealed with suitable materials to prevent release of radionuclides into the biosphere. In the framework of the THM-TON project during the last ten years from 2007 to 2016, which was funded by the German Federal Ministry for Economic Affairs and Energy (BMWi) under contract number 02E10377, GRS investigated the thermo-hydro-mechanical properties and responses of clay rocks and clay-based backfill/seal materials. The results obtained during the first time period of 2007 to 2013 are summarized in the GRS report ''Thermo-Hydro-Mechanical Processes in the Nearfield around a HLW Repository in Argillaceous Formations'' with two volumes: Volume I - Laboratory Investigations (GRS-312) /ZHA 13a/ and Volume II - In-situ-Investigations and Interpretative Modelling (GRS-313) /ZHA 14a/.

  4. Low frequency complex dielectric (conductivity) response of dilute clay suspensions: Modeling and experiments.

    Science.gov (United States)

    Hou, Chang-Yu; Feng, Ling; Seleznev, Nikita; Freed, Denise E

    2018-04-11

    In this work, we establish an effective medium model to describe the low-frequency complex dielectric (conductivity) dispersion of dilute clay suspensions. We use previously obtained low-frequency polarization coefficients for a charged oblate spheroidal particle immersed in an electrolyte as the building block for the Maxwell Garnett mixing formula to model the dilute clay suspension. The complex conductivity phase dispersion exhibits a near-resonance peak when the clay grains have a narrow size distribution. The peak frequency is associated with the size distribution as well as the shape of clay grains and is often referred to as the characteristic frequency. In contrast, if the size of the clay grains has a broad distribution, the phase peak is broadened and can disappear into the background of the canonical phase response of the brine. To benchmark our model, the low-frequency dispersion of the complex conductivity of dilute clay suspensions is measured using a four-point impedance measurement, which can be reliably calibrated in the frequency range between 0.1 Hz and 10 kHz. By using a minimal number of fitting parameters when reliable information is available as input for the model and carefully examining the issue of potential over-fitting, we found that our model can be used to fit the measured dispersion of the complex conductivity with reasonable parameters. The good match between the modeled and experimental complex conductivity dispersion allows us to argue that our simplified model captures the essential physics for describing the low-frequency dispersion of the complex conductivity of dilute clay suspensions. Copyright © 2018 Elsevier Inc. All rights reserved.

  5. Mean electrostatic and Poisson-Boltzmann models for multicomponent transport through compacted clay

    International Nuclear Information System (INIS)

    Steefel, C.I.; Galindez, J.M.

    2012-01-01

    Document available in extended abstract form only. Electrical double layer effects in the pore space of clays become increasingly important as the level of compaction increases and intergrain and interlayer spacings shift towards the range of nano-meters. At such scales, solute transport can no longer be explained by concentration gradients alone and it becomes necessary to include the electrostatic effects on chemical potentials. In fact, the electrical double layer (EDL) that develops in the neighborhood of the negatively charged clay surfaces can extend well into the aqueous phase, effectively constraining the space available to anions (known as anion exclusion), thus distorting the spatial distribution of ionic species in solution. In this study, we make use of two approaches for addressing the accumulation and transport of charged ionic species in the electrical double layers of compacted bentonite: 1) a mean electrostatic approach based on the assumption of Donnan equilibrium, and 2) a 2D numerical approach based on the multicomponent Poisson-Nernst-Planck (NPP) set of equations. For the mean electrostatic or Donnan approach to the electrical double layer [1], two options are considered: 1) a model in which surface complexation in the Stern layer may partly balance the fixed charge of the montmorillonite making up the bentonite buffer, and 2) a model in which the fixed mineral charge is balanced completely by the diffuse layer. In the mean electrostatic approach, one additional equation that balances the charge between the Stern layer and the diffuse layer is added to the multicomponent reactive transport code CrunchFlow. The only additional unknown that is required is the mean electrostatic potential, although it may be necessary in certain cases to consider the volume (or width) of the electrical double layer as an additional implicit unknown. Both ions and neutral species may diffuse within the diffuse layer according to their gradients and species

  6. Factors affecting the hydraulic performance of infiltration based SUDS in clay

    DEFF Research Database (Denmark)

    Bockhorn, B.; Klint, K.E.S.; Locatelli, Luca

    2017-01-01

    The influence of small scale soil heterogeneity on the hydraulic performance of infiltration based SUDS was studied using field data from a clayey glacial till and groundwater simulations with the integrated surface water and groundwater model HydroGeoSphere. Simulations of homogeneous soil blocks...... with hydraulic properties ranging from sand to clay showed that infiltration capacities vary greatly for the different soil types observed in glacial till. The inclusion of heterogeneities dramatically increased infiltration volume by a factor of 22 for a soil with structural changes above and below the CaC03...... boundary. Infiltration increased further by 8% if tectonic fractures were included and by another 61% if earthworm burrows were added. Comparison of HydroGeoSphere infiltration hydrographs with a simple soakaway model (Roldin et al. 2012) showed similar results for homogenous soils but indicated...

  7. Assessment of Calculation Procedures for Piles in Clay Based on Static Loading Tests

    DEFF Research Database (Denmark)

    Augustesen, Anders; Andersen, Lars

    2008-01-01

    College in London. The calculation procedures are assessed based on an established database of static loading tests. To make a consistent evaluation of the design methods, corrections related to undrained shear strength and time between pile driving and testing have been employed. The study indicates...... that the interpretation of the field tests is of paramount importance, both with regard to the soil profile and the loading conditions. Based on analyses of 253 static pile loading tests distributed on 111 sites, API-RP2A provides the better description of the data. However, it should be emphasised that some input......Numerous methods are available for the prediction of the axial capacity of piles in clay. In this paper, two well-known models are considered, namely the current API-RP2A (1987 to present) and the recently developed ICP method. The latter is developed by Jardine and his co-workers at Imperial...

  8. Ternary and quaternary nanocomposites based on polystyrene, SBS, organically modified clay and silicone-polyether

    International Nuclear Information System (INIS)

    Kaneko, Manuela L.Q.A.; Lourenco, Emerson; Paiva, Raphael E.F.; Felisberti, Maria I.; Yoshida, Inez V.P.

    2009-01-01

    This work aims the study of toughened nanocomposites based on polystyrene (PS), poly(styrene-b-butadiene-b-styrene) (SBS), organically modified clay (C20A) and silicone-polyether, PDMS-POE. The intercalation of the copolymer PDMS-POE into the clay galleries increased the interlamellar distance, improving the exfoliation of the clay during the extrusion process of the materials. C20A/PDMS-POE nanocomposite, MC20A, was prepared by mechanical mixture using 1:1 wt% ratio. MC20A was incorporated into PS and PS/SBS blends using an extruder. The materials were characterized by X-ray diffraction and stress-strain mechanical tests. MC20A/PS/SBS, prepared by extrusion, showed an increase in the interlamellar distance, suggesting the intercalation of PS or SBS into the clay galleries. The PDMSPOE acted as a 'plasticizer' for PS and PS/SBS blend. However, this effect was not reverted by the clay addition. On the contrary, the 'plasticizer' effect was intensified by the clay maybe due to the slip characteristics of PDMS-POE associated with the lamella orientation. (author)

  9. Simplified modeling of HM behavior of swelling clays for nuclear waste disposal buffers

    International Nuclear Information System (INIS)

    Hoxha, Dashnor; Belayachi, Naima; Do, Duc-Phi; Poutrel, Adrien; Wendling, Jacques

    2010-01-01

    Document available in extended abstract form only. The swelling clays are extensively studied these last decades in relation with many industrial applications: foundations in civil engineering, sealing of waste disposals., etc. Especially in the case of waste disposals buffers the swelling pressure and its kinetics are of great importance. In the research programme of ANDRA (French National Radioactive Waste Management Agency), a mixing of bentonite MX80 with 30% of sands has been chosen as a buffering material. The modelling of behaviour of this material has been object of several works and several sophisticated models have been proposed. However as the practice of nuclear waste disposals proves, the needs for robust and simple models, able to describe the most important features of buffers, are yet to be meet by engineers and researches. This paper aims at a simplified model for the buffers behaviour based upon an extension of previous works and laboratory results. As discussed and proposed by many authors modeling of swelling clays behavior needs to consider both crystalline and osmotic swelling. While molecular dynamics could be used to understand the relation between the structure of clay minerals and its swelling properties a multiscale approach counting for chemical and hydro-mechanical couplings in various scale is revealed to give insights on the mechanisms governing clayey soil swelling. However in many industrial application large scale problems would be considered for which macroscopic and robust models should be used. From macroscopic point of view, basically two alternative approaches are used: effective stress approach and so called independent stress state variables. For an isotropic material, the volumetric strain of unsaturated media predicted by BBM model, could be written as a function of: the mean stress of applied mechanical stress, the air pressure, the suction (or pore pressure where the media is fully saturated), the drained bulk

  10. Cement/clay interactions: feedback on the increasing complexity of modeling assumptions

    International Nuclear Information System (INIS)

    Marty, Nicolas C.M.; Gaucher, Eric C.; Tournassat, Christophe; Gaboreau, Stephane; Vong, Chan Quang; Claret, F.; Munier, Isabelle; Cochepin, Benoit

    2012-01-01

    Document available in extended abstract form only. Cementitious materials will be widely used in French concept of radioactive waste repositories. During their degradation over time, in contact with geological pore water, they will release hyper-alkaline fluids rich in calcium and alkaline cations. This chemical gradient likely to develop at the cement/clay interfaces will induce geochemical transformations. The first simplified calculations based mainly on simple mass balance calculation led to a very pessimistic understanding of the real expansion mechanism of the alkaline plume. However, geochemical and migration processes are much more complex because of the dissolution of the barrier's accessory phases and the precipitation of secondary minerals. To describe and to understand this complexity, coupled geochemistry and transport calculations are a useful and a mandatory tool. Furthermore, such sets of modeling when properly calibrated on experimental results are able to give insights on larger time scale unreachable with experiments. Since approximately 20 years, numerous papers have described the results of reactive transport modeling of cement/clay interactions with various numerical assumptions. For example, some authors selected a purely thermodynamic approach while others preferred a coupled thermodynamic/kinetic approach. Unfortunately, most of these studies used different and not comparable parameters as space discretization, initial and boundary conditions, thermodynamic databases, clayey and cementitious materials, etc... This study revisits the types of simulations proposed in the past to represent the effect of an alkaline perturbation with regard to the degree of complexity that was considered. The main goal of the study is to perform simulations with a consistent set of data and an increasing complexity. In doing so, the analysis of numerical results will give a clear vision of key parameters driving the expansion of alteration fronts and

  11. Report on Modeling Coupled Processes in the Near Field of a Clay Repository

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Hui -Hai [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Houseworth, Jim [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Rutqvist, Jonny [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Li, Lianchong [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Asahina, Daisuke [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Chen, Fei [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Birkholzer, Jens [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2012-08-01

    Clay/shale has been considered as potential host rock for geological disposal of high-level radioactive waste throughout the world. Coupled thermal, hydrological, mechanical, and chemical (THMC) processes have a significant impact on the long-term safety of a clay repository. For example, the excavation damaged zone (EDZ) near repository tunnels can modify local permeability (resulting from induced fractures), potentially leading to less confinement capability. This report documents results from three R&D activities: (1) implementation and validation of constitutive relationships, (2) development of a discrete fracture network (DFN) model for investigating coupled processes in the EDZ, and (3) development of a THM model for the FE tests at Mont Terri, Switzerland, for the purpose of model validation. The overall objective of these activities is to provide an improved understanding of EDZ evolution in clay repositories and the associated coupled processes, and to develop advanced relevant modeling capabilities.

  12. Numerical modeling of the creep behavior of clays with emphasis on tunnels and underground openings

    International Nuclear Information System (INIS)

    1990-02-01

    This report presents an interpretive overview and critical assessment of the state-of-the-art for numerical modeling of the creep behavior of clays. The overview and assessment is focused upon application to underground openings. Field and laboratory observations of time-dependent behavior, constitutive modeling of creep behavior, and numerical implementation of constitutive equations are addressed. A critical assessment of the ability of existing models to predict aspects of creep behavior relevant to waste repository design and suggestions for improved analyses that can be developed with existing technology are provided. Both heuristic and mathematical constitutive models are reviewed. Heuristic models provide a basis for evaluation of the required parameters for the continuum mechanics based mathematical models. The continuum mechanics models are required for numerical analysis. It has been demonstrated that, by using iterative and incremental analysis, virtually any viscous or inviscid continuum mechanics material model can be adapted to consider time-dependent behavior. Available numerical models for numerical analysis of geotechnical problems involving creep deformations are reviewed. Models for thermo-mechanical coupling are also addressed in this review. Cases where creep-inclusive analyses have been applied to analysis of prototype behavior are cited. However, the lack of well documented case histories of time-dependent deformations over significant time spans is identified as a major obstacle to model verification. Recommendations are made for an alternative design approach capable of guaranteeing the very long term mechanical integrity of the liner. 167 refs., 22 figs., 6 tabs

  13. Hollow Cylinder Tests on Boom Clay: Modelling of Strain Localization in the Anisotropic Excavation Damaged Zone

    Science.gov (United States)

    François, Bertrand; Labiouse, Vincent; Dizier, Arnaud; Marinelli, Ferdinando; Charlier, Robert; Collin, Frédéric

    2014-01-01

    Boom Clay is extensively studied as a potential candidate to host underground nuclear waste disposal in Belgium. To guarantee the safety of such a disposal, the mechanical behaviour of the clay during gallery excavation must be properly predicted. In that purpose, a hollow cylinder experiment on Boom Clay has been designed to reproduce, in a small-scale test, the Excavation Damaged Zone (EDZ) as experienced during the excavation of a disposal gallery in the underground. In this article, the focus is made on the hydro-mechanical constitutive interpretation of the displacement (experimentally obtained by medium resolution X-ray tomography scanning). The coupled hydro-mechanical response of Boom Clay in this experiment is addressed through finite element computations with a constitutive model including strain hardening/softening, elastic and plastic cross-anisotropy and a regularization method for the modelling of strain localization processes. The obtained results evidence the directional dependency of the mechanical response of the clay. The softening behaviour induces transient strain localization processes, addressed through a hydro-mechanical second grade model. The shape of the obtained damaged zone is clearly affected by the anisotropy of the materials, evidencing an eye-shaped EDZ. The modelling results agree with experiments not only qualitatively (in terms of the shape of the induced damaged zone), but also quantitatively (for the obtained displacement in three particular radial directions).

  14. A remediation performance model for enhanced metabolic reductive dechlorination of chloroethenes in fractured clay till

    Science.gov (United States)

    Manoli, Gabriele; Chambon, Julie C.; Bjerg, Poul L.; Scheutz, Charlotte; Binning, Philip J.; Broholm, Mette M.

    2012-04-01

    A numerical model of metabolic reductive dechlorination is used to describe the performance of enhanced bioremediation in fractured clay till. The model is developed to simulate field observations of a full scale bioremediation scheme in a fractured clay till and thereby to assess remediation efficiency and timeframe. A relatively simple approach is used to link the fermentation of the electron donor soybean oil to the sequential dechlorination of trichloroethene (TCE) while considering redox conditions and the heterogeneous clay till system (clay till matrix, fractures and sand stringers). The model is tested on lab batch experiments and applied to describe sediment core samples from a TCE-contaminated site. Model simulations compare favorably to field observations and demonstrate that dechlorination may be limited to narrow bioactive zones in the clay matrix around fractures and sand stringers. Field scale simulations show that the injected donor is expected to be depleted after 5 years, and that without donor re-injection contaminant rebound will occur in the high permeability zones and the mass removal will stall at 18%. Long remediation timeframes, if dechlorination is limited to narrow bioactive zones, and the need for additional donor injections to maintain dechlorination activity may limit the efficiency of ERD in low-permeability media. Future work should address the dynamics of the bioactive zones, which is essential to understand for predictions of long term mass removal.

  15. A three-scale model for ionic solute transport in swelling clays incorporating ion-ion correlation effects

    Science.gov (United States)

    Le, Tien Dung; Moyne, Christian; Murad, Marcio A.

    2015-01-01

    A new three-scale model is proposed to describe the movement of ionic species of different valences in swelling clays characterized by three separate length scales (nano, micro, and macro) and two levels of porosity (nano- and micropores). At the finest (nano) scale the medium is treated as charged clay particles saturated by aqueous electrolyte solution containing monovalent and divalent ions forming the electrical double layer. A new constitutive law is constructed for the disjoining pressure based on the numerical resolution of non-local problem at the nanoscale which, in contrast to the Poisson-Boltzmann theory for point charge ions, is capable of capturing the short-range interactions between the ions due to their finite size. At the intermediate scale (microscale), the two-phase homogenized particle/electrolyte solution system is represented by swollen clay clusters (or aggregates) with the nanoscale disjoining pressure incorporated in a modified form of Terzaghi's effective principle. At the macroscale, the electro-chemical-mechanical couplings within clay clusters is homogenized with the ion transport in the bulk fluid lying in the micro pores. The resultant macroscopic picture is governed by a three-scale model wherein ion transport takes place in the bulk solution strongly coupled with the mechanics of the clay clusters which play the role of sources/sinks of mass to the bulk fluid associated with ion adsorption/desorption in the electrical double layer at the nanoscale. Within the context of the quasi-steady version of the multiscale model, wherein the electrolyte solution in the nanopores is assumed at instantaneous thermodynamic equilibrium with the bulk fluid in the micropores, we build-up numerically the ion-adsorption isotherms along with the constitutive law of the retardation coefficients of monovalent and divalent ions. In addition, the constitutive law for the macroscopic swelling pressure is reconstructed numerically showing patterns of

  16. Gravel-Sand-Clay Mixture Model for Predictions of Permeability and Velocity of Unconsolidated Sediments

    Science.gov (United States)

    Konishi, C.

    2014-12-01

    Gravel-sand-clay mixture model is proposed particularly for unconsolidated sediments to predict permeability and velocity from volume fractions of the three components (i.e. gravel, sand, and clay). A well-known sand-clay mixture model or bimodal mixture model treats clay contents as volume fraction of the small particle and the rest of the volume is considered as that of the large particle. This simple approach has been commonly accepted and has validated by many studies before. However, a collection of laboratory measurements of permeability and grain size distribution for unconsolidated samples show an impact of presence of another large particle; i.e. only a few percent of gravel particles increases the permeability of the sample significantly. This observation cannot be explained by the bimodal mixture model and it suggests the necessity of considering the gravel-sand-clay mixture model. In the proposed model, I consider the three volume fractions of each component instead of using only the clay contents. Sand becomes either larger or smaller particles in the three component mixture model, whereas it is always the large particle in the bimodal mixture model. The total porosity of the two cases, one is the case that the sand is smaller particle and the other is the case that the sand is larger particle, can be modeled independently from sand volume fraction by the same fashion in the bimodal model. However, the two cases can co-exist in one sample; thus, the total porosity of the mixed sample is calculated by weighted average of the two cases by the volume fractions of gravel and clay. The effective porosity is distinguished from the total porosity assuming that the porosity associated with clay is zero effective porosity. In addition, effective grain size can be computed from the volume fractions and representative grain sizes for each component. Using the effective porosity and the effective grain size, the permeability is predicted by Kozeny-Carman equation

  17. Physicochemical characterization of modified clay based composites obtained by a novel method

    Science.gov (United States)

    Kalra, Swati; Dudi, D.; Singh, G. P.; Verma, S. K.; Bhojak, N.

    2018-05-01

    Material science is one of the important fields where, absorption spectra of lanthanide ions have been a subject of several investigations because of their possible use as laser materials, diagnostic tools and sensors. Study of absorption spectra in visible and near infrared regions yields useful information regarding energy and intensity parameters, and nature and probabilities of transitions. Chemical physics provides fundamental tool to develop lanthanide chemistry, which has been increasingly significant in the last few years due to the wide variety of potential applications of their complexes in many important areas of biology and medicines. The present work describes the development of a novel method of composite preparation based on clay and its physiochemical characterization. Simultaneous measurement of some thermal properties has made study more useful. Results match with accepted models.

  18. The effect of clay nanoparticles as reinforcement on mechanical properties of bioplastic base on cassava starch

    Science.gov (United States)

    Harunsyah; Sariadi; Raudah

    2018-01-01

    Plastics have been used widely for packaging material since long time ago. However, environmentally friendly plastics or plastics whose raw materials come from natural polymers are still very low in development. Efforts have been conducted to develop environmental friendly plastic from renewable resources such as biopolymer. The aim of this paper is to study the influence of clay nanoparticles as reinforcment on the mechanical properties of bioplastic were prepared by solution-casting method. The content of clay nanoparticles in the bioplastic was varied from 0.2%, 0.4%, 0.6%, 0.8% and 1.0% (w/w) by weight of starch. Structural characterization was done by Fourier Transform Infrared Spectroscopy. Surface morphologies of the plastic film were examined by scanning electron microscope.The result showed that the Tensile strength was improved significantly with the addition of clay nanoparticles. The maximum tensile strength obtained was 24.18 M.Pa on the additional of clay nanoparticles by 0.6% and plasticizer by 25%. Based on data of FTIR, the produced bioplastic did not change the group function and it can be concluded that the interaction in bioplastic produced was only a physical interaction. The bioplastic based on cassava starch-clay nanoparticles and plasticizer glycerin showed that interesting mechanical properties being transparent, clear, homogeneous, flexible and easy to be handled.

  19. Experimental study and modelling of selenite sorption onto illite and smectite clays.

    Science.gov (United States)

    Missana, T; Alonso, U; García-Gutiérrez, M

    2009-06-15

    This study provides a large set of experimental selenite sorption data for pure smectite and illite. Similar sorption behavior existed in both clays: linear within a large range of the Se concentrations investigated (from 1x10(-10) to 1x10(-3) M); and independent of ionic strength. Selenite sorption was also analysed in the illite/smectite system with the clays mixed in two different proportions, as follows: (a) 30% illite-70% smectite and (b) 43% illite-57% smectite. The objective of the study was to provide the simplest model possible to fit the experimental data, a model also capable of describing selenite sorption in binary illite/smectite clay systems. Selenite sorption data, separately obtained in the single mineral systems, were modeled using both a one- and a two-site non-electrostatic model that took into account the formation of two complexes at the edge sites of the clay. Although the use of a two-site model slightly improved the fit of data at a pH below 4, the simpler one-site model reproduced satisfactorily all the sorption data from pH 3 to 8. The complexation constants obtained by fitting sorption data of the individual minerals were incorporated into a model to predict the adsorption of selenium in the illite/smectite mixtures; the model's predictions were consistent with the experimental adsorption data.

  20. Simulation of pesticide leaching in a cracking clay soil with the PEARL model

    NARCIS (Netherlands)

    Scorza, R.P.; Boesten, J.J.T.I.

    2005-01-01

    Testing of pesticide leaching models is important to increase confidence in their use in pesticide registration procedures world-wide. The chromatographic PEARL model was tested against the results of a field leaching study on a cracking clay soil with a tracer (bromide), a mobile pesticide

  1. Modelling tools for assessing bioremediation performance and risk of chlorinated solvents in clay tills

    DEFF Research Database (Denmark)

    Chambon, Julie Claire Claudia

    design are challenging. This thesis presents the development and application of analytical and numerical models to improve our understanding of transport and degradation processes in clay tills, which is crucial for assessing bioremediation performance and risk to groundwater. A set of modelling tools...... to groundwater and bioremediation performance in low-permeability media....

  2. Micromechanics of non-active clays in saturated state and DEM modelling

    Directory of Open Access Journals (Sweden)

    Pagano Arianna Gea

    2017-01-01

    Full Text Available The paper presents a conceptual micromechanical model for 1-D compression behaviour of non-active clays in saturated state. An experimental investigation was carried out on kaolin clay samples saturated with fluids of different pH and dielectric permittivity. The effect of pore fluid characteristics on one-dimensional compressibility behaviour of kaolin was investigated. A three dimensional Discrete Element Method (DEM was implemented in order to simulate the response of saturated kaolin observed during the experiments. A complex contact model was introduced, considering both the mechanical and physico-chemical microscopic interactions between clay particles. A simple analysis with spherical particles only was performed as a preliminary step in the DEM study in the elastic regime.

  3. Calibration of mathematical models for simulation of thermal, seepage and mechanical behaviour of boom clay

    International Nuclear Information System (INIS)

    Baldi, G.; Borsetto, M.; Hueckel, T.

    1987-01-01

    This report presents results of research on the verification of the validity of a generalized thermo-elastoplastic-hydraulic mathematical model elaborated at Ismes for description of the behaviour of boom clay. The model is described in Section 2. Experimental results performed at Ismes for the identification of the material constants in athermal and thermal drained conditions are then presented. Procedures for the identification are described in Section 4. The undrained consolidated constant total stress heating test is then discussed. The undrained test shows the possibility of clay yielding due to effective pressure decrease during heating, caused by water pressure growth. The test has been simulated numerically, confirming the interpretation of the experiment. Further simulation of plane strain and plane stress central heating axisymmetric problem shows again a formation of a yielded clay zone around the heater. Interpretation of the results and recommendations for further research are given

  4. Experimental Study and modelling of the Sorption of Selenite and Europium Onto Smectite and Illite Clays

    International Nuclear Information System (INIS)

    Missana, T.; Alonso, U.; Garcia-Gutierrez, M.

    2009-01-01

    This study provides a large set of experimental selenite sorption data for pure smectite and illite. Similar sorption behavior existed in both clays: linear within a large range of the Se concentrations investigated and independent of ionic strength. Selenite sorption was also analysed in the illite/smectite system with the clays mixed in two different proportions. The objective of the study was to provide the simplest model possible to fit the experimental data, a model also capable of describing selenite sorption in binary illite/smectite clay systems. Selenite sorption data were modeled using both a one-and a two-site non-electrostatic model that took into account the formation of two complexes at the edge sites of the clay. The complexation constants obtained by fitting sorption data of the individual minerals were incorporated into a model to predict the adsorption of selenium in the illite/ smectite mixtures; the models predictions were consistent with the experimental adsorption data. (Author) 42 refs

  5. Experimental Study and modelling of the Sorption of Selenite and Europium Onto Smectite and Illite Clays

    Energy Technology Data Exchange (ETDEWEB)

    Missana, T.; Alonso, U.; Garcia-Gutierrez, M.

    2009-10-12

    This study provides a large set of experimental selenite sorption data for pure smectite and illite. Similar sorption behavior existed in both clays: linear within a large range of the Se concentrations investigated and independent of ionic strength. Selenite sorption was also analysed in the illite/smectite system with the clays mixed in two different proportions. The objective of the study was to provide the simplest model possible to fit the experimental data, a model also capable of describing selenite sorption in binary illite/smectite clay systems. Selenite sorption data were modeled using both a one-and a two-site non-electrostatic model that took into account the formation of two complexes at the edge sites of the clay. The complexation constants obtained by fitting sorption data of the individual minerals were incorporated into a model to predict the adsorption of selenium in the illite/ smectite mixtures; the models predictions were consistent with the experimental adsorption data. (Author) 42 refs.

  6. A model for predicting embankment slope failures in clay-rich soils; A Louisiana example

    Science.gov (United States)

    Burns, S. F.

    2015-12-01

    A model for predicting embankment slope failures in clay-rich soils; A Louisiana example It is well known that smectite-rich soils significantly reduce the stability of slopes. The question is how much smectite in the soil causes slope failures. A study of over 100 sites in north and south Louisiana, USA, compared slopes that failed during a major El Nino winter (heavy rainfall) in 1982-1983 to similar slopes that did not fail. Soils in the slopes were tested for per cent clay, liquid limits, plasticity indices and semi-quantitative clay mineralogy. Slopes with the High Risk for failure (85-90% chance of failure in 8-15 years after construction) contained soils with a liquid limit > 54%, a plasticity index over 29%, and clay contents > 47%. Slopes with an Intermediate Risk (55-50% chance of failure in 8-15 years) contained soils with a liquid limit between 36-54%, plasticity index between 16-19%, and clay content between 32-47%. Slopes with a Low Risk chance of failure (soils with a liquid limit plasticity index soil characteristics before construction. If the soils fall into the Low Risk classification, construct the embankment normally. If the soils fall into the High Risk classification, one will need to use lime stabilization or heat treatments to prevent failures. Soils in the Intermediate Risk class will have to be evaluated on a case by case basis.

  7. Preparation and characterization of polymer nanocomposites based on chitosan and clay minerals

    International Nuclear Information System (INIS)

    Fiori, Ana Paula Santos de Melo; Gabiraba, Victor Parizio; Praxedes, Ana Paula Perdigao; Nunes, Marcelo Ramon da Silva; Balliano, Tatiane L.; Silva, Rosanny Christhinny da; Tonholo, Josealdo; Ribeiro, Adriana Santos

    2014-01-01

    In this work nanocomposites based on chitosan and different clays were prepared using polyethyleneglycol (PEG) as plasticizer. The samples obtained were characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), thermogravimetric analysis (TGA/DTG) and by mechanical characterization (tensile test) with the aim of investigating the interactions between chitosan and clay. The nanocomposite films prepared using sodium bentonite (Ben) showed an increase of 81.2% in the maximum tensile stress values and a decrease of 16.0% in the Young’s modulus when compared to the chitosan with PEG (QuiPEG) films, evidencing that the introduction of the clay into the polymer matrix provided a more flexible and resistant film, whose elongation at break was 93.6% higher than for the QuiPEG film. (author)

  8. Elaboration, morphology and properties of starch/polyester nano-biocomposites based on sepiolite clay.

    Science.gov (United States)

    Olivato, J B; Marini, J; Pollet, E; Yamashita, F; Grossmann, M V E; Avérous, L

    2015-03-15

    The incorporation of nano-sized sepiolite clays into thermoplastic starch/poly(butylene adipate-co-terephthalate) (TPS/PBAT) blends has been investigated with the goal of improving the matrix properties. TPS/PBAT nano-biocomposites were elaborated with two different proportions of the polymeric phases. The influence of the sepiolite nanoclays on the mechanical, thermal and structural properties of the corresponding blends was evaluated. SEM images confirmed the good dispersion of the sepiolite clay, with a low occurrence of small aggregates in the polymeric matrix. Wide-angle X-ray diffraction showed no significant alteration of the crystalline structures of PBAT and starch induced by the sepiolite clay. The addition of sepiolite slightly affected the thermal degradation of the nano-biocomposites; however, the mechanical tests revealed an increase in some mechanical properties, demonstrating that sepiolite is a promising nanofiller for TPS-based materials. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Installation process of suction anchors in Gulf of Guinea clay : Centrifuge modelling

    OpenAIRE

    THOREL, Luc; GARNIER, Jacques; RAULT, Gérard; DENDANI, Hédi; COLLIAT, JL

    2010-01-01

    The preparation process of a deepwater Gulf of Guinea clay for modelling of 24 m long suction anchors at a scale of 1/100 in the LCPC centrifuge, the clay characteristics and the installation phase (self-weight and suction) are presented. Two types of caissons have been tested in each tub : one with stiffeners and the other without stiffener. The embedment ratio is close to the suction caisson's slenderness of 3. An analysis of the forces of suction and soil friction shows, as expected, hi...

  10. The CEC benchmark interclay on rheological models for clays results of pilot phase (January-June 1989) about the boom clay at Mol (B)

    International Nuclear Information System (INIS)

    Come, B.

    1990-01-01

    A pilot phase of a benchmark exercise for rheological models for boom clay, called interclay, was launched by the CEC in January 1989. The purpose of the benchmark is to compare predictions of calculations made about well-defined rock-mechanical problems, similar to real cases at the Mol facilities, using existing data from laboratory tests on samples. Basically, two approaches were to be compared: one considering clay as an elasto-visco-plastic medium (rock-mechanics approach), and one isolating the role of pore-pressure dissipation (soil-mechanics approach)

  11. Clay modeling versus written modules as effective interventions in understanding human anatomy.

    Science.gov (United States)

    Bareither, Mary Lou; Arbel, Vered; Growe, Meghan; Muszczynski, Emily; Rudd, Adam; Marone, Jane R

    2013-01-01

    The effectiveness of clay modeling to written modules is examined to determine the degree of improvement in learning and retention of anatomical 3D relationships among students with different learning preferences. Thirty-nine undergraduate students enrolled in a cadaver dissection course completed a pre-assessment examination and the VARK questionnaire, classifying learning preference as visual, auditory, read/write, or kinesthetic. Students were divided into clay, module, and control groups with preference for learning style distributed among groups. The clay and module groups participated in weekly one-hour classes using either clay models or answering written questions (modules) about anatomical relationships, respectively. The control group received no intervention. Post-assessment and retention examinations were administered at the end of the semester, and three months later, respectively. Two variables (Δ1, Δ2) represented examination score differences between pre- and post-assessment and between post-assessment and retention examinations, respectively. The Δ1 for clay and module groups were each significantly higher than controls (21.46 ± 8.2 vs. 15.70 ± 7.5, P ≤ 0.05; and 21.31 ± 6.9 vs. 15.70 ± 7.5, P ≤0.05, respectively). The Δ2 for clay and module groups approached but did not achieve significance over controls (-6.09 ± 5.07 vs. -8.80 ± 4.60, P = 0.16 and -5.73 ± 4.47 vs. -8.80 ± 4.60, P = 0.12, respectively). No significant differences were seen between interventions or learning preferences in any group. However, students of some learning styles tended to perform better when engaging in certain modalities. Multiple teaching modalities may accommodate learning preferences and improve understanding of anatomy. Copyright © 2012 American Association of Anatomists.

  12. Implementation of geomechanical models for engineered clay barriers in multi-physic partial differential equation solvers

    International Nuclear Information System (INIS)

    Navarro, V.; Alonso, J.; Asensio, L.; Yustres, A.; Pintado, X.

    2012-01-01

    Document available in extended abstract form only. The use of numerical methods, especially the Finite Element Method (FEM), for solving boundary problems in Unsaturated Soil Mechanics has experienced significant progress. Several codes, both built mainly for research purposes and commercial software, are now available. In the last years, Multi-physic Partial Differentiation Equation Solvers (MPDES) have turned out to be an interesting proposal. In this family of solvers, the user defines the governing equations and the behaviour models, generally using a computer algebra environment. The code automatically assembles and solves the equation systems, saving the user having to redefine the structures of memory storage or to implement solver algorithms. The user can focus on the definition of the physics of the problem, while it is possible to couple virtually any physical or chemical process that can be described by a PDE. This can be done, for instance, in COMSOL Multiphysics (CM). Nonetheless, the versatility of CM is compromised by the impossibility to implement models with variables defined by implicit functions. Elasto-plastic models involve an implicit coupling among stress increments, plastic strains and plastic variables increments. For this reason, they cannot be implemented in CM in a straightforward way. This means a very relevant limitation for the use of this tool in the analysis of geomechanical boundary value problems. In this work, a strategy to overcome this problem using the multi-physics concept is presented. A mixed method is proposed, considering the constitutive stresses, the pre-consolidation pressure and the plastic variables as main unknowns of the model. Mixed methods usually present stability problems. However, the algorithmics present in CM include several numerical strategies to minimise this kind of problems. Besides, CM is based on the application of the FEM with Lagrange multipliers, an approach that significantly contributes stability

  13. Clay Modeling versus Written Modules as Effective Interventions in Understanding Human Anatomy

    Science.gov (United States)

    Bareither, Mary Lou; Arbel, Vered; Growe, Meghan; Muszczynski, Emily; Rudd, Adam; Marone, Jane R.

    2013-01-01

    The effectiveness of clay modeling to written modules is examined to determine the degree of improvement in learning and retention of anatomical 3D relationships among students with different learning preferences. Thirty-nine undergraduate students enrolled in a cadaver dissection course completed a pre-assessment examination and the VARK…

  14. Creating Clay Models of a Human Torso as an Alternative to Dissection

    Science.gov (United States)

    Shipley, Gwendolyn

    2010-01-01

    Instead of dissecting animals, students create small clay models of human internal organs to demonstrate their understanding of the positioning and interlocking shapes of the organs. Not only is this approach more environmentally friendly, it also forces them to learn human anatomy--which is more relevant to them than the anatomy of other…

  15. Advanced clay nanocomposites based on in situ photopolymerization utilizing novel polymerizable organoclays

    Science.gov (United States)

    Kim, Soon Ki

    Polymer nanocomposite technology has had significant impact on material design. With the environmental advantages of photopolymerization, a research has recently focused on producing nanocomposites utilizing inexpensive clay particles based on in situ photopolymerization. In this research, novel polymerizable organoclays and thiol-ene photopolymerization have been utilized to develop advanced photopolymer clay nanocomposites and to overcome several limitations in conventional free radical photopolymers. To this end, factors important in nanocomposite processes such as monomer composition, clay dispersion, and photopolymerization behavior in combination with the evolution of ultimate nanocomposite properties have been investigated. For monomer-organoclay compositions, higher chemical compatibility of components induces enhanced clay exfoliation, resulting in photopolymerization rate increases due to an amplified clay template effect. Additionally, by affecting the stoichiometric ratio between thiol and acrylate double bond in the clay gallery, thiolated organoclays enhance thiol-ene copolymerization with increased final thiol conversion while acrylated organoclays encourage acrylate homopolymerization. In accordance with the reaction behavior, incorporation of thiolated organoclays makes polymer chains more flexible with decreased glass transition temperature due to higher formation of thio-ether linkages while adding acrylated organoclays significantly increases the modulus. Photopolymer nanocomposites also help overcome two major drawbacks in conventional free radical photopolymerization, namely severe polymerization shrinkage and oxygen inhibition during polymerization. With addition of a low level of thiol monomers, the oxygen inhibition in various acrylate systems can be overcome by addition of only 5wt% thiolated organoclay. The same amount of polymerizable organoclay also induces up to 90% decreases in the shrinkage stress for acrylate or thiol

  16. Towards a numerical run-out model for quick-clay slides

    Science.gov (United States)

    Issler, Dieter; L'Heureux, Jean-Sébastien; Cepeda, José M.; Luna, Byron Quan; Gebreslassie, Tesfahunegn A.

    2015-04-01

    Highly sensitive glacio-marine clays occur in many relatively low-lying areas near the coasts of eastern Canada, Scandinavia and northern Russia. If the load exceeds the yield stress of these clays, they quickly liquefy, with a reduction of the yield strength and the viscosity by several orders of magnitude. Leaching, fluvial erosion, earthquakes and man-made overloads, by themselves or combined, are the most frequent triggers of quick-clay slides, which are hard to predict and can attain catastrophic dimensions. The present contribution reports on two preparatory studies that were conducted with a view to creating a run-out model tailored to the characteristics of quick-clay slides. One study analyzed the connections between the morphological and geotechnical properties of more than 30 well-documented Norwegian quick-clay slides and their run-out behavior. The laboratory experiments by Locat and Demers (1988) suggest that the behavior of quick clays can be reasonably described by universal relations involving the liquidity index, plastic index, remolding energy, salinity and sensitivity. However, these tests should be repeated with Norwegian clays and analyzed in terms of a (shear-thinning) Herschel-Bulkley fluid rather than a Bingham fluid because the shear stress appears to grow in a sub-linear fashion with the shear rate. Further study is required to understand the discrepancy between the material parameters obtained in laboratory tests of material from observed slides and in back-calculations of the same slides with the simple model by Edgers & Karlsrud (1982). The second study assessed the capability of existing numerical flow models to capture the most important aspects of quick-clay slides by back-calculating three different, well documented events in Norway: Rissa (1978), Finneidfjord (1996) and Byneset (2012). The numerical codes were (i) BING, a quasi-two-dimensional visco-plastic model, (ii) DAN3D (2009 version), and (iii) MassMov2D. The latter two are

  17. Simulation Of Enhanced Reductive Dechlorination For Remediation Of Tce In A Fractured Clay System: A New Model Approach And Application To Field Site

    DEFF Research Database (Denmark)

    Manoli, Gabriele; Chambon, Julie Claire Claudia; Christiansen, Camilla Maymann

    2010-01-01

    with interspersed sand lenses and stringers. The transport model couples diffusion dominated transport in the clay matrix, with advective‐dispersive transport in the fractures and higher permeability sand lenses. The reactive model calculates sequential reductive dechlorination of TCE (trichloroethylene) to its...... a contamination of trichloroethylene located in a fractured clay till. The site is simulated using the model developed. Fracture geometry, site parameters and degradation rates are based on observations from the site and lab studies. The risk for drinking water is assessed and cleanup times are simulated using...

  18. Coupled modelling (transport-reaction) of the fluid-clay interactions and their feed back on the physical properties of the bentonite engineered clay barrier system

    International Nuclear Information System (INIS)

    Marty, N.

    2006-11-01

    The originality of this work is to process feed back effects of mineralogical and chemical modifications of clays, in storage conditions, on their physical properties and therefore on their transport characteristics (porosity, molecular diffusion, permeability). These feed back effects are modelled using the KIRMAT code (Kinetic of Reaction and MAss Transfer) developed from the kinetic code KINDIS by adding the effect of water renewal in the mineral-solution reactive cells. KIRMAT resolves mass balance equations associated with mass transport together with the geochemical reactions in a 1D approach. After 100 000 years of simulated interaction at 100 C, with the fluid of the Callovo-Oxfordian geological level (COX) and with iron provided by the steel overpack corrosion, the montmorillonite of the clay barrier is only partially transformed (into illite, chlorite, saponite...). Only outer parts of the modelled profile seem to be significantly affected by smectite dissolution processes, mainly at the interface with the geological environment. The modifications of physical properties show a closure of the porosity at the boundaries of the barrier, by creating a decrease of mass transport by molecular diffusion, essentially at the interface with the iron. Permeability laws applied to this system show a decrease of the hydraulic conductivity correlated with the porosity evolution. Near the COX, the swelling pressure of the clays from the barrier decreases. In the major part of the modelled profile, the engineered clay barrier system seems to keep its initial physical properties (porosity, molecular diffusion, permeability, swelling pressure) and functionalities. (author)

  19. Chemical processes at the surface of various clays on acid-base titration

    International Nuclear Information System (INIS)

    Park, K. K.; Park, Y. S.; Jung, E. C.

    2010-01-01

    The chemical reaction of radionuclides at the interface between groundwater and geological mineral is an important process determining their retardation of transport through groundwater flow in a nuclear waste disposal. Clay minerals are major components of soil and argillaceous rock, and some of them are considered to be important base materials in the design of high-level nuclear waste repository due to their large swelling, low-permeability, large surface area, and strong and large sorption of radionuclides. Clay materials are phyllosilicates containing accessory minerals such as metal oxides, hydroxides, oxyhydroxides. Their structures are condensed 1:1 or 2:1 layers of tetrahedral SiO 3/2 OH and octahedral Al(OH) 6/2 sheets. An accurate knowledge about the properties of clay surface is required as a parameter for a long-term estimation of radionuclide retardation effects. Electric surface charge is a primary property determining ion exchange and surface complexation of radionuclides on its surface. The sources of electric surface charge are a permanent structural negative charge on a basal plane and a dissociable charge at an edge surface. Investigation of proton sorption is a prerequisite to the understanding of radionuclide sorption. The reactions on a permanently charged site and on an edge site are measured by an electrokinetic measurement and by potentiometric titration, respectively. However, side reactions such as complexation, proton/cation exchange, dissolution, hydrolysis, precipitation and re adsorption, and the reaction of secondary minerals hinder an experimental measurement of accurate acid-base properties. This presentation describes the pH change on dispersing various clays in water and adding acid, base or Eu(III) ion to these solutions, and the effect of Eu(III) ion on acid-base titration of clay solutions

  20. Chemical processes at the surface of various clays on acid-base titration

    Energy Technology Data Exchange (ETDEWEB)

    Park, K. K.; Park, Y. S.; Jung, E. C. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2010-10-15

    The chemical reaction of radionuclides at the interface between groundwater and geological mineral is an important process determining their retardation of transport through groundwater flow in a nuclear waste disposal. Clay minerals are major components of soil and argillaceous rock, and some of them are considered to be important base materials in the design of high-level nuclear waste repository due to their large swelling, low-permeability, large surface area, and strong and large sorption of radionuclides. Clay materials are phyllosilicates containing accessory minerals such as metal oxides, hydroxides, oxyhydroxides. Their structures are condensed 1:1 or 2:1 layers of tetrahedral SiO{sub 3/2}OH and octahedral Al(OH){sub 6/2} sheets. An accurate knowledge about the properties of clay surface is required as a parameter for a long-term estimation of radionuclide retardation effects. Electric surface charge is a primary property determining ion exchange and surface complexation of radionuclides on its surface. The sources of electric surface charge are a permanent structural negative charge on a basal plane and a dissociable charge at an edge surface. Investigation of proton sorption is a prerequisite to the understanding of radionuclide sorption. The reactions on a permanently charged site and on an edge site are measured by an electrokinetic measurement and by potentiometric titration, respectively. However, side reactions such as complexation, proton/cation exchange, dissolution, hydrolysis, precipitation and re adsorption, and the reaction of secondary minerals hinder an experimental measurement of accurate acid-base properties. This presentation describes the pH change on dispersing various clays in water and adding acid, base or Eu(III) ion to these solutions, and the effect of Eu(III) ion on acid-base titration of clay solutions

  1. Learning Outcomes and Student-Perceived Value of Clay Modeling and Cat Dissection in Undergraduate Human Anatomy and Physiology

    Science.gov (United States)

    DeHoff, Mary Ellen; Clark, Krista L.; Meganathan, Karthikeyan

    2011-01-01

    Alternatives and/or supplements to animal dissection are being explored by educators of human anatomy at different academic levels. Clay modeling is one such alternative that provides a kinesthetic, three-dimensional, constructive, and sensory approach to learning human anatomy. The present study compared two laboratory techniques, clay modeling…

  2. The methodology of choice Cam-Clay model parameters for loess subsoil

    Science.gov (United States)

    Nepelski, Krzysztof; Błazik-Borowa, Ewa

    2018-01-01

    The paper deals with the calibration method of FEM subsoil model described by the constitutive Cam-Clay model. The four-storey residential building and solid substrate are modelled. Identification of the substrate is made using research drilling, CPT static tests, DMT Marchetti dilatometer, and laboratory tests. Latter are performed on the intact soil specimens which are taken from the wide planning trench at the depth of foundation. The real building settlements was measured as the vertical displacement of benchmarks. These measurements were carried out periodically during the erection of the building and its operation. Initially, the Cam Clay model parameters were determined on the basis of the laboratory tests, and later, they were corrected by taking into consideration numerical analyses results (whole building and its parts) and real building settlements.

  3. Modeling spatial variability of sand-lenses in clay till settings using transition probability and multiple-point geostatistics

    DEFF Research Database (Denmark)

    Kessler, Timo Christian; Nilsson, Bertel; Klint, Knud Erik

    2010-01-01

    (TPROGS) of alternating geological facies. The second method, multiple-point statistics, uses training images to estimate the conditional probability of sand-lenses at a certain location. Both methods respect field observations such as local stratigraphy, however, only the multiple-point statistics can...... of sand-lenses in clay till. Sand-lenses mainly account for horizontal transport and are prioritised in this study. Based on field observations, the distribution has been modeled using two different geostatistical approaches. One method uses a Markov chain model calculating the transition probabilities...

  4. Modelling desiccation cracking in a homogenous soil clay layer: comparison between different hypotheses on constitutive behaviour

    Directory of Open Access Journals (Sweden)

    Jommi Cristina

    2016-01-01

    Full Text Available Desiccation cracks are usually thought to start from the surface of an evaporating soil layer, and the available simplified models for crack initiation and propagation are based on this hypothesis. On the contrary, experimental results on a Dutch river clay showed that cracks in an evaporating soil layer may start and propagate below the surface, confirming earlier findings by other researchers. A simple one-dimensional model was set up to analyse the consequences of different hypotheses about the material behaviour on the crack onset in a homogenous soil layer undergoing surface drying. The results of the model show that dependence of the material behaviour on the rate of water content change is a necessary requirement for cracks to initiate below the surface. The conclusion suggests that, to properly understand cracking in an evaporating soil layer, an intrinsic time scale for the mechanical response must be accounted for, among all the other factors which were previously highlighted by other researchers. The key factor to predict crack onset below the surface is the dependence of the drying branch of the water retention curve of the compressible soil on the rate of drying, which would be justified by a rate dependent fabric evolution.

  5. Biogeochemical processes in a clay formation in situ experiment: Part F - Reactive transport modelling

    Energy Technology Data Exchange (ETDEWEB)

    Tournassat, Christophe, E-mail: c.tournassat@brgm.fr [BRGM, French Geological Survey, Orleans (France); Alt-Epping, Peter [Rock-Water Interaction Group, Institute of Geological Sciences, University of Bern (Switzerland); Gaucher, Eric C. [BRGM, French Geological Survey, Orleans (France); Gimmi, Thomas [Rock-Water Interaction Group, Institute of Geological Sciences, University of Bern (Switzerland)] [Laboratory for Waste Management, Paul Scherrer Institut, Villigen (Switzerland); Leupin, Olivier X. [NAGRA, CH-5430 Wettingen (Switzerland); Wersin, Paul [Gruner Ltd., CH-4020 Basel (Switzerland)

    2011-06-15

    Highlights: > Reactive transport modelling was used to simulate simultaneously solute transport, thermodynamic reactions, ion exchange and biodegradation during an in-situ experiment in a clay-rock formation. > Opalinus clay formation has a high buffering capacity in terms of chemical perturbations caused by bacterial activity. > Buffering capacity is mainly attributed to the carbonate system and to the reactivity of clay surfaces (cation exchange, pH buffering). - Abstract: Reactive transport modelling was used to simulate solute transport, thermodynamic reactions, ion exchange and biodegradation in the Porewater Chemistry (PC) experiment at the Mont Terri Rock Laboratory. Simulations show that the most important chemical processes controlling the fluid composition within the borehole and the surrounding formation during the experiment are ion exchange, biodegradation and dissolution/precipitation reactions involving pyrite and carbonate minerals. In contrast, thermodynamic mineral dissolution/precipitation reactions involving alumo-silicate minerals have little impact on the fluid composition on the time-scale of the experiment. With the accurate description of the initial chemical condition in the formation in combination with kinetic formulations describing the different stages of bacterial activities, it has been possible to reproduce the evolution of important system parameters, such as the pH, redox potential, total organic C, dissolved inorganic C and SO{sub 4} concentration. Leaching of glycerol from the pH-electrode may be the primary source of organic material that initiated bacterial growth, which caused the chemical perturbation in the borehole. Results from these simulations are consistent with data from the over-coring and demonstrate that the Opalinus Clay has a high buffering capacity in terms of chemical perturbations caused by bacterial activity. This buffering capacity can be attributed to the carbonate system as well as to the reactivity of

  6. Modelling of the mechanical behaviour and damage of clay-stones: application to the East argillite

    International Nuclear Information System (INIS)

    Aublive-Conil, N.

    2003-03-01

    The storage in deep geological formation is one of the solutions retained by France for the management of highly long life radioactive waste. The retained host rock is a clay-stone named East argillite located in the departments of Meuse and Haute-Marne. A thermodynamic formulation is used to propose a rheological model, which reproduces the mechanical behavior of clay-stones. Initially, an anisotropic damage plastic model was formulated in order to describe material degradations. Then, the damage plastic model is reformulated in order to taken into account the damage influence on the hydraulic behavior of porous material. The numerical simulations correctly reproduce the mechanical behavior of East Argillites but also the anisotropy of the hydraulic behavior introduced by the damage effect. (author)

  7. Determination of the numerical parameters of a continuous damage model for the structural analysis of clay brick masonry

    Directory of Open Access Journals (Sweden)

    Felipe Barbosa Mangueira

    2012-12-01

    Full Text Available Models based on the continuous damage theory present good responses in representing the nonlinear behavior of reinforced concrete structures with loss of strength and stiffness of the material. However, damage theory is rarely employed in the analysis of masonry structures and numerical simulations are currently performed mostly by Finite Element Method formulations. A computational program was designed to determine the numerical parameters of a damage model of the physical properties of masonry components, solid clay brick and mortar. The model was formulated based on the composition of tensile and compressive surface strengths in the plane stress state. The numerical parameters, the corresponding curves of the activation surfaces and the evolution of the surfaces are presented. The results were fed into the computational program based on the Boundary Element Method (BEM for the simulation of masonry walls, and two types of masonry were simulated. The results confirm the good performance of the model and the program based on the BEM.

  8. GMM - a general microstructural model for qualitative and quantitative studies of smectite clays

    International Nuclear Information System (INIS)

    Pusch, R.; Karnland, O.; Hoekmark, H.

    1990-12-01

    A few years ago an attempt was made to accommodate a number of basic ideas on the fabric and interparticle forces that are assumed to be valid in montmorillonite clay in an integrated microstructural model and this resulted in an SKB report on 'Outlines of models of water and gas flow through smectite clay buffers'. This model gave reasonable agreement between predicted hydraulic conductivity values and actually recorded ones for room temperature and porewater that is poor in electrolytes. The present report describes an improved model that also accounts for effects generated by salt porewater and heating, and that provides a basis for both quantitative determination of transport capacities in a more general way, and also for analysis and prediction of rheological behaviour in bulk. It has been understood very early by investigators in this scientific field that full understanding of the physical state of porewater is asked for in order to make it possible to develop models for clay particle interaction. In particular, a deep insight in the nature of the interlamellar water and of the hydration mechanisms leading to an equilibrium state between the two types of water, and of forcefields in matured smectite clay, requires very qualified multi-discipline research and attempts have been made by the senior author to initiate and coordinate such work in the last 30 years. Despite this effort it has not been possible to get an unanimous understanding of these things but a number of major features have become more clear through the work that we have been able to carry out in the current SKB research work. Thus, NMR studies and precision measurements of the density of porewater as well as comprehensive electron microscopy and rheological testing in combination with application of stochastical mechanics, have led to the hypothetical microstructural model - the GMM - presented in this report. (au)

  9. Geological modeling of a fault zone in clay rocks at the Mont-Terri laboratory (Switzerland)

    Science.gov (United States)

    Kakurina, M.; Guglielmi, Y.; Nussbaum, C.; Valley, B.

    2016-12-01

    Clay-rich formations are considered to be a natural barrier for radionuclides or fluids (water, hydrocarbons, CO2) migration. However, little is known about the architecture of faults affecting clay formations because of their quick alteration at the Earth's surface. The Mont Terri Underground Research Laboratory provides exceptional conditions to investigate an un-weathered, perfectly exposed clay fault zone architecture and to conduct fault activation experiments that allow explore the conditions for stability of such clay faults. Here we show first results from a detailed geological model of the Mont Terri Main Fault architecture, using GoCad software, a detailed structural analysis of 6 fully cored and logged 30-to-50m long and 3-to-15m spaced boreholes crossing the fault zone. These high-definition geological data were acquired within the Fault Slip (FS) experiment project that consisted in fluid injections in different intervals within the fault using the SIMFIP probe to explore the conditions for the fault mechanical and seismic stability. The Mont Terri Main Fault "core" consists of a thrust zone about 0.8 to 3m wide that is bounded by two major fault planes. Between these planes, there is an assembly of distinct slickensided surfaces and various facies including scaly clays, fault gouge and fractured zones. Scaly clay including S-C bands and microfolds occurs in larger zones at top and bottom of the Mail Fault. A cm-thin layer of gouge, that is known to accommodate high strain parts, runs along the upper fault zone boundary. The non-scaly part mainly consists of undeformed rock block, bounded by slickensides. Such a complexity as well as the continuity of the two major surfaces are hard to correlate between the different boreholes even with the high density of geological data within the relatively small volume of the experiment. This may show that a poor strain localization occurred during faulting giving some perspectives about the potential for

  10. Porosity model for simultaneous radionuclide transfer in compact clay

    International Nuclear Information System (INIS)

    Grambow, B.; Ribet, S.; Landesman, C.; Altman, S.

    2010-01-01

    Document available in extended abstract form only. Both, a mono and a dual porosity model have been developed to describe diffusion in bentonite as function of compaction, which give similar results for the diffusion coefficients. There are little advantages but more computation time for the dual porosity model compared to the mono-porosity model. A significant change in paradigm has been proposed to describe diffusion accessible porosity in bentonite: Only a single micro-porosity value is considered for anions, cations and neutral species. Hydration water in the interlayers is considered as part of the solid phase and is not considered as a constitutive part of overall porosity. Since hydration water takes part of the solid phase, it is now possible to explicitly account for retention of HTO by formulating exchange between HTO and water in the interlayers. In the adaptation of the model to experimental data, a single fit constant, the geometric factor G = 7 was used, common to all ions and neutral species and for densities between 0.2 and 1.8 kg.dm -3 . The only input parameters to describe the effect of dry density on diffusion coefficients are the micro porosity (total porosity minus interlayer porosity) and the hydration numbers of exchanging cations in the interlayers, both of which can be measured by independent means (DRX, water sorption isotherms). The modelling of simultaneous mass transfer of HTO, Cs, Br and Ni has been undertaken. From the results apparent diffusion coefficients were obtained. Effective diffusion coefficients can of course only be compared to literature data if the the same porosity hypothesis is used for Da-De conversion as used in literature (total porosity for anions and HTO, micro-porosity for anions). Then, the calculated apparent diffusion coefficients for HTO match closely the measured values in the mentioned density range. Considering large experimental data uncertainty the agreement between anion diffusion data and calculations

  11. Screening of waste for use in clay-based bricks in the Arctic

    DEFF Research Database (Denmark)

    Belmonte, Louise Josefine; Ottosen, Lisbeth M.; Kirkelund, Gunvor Marie

    2014-01-01

    Clay-based ceramics, such as bricks, are heterogeneous materials, which can incorporate raw materials ofwide ranging compositions, without impairing their technical properties (Dondi et al., 1997a,b). Due to thisability, bricks have become a popular material in waste management research worldwide...... and several studies have demonstrated that clay-based bricks and tiles can successfully accommodate waste types,such as incineration ashes, mine tailings and dredged harbour sediments (Zhang et al., 2011; Roy et al.,2007; Mezencevova et al., 2012). In the vulnerable Arctic environment, the impact...... a strong tradition for masonry structures. In Greenland, for example, bricks are neither currently produced locally nor frequently appliedfor construction purposes. Recent studies have, however, established that deposits of marine glaciogeneclay, which are found throughout the former glaciated areas...

  12. An update on synthetic dyes adsorption onto clay based minerals: A state-of-art review

    CSIR Research Space (South Africa)

    Ngulube, T

    2017-04-01

    Full Text Available of Environmental Management An update on synthetic dyes adsorption onto clay based minerals: A state- of-art review Tholiso Ngulube a,*, Jabulani Ray Gumbo b, Vhahangwele Masindi c,d, Arjun Maity e a Department of Ecology and Resources Management..., University of Venda, Private Bag X5050, Thohoyandou, 0950, Limpopo, South Africa b Department of Hydrology and Water Resources, School of Environmental Sciences, University of Venda, Private Bag X5050, Thohoyandou, 0950, Limpopo, South Africa c Council...

  13. Preparation of affordable and multifunctional clay-based ceramic filter matrix for treatment of drinking water.

    Science.gov (United States)

    Shivaraju, H Puttaiah; Egumbo, Henok; Madhusudan, P; Anil Kumar, K M; Midhun, G

    2018-02-01

    Affordable clay-based ceramic filters with multifunctional properties were prepared using low-cost and active ingredients. The characterization results clearly revealed well crystallinity, structural elucidation, extensive porosity, higher surface area, higher stability, and durability which apparently enhance the treatment efficiency. The filtration rates of ceramic filter were evaluated under gravity and the results obtained were compared with a typical gravity slow sand filter (GSSF). All ceramic filters showed significant filtration rates of about 50-180 m/h, which is comparatively higher than the typical GSSF. Further, purification efficiency of clay-based ceramic filters was evaluated by considering important drinking water parameters and contaminants. A significant removal potential was achieved by the clay-based ceramic filter with 25% and 30% activated carbon along with active agents. Desired drinking water quality parameters were achieved by potential removal of nitrite (98.5%), nitrate (80.5%), total dissolved solids (62%), total hardness (55%), total organic pollutants (89%), and pathogenic microorganisms (100%) using ceramic filters within a short duration. The remarkable purification and disinfection efficiencies were attributed to the extensive porosity (0.202 cm 3  g -1 ), surface area (124.61 m 2  g -1 ), stability, and presence of active nanoparticles such as Cu, TiO 2 , and Ag within the porous matrix of the ceramic filter.

  14. Optimization of organo clay production for applications in based oil drilling fluid; Otimizacao do processo de organofilizacao para aplicacoes em fluidos de perfuracao base oleo

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Heber S; Martins, Alice B; Costa, Danubia L. da; Ferreira, Heber C; Neves, Gelmires de A; Melo, Tomas J.A. de [Universidade Federal de Campina Grande (UFCG), PB (Brazil); Teixeira Neto, Erico [Universidade Federal do ABC (UFABC), Santo Andre, SP (Brazil)

    2008-07-01

    The organophilic clays are widely used as an agent dispersed in the composition of oil based drilling fluids. The organophilic clays are gotten from bentonite clays treated, in watery way, with ionic surfactants, that are adsorbed in the surface of interlayer of the clays, re-covered them with a organic layer. A fundamental stage of production of the organophilic clays is the dispersion of bentonite clays, in way that variables like: speed of agitation, temperature and time of cure, influences directly in plastic and apparent viscosities of these dispersions, together with other variables of organophilization process, like, temperature and time of cure of organophilization, has direct influence in efficiency of the organophilization process. This work considers a study of these variable, using bentonite clays: Brasgel PA{sup R} and Cloisite Na{sup +R}, treated with the ionic surfactant Praepagem WB{sup R}. The organophilic clays gotten had been characterized by rays X diffraction, Foster's swelling, and the results were compared with the commercial organophilic clay VG-69{sup R}, industrially treated with ionic surfactant. Viscosities plastic and apparent of the dispersions had been measured in the midst of organic dispersant diesel oil used to obtain the oil based drilling fluids. Preliminary results of Foster's swelling and preparation of fluids show that the clays have affinity with the means liquid organic dispersants, and the fluids meet specifications of PETROBRAS (N-22581-1997 and N-2259 to 1997) for use in the of diesel oil based drilling fluids. (author)

  15. Anisotropic modelling of Opalinus Clay behaviour: From triaxial tests to gallery excavation application

    Directory of Open Access Journals (Sweden)

    François Bertrand

    2017-06-01

    Full Text Available Deep repository in geological formations is the preferential solution considered in many countries to manage high-level nuclear wastes. In Switzerland, the Opalinus Clay is a candidate host rock. In this context, in situ and laboratory tests are conducted on Opalinus Clay to demonstrate the feasibility of deep disposal in this argillaceous formation. This paper presents a constitutive model able to fit the experimental data obtained from some triaxial tests conducted by Jahns (2013 on cores from borehole Schlattingen SLA-1. The elasto-plastic behaviour of Opalinus Clay is reproduced thanks to a Drucker-Prager model, taking into account the anisotropy behaviour of this sedimentary rock. The objective is to employ a single set of parameters representative of the material. In a second version of the model, the stress-dependence of the elastic properties and damage are taken into account. Finally, the parameters calibrated with experimental tests are used to simulate the excavation of a gallery with a second gradient approach.

  16. A viscoplastic model with plasticity for dry clay. Application to underground structures

    International Nuclear Information System (INIS)

    Tchiyep Piepi, G.

    1995-10-01

    Stiff clays are generally encountered at a great depth (more than 300 m). These materials have a relatively low water content. A lot of industrial studies justify the recent interest borne by these materials. This work deals in particular with stiff clays able to answer to stresses by elastic, plastic and viscoplastic deformations. In the first part are given the experimental study and the modelling of the stiff clays mechanical behavior. In this part, considered materials are described as well as the tests carried out. The obtained results are discussed and a viscoplastic model with rupture is elaborated. The second part deals with the elaboration of an original semi analytical solution and of an algorithm implemented in GEOMEC91. The third part shows the influence of the model on the tunnel convergence at the moment of the support laying and by consequently on the stresses of this last one. The calculations results show a strong influence of the short-term cohesion on the tunnel convergence. (O.M.)

  17. Controls of Ca/Mg/Fe activity ratios in pore water chemistry models of the Callovian-Oxfordian clay formation

    Energy Technology Data Exchange (ETDEWEB)

    Lerouge, C.; Grangeon, S.; Wille, G.; Flehoc, C.; Gailhanou, H.; Gaucher, E.C.; Tournassat, C. [BRGM av. Claude Guillemin BP6009 45060 Orleans cedex 2 (France); Vinsot, A. [ANDRA Meuse/Haute-Marne Underground research Laboratory (URL), RD 960, 55290 Bure (France); Made, B.; Altmann, S. [ANDRA - Parc de la Croix Blanche, 1-7 rue Jean Monnet, 92298 Chatenay-Malabry Cedex (France)

    2013-07-01

    In the pore water chemistry model of the Callovian-Oxfordian clay formation, the divalent cations Ca, Mg, and Fe are controlled by equilibrium reactions with pure carbonates: calcite for Ca, dolomite for Mg, and siderite for Fe. Results of a petrological study and computing of the Ca/Mg and Ca/Fe activity ratios based on natural pore water chemistry provide evidence that equilibrium with pure calcite and pure dolomite is a reasonable assumption for undisturbed pore waters; on the other hand, siderite cannot be considered at equilibrium with pore waters at the formation scale. (authors)

  18. Controls of Ca/Mg/Fe activity ratios in pore water chemistry models of the Callovian-Oxfordian clay formation

    International Nuclear Information System (INIS)

    Lerouge, C.; Grangeon, S.; Wille, G.; Flehoc, C.; Gailhanou, H.; Gaucher, E.C.; Tournassat, C.; Vinsot, A.; Made, B.; Altmann, S.

    2013-01-01

    In the pore water chemistry model of the Callovian-Oxfordian clay formation, the divalent cations Ca, Mg, and Fe are controlled by equilibrium reactions with pure carbonates: calcite for Ca, dolomite for Mg, and siderite for Fe. Results of a petrological study and computing of the Ca/Mg and Ca/Fe activity ratios based on natural pore water chemistry provide evidence that equilibrium with pure calcite and pure dolomite is a reasonable assumption for undisturbed pore waters; on the other hand, siderite cannot be considered at equilibrium with pore waters at the formation scale. (authors)

  19. Production of building elements based on alkali-activated red clay brick waste

    Directory of Open Access Journals (Sweden)

    Rafael Andres Robayo-Salazar

    2016-09-01

    Full Text Available This paper analyzes the feasibility of reusing a red clay brick waste (RCBW in order to produce building elements such as blocks, pavers and tiles, by using the technique of alkaline activation. The production of these building elements was based on the design of a hybrid mortar with 48.61 MPa of compressive strength, at 28 curing days at room temperature (25 °C. The hybrid mortar was synthesized by adding 10% by weight of Portland cement (OPC to the RCBW, Red Clay Brick Waste. As alkaline activators were used commercial industrial grade sodium hydroxide (NaOH and sodium silicate (Na2SiO3. Building elements were physically and mechanically characterized, according to Colombian Technical Standards (NTC. This technology process is presented as an alternative for the reuse of RCBW and its contribution to the environmental sustainability.

  20. Bio-Based Nano Composites from Plant Oil and Nano Clay

    Science.gov (United States)

    Lu, Jue; Hong, Chang K.; Wool, Richard P.

    2003-03-01

    We explored the combination of nanoclay with new chemically functionalized, amphiphilic, plant oil resins to form bio-based nanocomposites with improved physical and mechanical properties. These can be used in many new applications, including the development of self-healing nanocomposites through controlled reversible exfoliation/intercalation, and self-assembled nano-structures. Several chemically modified triglyceride monomers of varying polarity, combined with styrene (ca 30include acrylated epoxidized soybean oil (AESO), maleated acrylated epoxidized soybean oil (MAESO) and soybean oil pentaerythritol glyceride maleates (SOPERMA), containing either hydroxyl group or acid functionality or both. The clay used is a natural montmorillonite modified with methyl tallow bis-2-hydroxyethyl quaternary ammonium chloride, which has hydroxyl groups. Both XRD and TEM showed a completely exfoliated structure at 3 wtwhen the clay content is above 5 wtconsidered a mix of intercalated and partially exfoliated structure. The controlled polarity of the monomer has a major effect on the reversible dispersion of clay in the polymer matrix. The bio-based nanocomposites showed a significant increase in flexural modulus and strength. Supported by EPA and DoE

  1. Modeling Air Permeability in Variably Saturated Soil from Two Natural Clay Gradients

    DEFF Research Database (Denmark)

    Chamindu, Deepagoda T K K; Arthur, Emmanuel; Møldrup, Per

    2013-01-01

    measurements from two Danish arable fields, each located on natural clay gradients, this study presents a pore tortuosity–disconnectivity analysis to characterize the soil–gas phase. The main objective of this study is to investigate the effect of soil–moisture condition, clay content, and other potential......Understanding soil–gas phase properties and processes is important for finding solutions to critical environmental problems such as greenhouse gas emissions and transport of gaseous-phase contaminants in soils. Soil–air permeability, ka (μm2), is the key parameter governing advective gas movement...... in soil and is controlled by soil physical characteristics representing soil texture and structure. Models predicting ka as a function of air-filled porosity (ɛ) often use a reference-point measurement, for example, ka,1000 at ɛ1000 (where the measurement is done at a suction of –1000 cm H2O). Using ka...

  2. chemo-Hydro-mechanical modelling of in-situ disposal of a bituminized radioactive waste in boom clay

    International Nuclear Information System (INIS)

    Mokni, N.; Olivella, S.; Valcke, E.; Marien, A.; Smets, S.; Li, X.; Sillen, X.

    2012-01-01

    Document available in extended abstract form only. The current reference solution of the Belgian Agency for the Management of Radioactive Waste and Fissile Materials (ONDRAF/NIRAS) envisages underground disposal of Eurobitum Bituminized radioactive Waste (BW) in a geologically stable clay formation. In Belgium, the Boom Clay, which is a 30 to 35 million years old and ∼100 m thick marine sediment is being studied as a potential host formation because of its favorable properties to limit and delay the migration of the leached radionuclides to the biosphere over extended periods of time. The current disposal concept foresees that several drums (220 litres) of Eurobitum would be grouped in thick-walled cement-based secondary containers, which in turn would be placed in concrete-lined disposal galleries that are excavated at mid-depth in the clay layer. Only 80-90 % of the total volume of the drum is filled with Eurobitum.The remaining voids between the containers would be backfilled with a cement-based material. The interaction between the BW and the host clay formation is a very complicated chemo-hydro-mechanical process and depends not only on the hydro-mechanical behaviour of the Boom Clay itself, but also on that of the BW. In fact, the osmosis-induced uptake of water by the dehydrated hygroscopic salts embedded in the waste induces a geo-mechanical perturbation of the host formation, caused by the swelling and the increase of the pressure in and around the waste. The objectives of the Chemo-Hydro-Chemical (CHM) analysis presented in this work are (i) to get insights on the kinetics of water uptake by BW, dissolution of the embedded NaNO 3 crystals, solute leaching, and maximum generated pressure under disposal conditions and (ii) to study the stress redistribution due to the recompression of the clay around a gallery caused by the swelling pressure of the bitumen and the admissible swelling pressure for Boom clay. Firstly, a CHM formulation of chemically and

  3. Clay Play

    Science.gov (United States)

    Rogers, Liz; Steffan, Dana

    2009-01-01

    This article describes how to use clay as a potential material for young children to explore. As teachers, the authors find that their dialogue about the potential of clay as a learning medium raises many questions: (1) What makes clay so enticing? (2) Why are teachers noticing different play and conversation around the clay table as compared to…

  4. Ball clay

    Science.gov (United States)

    Virta, R.L.

    2001-01-01

    Part of the 2000 annual review of the industrial minerals sector. A general overview of the ball clay industry is provided. In 2000, sales of ball clay reached record levels, with sanitary ware and tile applications accounting for the largest sales. Ball clay production, consumption, prices, foreign trade, and industry news are summarized. The outlook for the ball clay industry is also outlined.

  5. Geochemical of clay formations : study of Spanish clay REFERENCE

    International Nuclear Information System (INIS)

    Turrero, M. J.; Pena, J.

    2003-01-01

    Clay rocks are investigated in different international research programs in order to assess its feasibility for the disposal of high level radioactive wastes. This is because different sepcific aspects: they have low hydraulic conductivity (10''-11-10''-15 m/s), a high sorption capacity, self-sealing capacity of facults and discontinuities and mechanical resistance. Several research programs on clay formations are aimed to study the chemistry of the groundwater and the water-rock reactions that control it: e. g. Boom Clay (Mol, Belgium), Oxford Clay /Harwell, United Kingdom), Toarcian Clay (Tournemire, France), Palfris formation (Wellenberg, Switzerland), Opalinus Clay (Bure, France). Based on these studies, considerable progress in the development of techniques for hydrologic, geochemical and hydrogeochemical characterization of mudstones has been accomplished (e. g. Beaufais et al. 1994, De Windt el al. 1998. Thury and Bossart 1999, Sacchi and Michelot 2000) with important advances in the knowledge of geochemical process in these materials (e. g. Reeder et al. 1993, Baeyens and Brandbury 1994, Beaucaire et al. 2000, Pearson et al., 2003).Furtermore, geochemical modeling is commonly used to simulate the evolution of water chemistry and to understand quantitatively the processes controlling the groundwater chemistry (e. g. Pearson et al. 1998, Tempel and Harrison 2000, Arcos et al., 2001). The work presented here is part of a research program funded by Enresa in the context of its R and D program. It is focused on the characterization of a clay formation (reference Argillaceous Formation, RAF) located within the Duero Basin (north-centralSpain). The characterisation of th ephysical properties,, fluid composition, mineralogy, water-rock reaction processes, geochemical modelling and sorption properties of the clays from the mentioned wells is the main purpose of this work. (Author)

  6. Coupled transport and chemistry in clay stone studied by advective displacement: experiments and model

    International Nuclear Information System (INIS)

    Landesman, C.; Grambow, B.; Bailly, C.; Ribet, S.; Perrigaud, K.; Baty, V.; Giffaut, E.

    2010-01-01

    porosity relations for anions and neutral species are determined. Strong effects of clay/calcite ratios on hydrodynamic properties were observed. Thereafter stable iodine and Se(VI) were injected to study radionuclide migration. No retention of iodine but strong retention of Se were observed. After test termination the clay core was sliced and elemental profiles were obtained. From anion analysis in the slices porosity distribution was obtained. The experimental results were modeled using a 1D coupled geochemical/transport code PHREEQC considering activity coefficients, electrical double layers, mineral solubility, ion exchange properties, transport in micropores linked to interlayer space, limited mineral inventories (Celestite) and hydrodynamic properties. Good agreement of model and data from out flowing water and slices was obtained simultaneously for anions, HTO, major (Na, K, Ca, Mg, Cl, SO 4 ) and minor (Sr) element concentration and pH evolution. (authors)

  7. Regional modelling of the confined aquifers below the Boom clay in NE-Belgium

    International Nuclear Information System (INIS)

    Vandersteen, K.; Gedeon, M.; Marivoet, J.; Wouters, L.

    2012-01-01

    Document available in extended abstract form only. In the framework of the Belgian research program on the long term management of high-level and/or long-lived radioactive waste coordinated by ONDRAF/NIRAS, the Boom Clay is considered as a reference host rock for the geological disposal of high-level radioactive waste in NE-Belgium (Campine area). The hydrogeological program at SCK.CEN supports the long-term performance assessments of the geological disposal of radioactive waste by performing a phenomenological research of the aquifer systems surrounding the studied disposal system. One of the important components of this programme is the regional hydrogeological modelling. The regional hydrogeology is studied using two main models - the steady state Neogene aquifer model (NAM) and the transient deep aquifer pumping model (DAP), developed to characterize and quantify the regional groundwater flow in, respectively, the aquifers lying above the Boom Clay in the Nete catchment area (NAM), and the aquifers lying below the Boom Clay in the Campine area (DAP). This paper describes the most recent update of the DAP model. The DAP model represents the confined part of the groundwater system located stratigraphically below the Boom Clay. This includes the parts of the Oligocene aquifer, the Bartoon aquitard system and the Ledo-Paniselian-Brusselian aquifer buried under the Boom Clay. Due to the considerable pumping from these aquifers in combination with a limited recharge, a gradual decrease in groundwater levels has been observed in more than 30-year piezometric records. In the DAP model, the shallow aquifer system overlying the Boom Clay is replaced by fixed head boundaries: this aquifer system is dominated by close-to-surface hydrological processes and the heads fluctuate seasonally without any apparent long-term trend. In the horizontal direction, the model extends to the south as far as the outcrops of the major aquitards: the Maldegem Formation confining the Ledo

  8. Assessing the interactions of a natural antibacterial clay with model Gram-positive and Gram-negative human pathogens

    Science.gov (United States)

    Londono, S. C.; Williams, L. B.

    2013-12-01

    The emergence of antibiotic resistant bacteria and increasing accumulations of antibiotics in reclaimed water, drive the quest for new natural antimicrobials. We are studying the antibacterial mechanism(s) of clays that have shown an ability to destroy bacteria or significantly inhibit their growth. One possible mode of action is from soluble transition metal species, particularly reduced Fe, capable of generating deleterious oxygen radical species. Yet another possibility is related to membrane damage as a consequence of physical or electrostatic interaction between clay and bacteria. Both mechanisms could combine to produce cell death. This study addresses a natural antibacterial clay from the NW Amazon basin, South America (AMZ clay). Clay mineralogy is composed of disordered kaolinite (28.9%), halloysite (17.8%) illite (12%) and smectite (16.7%). Mean particle size is 1.6μm and total and specific surface area 278.82 and 51.23 m2/g respectively. The pH of a suspension (200mg/ml) is 4.1 and its Eh is 361mV after 24h of equilibration. The ionic strength of the water in equilibrium with the clay after 24 h. is 6 x10-4M. These conditions, affect the element solubility, speciation, and interactions between clay and bacteria. Standard microbiological methods were used to assess the viability of two model bacteria (Escherichia coli and Bacillus subtilis) after incubation with clay at 37 degC for 24 hrs. A threefold reduction in bacterial viability was observed upon treatment with AMZ clay. We separated the cells from the clay using Nycodenz gradient media and observed the mounts under the TEM and SEM. Results showed several membrane anomalies and structural changes that were not observed in the control cells. Additionally, clay minerals appeared in some places attached to cell walls. Experiments showed that exchanging AMZ clay with KCl caused loss of antibacterial property. Among the exchangeable -and potentially toxic- ions we measured Al+3, Cu+2, Zn+2, Ba+2 and Co+2

  9. The Tournemire industrial analogue: reactive-transport modelling of cement-clay interfaces

    International Nuclear Information System (INIS)

    Watson, C.; Wilson, J.; Benbow, S.; Savage, D.; Walker, C.; Norris, S.

    2012-01-01

    Document available in extended abstract form only. In a number of concepts for geological disposal facilities (GDFs) for radioactive waste, cement-based materials are used for a variety of purposes including mechanical support, backfilling of cavities, grouting of fractures in the host rock, and immobilisation of radionuclides in waste-forms. Such facilities will ultimately re-saturate with encroaching groundwater, at which point leaching of the cement components is likely to give rise to an alkaline pore fluid, regardless of cement type. This pore fluid will be in disequilibrium with both the host rock and other engineered barrier system (EBS) materials used in the construction of the facility, such as bentonite. The interaction of the pore fluid could lead, for example, to the reduction in the swelling capacity of the clay, alteration of porosity and permeability both in the host rock and in EBS materials, and reduction of sorption capacities. Analogue systems can provide information about hyper-alkaline alteration that it is not possible to obtain from short-term experimental studies alone, because they have evolved in situ over many tens, hundreds or thousands of years. These systems can be used to improve scientific understanding and consequently mathematical models, which in turn can be used to simulate the performance of the engineered and natural materials over the lifetime of the GDF. Industrial analogues provide a kind of 'halfway house' between natural analogues and laboratory experimental studies; the initial and boundary conditions are often better understood than natural analogues, and the timescales involved, whilst much shorter than natural analogues, are generally of much greater duration than laboratory studies. One such analogue can be found at Tournemire, southern France, where a tunnel excavated in the 1880's had several exploration boreholes drilled into its basement in the 1990's. These boreholes were then filled with concrete and cement

  10. Clastic compaction unit classification based on clay content and integrated compaction recovery using well and seismic data

    Directory of Open Access Journals (Sweden)

    Zhong Hong

    2016-11-01

    Full Text Available Abstract Compaction correction is a key part of paleo-geomorphic recovery methods. Yet, the influence of lithology on the porosity evolution is not usually taken into account. Present methods merely classify the lithologies as sandstone and mudstone to undertake separate porosity-depth compaction modeling. However, using just two lithologies is an oversimplification that cannot represent the compaction history. In such schemes, the precision of the compaction recovery is inadequate. To improve the precision of compaction recovery, a depth compaction model has been proposed that involves both porosity and clay content. A clastic lithological compaction unit classification method, based on clay content, has been designed to identify lithological boundaries and establish sets of compaction units. Also, on the basis of the clastic compaction unit classification, two methods of compaction recovery that integrate well and seismic data are employed to extrapolate well-based compaction information outward along seismic lines and recover the paleo-topography of the clastic strata in the region. The examples presented here show that a better understanding of paleo-geomorphology can be gained by applying the proposed compaction recovery technology.

  11. A Visual Basic program to classify sediments based on gravel-sand-silt-clay ratios

    Science.gov (United States)

    Poppe, L.J.; Eliason, A.H.; Hastings, M.E.

    2003-01-01

    Nomenclature describing size distributions is important to geologists because grain size is the most basic attribute of sediments. Traditionally, geologists have divided sediments into four size fractions that include gravel, sand, silt, and clay, and classified these sediments based on ratios of the various proportions of the fractions. Definitions of these fractions have long been standardized to the grade scale described by Wentworth (1922), and two main classification schemes have been adopted to describe the approximate relationship between the size fractions.Specifically, according to the Wentworth grade scale gravel-sized particles have a nominal diameter of ⩾2.0 mm; sand-sized particles have nominal diameters from <2.0 mm to ⩾62.5 μm; silt-sized particles have nominal diameters from <62.5 to ⩾4.0 μm; and clay is <4.0 μm. As for sediment classification, most sedimentologists use one of the systems described either by Shepard (1954) or Folk (1954, 1974). The original scheme devised by Shepard (1954) utilized a single ternary diagram with sand, silt, and clay in the corners to graphically show the relative proportions among these three grades within a sample. This scheme, however, does not allow for sediments with significant amounts of gravel. Therefore, Shepard's classification scheme (Fig. 1) was subsequently modified by the addition of a second ternary diagram to account for the gravel fraction (Schlee, 1973). The system devised by Folk (1954, 1974) is also based on two triangular diagrams (Fig. 2), but it has 23 major categories, and uses the term mud (defined as silt plus clay). The patterns within the triangles of both systems differ, as does the emphasis placed on gravel. For example, in the system described by Shepard, gravelly sediments have more than 10% gravel; in Folk's system, slightly gravelly sediments have as little as 0.01% gravel. Folk's classification scheme stresses gravel because its concentration is a function of

  12. Thermal volume changes in clays and clay-stones

    International Nuclear Information System (INIS)

    Delage, P.; Sulem, J.; Mohajerani, M.; Tang, A.M.; Monfared, M.

    2012-01-01

    enlarge the understanding about the thermal volume changes of clay-stones. The COx clay-stone does not behave like an over-consolidated clay since it exhibits plastic contraction when submitted to heating. However, previous compression develops a thermo-elastic initial behaviour, a first illustration of coupled thermomechanical hardening. The Opalinus clay exhibits an elasto-plastic thermal response with another illustration of thermal hardening. These data are expected to be of some interest in the modelling of thermal volume changes around galleries that was up to now based on a thermoelastic simplified hypothesis. (authors)

  13. Cohesion between two clay lamellae: From Primitive Model to Full Molecular Simulation

    International Nuclear Information System (INIS)

    Carrier, Benoit; Vandamme, Matthieu; Pellenq, Roland; Van Damme, Henri

    2012-01-01

    Document available in extended abstract form only. The objective of this work is to investigate the range of validity of various models to describe accurately the cohesion between two charged clay lamellae. These models, in order of increasing complexity, are the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, the primitive model, the explicit solvent primitive model and the full molecular model. We aim at providing a clear picture of which physical mechanisms play a significant role for various interlayer spacings, surface charges and cationic charges. The up-scaling of the mechanical properties starting from the lamellar microstructure of a smectite is usually performed within the framework of the DLVO theory. In this case, the interaction between two charged lamellae with cations between them is the sum of the repulsive double layer electrostatic interaction and of the attractive Van der Waals interaction. However, the Primitive Model shows that concentration fluctuations of counter-ions can generate a strongly attractive ionic correlation force. The Primitive Model is a Monte-Carlo simulation of hydrated counter-ions between two infinite charges surfaces and the water is implicitly modeled by scaling all electrostatic interactions by the dielectric permittivity of bulk water. Nevertheless, for very small inter-layer spacings (1 nm), molecular simulations and experiments show that water is organized in a layered structure and does not behave like bulk water. Therefore, we investigate the role of the solvent in the cohesion of clay lamellae. For this purpose, we use a modified version of the original Primitive Model in which the solvent is modeled by point-dipoles: This model is called the Explicit Solvent Primitive Model. We consider four different systems: A Na + -montmorillonite, a Ca 2+ -montmorillonite, a Na + -vermiculite, a Ca 2+ -vermiculite. The vermiculite layers are twice as charged as the montmorillonite layers. We use a full molecular model as a

  14. Clay nanocomposites based on poly(vinylidene fluoride-co-hexafluoropropylene): Structure and properties

    KAUST Repository

    Kelarakis, Antonios; Hayrapetyan, Suren; Ansari, Seema; Fang, Jason; Estevez, Luis; Giannelis, Emmanuel P.

    2010-01-01

    of the polymer crystals. The degree of transformation depends on the nature of the clay surface modifier and scales with the strength of the interactions between the clay and the polymer. The nanocomposites exhibit significant increases in elongation to failure

  15. Simulation of water movement and isoproturon behaviour in a heavy clay soil using the MACRO model

    Directory of Open Access Journals (Sweden)

    T. J. Besien

    1997-01-01

    Full Text Available In this paper, the dual-porosity MACRO model has been used to investigate methods of reducing leaching of isoproturon from a structured heavy clay soil. The MACRO model was applied to a pesticide leaching data-set generated from a plot scale experiment on a heavy clay soil at the Oxford University Farm, Wytham, England. The field drain was found to be the most important outflow from the plot in terms of pesticide removal. Therefore, this modelling exercise concentrated on simulating field drain flow. With calibration of field-saturated and micropore saturated hydraulic conductivity, the drain flow hydrographs were simulated during extended periods of above average rainfall, with both the hydrograph shape and peak flows agreeing well. Over the whole field season, the observed drain flow water budget was well simulated. However, the first and second drain flow events after pesticide application were not simulated satisfactorily. This is believed to be due to a poor simulation of evapotranspiration during a period of low rainfall around the pesticide application day. Apart from an initial rapid drop in the observed isoproturon soil residue, the model simulated isoproturon residues during the 100 days after pesticide application reasonably well. Finally, the calibrated model was used to show that changes in agricultural practice (deep ploughing, creating fine consolidated seed beds and organic matter applications could potentially reduce pesticide leaching to surface waters by up to 60%.

  16. Using mixture design of experiments to assess the environmental impact of clay-based structural ceramics containing foundry wastes

    Energy Technology Data Exchange (ETDEWEB)

    Coronado, M. [Department of Chemistry and Process and Resources Engineering, University of Cantabria, 39005 Santander (Spain); Department of Materials and Ceramics Engineering (CICECO), University of Aveiro, 3810-193 Aveiro (Portugal); Segadães, A.M. [Department of Materials and Ceramics Engineering (CICECO), University of Aveiro, 3810-193 Aveiro (Portugal); Andrés, A., E-mail: andresa@unican.es [Department of Chemistry and Process and Resources Engineering, University of Cantabria, 39005 Santander (Spain)

    2015-12-15

    Highlights: • Modelling of the environmental risk in terms of clay and by-products contents. • M-DoE and response surface plots enable quick comparison of three ceramic processes. • Basicity of the mixture increases the leaching, especially at low firing temperatures. • Liquid phase content plays a major role decreasing the leaching of Cr and Mo. • Together, M-DoE and phase diagrams enable better prediction of pollutants leaching. - Abstract: This work describes the leaching behavior of potentially hazardous metals from three different clay-based industrial ceramic products (wall bricks, roof tiles, and face bricks) containing foundry sand dust and Waelz slag as alternative raw materials. For each product, ten mixtures were defined by mixture design of experiments and the leaching of As, Ba, Cd, Cr, Cu, Mo, Ni, Pb, and Zn was evaluated in pressed specimens fired simulating the three industrial ceramic processes. The results showed that, despite the chemical, mineralogical and processing differences, only chrome and molybdenum were not fully immobilized during ceramic processing. Their leaching was modeled as polynomial equations, functions of the raw materials contents, and plotted as response surfaces. This brought to evidence that Cr and Mo leaching from the fired products is not only dependent on the corresponding contents and the basicity of the initial mixtures, but is also clearly related with the mineralogical composition of the fired products, namely the amount of the glassy phase, which depends on both the major oxides contents and the firing temperature.

  17. Physicochemical analysis of clays and ceramics of the regional state of Calakmul: production models, distribution and consumption

    International Nuclear Information System (INIS)

    Dominguez C, M.R.; Folan, W.J.; Espinosa P, M.E.; Rodriguez L, V.

    2005-01-01

    This work presents the final results of the research project 'Sources, production and consumption of ceramics in the regional state of Calakmul: a socio-political approach', with the proposal of models of production and ceramic specialization as well as of distribution and consumption of these goods in the territory that occupied the regional state of Calakmul, with base in the typological analysis of the ceramics of Calakmul and 72 sites registered in its environs as well as in comparative studies with ceramics of other greater sites near Calakmul and complemented with the application of analytical techniques in the study of clays and sherds diagnoses of the Mayan Classic period. These models were proposed also, according to a socio-political approach based on the social and political relations that Calakmul maintained with other political entities of diverse ranks derived from the obtained epigraphic evidences. (Author)

  18. High temperature proton exchange membranes based on polybenzimidazole and clay composites for fuel cells

    DEFF Research Database (Denmark)

    Plackett, David; Siu, Ana; Li, Qingfeng

    2011-01-01

    dispersion of modified laponite clay was achieved in polybenzimidazole (PBI) solutions which, when cast and allowed to dry, resulted in homogeneous and transparent composite membranes containing up to 20 wt% clay in the polymer. The clay was organically modified using a series of ammonium and pyr...

  19. A data analysis workflow to enhance clay and organic carbon models using proximal Vis-NIR data

    DEFF Research Database (Denmark)

    Tabatabai, Salman; Knadel, Maria; Greve, Mogens Humlekrog

    Modelling proximal sensors data is becoming a norm in soil characterization and mapping. In many cases, these models still have low predictive capabilities and lack robustness due to the large amount of noise from several environmental factors. In this study we proposed a combination of extensive...... data preprocessing (preprocessing survey) and two variable selection methods to significantly increase visible near-infrared spectroscopy (Vis-NIRS) model performance and stability. Spectra of eight agricultural fields were measured in the range of 350-2200 nm using a mobile sensor platform (Veris...... Technologies, USA) towed by a tractor. A fuzzy c-means clustering was performed based on the first 3 principal components to select 15 representative sampling locations in each field. Clay and organic carbon (OC) were determined for all calibration samples using pipette and ignition methods, respectively...

  20. Electrochemical energy storage in montmorillonite K10 clay based composite as supercapacitor using ionic liquid electrolyte.

    Science.gov (United States)

    Maiti, Sandipan; Pramanik, Atin; Chattopadhyay, Shreyasi; De, Goutam; Mahanty, Sourindra

    2016-02-15

    Exploring new electrode materials is the key to realize high performance energy storage devices for effective utilization of renewable energy. Natural clays with layered structure and high surface area are prospective materials for electrical double layer capacitors (EDLC). In this work, a novel hybrid composite based on acid-leached montmorillonite (K10), multi-walled carbon nanotube (MWCNT) and manganese dioxide (MnO2) was prepared and its electrochemical properties were investigated by fabricating two-electrode asymmetric supercapacitor cells against activated carbon (AC) using 1.0M tetraethylammonium tetrafluroborate (Et4NBF4) in acetonitrile (AN) as electrolyte. The asymmetric supercapacitors, capable of operating in a wide potential window of 0.0-2.7V, showed a high energy density of 171Whkg(-1) at a power density of ∼1.98kWkg(-1). Such high EDLC performance could possibly be linked to the acid-base interaction of K10 through its surface hydroxyl groups with the tetraethylammonium cation [(C2H5)4N(+) or TEA(+)] of the ionic liquid electrolyte. Even at a very high power density of 96.4kWkg(-1), the cells could still deliver an energy density of 91.1Whkg(-1) exhibiting an outstanding rate capability. The present study demonstrates for the first time, the excellent potential of clay-based composites for high power energy storage device applications. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. Chemically-bonded brick production based on burned clay by means of semidry pressing

    Energy Technology Data Exchange (ETDEWEB)

    Voroshilov, Ivan, E-mail: Nixon.06@mail.ru; Endzhievskaya, Irina, E-mail: icaend@mail.ru; Vasilovskaya, Nina, E-mail: icaend@mail.ru [FSAEI HVE Siberian Federal University, 82 Svobodny Prospekt, Krasnoyarsk, 660130 (Russian Federation)

    2016-01-15

    We presented a study on the possibility of using the burnt rocks of the Krasnoyarsk Territory for production of chemically-bonded materials in the form of bricks which are so widely used in multistory housing and private house construction. The radiographic analysis of the composition of burnt rock was conducted and a modifier to adjust the composition uniformity was identified. The mixing moisture content was identified and optimal amount at 13-15% was determined. The method of semidry pressing has been chosen. The process of obtaining moldings has been theoretically proved; the advantages of chemically-bonded wall materials compared to ceramic brick were shown. The production of efficient artificial stone based on material burnt rocks, which is comparable with conventionally effective ceramic materials or effective with cell tile was proved, the density of the burned clay-based cell tile makes up to 1630-1785 kg \\ m{sup 3}, with compressive strength of 13.6-20.0 MPa depending on the compression ratio and cement consumption, frost resistance index is F50, and the thermal conductivity in the masonry is λ = 0,459-0,546 W \\ m {sup *} °C. The clear geometric dimensions of pressed products allow the use of the chemically-bonded brick based on burnt clay as a facing brick.

  2. Application of a new thermo-mechanical model for the study of the nuclear waste disposal in clay rocks

    International Nuclear Information System (INIS)

    Dizier, A.; Li, X.L.; Francois, B.; Collin, F.; Charlier, R.

    2012-01-01

    Document available in extended abstract form only. One of the cornerstones of the nuclear waste disposal researches concerns the evolution of the damaged zone which can offer a preferential path for migration of radionuclide through modifications of its mechanical and hydraulic properties. Even if the thermo-mechanical behaviour of clays is well documented in the literature, the development of the damaged zone induced by an excavation with temperature is not well known. To investigate this problem, a new thermo-mechanical constitutive law has been implemented in the non-linear finite element code LAGAMINE developed at ULg (Universite de Liege) and has been used to model the PRACLAY experiment (Preliminary demonstration test for clay disposal of vitrified high level radioactive waste) at Mol URL (Underground Research Laboratory). Though several models are being to reproduce the different phenomena met when a thermal loading is applied to a clay specimen, the applications of such thermo-mechanical models to simulate large scale in-situ experiment are rare. Based on the work of Sultan a new thermo-mechanical constitutive law has been implemented in combination with a Cap model in the code LAGAMINE. The Cap model is a combination of a frictional criterion, a Cam-Clay model and a traction criterion. The influence of the temperature is considered through the thermo-mechanical law developed by Cui et al. (2000). This law permits to reproduce common features of the thermo-mechanical behaviour of clay, such as the decrease of the pre-consolidation pressure with temperature, the volume change, the thermal hardening, the transition between thermal dilation and thermal contraction for over-consolidated clays. These aspects are modelled with two curves in the (p',T) plane. The first one is related to the generation of the thermal volumetric plastic strains (TY curve (Thermal Yield)). The second one reproduces the decrease of the pre-consolidation pressure with the temperature

  3. Clay Houses

    Science.gov (United States)

    Pedro, Cathy

    2011-01-01

    In this article, the author describes a project designed for fourth-graders that involves making clay relief sculptures of houses. Knowing the clay houses will become a family heirloom makes this lesson even more worth the time. It takes three classes to plan and form the clay, and another two to underglaze and glaze the final products.

  4. Adsorption of Nucleic Acid Bases, Ribose, and Phosphate by Some Clay Minerals

    Directory of Open Access Journals (Sweden)

    Hideo Hashizume

    2015-02-01

    Full Text Available Besides having a large capacity for taking up organic molecules, clay minerals can catalyze a variety of organic reactions. Derived from rock weathering, clay minerals would have been abundant in the early Earth. As such, they might be expected to play a role in chemical evolution. The interactions of clay minerals with biopolymers, including RNA, have been the subject of many investigations. The behavior of RNA components at clay mineral surfaces needs to be assessed if we are to appreciate how clays might catalyze the formation of nucleosides, nucleotides and polynucleotides in the “RNA world”. The adsorption of purines, pyrimidines and nucleosides from aqueous solution to clay minerals is affected by suspension pH. With montmorillonite, adsorption is also influenced by the nature of the exchangeable cations. Here, we review the interactions of some clay minerals with RNA components.

  5. Fire and Gas Barrier Properties of Poly(styrene-co-acrylonitrile Nanocomposites Using Polycaprolactone/Clay Nanohybrid Based-Masterbatch

    Directory of Open Access Journals (Sweden)

    S. Benali

    2008-01-01

    Full Text Available Exfoliated nanocomposites are prepared by dispersion of poly(ε-caprolactone (PCL grafted montmorillonite nanohybrids used as masterbatches in poly(styrene-co-acrylonitrile (SAN. The PCL-grafted clay nanohybrids with high inorganic content are synthesized by in situ intercalative ring-opening polymerization of ε-caprolactone between silicate layers organomodified by alkylammonium cations bearing two hydroxyl functions. The polymerization is initiated by tin alcoholate species derived from the exchange reaction of tin(II bis(2-ethylhexanoate with the hydroxyl groups borne by the ammonium cations that organomodified the clay. These highly filled PCL nanocomposites (25 wt% in inorganics are dispersed as masterbatches in commercial poly(styrene-co-acrylonitrile by melt blending. SAN-based nanocomposites containing 3 wt% of inorganics are accordingly prepared. The direct blend of SAN/organomodified clay is also prepared for sake of comparison. The clay dispersion is characterized by wide-angle X-ray diffraction (WAXD, atomic force microscopy (AFM, and solid state NMR spectroscopy measurements. The thermal properties are studied by thermogravimetric analysis. The flame retardancy and gas barrier resistance properties of nanocomposites are discussed both as a function of the clay dispersion and of the matrix/clay interaction.

  6. Deformation and Fabric in Compacted Clay Soils

    Science.gov (United States)

    Wensrich, C. M.; Pineda, J.; Luzin, V.; Suwal, L.; Kisi, E. H.; Allameh-Haery, H.

    2018-05-01

    Hydromechanical anisotropy of clay soils in response to deformation or deposition history is related to the micromechanics of platelike clay particles and their orientations. In this article, we examine the relationship between microstructure, deformation, and moisture content in kaolin clay using a technique based on neutron scattering. This technique allows for the direct characterization of microstructure within representative samples using traditional measures such as orientation density and soil fabric tensor. From this information, evidence for a simple relationship between components of the deviatoric strain tensor and the deviatoric fabric tensor emerge. This relationship may provide a physical basis for future anisotropic constitutive models based on the micromechanics of these materials.

  7. Coupling diffusion and high-pH precipitation/dissolution in the near field of a HLW repository in clay by means of reactive solute transport models

    Science.gov (United States)

    Samper, J.; Font, I.; Yang, C.; Montenegro, L.

    2004-12-01

    The reference concept for a HLW repository in clay in Spain includes a 75 cm thick bentonite buffer which surrounds canisters. A concrete sustainment 20 cm thick is foreseen between the bentonite buffer and the clay formation. The long term geochemical evolution of the near field is affected by a high-pH hyperalkaline plume induced by concrete. Numerical models of multicomponent reactive transport have been developped in order to quantify the evolution of the system over 1 Ma. Water flow is negligible once the bentonite buffer is saturated after about 20 years. Therefore, solute transport occurs mainly by diffusion. Models account for aqueous complexation, acid-base and redox reactions, cation exchange, and mineral dissolution precipitation in the bentonite, the concrete and the clay formation. Numerical results obtained witth CORE2D indicate that the high-pH plume causes significant changes in porewater chemistry both in the bentonite buffer and the clay formation. Porosity changes caused by mineral dissolution/precipitation are extremely important. Therefore, coupled modes of diffusion and reactive transport accounting for changes in porosity caused by mineral precipitation are required in order to obtain realistic predictions.

  8. ALKALI-ACTIVATED CEMENT MORTARS CONTAINING RECYCLED CLAY-BASED CONSTRUCTION AND DEMOLITION WASTE

    Directory of Open Access Journals (Sweden)

    F. Puertas

    2015-09-01

    Full Text Available The use of clay-based waste as an aggregate for concrete production is an amply studied procedure. Nonetheless, research on the use of this recycled aggregate to prepare alkaline cement mortars and concretes has yet to be forthcoming. The present study aimed to determine: the behaviour of this waste as a pozzolan in OPC systems, the mechanical strength in OPC, alkali-activated slag (AAS and fly ash (AAFA mortars and the effect of partial replacement of the slag and ash themselves with ground fractions of the waste. The pozzolanic behaviour of clay-based waste was confirmed. Replacing up to 20 % of siliceous aggregate with waste aggregate in OPC mortars induced a decline in 7 day strength (around 23 wt. %. The behaviour of waste aggregate in AAMs mortars, in turn, was observed to depend on the nature of the aluminosilicate and the replacement ratio used. When 20 % of siliceous aggregate was replaced by waste aggregate in AAS mortars, the 7 day strength values remained the same (40 MPa. In AAFA mortars, waste was found to effectively replace both the fly ash and the aggregate. The highest strength for AAFA mortars was observed when they were prepared with both a 50 % replacement ratio for the ash and a 20 % ratio for the aggregate.

  9. Electrical properties of multiphase composites based on carbon nanotubes and an optimized clay content

    Science.gov (United States)

    Egiziano, Luigi; Lamberti, Patrizia; Spinelli, Giovanni; Tucci, Vincenzo; Guadagno, Liberata; Vertuccio, Luigi

    2016-05-01

    The experimental results concerning the characterization of a multiphase nanocomposite systems based on epoxy matrix, loaded with different amount of multi-walled carbon nanotubes (MWCNTs) and an optimized Hydrotalcite (HT) clay content (i.e. 0.6 wt%), duly identified by an our previous theoretical study based on Design of Experiment (DoE), are presented. Dynamic-mechanical analysis (DMA) reveal that even the introduction of higher HT loading (up to 1%wt) don't affect significantly the mechanical properties of the nanocomposites while morphological investigations show an effective synergy between clay and carbon nanotubes that leads to peculiar micro/nanostructures that favor the creation of the electrical conductive network inside the insulating resin. An electrical characterization is carried out in terms of DC electrical conductivity, percolation threshold (EPT) and frequency response in the range 10Hz-1MHz. In particular, the measurements of the DC conductivity allow to obtain the typical "percolation" curve also found for classical CNT-polymer mixtures and a value of about 2 S/m for the electrical conductivity is achieved at the highest considered CNTs concentration (i.e. 1 wt%). The results suggest that multiphase nanocomposites obtained incorporating dispersive nanofillers, in addition to the conductive one, may be a valid alternative to the polymer blends, to improve the properties of the polymeric materials thus able to meet high demands, particularly concerning their mechanical and thermal stability and electrical features required in the aircraft engineering.

  10. Water diffusion in clays with added organic surfactants

    International Nuclear Information System (INIS)

    Pineda-Pinon, J; Mendoza-Lopez, M L; Manzano-RamIrez, A; Perez-Robles, J F; Vega-Duran, J T

    2007-01-01

    Tensoactive agents may decrease water absorption in clay products like adobes. They modify the characteristics of the surface of clay particles. Characterization of water diffusion through the pores of modified clays is important to apply appropriate surface modifiers and to improve their performance. We established a simple model for water diffusion in test samples of defined dimensions to estimate real physical parameters and their effect on water absorption. Adsorption mechanisms are examined based on experimental results. The fitting of the experimental data to the model provides a deep understanding of water adsorption in chemically modified clays. A better agreement between the model and the experimental data is achieved for complex molecules

  11. Modeling selenate adsorption behavior on oxides, clay minerals, and soils using the triple layer model

    Science.gov (United States)

    Selenate adsorption behavior was investigated on amorphous aluminum oxide, amorphous iron oxide, goethite, clay minerals: kaolinites, montmorillonites, illite, and 18 soil samples from Hawaii, and the Southwestern and the Midwestern regions of the US as a function of solution pH. Selenate adsorpti...

  12. Determination of p-y Curves using Finite Element Modelling for Bucket Foundation in Undrained Soft and Medium Clay

    DEFF Research Database (Denmark)

    Hvidberg, Mogens Bonde; Ibsen, Lars Bo

    In many years the types of foundation, such as monopiles and bucket foundation which are used in the offshore wind turbine industry, have been analysed analytically with formulations that are based on much slender piles, than are used today. Because of that, the analytical calculation...... is not describing the connection between the horizontal bearing capacity of the soil and the displacement of the foundation accurate, in particular for the bucket foundation because of the much smaller slenderness of the profile. Numerical modelling is used to examine that bearing capacity the bucket foundation has...... in soft and medium clay at different dimensions of the bucket, to a horizontal displacement. After that a mathematical formulation is determined, based on (Reese et al, 1975), so it is possible to get a more accurate result in an analytical calculation....

  13. Optimization of organo clay production for applications in based oil drilling fluid; Otimizacao do processo de organofilizacao para aplicacoes em fluidos de perfuracao base oleo

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Heber S.; Martins, Alice B.; Costa, Danubia L. da; Ferreira, Heber C.; Neves, Gelmires de A.; Melo, Tomas J.A. de [Universidade Federal de Campina Grande (UFCG), PB (Brazil); Teixeira Neto, Erico [Universidade Federal do ABC (UFABC), Santo Andre, SP (Brazil)

    2008-07-01

    The organophilic clays are widely used as an agent dispersed in the composition of oil based drilling fluids. The organophilic clays are gotten from bentonite clays treated, in watery way, with ionic surfactants, that are adsorbed in the surface of interlayer of the clays, re-covered them with a organic layer. A fundamental stage of production of the organophilic clays is the dispersion of bentonite clays, in way that variables like: speed of agitation, temperature and time of cure, influences directly in plastic and apparent viscosities of these dispersions, together with other variables of organophilization process, like, temperature and time of cure of organophilization, has direct influence in efficiency of the organophilization process. This work considers a study of these variable, using bentonite clays: Brasgel PA{sup R} and Cloisite Na{sup +R}, treated with the ionic surfactant Praepagem WB{sup R}. The organophilic clays gotten had been characterized by rays X diffraction, Foster's swelling, and the results were compared with the commercial organophilic clay VG-69{sup R}, industrially treated with ionic surfactant. Viscosities plastic and apparent of the dispersions had been measured in the midst of organic dispersant diesel oil used to obtain the oil based drilling fluids. Preliminary results of Foster's swelling and preparation of fluids show that the clays have affinity with the means liquid organic dispersants, and the fluids meet specifications of PETROBRAS (N-22581-1997 and N-2259 to 1997) for use in the of diesel oil based drilling fluids. (author)

  14. Influence of cracking clays on satellite estimated and model simulated soil moisture

    Directory of Open Access Journals (Sweden)

    Y. Y. Liu

    2010-06-01

    Full Text Available Vertisols are clay soils that are common in the monsoonal and dry warm regions of the world. One of the characteristics of these soil types is to form deep cracks during periods of extended dry, resulting in significant variation of the soil and hydrologic properties. Understanding the influence of these varying soil properties on the hydrological behavior of the system is of considerable interest, particularly in the retrieval or simulation of soil moisture. In this study we compare surface soil moisture (θ in m3 m−3 retrievals from AMSR-E using the VUA-NASA (Vrije Universiteit Amsterdam in collaboration with NASA algorithm with simulations from the Community Land Model (CLM over vertisol regions of mainland Australia. For the three-year period examined here (2003–2005, both products display reasonable agreement during wet periods. During dry periods however, AMSR-E retrieved near surface soil moisture falls below values for surrounding non-clay soils, while CLM simulations are higher. CLM θ are also higher than AMSR-E and their difference keeps increasing throughout these dry periods. To identify the possible causes for these discrepancies, the impacts of land use, topography, soil properties and surface temperature used in the AMSR-E algorithm, together with vegetation density and rainfall patterns, were investigated. However these do not explain the observed θ responses. Qualitative analysis of the retrieval model suggests that the most likely reason for the low AMSR-E θ is the increase in soil porosity and surface roughness resulting from cracking of the soil. To quantitatively identify the role of each factor, more in situ measurements of soil properties that can represent different stages of cracking need to be collected. CLM does not simulate the behavior of cracking soils, including the additional loss of moisture from the soil continuum during drying and the infiltration into cracks during rainfall events

  15. Evaluation of a clay-based acidic bedding conditioner for dairy cattle bedding.

    Science.gov (United States)

    Proietto, R L; Hinckley, L S; Fox, L K; Andrew, S M

    2013-02-01

    This study investigated the effects of a clay-based acidic bedding conditioner on sawdust bedding pH, dry matter (DM), environmental pathogen counts, and environmental bacterial counts on teat ends of lactating dairy cows. Sixteen lactating Holstein cows were paired based on parity, days in milk, milk yield, and milk somatic cell count, and were negative for the presence of an intramammary pathogen. Within each pair, cows were randomly assigned to 1 of 2 treatments with 3-wk periods in a crossover design. Treatment groups consisted of 9 freestalls per group bedded with either untreated sawdust or sawdust with a clay-based acidic bedding conditioner, added at 3- to 4-d intervals over each 21-d period. Bedding and teat ends were aseptically sampled on d 0, 1, 2, 7, 14, and 21 for determination of environmental bacterial counts. At the same time points, bedding was sampled for DM and pH determination. The bacteria identified in the bedding material were total gram-negative bacteria, Streptococcus spp., and coliform bacteria. The bacteria identified on the teat ends were Streptococcus spp., coliform bacteria, and Klebsiella spp. Teat end score, milk somatic cell count, and intramammary pathogen presence were measured weekly. Bedding and teat cleanliness, environmental high and low temperatures, and dew point data were collected daily. The bedding conditioner reduced the pH, but not the DM, of the sawdust bedding compared with untreated sawdust. Overall environmental bacterial counts in bedding were lower for treated sawdust. Total bacterial counts in bedding and on teat ends increased with time over both periods. Compared with untreated sawdust, the treated bedding had lower counts of total gram-negative bacteria and streptococci, but not coliform counts. Teat end bacterial counts were lower for cows bedded on treated sawdust for streptococci, coliforms, and Klebsiella spp. compared with cows bedded on untreated sawdust. The clay-based acidic bedding conditioner

  16. A dynamic model for smectite clay swelling, expansion and colloid generation

    International Nuclear Information System (INIS)

    Liu, Longcheng; Neretnieks, Ivars; Moreno, Luis

    2010-01-01

    clay is highly compacted. In developing the dynamic force balance model for colloidal expansion, it is acknowledged that accurate description of the viscous drag force, or equivalently the permeability, is very important to describe the swelling process of compacted bentonite as it expands and eventually turns from a gel into a sol in low ionic strength waters. For this reason, a Kozeny-Carman-like equation is elaborated in order to satisfactorily predict the permeability of the purified and fully Na-exchanged bentonite in dilute homo-ionic solutions, based on a set of permeability measurements. We present the measured versus predicted values of the permeabilities for Na-bentonites in different NaCl solutions. It is seen that the measured values are aligned in a narrow band along the predicted ones, falling well in the range of 1/2 and 2 times the predicted permeabilities. For usual laboratory results of the permeability test, this is definitely within the expected margin of variations. The force balance model, together with a friction model derived from the permeability, is then validated against accurate observations of the expansion process of the Na-exchanged bentonite in a water filled vertical test tube. The expansion is followed in detail over a month, by use of the magnetic resonance imaging technique with a spatial resolution of 0.2 mm, as an initially compacted tablet of Na-bentonite expands in water. The model accurately predicts not only the expansion rate, the general features of the expansion but also the basic behaviour at the expanding gel/sol interface, as exemplified for the case of expansion of a purified and fully Na-exchanged bentonite (WyNa) in an initially 0.5 mM CaCl 2 solution. The agreements demonstrate in turn that the Kozeny-Carman-like equation is successful in predicting the permeability of the Na-bentonite in dilute homo-ionic solutions. The model will be used to quantify the release of colloidal particles from an expanding buffer around

  17. Properties and applications of polymer nanocomposites clay and carbon based polymer nanocomposites

    CERN Document Server

    Prasad Sahoo, Bibhu

    2017-01-01

    The aim of the present edited book is to furnish scientific information about manufacturing, properties, and application of clay and carbon based polymer nanocomposites. It can be used as handbook for undergraduate and post graduate courses (for example material science and engineering, polymer science and engineering, rubber technology, manufacturing engineering, etc.) as well as as reference book for research fellows and professionals. Polymer nanocomposites have received outstanding importance in the present decade because of their broad range of high-performance applications in various areas of engineering and technology due to their special material properties. A great interest is dedicated to nanofiller based polymeric materials, which exhibit excellent enhancement in macroscopic material properties (mechanical, thermal, dynamic mechanical, electrical and many more) at very low filler contents and can therefore be used for the development of next-generation composite materials.

  18. Effect of injection molding parameters on nanofillers dispersion in masterbatch based PP-clay nanocomposites

    OpenAIRE

    J. Soulestin; J. J. Rajesh; M. F. Lacrampe; P. Krawczak

    2012-01-01

    The effect of injection molding parameters (screw rotational speed, back pressure, injec-tion flow rate and holding pressure) on the nanofiller dispersion of melt-mixed PP/clay nanocomposites was investigated. The nanocomposites containing 4 wt% clay were obtained by dilution of a PP/clay masterbatch into a PP matrix. The evaluation of the dispersion degree was obtained from dynamic rheological measurements. The storage modulus and complex viscosity exhibit significant dependence on the injec...

  19. Modelling of clay diagenesis using a combined approach of crystalchemistry and thermochemistry: a case study in the smectite illitization.

    Science.gov (United States)

    Geloni, Claudio; Previde Massara, Elisabetta; Di Paola, Eleonora; Ortenzi, Andrea; Gherardi, Fabrizio; Blanc, Philippe

    2017-04-01

    Diagenetic transformations occurring in clayey and arenaceous sediments is investigated in a number of hydrocarbon reservoirs with an integrated approach that combines mineralogical analysis, crystalchemistry, estimation of thermochemical parameters of clay minerals, and geochemical modelling. Because of the extremely variable crystalchemistry of clays, especially in the smectite - illite compositional range, the estimation of thermochemical parameters of site-specific clay-rich rocks is crucial to investigate water-rock equilibria and to predict mineralogical evolutionary patterns at the clay-sandstone interface. The task of estimating the thermochemical properties of clay minerals and predicting diagenetic reactions in natural reservoirs is accomplished through the implementation of an informatized, procedure (IP) that consists of: (i) laboratory analysis of smectite, illite and mixed layers (I/S) for the determination of their textural characteristics and chemical composition; (ii) estimation of the thermodynamic and structural parameters (enthalpy, entropy, and free energy of formation, thermal capacity, molar volume, molar weight) with a MS Excel tool (XLS) specifically developed at the French Bureau of Geological and Mining Researches (BRGM); (iii) usage of the SUPCRT (Johnson et al., 1992) software package (thereinafter, SSP) to derive log K values to be incorporated in thermodynamic databases of the standard geochemical codes; (iv) check of the consistency of the stability domains calculated with these log K values with relevant predominance diagrams; (v) final application of geochemical and reactive transport models to investigate the reactive mechanisms under different thermal conditions (40-150°C). All the simulations consider pore waters having roughly the same chemical composition of reservoir pore waters, and are performed with The Geochemist Workbench (Bethke and Yeakel, 2015), PHREEQC (Parkhurst, 1999) and TOUGHREACT (Xu, 2006). The overall

  20. Interaction between clay-based sealing components and crystalline host rock

    Science.gov (United States)

    Priyanto, D. G.; Dixon, D. A.; Man, A. G.

    The results of hydraulic-mechanical (H-M) numerical simulation of a shaft seal installed at a fracture zone (FZ) in a crystalline host rock using the finite element method are presented. The primary function of a shaft seal is to limit short-circuiting of the groundwater flow regime via the shaft in a deep geological repository. Two different stages of system evolution were considered in this numerical modelling. Stage 1 simulates the groundwater flow into an open shaft, prior to seal installation. Stage 2 simulates the groundwater flow into the shaft seal after seal installation. Four different cases were completed to: (i) evaluate H-M response due to the interaction between clay-based sealing material and crystalline host rock in the shaft seal structure; (ii) quantify the effect of the different times between the completion of the shaft excavation and the completion of shaft seal installation on the H-M response; and (iii) define the potential effects of different sealing material configurations. Shaft sealing materials include the bentonite-sand mixture (BSM), dense backfill (DBF), and concrete plug (CP). The BSM has greater swelling capacity and lower hydraulic conductivity ( K) than the DBF. The results of these analyses show that the decrease of the pore water pressure is concentrated along the fracture zone (FZ), which has the greatest K. As the time increases, the greatest decrease in pore water pressure is found around the FZ. Following FZ isolation and the subsequent filling of the shaft with water as it floods, the pore water pressure profile tends to recover back to the initial conditions prior to shaft excavation. The majority of the fluids that ultimately saturate the centre of the shaft seal flow radially inwards from the FZ. The time between the completion of the shaft excavation and the completion of shaft seal installation has a significant effect on the saturation time. A shorter time can reduce the saturation time. Since most of the inflow

  1. Study of smectite clays of the city Pedra Lavrada - PB for use in water-based drilling fluids

    International Nuclear Information System (INIS)

    Silva, I.A. da; Costa, J.M.R.; Cardoso, M.A.F.; Neves, G.A.; Ferreira, H.C.

    2011-01-01

    Paraiba has large reserves of bentonite clays, with the largest deposits in Boa Vista, PB. Recently new deposits were discovered in the cities of Cubati and Pedra Lavrada-PB, creating great expectations for further expansion of reserves for industrial production. The aim of this work is the study of smectite clays from the city of Pedra Lavrada, PB for use in drilling fluids water based. The characterization was made by the diffraction of laser (AG), thermogravimetric and differential thermal analysis (TGA and DTA), chemical composition by X-ray fluorescence (EDX), X-ray diffraction (XRD), exchange capacity of cations (ECC) and surface area (SA). The results obtained so far showed that the samples presented at its mineral composition smectite, kaolinite and quartz. In relation to rheological properties showed that the bentonite clay sample Dark presents promising features for use in water based drilling fluids. (author)

  2. Organophilization of bentonite clays with non-ionic surfactants aiming their use in drilling fluids base oil

    International Nuclear Information System (INIS)

    Silva, I.A.; Costa, J.M.R.; Neves, G.A.; Ferreira, H.C.; Ferreira, H.S.

    2010-01-01

    The use of nonionic surfactants has been replacing the traditional ionic surfactants among others by its high potential for resistance to thermal degradation. This work aims at the development of organoclay by the addition of nonionic surfactants for use in drilling fluids for oil wells based oil. The bentonite clay was organophilized and then characterized by X-ray diffraction and swelling Foster, seeking the most appropriate choice of surfactant to liquid organic dispersing media: ester, diesel and paraffin. With the obtained dispersions were measured apparent viscosities and plastic. The results showed that incorporation of surfactants used in the clay interlayer spacing increased significantly and that the dispersions showed rheological properties within the specifications of PETROBRAS, for the use of organophilic clays in drilling fluids in a non-aqueous base. (author)

  3. Desaturation of a clay-stone around a ventilated gallery: numerical modelling of pressures and water contents under various conditions

    International Nuclear Information System (INIS)

    Ababou, Rachid; Mansouri, Nahla; Bailly, David; Poutrel, Adrien

    2012-01-01

    Document available in extended abstract form only. We present simulation tests focusing on the drying process around a gallery in an initially saturated (water-filled) porous clay rock, in the framework of a research on the isolation properties and hydro-mechanical behaviour of a clayey geologic repository for radioactive waste. The saturated/unsaturated hydrodynamic parameters used in these tests correspond to a hypothetical clay-stone, similar to the 130 m thick Callovo-Oxfordian formation located between depths 400 m and 600 m at the Meuse / Haute-Marne (MHM) Underground Research Laboratory (URL), operated by ANDRA (Bure, France). The simulations tests were designed according to 3 'types' of computational geometries. The drying period was extended to very long time scales in some cases. The clay rock was taken homogeneous in many tests, but the damaged zone was represented in some (Type III) tests. Type (I) tests are conducted in a simplified non circular geometry. Assuming a square cross-section for the drift, the drying process is obtained by imposing a fixed suction on a flat piece of wall at the roof. The bottom of the porous domain coincides with the roof of the drift. The imposed suction at the roof affects the near field pressure both horizontally and vertically. Type (II) tests reproduce the circular cylindrical geometry of a partially or perfectly filled gallery, with drying conditions imposed at both ends of the drift. Finally, Type (III) tests consider the case of an empty ventilated cylindrical drift with circular cross-section. In this case the drying is imposed on the curved walls of the drift via a transmission mechanism thanks the 'macro-porous immersion' method. In all cases, the drying of the porous clay rock is modeled by imposing a suction condition (ψ), obtained from relative air humidity (HR) via Kelvin's law (ψ). Briefly, the macro-porous immersion method consists in the following interrelated procedures. First, the volumetric excavation

  4. Investigation on Insar Time Series Deformation Model Considering Rheological Parameters for Soft Clay Subgrade Monitoring

    Science.gov (United States)

    Xing, X.; Yuan, Z.; Chen, L. F.; Yu, X. Y.; Xiao, L.

    2018-04-01

    The stability control is one of the major technical difficulties in the field of highway subgrade construction engineering. Building deformation model is a crucial step for InSAR time series deformation monitoring. Most of the InSAR deformation models for deformation monitoring are pure empirical mathematical models, without considering the physical mechanism of the monitored object. In this study, we take rheology into consideration, inducing rheological parameters into traditional InSAR deformation models. To assess the feasibility and accuracy for our new model, both simulation and real deformation data over Lungui highway (a typical highway built on soft clay subgrade in Guangdong province, China) are investigated with TerraSAR-X satellite imagery. In order to solve the unknows of the non-linear rheological model, three algorithms: Gauss-Newton (GN), Levenberg-Marquarat (LM), and Genetic Algorithm (GA), are utilized and compared to estimate the unknown parameters. Considering both the calculation efficiency and accuracy, GA is chosen as the final choice for the new model in our case study. Preliminary real data experiment is conducted with use of 17 TerraSAR-X Stripmap images (with a 3-m resolution). With the new deformation model and GA aforementioned, the unknown rheological parameters over all the high coherence points are obtained and the LOS deformation (the low-pass component) sequences are generated.

  5. Self-healing coatings based on halloysite clay polymer composites for protection of copper alloys.

    Science.gov (United States)

    Abdullayev, Elshad; Abbasov, Vagif; Tursunbayeva, Asel; Portnov, Vasiliy; Ibrahimov, Hikmat; Mukhtarova, Gulbaniz; Lvov, Yuri

    2013-05-22

    Halloysite clay nanotubes loaded with corrosion inhibitors benzotriazole (BTA), 2-mercaptobenzimidazole (MBI), and 2-mercaptobenzothiazole (MBT) were used as additives in self-healing composite paint coating of copper. These inhibitors form protective films on the metal surface and mitigate corrosion. Mechanisms involved in the film formation have been studied with optical and electron microscopy, UV-vis spectrometry, and adhesivity tests. Efficiency of the halloysite lumen loading ascended in the order of BTA halloysite formulations have shown the best protection. Inhibitors were kept in the tubes buried in polymeric paint layer for a long time and release was enhanced in the coating defects exposed to humid media with 20-50 h, sufficient for formation of protective layer. Anticorrosive performance of the halloysite-based composite acrylic and polyurethane coatings have been demonstrated for 110-copper alloy strips exposed to 0.5 M aqueous NaCl for 6 months.

  6. Reactive transport modeling of interaction processes between clay stone and cement

    International Nuclear Information System (INIS)

    Windt, L. de; van der Lee, J.; Pellegrini, D.

    2001-01-01

    The disposal of radioactive wastes in clayey formations may require the use of large amounts of concrete and cement. The chemical interactions between these industrial materials and the host rock are modeled with the reactive transport code HYTEC for time scales and a geometry representative of disposal projects. The pH evolution, a key parameter in element mobility, is studied more specifically. It depends on several interdependent processes: i) diffusion of highly alkaline cement pore solution, ii) strong buffering related to important mineral transformations both in the cement and in the clay, and iii) cation exchange processes, beyond the zone of intense mineral transformations. In addition, precipitation of secondary minerals may lead to a partial or complete clogging of the pore space, almost stopping the propagation of the high pH plume. In a second step, preliminary results on the migration of strontium and uranium in these strongly coupled systems are presented as an example of transport parameter derivation. (authors)

  7. Microanalysis of clay-based pigments in paintings by XRD techniques

    Czech Academy of Sciences Publication Activity Database

    Hradil, David; Bezdička, Petr; Hradilová, J.; Vašutová, V.

    2016-01-01

    Roč. 125, MAR (2016), s. 10-20 ISSN 0026-265X R&D Projects: GA ČR(CZ) GA14-22984S Institutional support: RVO:61388980 Keywords : Clay minerals * Earth pigments * Clay-binder interaction * Powder X-ray micro-diffraction * Quantitative phase microanalysis Subject RIV: DB - Geology ; Mineralogy Impact factor: 3.034, year: 2016

  8. Comparative study of illite clay and illite-based geopolymer products

    International Nuclear Information System (INIS)

    Sperberga, I; Sedmale, G; Zeila, K; Ulme, D; Stinkulis, G

    2011-01-01

    Quaternary (Q-clay) clayey deposits are one of the dominating parts of mineral raw materials of the sedimentary cover at present area of Latvia. These clays can be characterised by illite content up to 75-80 %. Two ways for use of illite clays were studied: conventional and geopolymers method. Purpose of the second mentioned method was showing the influence of alkali (KOH) on the transformation of Q-clay/illite structure. Obtained products were investigated by IR-spectroscopy, DTA and XRD, pore size distribution was determined as well. Some ceramic properties and compressive strength were determined and compared. IR-spectrum showed the effect of alkali on the transformation of Q-clay/illite structure in three main absorption bands: 3620-3415 cm -1 which is related to the vibrational modes of adsorbed water between SiO 4 and AlO 6 layers; new stronger absorption bands at 1635 cm -1 and 1435 cm -1 indicate on the appearance of vibrations in Q-KOH and are related to the K-O-Si bonds; the most essential changes are vibrations at 850 cm -1 showing the changes in the coordination number of Al from 6 to 4 for Q-KOH. Investigations of the bulk density in dependence on temperature showed the small increase of bulk density for Q-clay while - the relatively remarkable decrease for Q-clay/KOH. Mentioned values correlate with the compressive strength of Q-clay and Q-KOH products.

  9. A batch adsorption study on bentonite clay Pertinence to transport modeling?

    Science.gov (United States)

    BOURG, I.; BOURG, A. C.; SPOSITO, G.

    2001-12-01

    Bentonite clay is often used as a component of engineered barriers for the isolation of high-level toxic wastes. This swelling clay is used for its physical (impermeability, self-healing) but also for its chemical properties, mostly a high cation exchange capacity (CEC). The adsorbed cations being temporarily immobilized, this should slow down the release of cations from the waste to the surrounding environment. In order to assess the performance of the engineered barrier, the partitioning of solutes between the liquid and solid phases needs to be quantified for use in transport models. The usual method for characterizing the adsorption is through batch adsorption experiments on dispersed suspensions of the solid, yielding an adsorption isotherm (adsorbed concentration vs. dissolved concentration). This isotherm however should be a function of various environmental variables (e.g., pH, ionic strength, concentrations of various ligands and competing adsorbents), so that extrapolation of lab data to performance assessment in the field is problematic. We present results from a study of the adsorption of cesium, strontium, cadmium and lead on dispersed suspensions of the standard BX-80 bentonite. Through a wide range of experimental parameters (pH, ionic strength, reaction time, reactor open or closed to the atmosphere, study of a range of cations of differing properties), we seek a mechanistic interpretation of the results instead of an empirical determination of adsorption parameters. Depending on the mechanisms that control the adsorption in different experimental ranges, we discuss the degree to which the partitioning coefficient (Kd) obtained in the lab can be extrapolated to a transport model through compacted bentonite in a natural environment.

  10. Water and clay based drilling fluids for oil wells; Fluidos hidroargilosos para perfuracao de pocos de petroleo

    Energy Technology Data Exchange (ETDEWEB)

    Medeiros, R.C.A. de; Amorim, L.V.; Santana, L.N. de L. [Universidade Federal de Campina Grande (UFCG), PB (Brazil)], e-mail: nalealves@hotmail.com

    2008-07-01

    In the onshore drilling of wells are commonly used aqueous fluids containing bentonite clays. However, to perform their functions generally there is the necessity of additives to drilling fluids, like viscositying, filtered reducer and lubricant. Thus, this work aims to develop water and clay base drilling fluids with low solid text, and with polymeric and lubricants additives. Were studied a sample of industrialized sodium bentonite clays, three polymeric compounds in the ternary form and a sample of lubricant, in different concentrations. Were determined the flow curves, the apparent and plastic viscosities, the yield limit and gel force in Fann 35A viscometer, the filtered volume in API filter-press and the lubricity coefficient in Ofite lubricimeter. The results showed that the fluid had pseudoplastic behavior, the polymeric additives adjusts their rheological properties and filtration and the addition of 1% of lubricant is sufficient to improve the lubricity of fluids. (author)

  11. Development of a simple model for the simultaneous degradation of concrete and clay in contact

    International Nuclear Information System (INIS)

    Neretnieks, Ivars

    2014-01-01

    Highlights: • The rate at which concrete and bentonite in contact degrade each other is modelled. • In portlandite and bentonite receding degradation fronts develop and move. • The model results compare well with results from complex models. - Abstract: In nuclear waste repositories concrete and bentonite are used, sometimes in contact with each other. The rate of mutual degradation of concrete and bentonite by alkaline fluids from concrete is explored using a simple model. The model considers dissolution of a soluble compound in the concrete (e.g. portlandite), which is gradually dissolved as the solubilised hydroxide and the cation(s) diffuse towards and into the bentonite in which smectite degrades by interaction with the solutes. Accounting for only the diffusion resistances in concrete and clay, the solubility of the concrete compound and the hydroxide consumption capacity of the smectite, results in a very simple analytical model. The model is tested against several published modelling results that account for reaction kinetics, reactive surface, and equilibrium data for tens to many tens of different secondary minerals. In the models that include several specified minerals often assumptions need to be made on which minerals can form. This introduces subjective assumptions. The degradation rates using the simple model are within the range of results obtained by the complex models. In the studies of the data used in these models it was found that the uncertainties in thermodynamic data are considerable and can give contradictory information on under what conditions smectite degrades. Some smectite models and thermodynamic data suggest that smectite will transform to other minerals spontaneously if there were no kinetic restrictions

  12. Ziegler-Natta Catalyst Based on MgCl₂/Clay/ID/TiCl₄ for the Synthesis of Spherical Particles of Polypropylene Nanocomposites.

    Science.gov (United States)

    Cardoso, Renata da Silva; Oliveira, Jaqueline da Silva; Ramis, Luciana Bortolin; Marques, Maria de Fátima V

    2018-07-01

    In the present work, we have designed MgCl2/clay/internal donor (ID)/TiCl4 based bisupported Ziegler-Natta catalysts containing varying amounts of organoclay (montmorillonite) in order to synthesize spherical particles of polypropylene/clay nanocomposites (PCN). The organoclay was introduced into the catalyst support formulation and PCN was obtained using the in situ polymerization technique. Decreasing the reaction time, it was possible to obtain nanocomposites with high concentrations of clay (masterbatches). Micrographs of SEM confirmed the spherical morphology of the catalysts. In addition, XRD patterns show that the active sites for polymerization were inserted in the clay galleries. The catalytic performance was evaluated in slurry propylene polymerization using triethylaluminium as cocatalyst and silane as external electron donor at 70 °C, 4 bar, and different reaction times. The PCNs obtained containing different clay amounts were characterized by X-ray diffraction, thermal analyses, transmission electronic microscopy, and extractables in heptane. The results revealed that the synthesized PP/clay particles were also spherical showing that the morphological control is possible even using catalysts containing high amounts of clay. The PCN presented high degradation temperature (459 °C). The XRD peak related to the clay interlamellar distance has shifted to lower angles, and TEM images confirmed the formation of exfoliated/intercalated clay on the PP matrix and absence of microparticles of clay.

  13. Nanoindentation Characterization of a Ternary Clay-Based Composite Used in Ancient Chinese Construction

    Directory of Open Access Journals (Sweden)

    Dongwei Hou

    2016-10-01

    Full Text Available Ternary clay-based composite material (TCC, composed of lime, clay and sand, and usually modified with sticky rice and other organic compounds as additives, was widely used historically in Chinese construction and buildings due to its high mechanical performance. In this study, to gain an insight into the micromechanical mechanism of this cementitious material, the nanomechanical properties and volume fraction of mechanically different phases of the binder matrix are derived from the analysis of grid nanoindentation tests. Results show that there are five distinct mechanical phases, where the calcium silicate hydrate (C-S-H and geopolymer present in the binder matrix are almost identical to those produced in ordinary Portland cement (OPC and alkali-activated fly-ash geopolymer materials in nano-mechanical performance. The nano-mechanical behavior of calcite produced by the carbonation of lime in this binder is close to the calcite porous outer part of some sea urchin shells. Compared to OPC, the C-S-H contained in the TCC has a relatively lower ratio of indentation modulus to indentation hardness, implying a relatively lower resistance to material fracture. However, the geopolymer and calcite, at nearly the same volume content as the C-S-H, help to enhance the strength and durability of the TCC by their higher energy resistance capacity or higher strength compared to the C-S-H. Rediscovering of TCC offers a potential way to improve modern concrete’s strength and durability through synergy of multi-binders and the addition of organic materials if TCC can be advanced in terms of its workability and hardening rate.

  14. CFD Modelling and Experimental Testing of Thermal Calcination of Kaolinite Rich Clay Particles - An Effort towards Green Concrete

    DEFF Research Database (Denmark)

    Gebremariam, Abraham Teklay

    Cement industry is one of the major industrial emitters of greenhouse gases, generating 5-7% of the total anthropogenic CO2 emissions. Consequently, use of supplementary cementitious materials (SCM) to replace part of the CO2-intensive cement clinker is an attractive way to mitigate CO2 emissions...... from cement industry. SCMs based on industrial byproducts like fly ashes and slags are subject to availability problems. Yet clays are the most ubiquitous material on earth's crust. Thus, properly calcined clays are a very promising candidate for SCMs to produce green cements. Calcination...... property of the calcined clay material, among which is the density of calcines. By using the variation in density of calcines, an optimum residence time has been marked. At this time the calcines display a minimum density that corresponds to the most dehydroxylated calcines. The behavior of flash calcined...

  15. Empirical Models for Power and Energy Requirements II : A Powered Implement Operation in Serdang Sandy Clay Loam, Malaysia

    Directory of Open Access Journals (Sweden)

    A. F. Kheiralla

    2017-12-01

    Full Text Available Power and energy requirements were measured with an instrumented tractor for rotary tilling in Serdang sandy clay loam soil.  The effects of travel speed and rotor speed upon the measured data were investigated.  Power model from orthogonal regression analysis was formulated based on linear and quadratic functions of travel speed and bite length.  Fuel consumption model from regression analysis was formulated based on linear tractor PTO power as well as linear equivalent tractor PTO power.  Fuel consumption rates predicted by ASAE D497.3 were found to be 25% to 28% overestimates of the values predicted by the model developed.  However, fuel consumption rates reported by OECD Tractor Test were found to be 1% to 9% lower than the fuel consumption rates predicted by the model developed.  A comparison of power and energy requirements for both powered and draught implements showed that the disk harrow was the most energy efficient implement in terms of fuel consumption and specific energy followed by the rotary tiller, disk plough and mouldboard.  Finally, average PTO power, fuel consumption, wheel slip, wheel power and specific energy for a powered implement are presented.

  16. Project Opalinus Clay: Sorption Data Bases For Opalinus Clay Influenced By A High pH Plume

    Energy Technology Data Exchange (ETDEWEB)

    Bradbury, M.H.; Baeyens, B

    2004-11-01

    The interaction of groundwater with the large quantities of cement/concrete used in the construction and backfilling of emplacement tunnels containing long-lived intermediate level radioactive waste may give rise to the release of a pulse of hyper alkaline fluid (pH plume) into the surrounding rock. Since the pH of this plume could remain in excess of 12.5 for tens of thousands of years, many minerals in a sedimentary host rock would be unstable leading to dissolution reactions, secondary mineral precipitation and changes in groundwater chemistry. An Opalinus day formation in the Zuercher Weinland, is under consideration by Nagra as a potential host rock for a repository of spent fuel (SF), vitrified high-level waste (HLW) from reprocessing of spent fuel and long-lived intermediate-Ievel radioactive waste (ILW). The purpose of this report is to assess the effects of the interactions between a pH plume and Opalinus day on the sorption properties of the formation and to provide appropriate sorption data bases. (author)

  17. An Evidence-Based Review on Medicinal Value of Clays in Traditional Persian Medicine.

    Science.gov (United States)

    Hosseinkhani, Ayda; Montaseri, Hashem; Hosamo, Ammar; Zarshenas, Mohammad Mehdi

    2017-01-01

    The use of earths and clays for medical purposes dates back to antiquity. In recent years, there has been an increasing interest in researches on traditional remedies in the hope of discovering new drug. Iran is an ancient country with a medical backbone acquired from the experiences of ancient Persian scholars, who had made a great contribution to the development of the medical sciences. Many medical and pharmaceutical books by early Persian scientists still exist and may have the potential of leading researchers to new drug discoveries. Owing to the emergence of new and antimicrobial-resistant infections, present-day medicine has recently begun focusing on medicinal earths and clays especially as mineral antimicrobials. The current study is, therefore, aimed at gathering information regarding medicinal clays in traditional Persian medicine (TPM). Five main Persian materia medica with the key word 'tin' (clay) and current databases such as PubMed, Scopus, ScienceDirect, and Google Scholar were searched by key words 'white, green, red, maroon, violet, black, grey and pink clays' and 'pharmacological effects'. Twenty three clays were found in Persian manuscripts. Although their mineralogical compositions are unknown, different pharmacological properties have been attributed to these mineral medicaments. Clay's properties were widely used in medieval times for the treatment of infections to poisoning. They were also used in compound formulations, possibly for their pharmaceutical formulation modifying effects. Modern scientific proofs have also been found in many of the medicinal clays reported in Persian manuscripts. Although many of the reported clays are still unknown, their characterization may lead to new medicinal developments. Novel analytical methods available today make it possible to elucidate the chemical compositions of these minerals as parameters responsible for their medicinal effects. Copyright© Bentham Science Publishers; For any queries, please

  18. New magnetic organic-inorganic composites based on hydrotalcite-like anionic clays for drug delivery

    International Nuclear Information System (INIS)

    Carja, Gabriela; Chiriac, Horia; Lupu, Nicoleta

    2007-01-01

    The structural 'memory effect' of anionic clays was used to obtain layered double hydroxides (LDHs) with tailored magnetic properties, by loading iron oxides and/or spinel structures on iron partially substituted hydrotalcite-like materials. The obtained magnetic layered structures were further used as precursors for new hybrid nanostructures, such as aspirin-hydrotalcite-like anionic clays. Transmission electron microscopy (TEM) analysis shows that small iron oxide or spinel nanoparticles coexist with the fibrous drug particles on the surface of partially aggregated typical clay-like particles. The specific saturation magnetization of the loaded LDHs can be increased up to 70 emu/g by using specific post-synthesis treatments

  19. Enhancement of the glass corrosion in the presence of clay minerals: testing experimental results with an integrated glass dissolution model

    International Nuclear Information System (INIS)

    Godon, N.; Vernaz, E.Y.

    1992-01-01

    Recent glass dissolution experiments, conducted at 90 deg C in the presence of potential backfill materials, indicate remarkably faster glass corrosion in the presence of clay, compared to tests where the glass is leached either alone or with alternative backfill materials. This effect correlates with the clay content in the backfill, and may be attributed to the removal of silica from solution. Scorpion, or dissolution with reprecipitation of a silica-rich clay, have been proposed as possible mechanisms for the silica consumption. The results of some experiments have been tested against a glass dissolution model, in which a widely used kinetic equation for glass corrosion is coupled with diffusive silica transport through a single porosity, linearly sorbing medium, which represents the backfilling. Because the glass corrosion rates imposed by the kinetic equation are inversely proportional to the silicic acid concentration of the leachant contacting the glass, the model predicts enhanced glass dissolution if silica is sorbed by the porous medium. The experimental data proved to be consistent with the predicted enhancement of the glass dissolution. Moreover, the model-estimated distribution coefficients for silica sorption (K d ) fall within the range of values extracted from available literature data, thus supporting the hypothesis that the observed high corrosion rates are due to sorption of silica on the clay mineral surfaces. (author)

  20. Preferential flow and pesticide transport in a clay-rich till: Field, laboratory, and modeling analysis

    Science.gov (United States)

    JøRgensen, Peter R.; Hoffmann, Martin; Kistrup, Jens P.; Bryde, Claus; Bossi, Rossana; Villholth, Karen G.

    2002-11-01

    This study investigates vertical flow and pesticide transport along fractures in water saturated unoxidized clayey till. From two experimental fields, each 40 m2, 96% and 98%, respectively, of total vertical flow was conducted along fractures in the till, while the remaining 2-4% of flow occurred in the clay matrix at very slow flow rate. An applied dye tracer was observed only along 10-26% of the total fracture length measured on the horizontal surface of the experimental fields. In vertical sections the dyed fracture portions constituted root channels, which penetrated the till vertically along the fractures into the local aquifer at 5 m depth. No dye tracer was observed in the fractures without root channels or in the unfractured clay matrix, suggesting that root growth along the fracture surfaces was the principal agent of fracture aperture enhancement. Using hydraulic fracture aperture values determined from large undisturbed column (LUC) collected from one of the experimental fields, it was estimated that 94% of flow in the fractures was conducted along the fracture root channels, while only 6% of flow was conducted along the fracture sections without root channels. For natural vertical hydraulic gradients (0.8-2.3 at the site), flow rates of 0.8-2 km/d were determined for a fracture root channel, while fracture sections without root channels revealed flow rates of 9-22 m/d. Corresponding flow rates in the unfractured matrix were 7-19 mm/yr. For infiltrated bromide (nonreactive tracer) and mobile pesticides mecoprop (MCPP) and metsulfuron, very rapid migration (0.28-0.5 m/d) and high relative breakthrough concentrations (30-60%) into the aquifer were observed to occur along the fracture root channels using a constant hydraulic gradient of 1. Only traces were measured from infiltration of the strongly sorbed pesticide prochloraz. The concentrations of the bromide and pesticides in the monitoring wells were modeled with a discrete fracture matrix diffusion

  1. Comparing uranyl sorption complexes on soil and reference clays

    International Nuclear Information System (INIS)

    Chisholm-Brause, C.J.; Berg, J.M.; Conradson, S.D.; Morris, D.E.; McKinley, J.P.; Zachara, J.M.

    1993-01-01

    Clay minerals and other components in natural soils may play a key role in limiting the mobility of uranium in the environment through the formation of sorption complexes. Reference clays are frequently used as models to study sorption processes because they have well-known chemical and physical properties, but they may differ chemically and morphologically from clays derived from natural soils. Therefore, inferences based on reference clay data have been questioned. The authors have used luminescence and x-ray absorption spectroscopies to characterize the sorption complexes of aqueous uranyl (UO 2 2+ ) species on two soil smectites from the Kenoma and Ringold formations, and compared these results to those obtained on reference smectite clays. The pH dependence of uptake suggests that the ratio of sorption on amphoteric edge sites is greater for the soil smectites than for reference clays such as Wyoming montmorillonite (SWy-1). The luminescence spectra for uranyl sorbed to the soil clays are very similar to those for uranyl sorbed principally to the edge sites of SWy-1. This observation supports the solution data suggesting that adsorption to amphoteric sites is a more important mechanism for soil clays. However, the spectral data indicate that the sorption complexes on natural and reference clays are quite similar. Furthermore, as with the reference clays, the authors have found that the chemistry of the solution plays a greater role in defining the sorption complex than does the clay matrix. Thus, if differences in surface properties are adequately taken into account, the reference clays may serve as useful analogs for soil clays in investigations of metal-ion sorption

  2. Clay nanocomposites based on poly(vinylidene fluoride-co-hexafluoropropylene): Structure and properties

    KAUST Repository

    Kelarakis, Antonios

    2010-01-01

    Structure-properties relationships in poly(vinylidene fluoride-co-hexafluoropropylene), PVDF-HFP, clay nanocomposites are reported for the first time. Addition of organically modified clays to PVDF-HFP promotes an α to β transformation of the polymer crystals. The degree of transformation depends on the nature of the clay surface modifier and scales with the strength of the interactions between the clay and the polymer. The nanocomposites exhibit significant increases in elongation to failure compared to the neat copolymer. In addition, their dielectric permittivity is higher over a wide temperature range. Their mechanical and dielectric properties scale similar to the amount of the β phase present in the nanocomposites. © 2009 Elsevier Ltd. All rights reserved.

  3. Modelling of radionuclide migration and heat transport from an High-Level-Radioactive-Waste-repository (HLW) in Boom clay

    International Nuclear Information System (INIS)

    Put, M.; Henrion, P.

    1992-01-01

    For the modelling of the migration of radionuclides in the Boom clay formation, the analytical code MICOF has been updated with a 3-dimensional analytical solution for discrete sources. the MICOF program is used for the calculation of the release of α and β emitters from the HIGH LEVEL RADIOACTIVE WASTES (HLW). A coherent conceptual model is developed which describes all the major physico-chemical phenomena influencing the migration of radionuclides in the Boom clay. The concept of the diffusion accessible porosity is introduced and included in the MICOF code. Different types of migration experiments are described with their advantages and disadvantages. The thermal impact of the HLW disposal in the stratified Boom clay formation has been evaluated by a finite element simulation of the coupled heat and mass transport equation. The results of the simulations show that under certain conditions thermal convection cells may form, but the convective heat transfer in the clay formation is negligible. 6 refs., 19 figs., 2 tabs., 5 appendices

  4. Use of Pillared Clay-Based Catalysts for Wastewater Treatment through Fenton-Like Processes

    OpenAIRE

    J. Herney-Ramírez; Luis M. Madeira

    2010-01-01

    Clays, both natural and physical-chemically modified, are attractive materials for the preparation of supported catalysts. In this chapter, a review is made regarding the use of pillared interlayered clays (PILCs) in heterogeneous Fenton-like advanced oxidation processes. Their applications in pollutants degradation is summarized, with particular emphasis on the effect of the main operating conditions (e.g., initial H2O2 or parent compound concentration, catalyst load, pH, or temperature) on ...

  5. Modelling the coupled chemico-osmotic and advective-diffusive transport of nitrate salts in the Callovo-Oxfordian clay

    International Nuclear Information System (INIS)

    Baechler, S.; Croise, J.; Altmann, S.

    2010-01-01

    Document available in extended abstract form only. Fine-grained saturated porous materials can act as a semi-permeable osmotic membrane when exposed to a solute concentration gradient. The ions diffusion is hindered while water movement towards higher concentrations takes place in the semi-permeable membrane. The capacity of the fine-grained porous material to act as a semi permeable osmotic membrane is referred to as the osmotic efficiency (its value is 1 when the membranes is ideal, less than 1 when the membrane is leaky, allowing diffusion). The efficiency to retain ions in solution is dependent on the thickness of the diffuse double layer which itself depends on the solution concentration in the membrane. Clay rich formations have been shown to act as non-ideal semi-permeable membrane. Andra is investigating the Callovo-Oxfordian clay as a host rock for intermediate-level to high-level radioactive waste. In this context, it has been feared that osmotic water flows generated by the release of sodium nitrate salt in high concentrations, out of intermediate radioactive bituminous waste, could induce important over-pressures. The latest would eventually lead to fracturing of the host rock around the waste disposal drifts. The purpose of the present study was to develop a simulation code with the capacity to assess the potential impact of osmosis on: the re-saturation of the waste disposal drifts, the pressure evolution and the solute transport in and around a waste disposal drift. A chemo-osmotic coupled flow and transport model was implemented using the FlexPDE-finite element library. Our model is based on the chemo-osmotic formulation developed by Bader and Kooi, 2005. The model has been extended to highly concentrated solutions based on Pitzer's equation. In order to assess the impact of osmotic flow on the re-saturation time, the model was also designed to allow unsaturated flow modelling. The model configuration consists of an initially unsaturated 2D

  6. Effect of injection molding parameters on nanofillers dispersion in masterbatch based PP-clay nanocomposites

    Directory of Open Access Journals (Sweden)

    J. Soulestin

    2012-03-01

    Full Text Available The effect of injection molding parameters (screw rotational speed, back pressure, injec-tion flow rate and holding pressure on the nanofiller dispersion of melt-mixed PP/clay nanocomposites was investigated. The nanocomposites containing 4 wt% clay were obtained by dilution of a PP/clay masterbatch into a PP matrix. The evaluation of the dispersion degree was obtained from dynamic rheological measurements. The storage modulus and complex viscosity exhibit significant dependence on the injection molding parameters. PP/clay nanocomposite molded using more severe injection parameters (high shear and long residence time displays the highest storage modulus and complex viscosity, which illustrates the improved dispersion of clay platelets. This better dispersion leads to better mechanical properties particularly higher Young modulus, tensile strength and unnotched impact strength. A Taguchi analysis was used to identify the influence of individual process parameters. The major individual parameter is the injection flow rate, whose increase improves nanoclay dispersion. The combination of high back pressure and high screw rotational speed is also necessary to optimize the dispersion of clay nanoplatelets.

  7. TECHNOLOGY OF PRODUCTION OF CERAMIC TILES BASED ON DOLERITE AND FUSIBLE CLAY

    Directory of Open Access Journals (Sweden)

    Pleshko Marianna Viktorovna

    2018-02-01

    Full Text Available The paper presents a completely new composition of the ceramic mass for production of ceramic tiles for interior lining of walls, on the basis of fusible clay. The optimal compositions of jade engobe and glossy glaze, the most suitable for this composition, are determined. A new technological scheme is developed for production of ceramic tiles for interior lining based on dolerite and fusible clay. The curve of firing, which is the most suitable for charge masses and decorative coating compositions being used, has been constructed. Subject: ceramic mass for the production of ceramic facing tiles. Ceramic tiles are the most popular building material in Russia. The most promising technology for its production from the standpoint of technical and economic efficiency is the technology of rapid single firing, which is rarely used at the plants of our country. In this regard, the development and implementation of new effective compositions of ceramic masses and decorative coatings that are the most compatible with the specifics of rapid single firing technology, based on new unconventional raw materials, are very relevant and promising. Research objectives: development of technological parameters, compositions of ceramic masses and decorative coatings of ceramic tiles for the internal wall lining that provide an increase in tiles production efficiency using the technology of rapid single firing through the use of non-traditional plagioclase-pyroxene raw materials: dolerites, loam and technogenic raw materials. Materials and methods: technological, numerical and experimental studies were conducted. To select the optimal composition of the ceramic mass, the method of mathematical planning was used, namely the simplex-centroid design of Scheffe. To identify the scientific foundations of the energy-efficient production technology being developed, differential thermal and X-ray phase, optical, electron microscopic and dilatometric studies were applied

  8. Mechanical and electrical properties of a polyester resin reinforced with clay-based fillers

    Energy Technology Data Exchange (ETDEWEB)

    Buncianu, Dorel; Jadaneant, Mihai [UPT Timisoara, Timisoara (Romania); Tessier-Doyen, Nicolas; Absi, Joseph [Centre Européen de la Céramique, Limoges Cedex (France); Courreges, Fabien [Laboratoire XLIM, 123, Limoges Cedex (France)

    2017-03-15

    In this study, composite polymer-based materials were fabricated, in which a significant proportion of polyester resin was substituted by low-cost and environmentally-friendly clay-based raw materials. The main objective is to improve mechanical properties while maintaining a reasonable electrical insulating behavior. A homogenized distribution of fillers within the matrix compatible with the processing parameters was obtained up to a maximum added fraction of 20 vol%. Mechanical characterization using uniaxial traction tests and Charpy impact pendulum machine showed that stress-to-rupture can be enhanced of approximately 25 %. In addition, fracture energy was doubled for the best formulation. Dielectric constant was decreased and loss factor was slightly increased when electrical resistivity remained almost constant. In general, the composite materials with metakaolin fillers exhibited higher mechanical properties and greater electrical insulating behavior. Microstructural observation showed the presence of decohesive agglomerates of particles at the interface with the matrix. The mechanical properties were found to be more sensitive than electrical properties to the homogeneity of filler dispersion in the matrix.

  9. Clays in natural and engineered barriers for radioactive waste confinement

    International Nuclear Information System (INIS)

    2007-01-01

    The meeting covers all topics concerning natural argillaceous geological barriers and the clay material based engineered barrier systems, investigated by means of: laboratory experiments on clay samples (new analytical developments), in situ experiments in underground research laboratories, mock-up demonstrations, natural analogues, as well as numerical modelling and global integration approaches (including up-scaling processes and treatment of uncertainties). The works presented deal with: examples of broad research programs (national or international) on the role of natural and artificial clay barriers for radionuclide confinement; clay-based repository concepts: repository designs, including technological and safety issues related to the use of clay for nuclear waste confinement; geology and clay characterisation: mineralogy, sedimentology, paleo-environment, diagenesis, dating techniques, discontinuities in rock clay, fracturing, self sealing processes, role of organic matter and microbiological processes; geochemistry: pore water geochemistry, clay thermodynamics, chemical retention, geochemical modelling, advanced isotopic geochemistry; mass transfer: water status and hydraulic properties in low permeability media, pore space geometry, water, solute and gas transfer processes, colloid mediated transport, large scale movements, long-term diffusion; alteration processes: oxidation effects, hydration-dehydration processes, response to thermal stress, iron-clay interactions, alkaline perturbation; geomechanics: thermo-hydro-mechanical behaviour of clay, rheological models, EDZ characterisation and evolution, coupled behaviour and models (HM, THM, THMC). A particular interest is given to potential contributions coming from fields of activities other than radioactive waste management, which take advantage of the confinement properties of the clay barrier (oil and gas industries, gas geological storage, CO 2 geological sequestration, chemical waste isolation

  10. Clays in natural and engineered barriers for radioactive waste confinement

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2007-07-01

    The meeting covers all topics concerning natural argillaceous geological barriers and the clay material based engineered barrier systems, investigated by means of: laboratory experiments on clay samples (new analytical developments), in situ experiments in underground research laboratories, mock-up demonstrations, natural analogues, as well as numerical modelling and global integration approaches (including up-scaling processes and treatment of uncertainties). The works presented deal with: examples of broad research programs (national or international) on the role of natural and artificial clay barriers for radionuclide confinement; clay-based repository concepts: repository designs, including technological and safety issues related to the use of clay for nuclear waste confinement; geology and clay characterisation: mineralogy, sedimentology, paleo-environment, diagenesis, dating techniques, discontinuities in rock clay, fracturing, self sealing processes, role of organic matter and microbiological processes; geochemistry: pore water geochemistry, clay thermodynamics, chemical retention, geochemical modelling, advanced isotopic geochemistry; mass transfer: water status and hydraulic properties in low permeability media, pore space geometry, water, solute and gas transfer processes, colloid mediated transport, large scale movements, long-term diffusion; alteration processes: oxidation effects, hydration-dehydration processes, response to thermal stress, iron-clay interactions, alkaline perturbation; geomechanics: thermo-hydro-mechanical behaviour of clay, rheological models, EDZ characterisation and evolution, coupled behaviour and models (HM, THM, THMC). A particular interest is given to potential contributions coming from fields of activities other than radioactive waste management, which take advantage of the confinement properties of the clay barrier (oil and gas industries, gas geological storage, CO{sub 2} geological sequestration, chemical waste isolation

  11. Adsorption of Amino Acids and Glutamic Acid-Based Surfactants on Imogolite Clays.

    Science.gov (United States)

    Bonini, Massimo; Gabbani, Alessio; Del Buffa, Stefano; Ridi, Francesca; Baglioni, Piero; Bordes, Romain; Holmberg, Krister

    2017-03-07

    Aluminum oxide surfaces are of utmost interest in different biotech applications, in particular for their use as adjuvants (i.e., booster of the immune response against infectious agents in vaccines production). In this framework, imogolite clays combine the chemical flexibility of an exposed alumina surface with 1D nanostructure. This work reports on the interaction between amino acids and imogolite, using turbidimetry, ζ-potential measurements, and Fourier transform infrared spectroscopy as main characterization tools. Amino acids with different side chain functional groups were investigated, showing that glutamic acid (Glu) has the strongest affinity for the imogolite surface. This was exploited to prepare a composite material made of a synthetic surfactant bearing a Glu polar head and a hydrophobic C 12 alkyl tail, adsorbed onto the surface of imogolite. The adsorption of a model drug (rhodamine B isothiocyanate) by the hybrid was evaluated both in water and in physiological saline conditions. The findings of this paper suggest that the combination between the glutamate headgroup and imogolite represents a promising platform for the fabrication of hybrid nanostructures with tailored functionalities.

  12. Effects of Organics on the Adsorption and Mobility of Metal Cations in Clay Systems: Computational Molecular Modeling Approach

    International Nuclear Information System (INIS)

    Kalinichev, Andrey G.; Ngouana Wakou, Brice F.; Loganathan, Narasimhan

    2013-01-01

    Understanding and prediction of many natural and anthropogenic environmental processes ultimately depend on a fundamental understanding of the chemistry occurring at the mineral-fluid inter-faces. Clay-related minerals and natural organic matter (NOM) are ubiquitous in the environment, and metal-NOM complexation induces strong correlations between the NOM concentration in water and the capacity of clay particles to bind metals, thus affecting their speciation, solubility and toxicity in the environment. Despite significant geochemical, environmental and technological interest, the molecular-level mechanisms and dynamics of the physical and chemical processes involving NOM are not yet well understood. In this presentation we compare three different molecular dynamics (MD) computer simulations of metal-NOM complexation in aqueous solutions. The simulation results indicate that despite some obvious quantitative variations in the computed values depending on the size of the simulated system and on the parameters of the force field models used, all three simulations are quite robust and consistent. In particular, approximately 35-50% of Ca 2+ ions in all simulations are associated with the carboxylic groups of NOM at near-neutral pH. The stability of bidentate-coordinated contact ion pair complexes is also always strongly preferred. Easy association of metal cations with negatively charged NOM functional groups and negatively charged clay surfaces allows us to predict that cationic bridging could be the most probable mechanism of NOM association with clays in natural environments. New MD simulations are currently in progress to quantitatively assess these predictions on a molecular scale for nuclear waste disposal applications. New larger-scale clay models incorporate a more realistic representation of the structural and compositional disorder of natural illites and smectites and employ CLAYFF - a fully flexible general force field suitable for the molecular simulations

  13. Integrated sorption and diffusion model for bentonite. Part 1. Clay-water interaction and sorption modeling in dispersed systems

    International Nuclear Information System (INIS)

    Tachi, Yukio; Suyama, Tadahiro; Ochs, Michael

    2014-01-01

    To predict the long-term migration of radionuclides (RNs) under variable conditions within the framework of safety analyses for geological disposal, thermodynamic sorption models are very powerful tools. The integrated sorption and diffusion (ISD) model for compacted bentonite was developed to achieve a consistent combination of clay–water interaction, sorption, and diffusion models. The basic premise considered in the ISD model was to consistently use the same simple surface model design and parameters for describing RNs sorption/diffusion as well as clay surface and porewater chemistry. A simple 1-site non-electrostatic surface complexation model in combination with a 1-site ion exchange model was selected to keep sorption model characteristics relatively robust for compacted systems. Fundamental parameters for the proposed model were evaluated from surface titration data for purified montmorillonite. The resulting basic model was then parameterized on the basis of selected published sorption data-sets for Np(V), Am(III), and U(VI) in dispersed systems, which cover a range of key geochemical conditions such as pH, ionic strength, and carbonate concentration. The sorption trends for these RNs can be quantitatively described by the model considering a full suite of surface species including hydrolytic and carbonate species. The application of these models to the description of diffusive-sorptive transport in compacted bentonites is presented in Part 2. (author)

  14. Perch-height specific predation on tropical lizard clay models: implications for habitat selection in mainland neotropical lizards

    Directory of Open Access Journals (Sweden)

    John E Steffen

    2009-09-01

    Full Text Available Predation has been hypothesized to be a strong selective force structuring communities of tropical lizards. Comparisons of perch height and size-based predation frequencies can provide a unique window into understanding how predation might shape habitat selection and morphological patterns in lizards, especially anoles. Here i use plasticine clay models, placed on the trunks of trees and suspended in the canopy to show that predation frequency on clay models differs primarily according to habitat (canopy vs. trunk-ground, but not according to size. These data are discussed in light of observed lizard abundances in the lowland forests of Costa Rica, and are presented as partial explanation for why fewer lizards are found in tree canopies, and more lizards are found on ground-trunk habitats. Rev. Biol. Trop. 57 (3: 859-864. Epub 2009 September 30.Existe la hipótesis de que la depredación es una fuerte fuerza selectiva que estructura las comunidades de lagartijas tropicales. Las comparaciones de las frecuencias de altura de la percha y de depredación con base en el tamaño pueden proveer una ventana única en el entendimiento de cómo la depredación podría moldear la selección del hábitat y los patrones morfológicos en las lagartijas, especialmente anoles. En este estudio uso modelos de plasticina, ubicados en troncos de árboles y suspendidos en el dosel para mostrar que la frecuencia de depredación en los modelos de plasticina difiere primariamente según el hábitat (dosel vs. tronco-suelo pero no según el tamaño. Estos datos se discuten a la luz de las abundancias de lagartijas observadas en los bosques de bajura de Costa Rica, y se presentan como una explicación parcial a porqué menos lagartijas se encuentran en los doseles, y más lagartijas se encuentran en los hábitats suelo-tronco.

  15. Model shear tests of canisters with smectite clay envelopes in deposition holes

    International Nuclear Information System (INIS)

    Boergesson, L.

    1986-01-01

    The consequences of rock displacement across a deposition hole has been investigated by some model tests. The model was scaled 1:10 to a real deposition hole. It was filled with a canister made of solid copper surrounded by highly compacted water saturated MX-80 bentonite. Before shear the swelling pressure was measured by six transducers in order to follow the water uptake process. During shear, pressure, strain, force and deformation were measured in altogether 18 points. The shearing was made at different rates in the various tests. An extensive sampling after shear was made through which the density, water content, degree of saturation, homogenization and the effect of shear on the bentonite and canister could be studied. One important conlusion from these tests was that the rate dependence is about 10% increased shear resistance per decade increased rate of shear. This resulted also in a very clear increase in strain in the canister with increased rate. The results also showed that the saturated bentonite has excellent stress distributing properties and that there is no risk of destroying the canister if the rock displacement is smaller than the thickness of the bentonite cover. The high density of the clay makes the bentonite produce such a high swelling pressure that the material will be very stiff. In the case of a larger shear deformation corresponding to ≅ 50% of the bentonite thickness the result will be a rather large deformation of the canister. A lower density would be preferable if it can be accepted with respect to other required isolating properties. The results also showed that three-dimensional FEM calculation using non-linear material properties is necessary to simulate the shear process. The rate dependence may be taken into account by adapting the properties to the actual rate of shear but might in a later stage be included in the model by giving the material viscous properties. (orig./HP)

  16. Rheological behavior of clay-nanoparticle hybrid-added bentonite suspensions: specific role of hybrid additives on the gelation of clay-based fluids.

    Science.gov (United States)

    Jung, Youngsoo; Son, You-Hwan; Lee, Jung-Kun; Phuoc, Tran X; Soong, Yee; Chyu, Minking K

    2011-09-01

    Two different types of clay nanoparticle hybrid, iron oxide nanoparticle clay hybrid (ICH) and Al(2)O(3)-SiO(2) nanoparticle clay hybrid (ASCH), were synthesized and their effects on the rheological properties of aqueous bentonite fluids in steady state and dynamic state were explored. When ICH particles were added, bentonite particles in the fluid cross-link to form relatively well-oriented porous structure. This is attributed to the development of positively charged edge surfaces in ICH that leads to strengthening of the gel structure of the bentonite susensions. The role of ASCH particles on the interparticle association of the bentonite fluids is different from that of ICH and sensitive to pH. As pH of ASCH-added bentonite suspensions increased, the viscosity, yield stress, storage modulus, and flow stress decreased. In contrast, at low pH, the clay suspensions containing ASCH additives were coagulated and their rheological properties become close to those of ICH added bentonite fluids. A correlation between the net surface charge of the hybrid additives and the rheological properties of the fluids indicates that the embedded nanoparticles within the interlayer space control the variable charge of the edge surfaces of the platelets and determine the particles association behavior of the clay fluids.

  17. New magnetic organic-inorganic composites based on hydrotalcite-like anionic clays for drug delivery

    Energy Technology Data Exchange (ETDEWEB)

    Carja, Gabriela [Department of Physical Chemistry, Faculty of Industrial Chemistry, Technical University of Iasi, 71 Mangeron Boulevard, 700050 Iasi (Romania); Chiriac, Horia [National Institute of Research and Development for Technical Physics, 47 Mangeron Boulevard, 700050 Iasi (Romania)]. E-mail: hchiriac@phys-iasi.ro; Lupu, Nicoleta [National Institute of Research and Development for Technical Physics, 47 Mangeron Boulevard, 700050 Iasi (Romania)

    2007-04-15

    The structural 'memory effect' of anionic clays was used to obtain layered double hydroxides (LDHs) with tailored magnetic properties, by loading iron oxides and/or spinel structures on iron partially substituted hydrotalcite-like materials. The obtained magnetic layered structures were further used as precursors for new hybrid nanostructures, such as aspirin-hydrotalcite-like anionic clays. Transmission electron microscopy (TEM) analysis shows that small iron oxide or spinel nanoparticles coexist with the fibrous drug particles on the surface of partially aggregated typical clay-like particles. The specific saturation magnetization of the loaded LDHs can be increased up to 70 emu/g by using specific post-synthesis treatments.

  18. Thermal properties of clay-based buffer materials for a nuclear fuel waste disposal vault

    International Nuclear Information System (INIS)

    Radhakrishna, H.S.

    1984-06-01

    The thermal properties of three types of bentonite clay, one illite-rich shale and one kaolin mixed with crushed granite were investigated. Thermal conductivity measurements were made over a range of mix proportions, moisture content, density and ambient temperature using the transient heat-probe method. The effects of thermal drying in the buffer zone prior to water uptake were investigated by means of laboratory-scale heater experiments. Illite-rich shale (Sealbond) and kaolin exhibited better compactability and thermal conductivity than the bentonite clays. The thermal conductivity of all types of clay buffers showed a high degree of moisture dependency and relatively no effect due to elevated temperature under high fluid pressure conditions. Bentonite buffers compacted to a dry density of 1200 to 1400 kg/m 3 showed extensive cracking due to differential shrinkage. Addition of crushed granite, and/or compaction to a higher density, reduced the thermal cracking of the buffer material

  19. An electrospun nanofiber matrix based on organo-clay for biosensors: PVA/PAMAM-Montmorillonite

    Science.gov (United States)

    Unal, Betul; Yalcinkaya, Esra Evrim; Demirkol, Dilek Odaci; Timur, Suna

    2018-06-01

    Diagnostic techniques based on biomolecules have huge a potential to be applied in the application in various areas such as food/beverage industries, diseases diagnostics, monitoring of bio-processes and environmental pollutants. Immobilization of biomolecules on a transducer is the key parameter to being able to prepare a highly stable diagnostic tests. Electrospun nanofibers are a good alternative to immobilize biomolecules. Here, electrospun nanofibers based on an organoclay were used to design the first generation amperometric enzyme biosensor. PAMAM G2 dendrimers were used to intercalate montmorillonite clay (Mt) and then the modification of Mt by PAMAM was characterized using FTIR, XRD, TGA and zeta potential measurements. After that nanofibers were prepared by electrospinning Mt and PAMAM-Mt using poly(vinyl) alcohol (PVA) as an auxiliary polymer and the formed PVA/PAMAM-Mt electrospun nanofibers were proved by SEM, TEM and AFM techniques. Finally, pyranose oxidases (PyOx) were immobilized on a glassy carbon electrode surface, which was modified using the PVA/PAMAM-Mt electrospun nanofibers. Amperometric measurements were carried out using buffer solution at -0.7 V under stirring conditions. The linear response for glucose was from 0.005 mM to 0.25 mM using PVA/Mt/PyOx and PVA/PAMAM-Mt/PyOx biosensors. The limit of detection was 0.7 μM glucose with PVA/PAMAM-Mt/PyOx biosensor. To detect glucose in real sample, measurements were carried out using soft drink cola as a substrate instead of glucose.

  20. Numerical simulation of the time-dependent deformation behaviour of clay-stone rock mass at the Tournemire site with 2D and 3D models

    International Nuclear Information System (INIS)

    Rutenberg, M.; Lux, K. H.

    2011-01-01

    Clay-stone rock masses are a reasonable alternative to e.g. salt rock masses as a host rock for underground radioactive waste repositories because of their very low permeability as well as their radionuclide retention capacity. Though clay-stone has been explored for many years, there is still a need for further research on its hydro-mechanical behaviour. Convergence measurements over a 4-year period in the tunnel system of the argillaceous Tournemire site in France yielded the presence of a time-dependent deformation behaviour in indurated clay. Moreover, a mine-by test was carried out with extensometer measurements capturing the rock mass deformation during the excavation process of a new gallery in 2003.This work focuses on the validation of a constitutive model by means of a three-dimensional (3D) simulation of the mine-by test. The utilised constitutive model Hou/Lux-T is based on the viscous constitutive model Lubby2 with which time-dependent deformation behaviour of salt rock can appropriately be simulated. It has been adapted to clay-stone by considering anisotropy effects, and in addition it features a strain-dependent fracture and failure criterion. The results of the mine-by-test simulation show that the calculated stresses and deformations in the rock mass seem to behave reasonably under this constitutive model with respect to time-dependency. A comparison of the 3D results to the results of a simplified two-dimensional (2D) simulation confirms the adequacy of using a 2D model with the constitutive model Hou/Lux-T for the setting at hand, described in the text (material parameters, time scale), in order to assess load-bearing capacity and deformability of the gallery near field away from heading face and tunnel crossing. Finally, a comparison of the 3D simulation results to the extensometer measurement results yields the principal ability of the used constitutive model to describe time-dependent evolutions of stresses and deformations during a three

  1. Screening of heavy metal containing waste types for use as raw material in Arctic clay-based bricks

    DEFF Research Database (Denmark)

    Belmonte, Louise Josefine; Ottosen, Lisbeth M.; Kirkelund, Gunvor Marie

    2016-01-01

    In the vulnerable Arctic environment, the impact of especially hazardous wastes can have severe consequences and the reduction and safe handling of these waste types are therefore an important issue. In this study, two groups of heavy metal containing particulate waste materials, municipal solid...... waste incineration (MSWI) fly and bottom ashes and mine tailings (i.e., residues from the mineral resource industry) from Greenland were screened in order to determine their suitability as secondary resources in clay-based brick production. Small clay discs, containing 20 or 40% of the different...... brick discs obtained satisfactory densities (1669-2007 kg/m3) and open porosities (27.9-39.9%). In contrast, the fly ash brick discs had low densities (1313-1578 kg/m3) and high open porosities (42.1-51. %). However, leaching tests on crushed brick discs revealed that heavy metals generally became more...

  2. Constructing wetlands: measuring and modeling feedbacks of oxidation processes between plants and clay-rich material

    Science.gov (United States)

    Saaltink, Rémon; Dekker, Stefan C.; Griffioen, Jasper; Wassen, Martin J.

    2016-04-01

    Interest is growing in using soft sediment as a building material in eco-engineering projects. Wetland construction in the Dutch lake Markermeer is an example: here the option of dredging some of the clay-rich lake-bed sediment and using it to construct 10.000 ha of wetland will soon go under construction. Natural processes will be utilized during and after construction to accelerate ecosystem development. Knowing that plants can eco-engineer their environment via positive or negative biogeochemical plant-soil feedbacks, we conducted a six-month greenhouse experiment to identify the key biogeochemical processes in the mud when Phragmites australis is used as an eco-engineering species. We applied inverse biogeochemical modeling to link observed changes in pore water composition to biogeochemical processes. Two months after transplantation we observed reduced plant growth and shriveling as well as yellowing of foliage. The N:P ratios of plant tissue were low and were affected not by hampered uptake of N but by enhanced uptake of P. Plant analyses revealed high Fe concentrations in the leaves and roots. Sulfate concentrations rose drastically in our experiment due to pyrite oxidation; as reduction of sulfate will decouple Fe-P in reducing conditions, we argue that plant-induced iron toxicity hampered plant growth, forming a negative feedback loop, while simultaneously there was a positive feedback loop, as iron toxicity promotes P mobilization as a result of reduced conditions through root death, thereby stimulating plant growth and regeneration. Given these two feedback mechanisms, we propose that when building wetlands from these mud deposits Fe-tolerant species are used rather than species that thrive in N-limited conditions. The results presented in this study demonstrate the importance of studying the biogeochemical properties of the building material and the feedback mechanisms between plant and soil prior to finalizing the design of the eco-engineering project.

  3. Influence of composition of the raw materials on phase formation in solid compounds based on slag and clay minerals

    International Nuclear Information System (INIS)

    Galkin, A.V.; Tolebaev, T.; Omarova, V.I.; Burkitbaev, M.; Blynskiy, A.P.; Bachilova, N.V.; Matsynina, V.I.

    2003-01-01

    Full text: Activation of solidification processes in a compound formed on the basis of slag and clay minerals using sodium hydroxide - the output product from processing the BN-350 sodium coolant it is expedient to form the final product with a phase composition representing (in terms of long term storage) hydro-alumino-silicates incorporating Na-22 and Cs-137 radionuclides, which isomorphly replace other atoms in the crystal lattice sites. Combination of mineral phases, such as alkaline and alkaline-earth hydro-alumino-silicates with zeolite-like structure, providing sorptive properties, and the tobermorite like low-base hydro silicates of calcium defining the physico-mechanical properties of compound is the necessary condition for the compound stability. Investigations of phase formation in the mixtures of Kazakhstan clay, slag materials and alkali have been conducted targeted to control the physico-chemical properties of solid compound. The mixtures of alkali, thermal power plant ashes and clays of various mineralogical genesis (kaolinite, bentonite, Ca-Na-smectite montmorillonite) have been studied. The ashes and phosphorous slag while interacting with alkali are determined to form the non-alkaline hydro-silicates of stavrolite and indianite (anortite) type with free alkali being found in an unbound state. Both alkaline and alkaline-alkaline-earth hydro-silicates of Na 2 Ca 2 Si 2 O 7 H 2 O type are only formed in a compounds containing metallurgical slag. Formation of alkaline hydro-alumino-silicates of NaAlSiO 4 H 2 0 type as well as tomsonite (Na 4 Ca 8 [Al 20S i 20 O 80 ] 24H 2 O) - the zeolite like mineral have been detected in a two-component alkali-clay mixtures. Besides the quantity of tomsonite was determined to be not only dependent on Al 2 O 3 content in clay component but is also defined by stoichiometric composition of the mixture, because zeolite synthesis takes place under conditions of gels co-deposition and high pH value. Maximum quantity of

  4. Intercomparison of reactive transport models applied to degradation of a concrete / clay interface

    International Nuclear Information System (INIS)

    Burnol, A.; Blanc, P.; Tournassat, C.; Lassin, A.; Gaucher, E.C.

    2005-01-01

    Full text of publication follows: Assuming a future disposal of spent nuclear fuel in deep geologic formation of Callovian- Oxfordian argillite in France, concrete will be used extensively to construct the disposal chambers in the host formation, and also as radioactive waste containment material. After being sealed, the repository will become saturated with interstitial waters from the Callovian-Oxfordian argillite, which will produce high pH solutions through interaction with the concrete. The aggressiveness of these alkaline solutions may weaken the clay's confinement properties (bentonite and argillite) with respect to long-lived radionuclides by change of the mineralogy. Conversely, the clayey formation with a high partial pressure of CO 2 represents an aggressive media for the concrete. The hydrogeological and chemical reactions of deep-underground systems are therefore intimately coupled and reactive transport models are increasingly used for performance assessment of nuclear waste disposal [1]. The main objective of this study is to present an intercomparison study using different reactive transport codes, where among PHREEQC1D [2], PHAST [3] and TOUGHREACT [4] applied to determine, in space and time, the extension of the alkaline perturbation and the associated degradation of concrete. The calculations were carried out after the definition of a complete mineralogy for both media. The experimental work made in the European Ecoclay II project [5] allowed a selection of reaction paths and of new phases for the thermodynamic database. Calculations were carried out over a simulated period of 100,000 years at different temperatures. Results of the different codes are compared and discussed. [1] De Windt L., Burnol A., Montarnal P., Van Der Lee.J., (2003) Intercomparison of reactive transport models applied to UO 2 oxidative dissolution and uranium migration., Journal of Contaminant Hydrology, 61, 1-4, 303-312; [2] Parkhurst D.L., Appelo C.A.J. (1999) - User

  5. Factors affecting microbial activity in compacted clay-based sealing materials proposed for use in a deep geologic repository for used nuclear fuel

    International Nuclear Information System (INIS)

    Stroes-Gascoyne, S.; Hamon, C.J.; Dixon, D.A.; Kjartanson, B.K.

    2006-01-01

    Microbial activity in clay-based barriers immediately adjacent to metal used-fuel containers in a repository could affect the longevity of such containers. The current emphasis is, therefore, on reducing or minimizing microbial activity in such clay-based barriers through material composition design. Factors affecting microbial activity in clay-based materials were studied in large-scale and smaller-scale experiments. Results suggested that keeping water activity (a w ) values below ∼0.95 may minimize microbial activity in clay-based barrier materials. A considerably higher effective montmorillonite dry density (EMDD), which partially controls a w , is achievable for 100% bentonite than for previously proposed reference buffer materials, which contain only 50% bentonite. (author)

  6. Modeling multi-component transport and enhanced anaerobic dechlorination processes in a single fracture-clay matrix system

    DEFF Research Database (Denmark)

    Chambon, Julie Claire Claudia; Broholm, Mette Martina; Binning, Philip John

    2010-01-01

    Clayey tills contaminated with chlorinated solvents are a threat to groundwater and are difficult to remediate. A numerical model is developed for assessing leaching processes and for simulating the remediation via enhanced anaerobic dechlorination. The model simulates the transport...... to the physical processes, mainly diffusion in the matrix, than to the biogeochemical processes, when dechlorination is assumed to take place in a limited reaction zone only. The inclusion of sequential dechlorination in clay fracture transport models is crucial, as the contaminant flux to the aquifer...

  7. Heat and water mass transfer in unsaturated swelling clay based buffer: discussion on the effect of the thermal gradient and on the diffusion of water vapour

    Energy Technology Data Exchange (ETDEWEB)

    Robinet, J.O. [Euro-Geomat-Consulting (France)]|[Institut National des Sciences Appliquees (INSA), 35 - Rennes (France); Plas, F. [Agence Nationale pour la Gestion des Dechets Radioactifs (ANDRA), 92 - Chatenay Malabry (France)

    2005-07-01

    on (i) the effect of the temperature and the gradient of temperature o n the water transfer and (ii) the diffusion of water vapour, in unsaturated compacted swelling clays. This discussion is based on experimental data and modelling data. Simulations using Soret effect and low values of water vapour diffusion coefficient give profiles of water saturation similar to those obtained with classical approach. (author)

  8. clay nanocomposites

    Indian Academy of Sciences (India)

    The present work deals with the synthesis of specialty elastomer [fluoroelastomer and poly (styrene--ethylene-co-butylene--styrene (SEBS)]–clay nanocomposites and their structure–property relationship as elucidated from morphology studies by atomic force microscopy, transmission electron microscopy and X-ray ...

  9. Organic material in clay-based buffer materials and its potential impact on radionuclide transport

    International Nuclear Information System (INIS)

    Vilks, P.; Goulard, M.; Stroes-Gascoyne, S.; Haveman, S.A.; Bachinski, D.B.; Hamon, C.J.; Comba, R.

    1997-03-01

    AECL has submitted an Environmental Impact Statement (EIS) to evaluate the concept of nuclear fuel disposal at depth in crystalline rock of the Canadian Shield. In this disposal concept used fuel would be emplaced in corrosion-resistant containers which would be surrounded by clay-based buffer and backfill materials. Once groundwater is able to penetrate the buffer and corrosion-resistant container, radionuclides could be transported from the waste form to the surrounding geosphere, and eventually to the biosphere. The release of radionuclides from the waste form and their subsequent transport would be determined by the geochemistry of the disposal vault and surrounding geosphere. Organic substances affect the geochemistry of radionuclides through complexation reactions that increase solubility and alter mobility, by affecting the redox of certain radionuclides and by providing food for microbes. The purpose of this study was to determine whether the buffer and backfill materials proposed for use in a disposal vault contain organics that could be leached by groundwater in large enough quantities to complex with radionuclides and affect their mobility within the disposal vault and surrounding geosphere. Buffer material, made from a mixture of 50 wt.% Avonlea sodium bentonite and 50 wt.% silica sand, was extracted with deionized water to determine the release of dissolved organic carbon, humic acid and fulvic acid. The effect of radiation and heat from the used fuel was simulated by treating samples of buffer before leaching to various amounts of heat (60 deg C and 90 deg C) for periods of 2, 4 and 6 weeks, and to ionizing radiation with doses of 25 kGy and 50 kGy. Humic substances were isolated from the leachates to determine the concentrations of humic and fulvic acids and to determine their functional group content by acid-base titrations. The results showed that groundwater would leach significant amounts of organics that would complex with radionuclides such as

  10. Groundwater age and lifetime expectancy modelling approach for site characterization and performance assessment of radwaste repository in clay formation

    International Nuclear Information System (INIS)

    Cornaton, F.; Perrochet, P.; Benabderrahmane, H.

    2010-01-01

    Document available in extended abstract form only. A deep geological repository of high level and long lived radwaste requires an understanding of the far field and near field groundwater flow and of the transport properties, at actual and future climatic conditions. Andra, French National radioactive waste management Agency, is developing since last 15 years an integrated multi-scale hydrogeological model of whole Paris basin of 200000 km 2 of area (regional scale) to produce a regional flow field associated to groundwater behavior. It includes locally the Meuse/Haute Marne clay site of about 250 km 2 of area in the eastern part of the Paris basin that was chosen for the emplacement of a repository. The Callovo-Oxfordian host formation is a clay layer characterized by a very low permeability of the order 10 -14 m/s, a mean thickness of 130 m at about 500 m depth, and is embedded by calcareous aquifer formations (Dogger and Oxfordian). The hydrogeological conceptual model is based on stratigraphic and petro-physic modeling of the Paris basin and is accounting for the structural, geological, hydrogeological and geochemical data in an integrated way. This model represents 27 hydrogeological units at the scale of the Paris Basin, and it is refined at the scale of the sector to represent 27 different layers that range in age from the Trias to the Portlandian. The finite element flow and transport simulator Ground Water (GW) is used to solve for groundwater flow at steady-state in a 3 Million elements model, considering current climatic conditions. The model is calibrated against about 1250 hydraulic head measurements, and results in maximum absolute hydraulic head differences of 20 meters at the regional scale and 3 meters at the local scale. The calibrated reference model includes transmissive major faults as well as structures acting as barrier to flow. Groundwater age (the time elapsed since recharge) and lifetime expectancy (the time remaining prior to exit) are

  11. Semi-industrial production of organo clays to use in base oil drilling fluid; Producao em escala piloto de argilas organofilicas visando uso em fluidos de perfuracao base oleo

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Heber S.; Martins, Alice B.; Costa, Danubia L. da; Ferreira, Heber C.; Neves, Gelmires de A.; Melo, Tomas J.A. de [Universidade Federal de Campina Grande (UFCG), PB (Brazil); Teixeira Neto, Erico [Universidade Federal do ABC (UFABC), Santo Andre, SP (Brazil)

    2008-07-01

    The drilling fluids are essential to the operations of exploration of oil. The organoclays are widely used in the composition of the oil based drilling fluids and raw materials are of high value added. These clays can be obtained, traditionally, from bentonitic clay treated, in water, with ionic surfactants, however, non-ionic surfactants can be adsorbed on the surface of interlamelar bentonitic clay, naturally hydrophilic, making them organophilic. A pilot plant for production of organoclays was mounted in the Recycling Laboratory / UFCG. The bentonitic clay imported Cloisite Na{sup +R} was treated with a non-ionic surfactant in levels of 40, 50 and 60% in scale and bench-scale pilot. The commercial organoclay VG-69{sup R} was used as a standard for comparison of results. The clay obtained were characterized by X-ray diffraction, and Foster's swelling. The oil based fluids were prepared in accordance with the standards of PETROBRAS (N-22581 1997 and N-2259, 1997). Tests show that the characterization of organoclays have obtained intercalation of non-ionic surfactant with great expansion of layers of clay, with interlayer distances more significant than the clay trade, both on clay obtained in the laboratory scale as in clays obtained by pilot scale, with results very similar for both methods. It appears that it is possible the pilot-scale production of organoclays with equivalent quality produced in the laboratory scale and quality compatible with the clay used commercially. (author)

  12. Stochastic Dynamics of Clay Translocation and Formation of Argillic Horizons

    Science.gov (United States)

    Calabrese, S.; Richter, D. D., Jr.; Porporato, A. M.

    2017-12-01

    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.

  13. Influence of clay particles on microfluidic-based preparation of hydrogel composite microsphere

    Science.gov (United States)

    Hong, Joung Sook

    2016-05-01

    For the successful fabrication of a hydrogel composite microsphere, this study aimed to investigate the influence of clay particles on microsphere formation in a microfluidic device which has flow focusing and a 4.5:1 contraction channel. A poly alginic acid solution (2.0 wt.%) with clay particles was used as the dispersed phase to generate drops in an oil medium, which then merged with drops of a CaCl2 solution for gelation. Drop generations were observed with different flow rates and particles types. When the flow rate increased, drop generation was enhanced and drop size decreased by the build-up of more favorable hydrodynamic flow conditions to detach the droplets. The addition of a small amount of particles insignificantly changed the drop generation behavior even though it reduced interfacial tension and increased the viscosity of the solution. Instead, clays particles significantly affected hydro-gelation depending on the hydrophobicity of particles, which produced further heterogeneity in the shape and size of microsphere.

  14. Studying the degradation of polyhydroxybutyrate-co-valerate during processing with clay-based nanofillers

    DEFF Research Database (Denmark)

    Cabedo, Luis; Plackett, David; Gimenez, Enrique

    2009-01-01

    Polyhydroxybutyrate-co-valerate (PHBV) is attracting interest as a new material for packaging applications and nanoparticulate layered silicates are being increasingly explored as a way to improve PHBV film properties. In this context, it is essential to understand how different types of nanofill......Polyhydroxybutyrate-co-valerate (PHBV) is attracting interest as a new material for packaging applications and nanoparticulate layered silicates are being increasingly explored as a way to improve PHBV film properties. In this context, it is essential to understand how different types...... of nanofillers could influence polymer properties. PHBV was processed with three-layered clay types using different mixing methods, and we examined the effect of processing time, clay type, and clay content on polymer molecular weight and composite morphology. PHBV molecular weight (Mw) decreased by 38% after......-ray diffraction studies indicated an intercalated morphology in the presence of modified montmorillonite but good dispersion was also achieved when unmodified kaolinite was blended with PHBV. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009...

  15. Model for Anomalous Moisture Diffusion through a Polymer-Clay Nanocomposite

    DEFF Research Database (Denmark)

    Drozdov, Aleksey D.; Christiansen, Jesper de Claville; Gupta, R.K.

    2003-01-01

    Experimental data are reported on moisture diffusion and the elastoplastic response of an intercalated nanocomposite with vinyl ester resin matrix and montmorillonite clay filler at room temperature. Observations in diffusion tests showed that water transport in the neat resin is Fickian, whereas...... platelets. Constitutive equations are developed for moisture diffusion through and the elastoplastic behavior of a nanocomposite. Adjustable parameters in these relations are found by fitting the experimental data. Fair agreement is demonstrated between the observations and the results of numerical...

  16. A model for anomalous moisture diffusion through a polymer-clay nanocomposite

    DEFF Research Database (Denmark)

    Drozdov, Aleksey D.; Christiansen, Jesper de Claville; Gupta, R.K.

    2002-01-01

    Experimental data are reported on moisture diffusion and the elastoplastic response in uniaxial tensile tests of an intercalated nanocomposite with vinyl ester resin matrix and montmorillonite clay filler at room temperature. Observations in diffusion tests show that the moisture transport...... diffusion through a nanocomposite and for its elastoplastic behavior. Adjustable parameters in these relations are found by fitting the experimental data. Fair agreement is demonstrated between the observations and the results of numerical simulation....

  17. Reconstruction of late Quaternary monsoon oscillations based on clay mineral proxies using sediment cores from the western margin of India

    Digital Repository Service at National Institute of Oceanography (India)

    Thamban, M.; Rao, V.P.; Schneider, R.R.

    sites were from the hinterland rocks and soils. Careful evaluations of several factors that could complicate the clay distribution in marine environment indicate that the clay mineral parameters can be used as proxies for the intensity of summer monsoon...

  18. Study of clay soils swelling by the new method based on Laser Interferometry and the classical Odometer test

    Directory of Open Access Journals (Sweden)

    Asselman Hassan

    2018-01-01

    Full Text Available Geotechnical engineering participates in the act of construction, which means that it must meet a double concern for securityand economy. Therefore, an essential part of the engineer's responsibility rests on the recognition of soils in order to determine their nature and properties (taking into account the flow of water. In the present work, we measure the swelling and the permeability by detection of the swelling, by our new optical method based on the interferometry-laser, invented by Hassan Asselman, within the team of Optics and photonics of sciences faculty, Tetouan-Morocco. This new prototype allows us to directly measure the following parameters: the permeability k (m / s, the Young module Eand the swelling index Cs. For the latter parameter, the evolution of the strain as a function of the stresses ρ (Pa is measured for a given degree of saturation (Until saturation. Moreover, we will use the classical odometer test, which reproduces the conditions of deformation of the soils. Using the results of the latter by the graphic methods of Taylor and Gasagrande, it is possible to determine the value of the coefficient of consolidation of the soil Cv. According to the Darcy theoretical modelfor a saturated medium, Cv depends on the permeability, the compressibility coefficient mv (or the inverse of the model of Young odometric and the voluminal weight of the water γw. These tests will be carried out at the GEORET Geotechnical Laboratory in Tetouan. To perform this work, we chose a sample of claydistrubed, already characterized by X-ray diffraction (whose clay fraction is illite. It is extracted from the so-called "Teffalin" quarry of the Tetouan region, used in the manufacture of pottery. Finally we give a comparison between our new patented method and the classic Odometric test

  19. Continuum equivalent model for the fractured EDZ around underground galleries in clay-stone

    International Nuclear Information System (INIS)

    Pouya, A.; Bourgeois, E.; Larbi, B.; Poutrel, A.

    2010-01-01

    Document available in extended abstract form only. The Excavation Damaged Zone (EDZ) around the underground galleries excavated in clay-stone for the CMHM project, includes several zones showing different types of cracking and/or fracturing. In the vicinity of the wall, a fractured zone is observed that spreads out on a distance of about 1 m from the wall; at a larger distance from the wall one observes another zone with micro-cracks. The first zone, called 'fractured EDZ', includes different families of fractures with different geometries and origins. The main one consists of a family of shear fractures called 'chevron', that have approximately the shape of conical surfaces slightly flattened with respect to the horizontal plane. The 'chevrons' observed in the galleries at 490 m depth in LMSMH are regularly spaced of about 50 cm to 1 m along the gallery's axis, make an angle of about 45 deg. with this axis and extend to about 2 or 3 m beyond the wall depending of the size and orientation of the gallery. The fractures have a significant effect on the hydro-mechanical properties of the EDZ. The present work is focused on the effect of the 'chevron' fractures on the mechanical behaviour of the EDZ. Due to the large number of fractures, introducing them individually to the modelling leads to heavy and not easy to handle numerical models and to long calculations. One is led to find some Continuum Equivalent Material (CEM) for the EDZ including the fractures' effect. The EDZ is not very large compared to the fractures, so that it may not be fully justified to apply a homogenization approach; however, this is the approach we have used to define the behaviour of CEM. The geometry of the fractures is first simplified and assumed to correspond to conical surfaces with axial symmetry around the gallery's axis. The local behaviour of the CEM is deduced from the model of an infinite medium containing a family of planar

  20. Modelling of solute and water transport in semi-permeable clay membranes: comparission with experiments

    NARCIS (Netherlands)

    Bader, S.; Kooi, H.

    2005-01-01

    Theories of osmosis in groundwater flow are increasingly used to explain anomalies of salinity in clayey environments. However, predictive modelling through mathematical analysis can hardly be found in literature. In this paper, a model of chemical osmosis based on non-equilibrium thermodynamics, is

  1. Retention of contaminants Cd and Hg adsorbed and intercalated in aluminosilicate clays: A first principles study

    Science.gov (United States)

    Crasto de Lima, F. D.; Miwa, R. H.; Miranda, Caetano R.

    2017-11-01

    Layered clay materials have been used to incorporate transition metal (TM) contaminants. Based on first-principles calculations, we have examined the energetic stability and the electronic properties due to the incorporation of Cd and Hg in layered clay materials, kaolinite (KAO) and pyrophyllite (PYR). The TM can be (i) adsorbed on the clay surface as well as (ii) intercalated between the clay layers. For the intercalated case, the contaminant incorporation rate can be optimized by controlling the interlayer spacing of the clay, namely, pillared clays. Our total energy results reveal that the incorporation of the TMs can be maximized through a suitable tuning of vertical distance between the clay layers. Based on the calculated TM/clay binding energies and the Langmuir absorption model, we estimate the concentrations of the TMs. Further kinetic properties have been examined by calculating the activation energies, where we found energy barriers of ˜20 and ˜130 meV for adsorbed and intercalated cases, respectively. The adsorption and intercalation of ionized TM adatoms were also considered within the deprotonated KAO surface. This also leads to an optimal interlayer distance which maximizes the TM incorporation rate. By mapping the total charge transfers at the TM/clay interface, we identify a net electronic charge transfer from the TM adatoms to the topmost clay surface layer. The effect of such a charge transfer on the electronic structure of the clay (host) has been examined through a set of X-ray absorption near edge structure (XANES) simulations, characterizing the changes of the XANES spectra upon the presence of the contaminants. Finally, for the pillared clays, we quantify the Cd and Hg K-edge energy shifts of the TMs as a function of the interlayer distance between the clay layers and the Al K-edge spectra for the pristine and pillared clays.

  2. Imaging techniques in clay sciences: a key tool to go a step further

    International Nuclear Information System (INIS)

    Robinet, J.C.; Michau, N.; Schaefer, T.

    2012-01-01

    the need to study microstructure of clay-rocks and clay based materials from multi-scale techniques and multiple scientific disciplines. Nevertheless at the end of the 90's, several scientific and/or technological bottlenecks, like the imaging the clays in 3D, limited our capacity to bridge small scale processes to macro-scale behaviors and properties. Over the last decade, R and D programs on nuclear waste disposal have tackled many issues to go further in our understanding of clays. Through different results and current studies, we have reviewed various developments and improvements on imaging techniques and their applications on clay-rocks and clay based materials currently under investigations. The presentation will address successively the different questions asked at each step, from the acquisition to the use of the data: - improvement and development of sampling and microstructure preservation methods to image undisturbed samples, - emergence of 3D techniques (X-ray microtomography, FIB/SEM...) and their application to clay based materials and clay rocks, - improvement of image acquisition and treatment of 2D/3D images, - development of multi-scale methodologies, - cross-cutting between imaging and analytical techniques to get quantitative information on pore and mineral spatial distribution, - imaging in 2D/3D the microstructure of clay materials under THMC conditions and environmental conditions, - extraction of quantitative information from image analysis using statistical approaches or cross-correlation to quantitative techniques, - correlation between microstructure characteristic parameters and macroscopic properties, - modeling of multi-scale THMC processes using data extracted from images. Conclusions drawn up from this review show up that imaging techniques have progressively turned into an essential tool to support THMC experimental or numerical studies in a sense that they have gradually evolved from a qualitative observation mean to a quantitative

  3. Dynamic Strength and Accumulated Plastic Strain Development Laws and Models of the Remolded Red Clay under Long-Term Cyclic Loads: Laboratory Test Results

    Directory of Open Access Journals (Sweden)

    Li Jian

    2015-09-01

    Full Text Available The dynamic strength and accumulated plastic strain are two important parameters for evaluating the dynamic response of soil. As a special clay, the remolded red clay is often used as the high speed railway subgrade filling, but studies on its dynamic characteristics are few. For a thorough analysis of the suitability of the remolded red clay as the subgrade filling, a series of long-term cyclic load triaxial test under different load histories are carried out. Considering the influence of compactness, confining pressure, consolidation ratio, vibration frequency and dynamic load to the remolded red clay dynamic property, the tests obtain the development curves of the dynamic strength and accumulated plastic strain under different test conditions. Then, through curve fitting method, two different hyperbolic models respectively for the dynamic strength and accumulated plastic strain are built, which can match the test datum well. By applying the dynamic strength model, the critical dynamic strength of the remolded red clay are gained. Meanwhile, for providing basic datum and reference for relevant projects, all key parameters for the dynamic strength and accumulated plastic strain of the remolded red clay are given in the paper.

  4. Prediction of clay content from water vapour sorption isotherms considering hysteresis and soil organic matter content

    DEFF Research Database (Denmark)

    Arthur, E.; Tuller, M.; Møldrup, Per

    2015-01-01

    Soil texture, in particular the clay fraction, governs numerous environmental, agricultural and engineering soil processes. Traditional measurement methods for clay content are laborious and impractical for large-scale soil surveys. Consequently, clay prediction models that are based on water...... within a RH range from 3 to 93%. The clay contents, which ranged between 1 and 56%, were measured with a combination of sieving and sedimentation methods. Two regression models were developed for both adsorption and desorption at 10 RH levels (5, 10, 20, 30, 40, 50, 60, 70, 80 and 90%). While the first...

  5. Design, construction and performance of the clay-based isolation of the SFR silo

    Energy Technology Data Exchange (ETDEWEB)

    Pusch, Roland [Geodevelopment AB, Lund (Sweden)

    2003-09-01

    accurate pressure evaluation for the utilized Gloetzl cell system and the predicted pressure level. Most of the recorded wall pressures are lower then predicted. The slight, successive pressure increase at the base and top of the silo is probably due to slow hydration but may also be partly or wholly caused by creep effects. Slip of rock wedges can hardly take place because of the lateral support provided by the wall fill but slight movement of a major wedge can occur before resistance is fully mobilized. It can cause minor densification of the fill and a slight increase in pressure on the silo wall. A major conclusion is that such events and build-up of swelling pressures can not damage the silo or displace it. No piezometric pressures have been recorded, which shows that the drainage system works satisfactorily. Movements yielding some compression or expansion of the wall fill are still small but may be important when the hydration becomes significant, which is not yet the case. Complete water saturation of the entire clay mass may take several hundred years. The wetting process should be of diffusion type as shown by pilot tests in the field and laboratory but local piping by inflowing water followed by self-sealing seems to have taken place as well. The system of interconnected drains works satisfactorily as demonstrated by the absence of pore water pressures in the pizometers and by the very small movements of the wall fill found by levelling of the cement pavement that covers the wall fill. In order to certify acceptable performance of the engineered barriers in the future recording of the settlement of the silo, build-up of soil pressure on the silo and rock, and drainage of the rock are recommended. The equipments used presently for the recording turn out to serve satisfactorily in principle.

  6. Design, construction and performance of the clay-based isolation of the SFR silo

    International Nuclear Information System (INIS)

    Pusch, Roland

    2003-09-01

    accurate pressure evaluation for the utilized Gloetzl cell system and the predicted pressure level. Most of the recorded wall pressures are lower then predicted. The slight, successive pressure increase at the base and top of the silo is probably due to slow hydration but may also be partly or wholly caused by creep effects. Slip of rock wedges can hardly take place because of the lateral support provided by the wall fill but slight movement of a major wedge can occur before resistance is fully mobilized. It can cause minor densification of the fill and a slight increase in pressure on the silo wall. A major conclusion is that such events and build-up of swelling pressures can not damage the silo or displace it. No piezometric pressures have been recorded, which shows that the drainage system works satisfactorily. Movements yielding some compression or expansion of the wall fill are still small but may be important when the hydration becomes significant, which is not yet the case. Complete water saturation of the entire clay mass may take several hundred years. The wetting process should be of diffusion type as shown by pilot tests in the field and laboratory but local piping by inflowing water followed by self-sealing seems to have taken place as well. The system of interconnected drains works satisfactorily as demonstrated by the absence of pore water pressures in the pizometers and by the very small movements of the wall fill found by levelling of the cement pavement that covers the wall fill. In order to certify acceptable performance of the engineered barriers in the future recording of the settlement of the silo, build-up of soil pressure on the silo and rock, and drainage of the rock are recommended. The equipments used presently for the recording turn out to serve satisfactorily in principle

  7. Hyperspectral analysis of clay minerals

    Science.gov (United States)

    Janaki Rama Suresh, G.; Sreenivas, K.; Sivasamy, R.

    2014-11-01

    A study was carried out by collecting soil samples from parts of Gwalior and Shivpuri district, Madhya Pradesh in order to assess the dominant clay mineral of these soils using hyperspectral data, as 0.4 to 2.5 μm spectral range provides abundant and unique information about many important earth-surface minerals. Understanding the spectral response along with the soil chemical properties can provide important clues for retrieval of mineralogical soil properties. The soil samples were collected based on stratified random sampling approach and dominant clay minerals were identified through XRD analysis. The absorption feature parameters like depth, width, area and asymmetry of the absorption peaks were derived from spectral profile of soil samples through DISPEC tool. The derived absorption feature parameters were used as inputs for modelling the dominant soil clay mineral present in the unknown samples using Random forest approach which resulted in kappa accuracy of 0.795. Besides, an attempt was made to classify the Hyperion data using Spectral Angle Mapper (SAM) algorithm with an overall accuracy of 68.43 %. Results showed that kaolinite was the dominant mineral present in the soils followed by montmorillonite in the study area.

  8. Effect of heterocyclic based organoclays on the properties of polyimide-clay nanocomposites.

    Science.gov (United States)

    Krishnan, P Santhana Gopala; Joshi, Mangala; Bhargava, Prachur; Valiyaveettil, Suresh; He, Chaobin

    2005-07-01

    Polyimide-clay nanocomposites were prepared from their precursor, namely, polyamic acid, by the solution-casting method. Organomodified montmorillonite (MMT) clay was prepared by treating Na+MMT (Kunipia F) with three different intercalating agents, namely, piperazine dihydrochloride, 1,3-bis(4-piperidinylpropane) dihydrochloride and 4,4'-bipiperidine dihydrochloride at 80 degrees C. Polyamic acid solutions containing various weight percentages of organomodified MMT were prepared by reacting 4,4'-(1,1'-biphenyl-4,4'-diyldioxy)dianiline with bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride in N-methyl-2-pyrrolidinone containing dispersed particles of organomodified MMT at 20 degrees C. Nanocomposite films were prepared from these solutions by solution casting and heated subsequently at a programmed heating rate. These films were transparent and brown in color. The extent of layer separation in nanocomposite films depends upon the chemical structure of the organoclay. These films were characterized by inherent viscosity, FT-IR, DSC, TMA, WAXD, TEM, UV, and TGA. The tensile behavior and surface energy studies were also investigated. The nanocomposite films had superior tensile properties, thermal behavior, and solvent resistance. Among the three organoclays, piperazine dihydrochloride was the best modifier.

  9. First principles molecular dynamics insight into acid-base chemistry of clay minerals

    International Nuclear Information System (INIS)

    Liu, Xiandong; Lu, Xiancai; Wang, Rucheng; Meijer, Evert Jan

    2012-01-01

    Document available in extended abstract form only. Microscopic knowledge on the interfaces between clay minerals (2:1- and 1:1-type) and water is critical for both understanding natural processes and guiding development of advanced hybrid materials. Due to the unique layered structures of clay minerals, their surfaces are usually grouped into basal surfaces and edge surfaces (i.e. broken surfaces). Thanks to previous studies, structures and properties of basal surfaces have been well recognized: these surfaces are terminated with siloxanes and surface Si-O six-member rings normally act as the adsorbing sites of cations. In contrast, edge surfaces are more complicated structures and have more subtle chemical properties. On these surfaces, there are a lot of dangling bonds and under ambient conditions they are usually saturated by chemically adsorbed waters. These edge groups are usually amphoteric, which is responsible to the pH dependent behaviors of many interfacial processes, such as cations complexing. For example, adsorption of heavy metal cations (e.g. Ni 2+ , Co 2+ , Zn 2+ , Cd 2+ ) on clay basal surfaces is through cation exchange mechanism and that is hardly influenced by environmental pH. In contrast, it has been well accepted that the adsorption on edge surfaces is pH-dependent. The ubiquitous isomorphic substitutions further increase the complexity of their interfacial chemistry. Due to the high heterogeneity and rather small sizes, it is quite difficult to reveal the complex interfacial chemistry with experiments alone. FPMD method (first principles molecular dynamics), a combination of density functional theory and molecular dynamics, can provide valuable information. With FPMD [1, 2] and free-energy calculation techniques [3, 4], we investigated the microscopic structures and acid chemistry of these clay-water interfaces [5, 6]. According to systematic simulations, the following has been achieved. (1) Acidity of interlayer waters. The simulations show

  10. Thermodynamic modelling of clay dehydration, stability and compositional evolution with temperature, pressure and H2O activity

    International Nuclear Information System (INIS)

    Vidal, O.; Dubacq, B.

    2010-01-01

    Document available in extended abstract form only. Full text of publication follows: The evaluation of the performance of clay-rich barrier considered for the disposal of radioactive waste and a reliable prediction of the impact of repository-induced disturbances upon the confinement properties of clay-rich geological formations requires reliable thermodynamic models for clay minerals. Such models have to take into account the variation of the hydration state of smectite as a function of temperature, pressure and water activity. We propose the first macroscopic thermodynamic model that account for the stepwise dehydration with increasing temperature or decreasing H 2 O activity of K, Na, Ca and Mg-smectite. The model relies on the relative stability of the different solid-solutions that describe the hydration of di- or tri-octahedral-smectites containing 0, 1, 2 or 3 interlayer water layers. The inclusion of anhydrous mica end-members makes it possible to cover, with the same solid-solution model, the entire range of composition from low-charge to high-charge smectite, through illite to mica. Non-ideal Margules parameters were used to describe the non-ideality of the solid solutions between the hydrated and dehydrated smectite end-members. Standard state properties of all smectite end-members as well as Ca- and Mg-muscovite and -phlogopite were initially estimated by oxide summation. These values were then refined and the other non-ideal interactions were estimated on the basis of different experimental data. The stepwise dehydration of smectite, and its stability and compatibility relations were calculated by Gibbs free energy minimizing. Our results account for the progressive evolution of smectite to inter-layered illite/smectite and then to mica, as observed in nature and experiments, and our model provides an explanation for the thermodynamic stability of smectite and illite/ smectite compared to mica + kaolinite or pyrophyllite assemblages. The results

  11. Law of nonlinear flow in saturated clays and radial consolidation

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    It was derived that micro-scale amount level of average pore radius of clay changed from 0.01 to 0.1 micron by an equivalent concept of flow in porous media. There is good agreement between the derived results and test ones. Results of experiments show that flow in micro-scale pore of saturated clays follows law of nonlinear flow. Theoretical analyses demonstrate that an interaction of solid-liquid interfaces varies inversely with permeability or porous radius. The interaction is an important reason why nonlinear flow in saturated clays occurs. An exact mathematical model was presented for nonlinear flow in micro-scale pore of saturated clays. Dimension and physical meanings of parameters of it are definite. A new law of nonlinear flow in saturated clays was established. It can describe characteristics of flow curve of the whole process of the nonlinear flow from low hydraulic gradient to high one. Darcy law is a special case of the new law. A mathematical model was presented for consolidation of nonlinear flow in radius direction in saturated clays with constant rate based on the new law of nonlinear flow. Equations of average mass conservation and moving boundary, and formula of excess pore pressure distribution and average degree of consolidation for nonlinear flow in saturated clay were derived by using an idea of viscous boundary layer, a method of steady state in stead of transient state and a method of integral of an equation. Laws of excess pore pressure distribution and changes of average degree of consolidation with time were obtained. Results show that velocity of moving boundary decreases because of the nonlinear flow in saturated clay. The results can provide geology engineering and geotechnical engineering of saturated clay with new scientific bases. Calculations of average degree of consolidation of the Darcy flow are a special case of that of the nonlinear flow.

  12. 1st International Conference on Calcined Clays for Sustainable Concrete

    CERN Document Server

    Favier, Aurélie

    2015-01-01

    This volume focuses on research and practical issues linked to Calcined Clays for Sustainable Concrete. The main subjects are geology of clays, hydration and performance of blended systems with calcined clays, alkali activated binders, economic and environmental impacts of the use of calcined clays in cement based materials. Topics addressed in this book include the influence of processing on reactivity of calcined clays, influence of clay mineralogy on reactivity, geology of clay deposits, Portland-calcined clay systems, hydration, durability, performance, Portland-calcined clay-limestone systems, hydration, durability, performance, calcined clay-alkali systems, life cycle analysis, economics and environmental impact of use of calcined clays in cement and concrete, and field applications. This book compiles the different contributions of the 1st International Conference on Calcined Clays for Sustainable Concrete, which took place in Lausanne, Switzerland, June, 23-25, 2015.The papers present the latest  res...

  13. Study of the influence of the addition of MMT clay in the preparation of biohydrogel based natural polymers

    International Nuclear Information System (INIS)

    Costa, M.P.M.; Ferreira, I.L.M.

    2014-01-01

    In this study, biohydrogels were produced from the combination of two polysaccharides (chitosan and sodium alginate). The concentrations of polysaccharide (0.5 to 3% m / m) and clay (0.5 and 2.0%) were varied. CaCl2 was used as a crosslinking agent. The samples were characterized by thermogravimetry (thermal stability), FTIR (chemical composition), scanning electron microscopy (SEM), and X-ray diffraction. The present work aims to study the influence of different clay content in biohydrogel produced. In the presence of clay, a differentiated morphology was observed by SEM. The degree of swelling was evaluated as a function of the composition of each mixture. The presence of clay caused a significant swelling of the hydrogel on the water absorption when the clay content was increased. The FTIR spectra showed the presence of characteristic bands of each polysaccharide, and the clay. The XRD showed that the amorphous presented biohydrogel behavior. (author)

  14. Weathering model in paleomagnetic field intensity measurements on ancient fired clays

    International Nuclear Information System (INIS)

    Singalas, I.; Gangas, N-H.J.; Danon, J.

    1978-03-01

    Nonlinearities observed in Thellier's plots are explained in terms of a weathering model. This model is based on the reduction in size of the originaly present iron oxide particles, due to leaching. In the general case, the slope of the Thellier's plot is a function of the particle size destributions of the magnetic particles, both newly formed and leached ones. In the special case in which the newly formed magnetic particles are superparamagnetic, the limiting value of the slope of th Thellier's plot towards the magnetic ordering temperature is equal to the ratio of the ancient field intensity to the modern one

  15. Removal of waterborne microorganisms by filtration using clay-polymer complexes.

    Science.gov (United States)

    Undabeytia, Tomas; Posada, Rosa; Nir, Shlomo; Galindo, Irene; Laiz, Leonila; Saiz-Jimenez, Cesareo; Morillo, Esmeralda

    2014-08-30

    Clay-polymer composites were designed for use in filtration processes for disinfection during the course of water purification. The composites were formed by sorption of polymers based on starch modified with quaternary ammonium ethers onto the negatively charged clay mineral bentonite. The performance of the clay-polymer complexes in removal of bacteria was strongly dependent on the conformation adopted by the polycation on the clay surface, the charge density of the polycation itself and the ratio between the concentrations of clay and polymer used during the sorption process. The antimicrobial effect exerted by the clay-polymer system was due to the cationic monomers adsorbed on the clay surface, which resulted in a positive surface potential of the complexes and charge reversal. Clay-polymer complexes were more toxic to bacteria than the polymers alone. Filtration employing our optimal clay-polymer composite yielded 100% removal of bacteria after the passage of 3L, whereas an equivalent filter with granular activated carbon (GAC) hardly yielded removal of bacteria after 0.5L. Regeneration of clay-polymer complexes saturated with bacteria was demonstrated. Modeling of the filtration processes permitted to optimize the design of filters and estimation of experimental conditions for purifying large water volumes in short periods. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Thermo-hydro mechanical modeling in unsaturated hard clay: application to nuclear waste storage

    International Nuclear Information System (INIS)

    Jia, Y.

    2006-07-01

    This work presents an elastoplastic damage model for argillite in unsaturated conditions. A short resume of experimental investigations is presented in the first part. The results obtained show an important plastic deformation coupled with damage induced by initiation and growth of microcracks. Influences of water content on the mechanical behaviour are also investigated. Based on experimental data and micro-mechanical considerations, a general constitutive model is proposed for the poro-mechanical behavior of argillite in unsaturated conditions. The time dependent creep has also been incorporated in they model. The performance of the model is examined by comparing numerical simulation with experimental data in various load paths under saturated and unsaturated conditions. Finally, the model is applied to hydro-mechanical coupling study of the REP experiment and thermo-hydro-mechanical coupling study of the HE-D experiment. A good agreement is obtained between experimental data and numerical predictions. It has been shown that the proposed model describe correctly the main features of the mechanical behaviour of unsaturated rocks. (author)

  17. Selective Clay Placement Within a Silicate-Clay Epoxy Blend Nanocomposite

    Science.gov (United States)

    Miller, Sandi G (Inventor)

    2013-01-01

    A clay-epoxy nanocomposite may be prepared by dispersing a layered clay in an alkoxy epoxy, such as a polypropylene oxide based epoxide before combining the mixture with an aromatic epoxy to improve the nanocomposite's thermal and mechanical properties.

  18. Modeling of Coupled Thermo-Hydro-Mechanical-Chemical Processes for Bentonite in a Clay-rock Repository for Heat-generating Nuclear Waste

    Science.gov (United States)

    Xu, H.; Rutqvist, J.; Zheng, L.; Birkholzer, J. T.

    2016-12-01

    Engineered Barrier Systems (EBS) that include a bentonite-based buffer are designed to isolate the high-level radioactive waste emplaced in tunnels in deep geological formations. The heat emanated from the waste can drive the moisture flow transport and induce strongly coupled Thermal (T), Hydrological (H), Mechanical (M) and Chemical (C) processes within the bentonite buffer and may also impact the evolution of the excavation disturbed zone and the sealing between the buffer and walls of an emplacement tunnel The flow and contaminant transport potential along the disturbed zone can be minimized by backfilling the tunnels with bentonite, if it provides enough swelling stress when hydrated by the host rock. The swelling capability of clay minerals within the bentonite is important for sealing gaps between bentonite block, and between the EBS and the surrounding host rock. However, a high temperature could result in chemical alteration of bentonite-based buffer and backfill materials through illitization, which may compromise the function of these EBS components by reducing their plasticity and capability to swell under wetting. Therefore, an adequate THMC coupling scheme is required to understand and to predict the changes of bentonite for identifying whether EBS bentonite can sustain higher temperatures. More comprehensive links between chemistry and mechanics, taking advantage of the framework provided by a dual-structure model, named Barcelona Expansive Model (BExM), was implemented in TOUGHREACT-FLAC3D and is used to simulate the response of EBS bentonite in in clay formation for a generic case. The current work is to evaluate the chemical changes in EBS bentonite and the effects on the bentonite swelling stress under high temperature. This work sheds light on the interaction between THMC processes, evaluates the potential deterioration of EBS bentonite and supports the decision making in the design of a nuclear waste repository in light of the maximum allowance

  19. The UK contribution to the CEC PACOMA Project: far-field modelling of radioactive waste disposal in clay

    International Nuclear Information System (INIS)

    Winters, K.H.; Jackson, C.P.; Clark, C.M.

    1990-06-01

    PACOMA (Performance Assessment of Confinement for Medium-active and Alpha-bearing wastes) is a multinational project supported as part of the Commission of the European Community's R and D programme on radioactive waste management and storage. The aim of the project is to assess the radiological impact of deep geological disposal of intermediate level waste in three different types of geological formation: clay, granite and salt. The contribution of AEA Technology is a study of the groundwater flow and radionuclide migration in the far field. This report describes the far-field modelling. The three-stratum model used in previous hydrogeological studies of the Harwell region is used as a basis for the far-field two-dimensional section through the chalk, clay and Corallian strata underlying Harwell. Each of the three layers is represented as a continuous porous medium with an assumed best-estimate value of permeability, and the groundwater flow is predicted by solving the Darcy equations over the complete section using the NAMMU finite-element code. Two-dimensional transport equations describing the migration of radionuclides in the groundwater are solved, also using NAMMU. The fluxes of radionuclides normal to the surface of the water table are calculated as a function of space and time. The most significant result of the calculations of radionuclide transport through the geosphere is the prediction of multiple pathways for radionuclide movement in the geological strata, and hence multiple release points into the biosphere. Particular attention is paid in the study to the performance and appropriation of the numerical methods and the physical models used for the far-field calculations. (author)

  20. Proceedings of the NEA Clay Club Workshop on Clay characterisation from nanoscopic to microscopic resolution

    International Nuclear Information System (INIS)

    2013-01-01

    A wide spectrum of argillaceous media are being considered in Nuclear Energy Agency (NEA) member countries as potential host rocks for the final, safe disposal of radioactive waste, and/or as major constituent of repository systems in which wastes will be emplaced. In this context, the NEA established the Working Group on the 'Characterisation, the Understanding and the Performance of Argillaceous Rocks as Repository Host Formations' in 1990, informally known as the 'Clay Club'. The Clay Club examines various argillaceous rocks that are being considered for the underground disposal of radioactive waste, ranging from soft clays to indurated shales. Very generally speaking, these clay rocks are composed of fine-grained minerals showing pore sizes from < 2 nm (micropores) up to > 50 nm (macro-pores). The water flow, solute transport and mechanical properties are largely determined by this microstructure, the spatial arrangement of the minerals and the chemical pore water composition. Examples include anion accessible ('geochemical') porosity and macroscopic membrane effects (chemical osmosis, hyper-filtration), geomechanical properties and the characteristics of two-phase flow properties (relevant for gas transport). At the current level of knowledge, there is a strong need to improve the nanoscale description of the phenomena observed at a more macroscopic scale. However, based on the scale of individual clay-minerals and pore sizes, for most of the imaging techniques this resolution is a clear challenge. The workshop, hosted by the Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology (KIT) in the Akademiehotel Karlsruhe (Germany) from 6 to 8 September 2011, was intended to give, inter alia, a discussion platform on: - The current state-of-the-art of different spectro-microscopic methods - New developments addressing the above mentioned knowledge gaps in clays. - The perception of the interplay between geometry

  1. Modelling the effects of pore-water chemistry on the behaviour of unsaturated clays

    Directory of Open Access Journals (Sweden)

    Lei Xiaoqin

    2016-01-01

    Full Text Available Due to their various applications in geo-environmental engineering, such as in landfill and nuclear waste disposals, the coupled chemo-hydro-mechanical analysis of expansive soils has gained more and more attention recently. These expansive soils are usually unsaturated under field conditions; therefore the capillary effects need to be taken into account appropriately. For this purpose, based on a rigorous thermodynamic framework (Lei et al., 2014, the authors have extended the chemo-mechanical model of Loret el al. (2002 for saturated homoionic expansive soils to the unsaturated case (Lei, 2015. In this paper, this chemo-mechanical unsaturated model is adopted to simulate the chemo-elastic-plastic consolidation process of an unsaturated expansive soil layer. Logical tendencies of changes in the chemical, mechanical and hydraulic field quantities are obtained.

  2. On the thermal behaviour of Boom clay

    International Nuclear Information System (INIS)

    Delage, P.; Cui Yu Jun; Sultan, N.

    2004-01-01

    When temperature is increased, the various phenomena that occur in a saturated natural potential host clay for nuclear waste disposal (Boom clay from SCK-CEN in Mol, Belgium) were experimentally investigated in a temperature controlled high stress triaxial cell. Firstly, the pore pressure build-up due to the difference in thermal dilation of both water and minerals was investigated through thermal consolidation tests. Interesting information was obtained about the dissipation of thermally induced pore pressure in Boom clay, based on the standard Terzaghi consolidation theory. Secondly, the volume change behaviour in drained conditions (i.e. under a very slow temperature increase) confirmed that the clay overconsolidation ratio (OCR) controlled the nature of the volume changes. Whereas overconsolidated soils use to dilate as any material when temperature is elevated, normally consolidated soils present a decrease in volume, which is less common. The principles of a coupled thermo-elasto-plastic model that was specifically developed to model this particular behaviour are finally presented. Obviously, it appears necessary to account in detail for these thermal phenomena in order to properly understand the response of the geological barrier in the near field once nuclear waste has been stored. (orig.)

  3. Thermal and mechanical properties of palm oil-based polyurethane acrylate/ clay nano composites prepared by in-situ intercalative method and electron beam radiation

    International Nuclear Information System (INIS)

    Salih, A.M.; Mansor Ahmad; Nor Azowa Ibrahim; Rida Tajau; Wan Mohd Zin Wan Yunus

    2013-01-01

    Full-text: Palm oil based-polyurethane acrylate (POBUA)/ clay nano composites were prepared via in-situ intercalative polymerization using epoxidized palm oil acrylate (EPOLA) and 4,4 ' methylene diphenyl diisocyante (MDI). Organically modified Montmorillonite (ODA-MMT) was incorporated in EPOLA (1, 3 and 5 % wt), and then subjected to polycondensation reaction with MDI. Nano composites solid films were obtained successfully by electron beam radiation induced free radical polymerization (curing). FTIR results reveal that the prepolymer was obtained successfully, with nano clay dispersed in the matrix. The intercalation of the clay in the polymer matrix was investigated by XRD and the interlayer spacing of clay was found to be increased up to 37 Angstrom, while the structure morphology of the nano composites was investigated by TEM and SEM. The nano composites were found to be a mixture of exfoliated and intercalated morphologies. The thermal stability of the nano composites was significantly increased by incorporation of nano clay into the polymer matrix. DSC results reveal that the T g was shifted to higher values, gradually with increasing the amount of filler in the nano composites. Tensile strength and Young's modulus of the nano composites showed remarkable improvement compared to the neat POBUA. (author)

  4. Deformability Parameters of Varved Clays From the Iłów (Central Poland Area Based on the Selected Field Tests

    Directory of Open Access Journals (Sweden)

    Zawrzykraj Piotr Zbigniew

    2017-03-01

    Full Text Available This publication presents the results of research carried out for the ice-dammed clays of the Iłów region, formed during Vistula glaciation. Pressuremeter tests, dilatometer tests and static probes were made. The tests were performed on the study site in Piskorzec near Iłów. In this region, ice-dammed clays are present almost from the land surface reaching the thickness of about 11 m. This site is the westernmost experimental site of clays of the “Warsaw Ice-Dammed Lake” among those presented in the literature. Research and their analysis showed differences in deformability due to the test procedure in connection with the structure of varved clays. Pressuremeter test, even though it is the most time consuming and challenging among the tests performed, allows the most complete characteristics of deformability of varved clays to be obtained. Vertical profile of clays being studied appears to be fairly homogeneous in terms of mechanical properties. Nevertheless, some parts of the profile clearly differ from the average values. This indicates the rate of post sedimentary changes varied in different parts of research profile. The data obtained are consistent with the values for ice-dammed clays from Radzymin and Sochaczew areas. Comparison of the engineering properties of varved clays to other experimental sites points to their similar geological history. It confirms that the experimental sites belong to one ice-dammed lake covering the areas of the Warsaw Basin.

  5. Efficiency of clay--TiO2 nanocomposites on the photocatalytic elimination of a model hydrophobic air pollutant.

    Science.gov (United States)

    Kibanova, Daria; Cervini-Silva, Javiera; Destaillats, Hugo

    2009-03-01

    Clay-supported TiO2 photocatalysts can potentially improve the performance of air treatment technologies via enhanced adsorption and reactivity of target volatile organic compounds (VOCs). In this study, a benchtop photocatalytic flow reactor was used to evaluate the efficiency of hectorite-TiO2 and kaolinite-TiO2, two novel composite materials synthesized in our laboratory. Toluene, a model hydrophobic VOC and a common indoor air pollutant, was introduced in the air stream at realistic concentrations, and reacted under UVA (lamda(max) = 365 nm) or UVC (lamda(max) = 254 nm) irradiation. The UVC lamp generated secondary emission at 185 nm, leading to the formation of ozone and other short-lived reactive species. Performance of clay-Ti02 composites was compared with that of pure TiO2 (Degussa P25), and with UV irradiation in the absence of photocatalyst under identical conditions. Films of clay-TiO2 composites and of P25 were prepared by a dip-coating method on the surface of Raschig rings, which were placed inside the flow reactor. An upstream toluene concentration of approximately 170 ppbv was generated by diluting a constant flow of toluene vapor from a diffusion source with dry air, or with humid air at 10, 33, and 66% relative humidity (RH). Toluene concentrations were determined by collecting Tenax-TA sorbent tubes downstream of the reactor, with subsequent thermal desorption--GC/MS analysis. The fraction of toluene removed, %R, and the reaction rate, Tr, were calculated for each experimental condition from the concentrations measured with and without UV irradiation. Use of UVC light (UV/TiO2/O3) led to overall higher reactivity, which can be partially attributed to the contribution of gas phase reactions by short-lived radical species. When the reaction rate was normalized to the light irradiance, Tr/Ilamda,the UV/TiO2 reaction under UVA irradiation was more efficient for samples with a higher content of TiO2 (P25 and Hecto-TiO2), but notfor Kao-TiO2. In all

  6. Preparation and characterization of polymer nanocomposites based on chitosan and clay minerals; Preparacao e caracterizacao de nanocompositos polimerico baseados em quitosana e argilo minerais

    Energy Technology Data Exchange (ETDEWEB)

    Fiori, Ana Paula Santos de Melo; Gabiraba, Victor Parizio; Praxedes, Ana Paula Perdigao [Instituto Federal de Alagoas (IFAL), Marechal Deodoro, AL (Brazil); Nunes, Marcelo Ramon da Silva; Balliano, Tatiane L.; Silva, Rosanny Christhinny da; Tonholo, Josealdo; Ribeiro, Adriana Santos, E-mail: aribeiro@qui.ufal.br [Universidade Federal de Alagoas (UFAL), Maceio, AL (Brazil)

    2014-09-15

    In this work nanocomposites based on chitosan and different clays were prepared using polyethyleneglycol (PEG) as plasticizer. The samples obtained were characterized by Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), thermogravimetric analysis (TGA/DTG) and by mechanical characterization (tensile test) with the aim of investigating the interactions between chitosan and clay. The nanocomposite films prepared using sodium bentonite (Ben) showed an increase of 81.2% in the maximum tensile stress values and a decrease of 16.0% in the Young’s modulus when compared to the chitosan with PEG (QuiPEG) films, evidencing that the introduction of the clay into the polymer matrix provided a more flexible and resistant film, whose elongation at break was 93.6% higher than for the QuiPEG film. (author)

  7. Cross flow microfiltration of oil-water emulsions using clay based ceramic membrane support and TiO2 composite membrane

    OpenAIRE

    Kanchapogu Suresh; G. Pugazhenthi

    2017-01-01

    The main objective of this work is to study the effect of cross flow filtration conditions on the separation of oily wastewater using ceramic support and TiO2 membrane. Firstly, the low cost clay based ceramic membrane support was prepared by uniaxial compaction method using combination of pyrophyllite, quartz, feldspar, kaolin, ball clay and calcium carbonate along with PVA as a binder. Subsequently, TiO2 composite membrane was fabricated via hydrothermal route employing TiO2 sol derived fro...

  8. Effect of clay structure and type of organomodifier on the thermal properties of poly(ethylene terephthalate) based nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Papageorgiou, George Z.; Karandrea, Eva; Giliopoulos, Dimitrios [Department of Chemistry, Aristotle University of Thessaloniki (AUTH), GR-54124 Thessaloniki (Greece); Papageorgiou, Dimitrios G. [Solid State Physics Department, School of Physics, Aristotle University of Thessaloniki AUTH, GR-54124 Thessaloniki (Greece); Ladavos, Athanasios; Katerinopoulou, Aikaterini [University of Patras, Agrinio 30100 (Greece); Achilias, Dimitris S.; Triantafyllidis, Konstantinos S. [Department of Chemistry, Aristotle University of Thessaloniki (AUTH), GR-54124 Thessaloniki (Greece); Bikiaris, Dimitrios N., E-mail: dbic@chem.auth.gr [Department of Chemistry, Aristotle University of Thessaloniki (AUTH), GR-54124 Thessaloniki (Greece)

    2014-01-20

    Graphical abstract: - Highlights: • Poly(ethylene terephthalate) nanocomposites were prepared using 4 different clay types. • Nanomer I30E clay was exfoliated into PET, as it was found from XRD. • The intercalation of Kunipia-CTAB resulted in less pronounced effect on PET crystallization. • The immobilized amorphous fraction, activation energy and nucleation activity were calculated. • Nanomer I30E clay facilitated the crystallization process. - Abstract: In the current investigation, nanocomposites of poly(ethylene terephthalate) (PET) with different types of organo-clays were produced using the melt mixing technique. Two types of commercial inorganic clays (Laponite-synthetic hectorite and Kunipia-montmorillonite) were studied after cation-exchange with hexadecyltrimethylammonium bromide (CTAB) while two commercial organo-modified montmorillonite clays (Nanomer I.30E modified with primary octadecylammonium ions and Cloisite 10A modified with quaternary dimethyl benzyl hydrogenated-tallow ammonium ions) were also investigated. The structure of the nanocomposites was studied by X-ray diffraction measurements. A detailed crystallization analysis was carried out by means of both isothermal and non-isothermal (melt and cold) measurements. All data were analyzed using the simple Avrami equation along with advanced isoconversional methods. The nucleation activity of the filler was investigated in every case. Lauritzen–Hoffman analysis was employed to isothermal data to estimate the nucleation parameters. From all these measurements it was found that the organo-clay I.30E induces the higher crystallization rates and lower activation energy and is more effective regarding the PET crystallization compared to the other types of organo-clays. The I.30E organo-clay nanocomposite exhibited also the higher immobilized amorphous fraction and the higher nucleation parameter K{sub g} in the Lauritzen–Hoffman analysis. This is due to its better dispersion and

  9. Effect of clay structure and type of organomodifier on the thermal properties of poly(ethylene terephthalate) based nanocomposites

    International Nuclear Information System (INIS)

    Papageorgiou, George Z.; Karandrea, Eva; Giliopoulos, Dimitrios; Papageorgiou, Dimitrios G.; Ladavos, Athanasios; Katerinopoulou, Aikaterini; Achilias, Dimitris S.; Triantafyllidis, Konstantinos S.; Bikiaris, Dimitrios N.

    2014-01-01

    Graphical abstract: - Highlights: • Poly(ethylene terephthalate) nanocomposites were prepared using 4 different clay types. • Nanomer I30E clay was exfoliated into PET, as it was found from XRD. • The intercalation of Kunipia-CTAB resulted in less pronounced effect on PET crystallization. • The immobilized amorphous fraction, activation energy and nucleation activity were calculated. • Nanomer I30E clay facilitated the crystallization process. - Abstract: In the current investigation, nanocomposites of poly(ethylene terephthalate) (PET) with different types of organo-clays were produced using the melt mixing technique. Two types of commercial inorganic clays (Laponite-synthetic hectorite and Kunipia-montmorillonite) were studied after cation-exchange with hexadecyltrimethylammonium bromide (CTAB) while two commercial organo-modified montmorillonite clays (Nanomer I.30E modified with primary octadecylammonium ions and Cloisite 10A modified with quaternary dimethyl benzyl hydrogenated-tallow ammonium ions) were also investigated. The structure of the nanocomposites was studied by X-ray diffraction measurements. A detailed crystallization analysis was carried out by means of both isothermal and non-isothermal (melt and cold) measurements. All data were analyzed using the simple Avrami equation along with advanced isoconversional methods. The nucleation activity of the filler was investigated in every case. Lauritzen–Hoffman analysis was employed to isothermal data to estimate the nucleation parameters. From all these measurements it was found that the organo-clay I.30E induces the higher crystallization rates and lower activation energy and is more effective regarding the PET crystallization compared to the other types of organo-clays. The I.30E organo-clay nanocomposite exhibited also the higher immobilized amorphous fraction and the higher nucleation parameter K g in the Lauritzen–Hoffman analysis. This is due to its better dispersion and exfoliation

  10. The UK contribution to the CEC PACOMA Project: far-field modelling of radioactive waste disposal in clay

    International Nuclear Information System (INIS)

    Winters, K.H.; Jackson, C.P.; Clark, C.M.

    1990-06-01

    This document describes a study of groundwater flow and radionuclide migration in the far field of a hypothetical repository located in the clay beneath Harwell Laboratory. The work forms part of the assessment of the radiological impact of disposal in a clay formation, carried out as the UK contribution to the CEC PACOMA project. (Author)

  11. Preparation and properties of recycled HDPE/clay hybrids

    Science.gov (United States)

    Yong Lei; Qinglin Wu; Craig M. Clemons

    2007-01-01

    Hybrids based on recycled high density polyethylene (RHDPE) and organic clay were made by melt compounding. The influence of blending method, compatibilizers, and clay content on clay intercalation and exfoliation, RHDPE crystallization behavior, and the mechanical properties of RHDPE/clay hybrids were investigated. Both maleated polyethylene (MAPE) and titanate could...

  12. The Implementation of Clay Modeling and Rat Dissection into the Human Anatomy and Physiology Curriculum of a Large Urban Community College

    Science.gov (United States)

    Haspel, Carol; Motoike, Howard K.; Lenchner, Erez

    2014-01-01

    After a considerable amount of research and experimentation, cat dissection was replaced with rat dissection and clay modeling in the human anatomy and physiology laboratory curricula at La Guardia Community College (LAGCC), a large urban community college of the City University of New York (CUNY). This article describes the challenges faculty…

  13. Differentiation between anonymous paintings of the 17th and the early 18th century by composition of clay-based grounds

    Czech Academy of Sciences Publication Activity Database

    Hradil, David; Hradilová, J.; Bezdička, Petr; Švarcová, Silvie

    2015-01-01

    Roč. 118, DEC (2015), s. 8-20 ISSN 0169-1317 R&D Projects: GA ČR GA14-22984S Institutional support: RVO:61388980 Keywords : paintings * clay-based grounds * X-ray powder micro-diffraction * historical technology Subject RIV: CA - Inorganic Chemistry Impact factor: 2.586, year: 2015

  14. Effect of addition of different nano-clays on the fumed silica-polyethylene glycol based shear-thickening fluids

    Science.gov (United States)

    Singh, Mansi; Mehta, Rajeev; Verma, Sanjeev K.; Biswas, Ipsita

    2018-01-01

    A comparative study of the rheology of shear thickening suspensions of 20% fumed silica in polyethylene glycol (PEG200) with different nano clays as additives has been done. The nano-clays used are montmorillonite (MMT), Closite15A, Kaolin and Halloysite clay. The objective was to study the effect of relatively cost-effective clays as a partial substitute of silica. Specifically, the effect of type, concentration, temperature and frequency were considered. The results indicate that the shear thickening properties of Closite15A as additive in temperature ranges of 25 °C-45 °C performs the best and Halloysite performs best at higher (55 °C) and lower temperatures (5, 15 °C). The elasticity effects in dynamic experiments were markedly enhanced by Halloysite clay addition. Addition of MMT, however, led to insignificant enhancement in critical viscosity in steady-state as well as dynamic state-rheology. Interestingly, shear thickening fluid (STF) with all clay except MMT was stable after storing for more than a month. These findings indicate that the introduction of nano-clay as additives is a promising and cost effective method for enhancing the STF behavior which can be utilized in high impact resistant (about 3000% strain and 300 rad s-1 frequency) applications.

  15. A consistent phenomenological model for natural organic matter linked migration of Cm(III), Pu(III/IV), Np(IV), Tc(IV) and Pa(V) in the Boom Clay

    International Nuclear Information System (INIS)

    Martens, E.; Maes, N.; Bruggeman, C.; Van Gompel, M.

    2010-01-01

    of magnitude lower than for the first cell. This indicates that the species that is transported is not a conservative tracer as otherwise the outlet concentration should equal the inlet concentration. Recently, Bruggeman and Maes (2009) put forward a phenomenological model which describes the Tc retention and transport mechanisms in Boom Clay. They hypothesise that Tc is transported as a Tc-NOM colloidal species exhibiting slow dissociation kinetics. This phenomenological model was now tested to describe the NOM related transport of Cm, Pu, Np, Tc and Pa in these 'sequential' migration experiments. All these RNs are known to form strong complexes with NOM in batch experiments. To describe the RN elution profiles from the second clay core, we used the migration parameters (diffusion coefficient, porosity and retardation factor) of NOM derived from small-scale lab experiments and validated by large-scale (long-term) in-situ tests in combination with a first order kinetic dissociation reaction. The transport feature of the geochemical code PHREEQC-2 was used for the simulations. Based on the original NOM transport parameters, and a narrow range for the parameter in the kinetic dissociation equation (2.4-8.5 x 10 -8 s -1 ), a good match with the experimental data could be achieved for all RNs considered in this study. This supports our hypothesis that for a large array of RNs (Tc, Pa, Np, Pu and Cm in this study), the transport behaviour observed in the experiments is indeed linked to NOM, irrespective of their dominant valence state (tri-, tetra-, pentavalent). Their overall transport potential (at longer times and distances) remains limited due to dissociation and subsequent sorption on the Boom Clay. The results presented in this study form an important step forward for safety assessments analysis: (i) the model is easy to implement, (ii) there is a link with a phenomenological description, and (iii) elements with a similar NOM association behaviour can be

  16. Comprehensive review of geosynthetic clay liner and compacted clay liner

    Science.gov (United States)

    Shankar, M. Uma; Muthukumar, M.

    2017-11-01

    Human activity inevitably produces waste materials that must be managed. Some waste can be reused. However many wastes that cannot be used beneficially must be disposed of ensuring environmental safety. One of the common methods of disposal is landfilling. The most common problems of the landfill site are environmental degradation and groundwater contamination caused by leachate produced during the decomposition process of organic material and rainfall. Liner in a landfill is an important component which prevent leachate migration and prevent groundwater contamination. Earthen liners have been widely used to contain waste materials in landfill. Liners and covers for municipal and hazardous waste containment facilities are often constructed with the use of fine-grained, low plasticity soils. Because of low permeability geosynthetic clay liners and compacted clay liners are the main materials used in waste disposal landfills. This paper summaries the important geotechnical characteristics such as hydraulic conductivity, liquid limit and free swell index of geosynthetic clay liner and compacted clay liner based on research findings. This paper also compares geosynthetic clay liner and compacted clay liner based on certain criteria such as thickness, availability of materials, vulnerability to damage etc.

  17. Modelling of the physical behaviour of water saturated clay barriers. Laboratory tests, material models and finite element application

    International Nuclear Information System (INIS)

    Boergesson, L.; Johannesson, L.E.; Sanden, T.; Hernelind, J.

    1995-09-01

    This report deals with laboratory testing and modelling of the thermo-hydro-mechanical (THM) properties of water saturated bentonite based buffer materials. A number of different laboratory tests have been performed and the results are accounted for. These test results have lead to a tentative material model, consisting of several sub-models, which is described in the report. The tentative model has partly been adapted to the material models available in the finite element code ABAQUS and partly been implemented and incorporated in the code. The model that can be used for ABAQUS calculations agrees with the tentative model with a few exceptions. The model has been used in a number of verification calculations, simulating different laboratory tests, and the results have been compared with actual measurements. These calculations show that the model generally can be used for THM calculations of the behaviour of water saturated buffer materials, but also that there is still a lack of some understanding. It is concluded that the available model is relevant for the required predictions of the THM behaviour but that a further improvement of the model is desirable

  18. Modeling of the sorptive behavior of a clay material used as reactive barrier for cesium migration in Huelva (Spain)

    International Nuclear Information System (INIS)

    Missana, Tiziana; Garcia-Gutierrez, Miguel

    2012-01-01

    different homo-ionic forms (Na, Ca, K) and sorption of caesium evaluated at different ionic strengths. Sorption data in the homo-ionic system were modeled considering the ionic exchange approach. Figure 1 shows an example of the procedure carried out. The Figure shows the sorption isotherms obtained on the Na-exchanged RC clay dispersed in NaCl at two different concentration 0.28 and 0.13 mol/L. The adsorption isotherm showed a non linear behavior, most probably dominated by the presence of illite, thus was modeled considering the existence of three sorption sites. The result of the modeling is superimposed to the experimental points. With the basic selectivity coefficient determined in this way the blind prediction of the sorption behavior of the material under different in-situ conditions was carried out along with a sensitivity study on the main parameters of interest (content of clay, site density, BET, presence of competing ions,...). The application of this modeling approach was shown to be quite successful in reproducing the distribution coefficient previously measured under different experimental conditions; furthermore it allowed estimating the actual experimental variability and range of uncertainty of Kd values determination

  19. Acid–base properties of pillared interlayered clays with single and mixed Zr–Al oxide pillars prepared from Tunisian-interstratified illite–smectite

    Directory of Open Access Journals (Sweden)

    Saida Mnasri

    2017-12-01

    Full Text Available Interstratified illite–smectite clay samples from Tunisia have been used in order to prepare Al, Zr and Zr–Al-pillared clays. Several Al/metal, OH/metal ratios were used in order to investigate the effect on the chemical and physical properties, specifically the point of zero charge (PZC of the synthesized pillared clays. The structure of the pillared materials is studied by XRD and cationic exchange capacity. The textural property is investigated by the nitrogen adsorption/desorption method. The acid–base chemistry “surface acidity” of these products was analysed by using mass and potentiometric titration in order to determine the PZC and the equilibrium constants (pKa of each sample. The resulting materials exhibited basal spacings in the range of 17.4–20.5 Å, with high surface areas (134–199 m2 g−1. Titration curves obtained by acid–base potentiometric titration for the starting material showed an indistinct cross-over point at about pH = 7.3, whereas in the case of pillared samples, points were observed at the acidic region between 4 and 6. In addition, the calculated pKas values of pillared clays show a shifting to the acidic values compared to the untreated sample.

  20. Nanocomposites based on epoxy resin and montmorillonite: effect of clay percent and dispersion state on thermomechanical properties

    International Nuclear Information System (INIS)

    Zaioncz, Soraia; Soares, Bluma G.

    2009-01-01

    Nanocomposites of epoxy resin modified with PMMA and montmorillonite organophilic were synthesized with clay content equal to 0.1, 1, 2.5, 5 and 7 (wt %). Dispersion state and the nano structure of materials has been investigated using small angle X-ray scattering (SAXS). The nanocomposites containing 0.1 (wt %) of clay showed an exfoliated morphology, while the nanocomposites with higher clay content (1 to 7 wt %) show that the dispersion state is less uniform and that large aggregates coexist with tactoids stacks of two or three platelets. The nano structure of materials was correlated with its thermomechanical properties obtained by DMTA. The results showed an increase in Tg of the materials to clay content of up to 5 wt % and an increase in the storage modulus for the epoxy matrix. (author)

  1. Synthesis and characterization of nanocomposites based on polyurethane in aqueous dispersions with non-modified hydrophilic clays

    International Nuclear Information System (INIS)

    Miranda, G.S.; Delpechi, M.C.; Santo, W.L.E.

    2010-01-01

    Several studies involving the formation of polyurethane nanocomposites employing clays of montmorillonite modified. This involves the presence of quaternary ammonium salts, the cation exchange needed to increase the interlayer space of clays that incorporate more than one step to the process, generates a higher cost. In this paper the synthesis of nanocomposite polyurethanes dispersed in water allowed not only the production of materials less harmful to the environment, but also the incorporation of hydrophilic clays, calcium and sodium in nature, without any modifications. Dispersions produced from 0.5, 1.0 and 2.5% clay (on the mass of prepolymer) were characterized in terms of total solids content, the films obtained by casting were evaluated for adhesiveness, diffraction X-rays, scanning electron microscopy. Most systems showed intercalated and partially exfoliated structures. (author)

  2. Fracture behavior of polypropylene/clay nanocomposites.

    Science.gov (United States)

    Chen, Ling; Wang, Ke; Kotaki, Masaya; Hu, Charmaine; He, Chaobin

    2006-12-01

    Polypropylene (PP)/clay nanocomposites have been prepared via a reactive compounding approach with an epoxy based masterbatch. Compared with PP and common PP/organoclay nanocomposites, the PP/clay nanocomposites based on epoxy/clay masterbatch have higher impact strength. The phenomenon can be attributed to the epoxy phase dispersed uniformly in the PP matrix, which may act as impact energy absorber and helps to form a large damage zone, thus a higher impact strength value is achieved.

  3. Investigations of Near-Field Thermal-Hydrologic-Mechanical-Chemical Models for Radioactive Waste Disposal in Clay/Shale Rock

    International Nuclear Information System (INIS)

    Liu, H.H.; Li, L.; Zheng, L.; Houseworth, J.E.; Rutqvist, J.

    2011-01-01

    Clay/shale has been considered as potential host rock for geological disposal of high-level radioactive waste throughout the world, because of its low permeability, low diffusion coefficient, high retention capacity for radionuclides, and capability to self-seal fractures. For example, Callovo-Oxfordian argillites at the Bure site, France (Fouche et al., 2004), Toarcian argillites at the Tournemire site, France (Patriarche et al., 2004), Opalinus Clay at the Mont Terri site, Switzerland (Meier et al., 2000), and Boom clay at the Mol site, Belgium (Barnichon and Volckaert, 2003) have all been under intensive scientific investigation (at both field and laboratory scales) for understanding a variety of rock properties and their relationships to flow and transport processes associated with geological disposal of radioactive waste. Figure 1-1 presents the distribution of clay/shale formations within the USA.

  4. Investigations of Near-Field Thermal-Hydrologic-Mechanical-Chemical Models for Radioactive Waste Disposal in Clay/Shale Rock

    Energy Technology Data Exchange (ETDEWEB)

    Liu, H.H.; Li, L.; Zheng, L.; Houseworth, J.E.; Rutqvist, J.

    2011-06-20

    Clay/shale has been considered as potential host rock for geological disposal of high-level radioactive waste throughout the world, because of its low permeability, low diffusion coefficient, high retention capacity for radionuclides, and capability to self-seal fractures. For example, Callovo-Oxfordian argillites at the Bure site, France (Fouche et al., 2004), Toarcian argillites at the Tournemire site, France (Patriarche et al., 2004), Opalinus Clay at the Mont Terri site, Switzerland (Meier et al., 2000), and Boom clay at the Mol site, Belgium (Barnichon and Volckaert, 2003) have all been under intensive scientific investigation (at both field and laboratory scales) for understanding a variety of rock properties and their relationships to flow and transport processes associated with geological disposal of radioactive waste. Figure 1-1 presents the distribution of clay/shale formations within the USA.

  5. Creep in buffer clay

    International Nuclear Information System (INIS)

    Pusch, R.; Adey, R.

    1999-12-01

    The study involved characterization of the microstructural arrangement and molecular forcefields in the buffer clay for getting a basis for selecting suitable creep models. It is concluded that the number of particles and wide range of the particle bond spectrum require that stochastical mechanics and thermodynamics will be considered and they are basic to the creep model proposed for predicting creep settlement of the canisters. The influence of the stress level on creep strain of MX-80 clay is not well known but for the buffer creep is approximately proportional to stress. Theoretical considerations suggest a moderate impact for temperatures up to 90 deg C and this is supported by model experiments. It is believed that the assumption of strain being proportional to temperature is conservative. The general performance of the stochastic model can be illustrated in principle by use of visco-elastic rheological models implying a time-related increase in viscosity. The shear-induced creep settlement under constant volume conditions calculated by using the proposed creep model is on the order of 1 mm in ten thousand years and up to a couple of millimeters in one million years. It is much smaller than the consolidation settlement, which is believed to be on the order of 10 mm. The general conclusion is that creep settlement of the canisters is very small and of no significance to the integrity of the buffer itself or of the canisters

  6. Anionic clay as the drug delivery vehicle: tumor targeting function of layered double hydroxide-methotrexate nanohybrid in C33A orthotopic cervical cancer model.

    Science.gov (United States)

    Choi, Goeun; Piao, Huiyan; Alothman, Zeid A; Vinu, Ajayan; Yun, Chae-Ok; Choy, Jin-Ho

    2016-01-01

    Methotrexate (MTX), an anticancer agent, was successfully intercalated into the anionic clay, layered double hydroxides to form a new nanohybrid drug. The coprecipitation and subsequent hydrothermal method were used to prepare chemically, structurally, and morphologically well-defined two-dimensional drug-clay nanohybrid. The resulting two-dimensional drug-clay nanohybrid showed excellent colloidal stability not only in deionized water but also in an electrolyte solution of Dulbecco's Modified Eagle's Medium with 10% fetal bovine serum, in which the average particle size in colloid and the polydispersity index were determined to be around 100 and 0.250 nm, respectively. The targeting property of the nanohybrid drug was confirmed by evaluating the tumor-to-blood and tumor-to-liver ratios of the MTX with anionic clay carrier, and these ratios were compared to those of free MTX in the C33A orthotopic cervical cancer model. The biodistribution studies indicated that the mice treated with the former showed 3.5-fold higher tumor-to-liver ratio and fivefold higher tumor-to-blood ratio of MTX than those treated with the latter at 30 minutes postinjection.

  7. Addendum to: Derivation of in situ opalinus clay porewater compositions from experimental and geochemical modelling studies

    International Nuclear Information System (INIS)

    Bradbury, M.H.; Baeyens; Pearson, F.J.; Berner, U.

    1998-01-01

    As part of the synthesis of water chemistry studies within the hydrochemical program at Mont Terri (Switzerland), a reexamination of the modelling method showed that it should lead to a range of water compositions rather than to a single composition. The single composition resulted from two compensating oversights, a theoretical one and a modelling one. These are discussed in this Addendum. (author)

  8. Hydraulic modeling of clay ceramic water filters for point-of-use water treatment.

    Science.gov (United States)

    Schweitzer, Ryan W; Cunningham, Jeffrey A; Mihelcic, James R

    2013-01-02

    The acceptability of ceramic filters for point-of-use water treatment depends not only on the quality of the filtered water, but also on the quantity of water the filters can produce. This paper presents two mathematical models for the hydraulic performance of ceramic water filters under typical usage. A model is developed for two common filter geometries: paraboloid- and frustum-shaped. Both models are calibrated and evaluated by comparison to experimental data. The hydraulic models are able to predict the following parameters as functions of time: water level in the filter (h), instantaneous volumetric flow rate of filtrate (Q), and cumulative volume of water produced (V). The models' utility is demonstrated by applying them to estimate how the volume of water produced depends on factors such as the filter shape and the frequency of filling. Both models predict that the volume of water produced can be increased by about 45% if users refill the filter three times per day versus only once per day. Also, the models predict that filter geometry affects the volume of water produced: for two filters with equal volume, equal wall thickness, and equal hydraulic conductivity, a filter that is tall and thin will produce as much as 25% more water than one which is shallow and wide. We suggest that the models can be used as tools to help optimize filter performance.

  9. Efficiency of clay-TiO2 nanocomposites on the photocatalytic eliminationof a model hydrophobic air pollutant

    Energy Technology Data Exchange (ETDEWEB)

    Kibanova, Daria; Cervini-Silva, Javiera; Destaillats, Hugo

    2009-01-01

    Clay-supported TiO2 photocatalysts can potentially improve the performance of air treatment technologies via enhanced adsorption and reactivity of target volatile organic compounds (VOCs). In this study, a bench-top photocatalytic flow reactor was used to evaluate the efficiency of hectorite-TiO2 and kaolinite-TiO2, two novel composite materials synthesized in our laboratory. Toluene, a model hydrophobic VOC and a common indoor air pollutant, was introduced in the air stream at realistic concentrations, and reacted under UVA (gamma max = 365 nm) or UVC (gamma max = 254 nm) irradiation. The UVC lamp generated secondary emission at 185 nm, leading to the formation of ozone and other short-lived reactive species. Performance of clay-TiO2 composites was compared with that of pure TiO2 (Degussa P25), and with UV irradiation in the absence of photocatalyst under identical conditions. Films of clay-TiO2 composites and of P25 were prepared by a dip-coating method on the surface of Raschig rings, which were placed inside the flow reactor. An upstream toluene concentration of ~;;170 ppbv was generated by diluting a constant flow of toluene vapor from a diffusion source with dry air, or with humid air at 10, 33 and 66percent relative humidity (RH). Toluene concentrations were determined by collecting Tenax-TA (R) sorbent tubes downstream of the reactor, with subsequent thermal desorption -- GC/MS analysis. The fraction of toluene removed, percentR, and the reaction rate, Tr, were calculated for each experimental condition from the concentration changes measured with and without UV irradiation. Use of UVC light (UV/TiO2/O3) led to overall higher reactivity, which can be partially attributed to the contribution of gas phase reactions by short-lived radical species. When the reaction rate was normalized to the light irradiance, Tr/I gamma, the UV/TiO2 reaction under UVA irradiation was more efficient for samples with a higher content of TiO2 (P25 and Hecto-TiO2), but not for Kao

  10. Clay-Inspired MXene-Based Electrochemical Devices and Photo-Electrocatalyst: State-of-the-Art Progresses and Challenges.

    Science.gov (United States)

    Wang, Hou; Wu, Yan; Yuan, Xingzhong; Zeng, Guangming; Zhou, Jin; Wang, Xin; Chew, Jia Wei

    2018-03-01

    MXene, an important and increasingly popular category of postgraphene 2D nanomaterials, has been rigorously investigated since early 2011 because of advantages including flexible tunability in element composition, hydrophobicity, metallic nature, unique in-plane anisotropic structure, high charge-carrier mobility, tunable band gap, and favorable optical and mechanical properties. To fully exploit these potentials and further expand beyond the existing boundaries, novel functional nanostructures spanning monolayer, multilayer, nanoparticles, and composites have been developed by means of intercalation, delamination, functionalization, hybridization, among others. Undeniably, the cutting-edge developments and applications of clay-inspired 2D MXene platform as electrochemical electrode or photo-electrocatalyst have conferred superior performance and have made significant impact in the field of energy and advanced catalysis. This review provides an overview of the fundamental properties and synthesis routes of pure MXene, functionalized MXene and their hybrids, highlights the state-of-the-art progresses of MXene-based applications with respect to supercapacitors, batteries, electrocatalysis and photocatalysis, and presents the challenges and prospects in the burgeoning field. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Cs adsorption mechanism on clay minerals based on material sciences using synchrotron radiation and first principle calculation

    International Nuclear Information System (INIS)

    Yaita, Tsuyoshi; Kobayashi, Toru; Ikeda, Takashi; Matsumura, Daiju; Machida, Masahiko; Okumura, Masahiko; Nakamura, Hiroki

    2014-01-01

    The radioactive Cs released from Fukushima Dai-ichi Nuclear Power Plant accident is one of the important sources to increase air dose rate in environment, and thus the local and Japanese governments are still promoting the decontamination project in the contaminated area in Fukushima. On this backgrounds, in this study, 'the comprehensive researches', i.e., the elucidation of Cs speciation through the structural and electronic structural studies in clay minerals for supporting to develop the promising volume reduction methods of soil wastes (we will not touch the chemical treatment, wet classification, incineration, and alkaline fusion methods in this article) and the evaluation of Cs stability in soil wastes over mid- to long-term period, and the field investigation for elucidation of seasonal variation of bottom soil of agricultural reservoir in litate village on considering the features of local soil in Fukushima, have been performed. In this article, we introduce a part of the results obtaining by the synchrotron based X-ray analysis and the first principle molecular dynamics simulation methods. (author)

  12. Origin of enhanced Brønsted acidity of NiF-modified synthetic mica-montmorillonite clay

    NARCIS (Netherlands)

    Liu, C.; Pidko, E.A.; Hensen, Emiel J M

    2018-01-01

    The Brønsted acidity of synthetic mica-montmorillonite (SMM) clay was studied by periodic DFT calculations. Different structural models were compared to determine the Brønsted acidity of protons of the SMM clay based on (i) isomorphous substitution of Si4+ by Al3+ in the

  13. Origin of enhanced Brønsted acidity of NiF-modified synthetic mica-montmorillonite clay

    NARCIS (Netherlands)

    Liu, Chong; Pidko, Evgeny A.; Hensen, Emiel J.M.

    2018-01-01

    The Brønsted acidity of synthetic mica-montmorillonite (SMM) clay was studied by periodic DFT calculations. Different structural models were compared to determine the Brønsted acidity of protons of the SMM clay based on (i) isomorphous substitution of Si4+ by Al3+ in the tetrahedral silicate layer

  14. Far Field Sorption Data Bases for Performance Assessment of a High-Level Radioactive Waste Repository in an Undisturbed Opalinus Clay Host Rock

    International Nuclear Information System (INIS)

    Bradburry, M.; Baeyens, B.

    2003-08-01

    An Opalinus Clay formation in the Zuercher Weinland is under consideration by Nagra as a potential location for a high-level and long-Iived intermediate-level radioactive waste repository. Performance assessment studies will be performed for this site and the purpose of this report is to describe the procedures used to develop sorption data bases appropriate for an undisturbed Opalinus Clay host rock which are required for such safety analysis calculations. In tight, low water content argillaceous rock formations such as Opalinus Clay, there is uncertainty concerning the in situ pH/P CO 2 . In order to take this intrinsic uncertainty into account porewater chemistries were calculated for a reference case, pH = 7.24, and for two other pH values, 6.3 and 7.8. Sorption data bases are given for the three cases. The basis for the sorption data bases is 'in-house' sorption measurements for Cs(I), Sr(II), Ni(II), Eu(III), Sn(IV), Se(IV), Th(IV) and I(-I) carried out on Opalinus Clay samples from Mont Terri (Canton Jura) since at the time the experiments were performed no core samples from the Benken borehole (Zuercher Weinland) were available. The Opalinus Clay at Mont Terri and Benken are part of the same geological formation . Despite having directly measured data for the above key radionuclides, some of the required distribution ratios (Rd) used to generate the sorption data bases still came from the open literature. An important part of this report is concerned with describing the procedures whereby these selected literature Rd values were modified so as to apply to the Benken Opalinus Clay mineralogy and groundwater chemistries calculated at the three pH values given above. The resulting Rd values were then further modified using so-called Lab→Field transfer factors to produce sorption values which were appropriate to the in situ bulk rock for the selected range of water chemistry conditions. Finally, it is important to have some appreciation of the uncertainties

  15. Far Field Sorption Data Bases for Performance Assessment of a High-Level Radioactive Waste Repository in an Undisturbed Opalinus Clay Host Rock

    Energy Technology Data Exchange (ETDEWEB)

    Bradburry, M.; Baeyens, B

    2003-08-01

    An Opalinus Clay formation in the Zuercher Weinland is under consideration by Nagra as a potential location for a high-level and long-Iived intermediate-level radioactive waste repository. Performance assessment studies will be performed for this site and the purpose of this report is to describe the procedures used to develop sorption data bases appropriate for an undisturbed Opalinus Clay host rock which are required for such safety analysis calculations. In tight, low water content argillaceous rock formations such as Opalinus Clay, there is uncertainty concerning the in situ pH/P{sub CO{sub 2}}. In order to take this intrinsic uncertainty into account porewater chemistries were calculated for a reference case, pH = 7.24, and for two other pH values, 6.3 and 7.8. Sorption data bases are given for the three cases. The basis for the sorption data bases is 'in-house' sorption measurements for Cs(I), Sr(II), Ni(II), Eu(III), Sn(IV), Se(IV), Th(IV) and I(-I) carried out on Opalinus Clay samples from Mont Terri (Canton Jura) since at the time the experiments were performed no core samples from the Benken borehole (Zuercher Weinland) were available. The Opalinus Clay at Mont Terri and Benken are part of the same geological formation . Despite having directly measured data for the above key radionuclides, some of the required distribution ratios (Rd) used to generate the sorption data bases still came from the open literature. An important part of this report is concerned with describing the procedures whereby these selected literature Rd values were modified so as to apply to the Benken Opalinus Clay mineralogy and groundwater chemistries calculated at the three pH values given above. The resulting Rd values were then further modified using so-called Lab{yields}Field transfer factors to produce sorption values which were appropriate to the in situ bulk rock for the selected range of water chemistry conditions. Finally, it is important to have some

  16. Chemo-hydro-mechanical behaviour of unsaturated clays

    International Nuclear Information System (INIS)

    Mokni, N.; Olivella, S.; Alonso, E.E.; Romero, E.

    2010-01-01

    Document available in extended abstract form only. Understanding of the chemical effects on clays is essential for many problems ranging from pollution studies and waste-containment. Several studies examined the effect of changes in pore fluid composition on the mechanical and hydraulic properties. Volume changes (contraction/ expansion) have been measured on clay specimens upon exposure to salt solutions or permeation with organic liquids. Moreover, it was shown that permeation of clay with brine induces an increase of the shear strength. In addition, several models have been proposed to describe the chemo-mechanical behaviour of saturated clays under saturated conditions. A new chemo-hydro-mechanical model for unsaturated clays is under development. The chemo-mechanical effects are described within an elasto-plastic framework using the concept that chemical effects act on the plastic properties by increasing or decreasing the pre-consolidation stress. The model is based on the distinction within the material of a microstructural and a macro-structural levels. Chemical loading has a significant effect on the microstructure. The negative pressure associated with the capillary water plays its role in the interconnected macro pores. By adopting simple assumptions concerning the coupling between the two levels it is intended to reproduce the features of the behaviour of unsaturated clays when there is a change in pore fluid composition (increase or decrease of concentration). A yield surface which defines the set of yield pre-consolidation stress values, for each associated capillary suction and concentration of pore fluid should be defined. In addition, the behaviour of clays under unsaturated condition and the behaviour at full saturation under chemical loading represent two limiting cases of the framework. Studies on the compatibility of Boom Clay with large amounts of nitrate- bearing bituminized radioactive waste have recently raised a particular interest on the

  17. Migration of Gas in Water Saturated Clays by Coupled Hydraulic-Mechanical Model

    Directory of Open Access Journals (Sweden)

    Aliaksei Pazdniakou

    2018-01-01

    Full Text Available Understanding the gas migration in highly water saturated sedimentary rock formations is of great importance for safety of radioactive waste repositories which may use these host rocks as barrier. Recent experiments on drainage in argillite samples have demonstrated that they cannot be represented in terms of standard two-phase flow Darcy model. It has been suggested that gas flows along highly localized dilatant pathways. Due to very small pore size and the opacity of the material, it is not possible to observe this two-phase flow directly. In order to better understand the gas transport, a numerical coupled hydraulic-mechanical model at the pore scale is proposed. The model is formulated in terms of Smoothed Particle Hydrodynamics (SPH and is applied to simulate drainage within a sample reconstructed from the Focused Ion Beam (FIB images of Callovo-Oxfordian claystone. A damage model is incorporated to take into account the degradation of elastic solid properties due to local conditions, which may lead to formation of new pathways and thus to modifications of fluid transport. The influence of the damage model as well as the possible importance of rigid inclusions is demonstrated and discussed.

  18. Thermal Behaviour of clay formations

    International Nuclear Information System (INIS)

    Tassoni, E.

    1985-01-01

    The programme carried out by ENEA to model the thermal-hydraulic-mechanical behaviour of the clay formations and to measure, in situ and in laboratory, the thermal properties of these rocks, is presented. An in situ heating experiment has been carried out in an open clay quarry in the area of Monterotondo, near Rome. The main goal of the experiment was to know the temperature field and the thermal effects caused by the high level radioactive waste disposed of in a clayey geological formation. The conclusions are as follows: - the thermal conduction codes are sufficiently accurate to forecast the temperature increases caused in the clay by the dissipation of the heat generated by high level radioactive waste; - the thermal conductivity deduced by means of the ''curve fitting'' method ranges from 0.015 to 0.017 W.cm -1 . 0 C -1 - the temperature variation associated with the transport of clay interstitial water caused by temperature gradient is negligible. A laboratory automated method has been designed to measure the thermal conductivity and diffusivity in clay samples. A review of experimental data concerning thermomechanical effects in rocks as well as results of thermal experiments performed at ISMES on clays are presented. Negative thermal dilation has been found both in the elastic and plastic range under constant stress. Thermoplastic deformation appears ten times greater than the thermoelastic one. A mathematical model is proposed in order to simulate the above and other effects that encompass thermal-elastic-plastic-pore water pressure response of clays at high temperature and effective pressure with undrained and transient drainage conditions. Implementation of the two versions into a finite element computer code is described

  19. Hydrogen transfer experiments and modelization in clay rocks for radioactive waste deep geological repository

    International Nuclear Information System (INIS)

    Boulin, P.

    2008-10-01

    Gases will be generated by corrosion of high radioactive waste containers in deep geological repositories. A gas phase will be generated. Gas pressure will build up and penetrated the geological formation. If gases do not penetrate the geological barrier efficiently, the pressure build up may create a risk of fracturing and of creation of preferential pathways for radionuclide migration. The present work focuses on Callovo-Oxfordian argillites characterisation. An experiment, designed to measure very low permeabilities, was used with hydrogen/helium and analysed using the Dusty Gas Model. Argillites close to saturation have an accessible porosity to gas transfer that is lower than 0,1% to 1% of the porosity. Analysis of the Knudsen effect suggests that this accessible network should be made of 50 nm to 200 nm diameter pores. The permeabilities values were integrated to an ANDRA operating model. The model showed that the maximum pressure expected near the repository would be 83 bar. (author)

  20. Anionic clay as the drug delivery vehicle: tumor targeting function of layered double hydroxide-methotrexate nanohybrid in C33A orthotopic cervical cancer model

    Directory of Open Access Journals (Sweden)

    Choi G

    2016-01-01

    Full Text Available Goeun Choi,1 Huiyan Piao,1 Zeid A Alothman,2 Ajayan Vinu,3 Chae-Ok Yun,4 Jin-Ho Choy1 1Center for Intelligent Nano-Bio Materials, Department of Chemistry and Nano Science, Ewha Womans University, Seoul, Korea; 2Advanced Materials Research Chair, Chemistry Department, College of Science, King Saud University, Riyadh, Saudi Arabia; 3Future Industries Institute, University of South Australia, Mawson Lakes, SA, Australia; 4Department of Bioengineering, College of Engineering, Hanyang University, Seoul, Korea Abstract: Methotrexate (MTX, an anticancer agent, was successfully intercalated into the anionic clay, layered double hydroxides to form a new nanohybrid drug. The coprecipitation and subsequent hydrothermal method were used to prepare chemically, structurally, and morphologically well-defined two-dimensional drug-clay nanohybrid. The resulting two-dimensional drug-clay nanohybrid showed excellent colloidal stability not only in deionized water but also in an electrolyte solution of Dulbecco’s Modified Eagle’s Medium with 10% fetal bovine serum, in which the average particle size in colloid and the polydispersity index were determined to be around 100 and 0.250 nm, respectively. The targeting property of the nanohybrid drug was confirmed by evaluating the tumor-to-blood and tumor-to-liver ratios of the MTX with anionic clay carrier, and these ratios were compared to those of free MTX in the C33A orthotopic cervical cancer model. The biodistribution studies indicated that the mice treated with the former showed 3.5-fold higher tumor-to-liver ratio and fivefold higher tumor-to-blood ratio of MTX than those treated with the latter at 30 minutes postinjection. Keywords: anionic clay, biodistribution, cervical cancer, colloidal stability, layered double hydroxide, methotrexate 

  1. Pesticide leaching in polders : field and model studies on cracked clays and loamy sand

    NARCIS (Netherlands)

    Groen, K.P.

    1997-01-01

    This thesis reports on a study of pesticide leaching in polder areas. The study comprises two aspects: a data collection program and the development, calibration and application of the model SWACRO for the simulation of pesticide transport.

    Field data were

  2. Modelling of niobium sorption on clay minerals in sodium and calcium perchlorate solutions

    Energy Technology Data Exchange (ETDEWEB)

    Ervanne, Heini; Hakanen, Martti; Lehto, Jukka [Helsinki Univ. (Finland). Laboratory of Radiochemistry

    2014-11-01

    The sorption behaviour of niobium on kaolinite and illite minerals in sodium and calcium perchlorate solutions was evaluated with use of the mass distribution coefficient, Rd, obtained in batch sorption experiments. Very high distribution coefficient values, about 100 m{sup 3}/kg, were obtained for both minerals in the neutral pH range between 6 and 8. Values were somewhat lower at pH 5. In NaClO{sub 4} solution, the sorption of niobium starts to decrease at pH higher than 8. This is in agreement with the increase, with pH, in the proportion of anionic niobate species, which are presumed to be low or non-sorbing. A similar decrease was not observed in Ca(ClO{sub 4}){sub 2} solution, probably owing to the influence of Ca on niobium solution speciation and surface species. The surface complexation model was applied to model the Rd values. The model fitted well for the NaClO{sub 4} solution but only at pH below 9 for the Ca(ClO{sub 4}){sub 2} solution. The discrepancy between the strong sorption of niobium in calcium-bearing solution at high pH and the calculated speciation is due in part to the non-inclusion of calcium niobate solution species and Ca-Nb compounds in the present NEA and other similar thermodynamic databases.

  3. Using digital elevation models as an environmental predictor for soil clay contents

    DEFF Research Database (Denmark)

    Greve, Mogens Humlekrog; Bou Kheir, Rania; Greve, Mette Balslev

    2012-01-01

    resolution) explained the variability of SCC measurements quasi-similarly (variance V = 60%) to the LIDAR tree models with 24-m (T2) or 90-m (T3) resolution (V = 60% for T2 and 61.5% for T3). The prediction performances (in terms of RMSE) of the produced maps (using these trees) compared with independent...... field observations from the validation data set (9000 sites) were estimated as follows: Map T1, RMSE = 3.57%; Map T2, RMSE = 3.25%; and Map T3, RMSE = 3.15%. The relative improvement of T2 compared with T1 or T3 varied between 8.96 and 11.76%, respectively. Independent validation data also reflected...... higher correlations between measured SCC and SCC predicted from T2 (R2 = 0.60) compared with the other tree models (T1, R2 = 0.56; T3, R2 = 0.54). The modeling results indicate that the SRTM (including derivatives) has less predictive power than the LIDAR DEMs (with different resolutions) for mapping SCC...

  4. Faults architecture and growth in clay-limestone alternation. Examples in the S-E Basin alternations (France) and numerical modeling

    International Nuclear Information System (INIS)

    Roche, Vincent

    2011-01-01

    The following work has been carried out in the framework of the studies conducted by IRSN in support of its safety evaluation of the geological disposal programme of high and intermediate level, long-lived radioactive waste. Such a disposal is planned to be hosted by the Callovian-Oxfordian indurate clay formation between two limestone formations in eastern Paris basin, France. Hypothetical faults may cross-cut this layered section, decreasing the clay containment ability by creating preferential pathways for radioactive solute towards limestones. This study aims at characterising the fault architecture and the normal fault growth in clay/limestone layered sections. Structural analysis and displacement profiles have been carried out in normal faults crossing several decimetres to metre thick sedimentary alternations in the South-Eastern Basin (France) and petrophysical properties have been determined for each layer. The studied faults are simple fault planes or complex fault zones showing are significantly controlled by the layering. The analysis of the fault characteristics and the results obtained on numerical models enlighten several processes such as fault nucleation, fault restriction, and fault growth through layered section. Some studied faults nucleated in the limestone layers, without using pre-existing fractures such as joints, and according to our numerical analysis, a strong stiffness, a low strength contrast between the limestone and the clay layer, and/or s a greater thickness of the clay layer are conditions which favour nucleation of faults in limestone. The range of mechanical properties leading to the fault nucleation in one layer type or another was investigated using a 3D modelling approach. After its nucleation, the fault propagates within a homogeneous medium with a constant displacement gradient until its vertical propagation is stopped by a restrictor. The evidenced restrictors are limestone-clay interfaces or faults in clays, sub

  5. Cytotoxicity and mechanical behavior of chitin-bentonite clay based polyurethane bio-nanocomposites.

    Science.gov (United States)

    Zia, Khalid Mahmood; Zuber, Mohammad; Barikani, Mehdi; Hussain, Rizwan; Jamil, Tahir; Anjum, Sohail

    2011-12-01

    Chitin based polyurethane bio-nanocomposites (PUBNC) were prepared using chitin, Delite HPS bentonite nanoclay enriched in montmorillonite (MMT), 4,4'-diphenylmethane diisocyanate (MDI) and polycaprolactone polyol CAPA 231 (3000 g/mol(-1)). The prepolymers having different concentration of Delite HPS bentonite nanoclay were extended with 2 moles of chitin. The structures of the resulted polymers were determined by FT-IR technique. The effect of nanoclay contents on mechanical properties and in vitro biocompatibility was investigated. The mechanical properties of the synthesized materials were improved with increase in the Delite HPS bentonite nanoclay contents. Optimum mechanical properties were obtained from the PU bio-nanocomposite samples having 4% Delite HPS bentonite nanoclay. The results revealed that the final PU bio-nanocomposite having 2% Delite HPS bentonite nanoclay contents is ideal contenders for surgical threads with on going investigations into their in vitro biocompatibility, non-toxicity, and mechanical properties. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. Luminescent Oxygen Gas Sensors Based on Nanometer-Thick Hybrid Films of Iridium Complexes and Clay Minerals

    Directory of Open Access Journals (Sweden)

    Hisako Sato

    2014-01-01

    Full Text Available The use of Ir(III complexes in photo-responsive molecular devices for oxygen gas sensing is reviewed. Attention is focused on the immobilization of Ir(III complexes in organic or inorganic host materials such as polymers, silica and clays in order to enhance robustness and reliability. Our recent works on constructing nanometer-thick films comprised of cyclometalated cationic Ir(III complexes and clay minerals are described. The achievement of multi-emitting properties in response to oxygen pressure is demonstrated.

  7. Formulation and characterization of polyethylenes and organo-clays. Barrier properties of the obtained nano-composites; Formulation et caracterisation de polyethylenes charges avec des argiles. Proprietes barriere des nanocomposites obtenus

    Energy Technology Data Exchange (ETDEWEB)

    Wache, R

    2004-10-01

    The particularity of polymer layered silicate nano-composites is based on the exfoliation of the clay platelets in the polymer matrix. Therefore properties may be dramatically modified with very low clay loading. In this work polyethylene and organo-clay have been melt blended. Due to a lack of polarity, the polymer chains do not intercalate the clay stacking. However exfoliation is achieved using maleate polyethylene. We used this polymer as a compatibilizer to promote clay exfoliation in the polyethylene matrix. Partial exfoliation is obtained. Barrier properties of these materials have been characterized. Permeability is higher for the clay reinforced products than their matrix. To understand the poor permeability results a tortuosity model has been developed. The quality of the interface seems to be involved. Several organo-clays and compatibilizers have been tested to improve it. But for the concentrations of these products used polyethylene clay interactions always exist and lead to an increase of diffusion. (author)

  8. The modeling method of diffusion of radio activated materials in clay waste disposals

    Energy Technology Data Exchange (ETDEWEB)

    Saberi, Reza; Sepanloo, Kamran [NSTRI, Tehran (Iran, Islamic Republic of); Alinejad, Majid [Engineering Research Institute of Natural Hazard, Isfahan (Iran, Islamic Republic of); Mozaffari, Ali [KNT Univ. of Technology, Tehran (Iran, Islamic Republic of)

    2017-02-15

    New nuclear power plants are necessary to meet today's and future challenges of energy supply. Nuclear power is the only large-scale energy source that takes full responsibility for all its wastes. Nuclear wastes are particularly hazardous and hard to manage relative to different toxic industrial wastes. Three methods are presented and analysed to model the diffusion of the waste from the waste disposal to the bottom surface. For this purpose three software programmes such as ABAQUS, Matlab coding, Geostudio and ArcGIS have been applied.

  9. The modeling method of diffusion of radio activated materials in clay waste disposals

    International Nuclear Information System (INIS)

    Saberi, Reza; Sepanloo, Kamran; Alinejad, Majid; Mozaffari, Ali

    2017-01-01

    New nuclear power plants are necessary to meet today's and future challenges of energy supply. Nuclear power is the only large-scale energy source that takes full responsibility for all its wastes. Nuclear wastes are particularly hazardous and hard to manage relative to different toxic industrial wastes. Three methods are presented and analysed to model the diffusion of the waste from the waste disposal to the bottom surface. For this purpose three software programmes such as ABAQUS, Matlab coding, Geostudio and ArcGIS have been applied.

  10. The implementation of clay modeling and rat dissection into the human anatomy and physiology curriculum of a large urban community college.

    Science.gov (United States)

    Haspel, Carol; Motoike, Howard K; Lenchner, Erez

    2014-01-01

    After a considerable amount of research and experimentation, cat dissection was replaced with rat dissection and clay modeling in the human anatomy and physiology laboratory curricula at La Guardia Community College (LAGCC), a large urban community college of the City University of New York (CUNY). This article describes the challenges faculty overcame and the techniques used to solve them. Methods involved were: developing a laboratory manual in conjunction with the publisher, holding training sessions for faculty and staff, the development of instructional outlines for students and lesson plans for faculty, the installation of storage facilities to hold mannequins instead of cat specimens, and designing mannequin clean-up techniques that could be used by more than one thousand students each semester. The effectiveness of these curricular changes was assessed by examining student muscle practical examination grades and the responses of faculty and students to questionnaires. The results demonstrated that the majority of faculty felt prepared to teach using clay modeling and believed the activity was effective in presenting lesson content. Students undertaking clay modeling had significantly higher muscle practical examination grades than students undertaking cat dissection, and the majority of students believed that clay modeling was an effective technique to learn human skeletal, respiratory, and cardiovascular anatomy, which included the names and locations of blood vessels. Furthermore, the majority of students felt that rat dissection helped them learn nervous, digestive, urinary, and reproductive system anatomy. Faculty experience at LAGCC may serve as a resource to other academic institutions developing new curricula for large, on-going courses. © 2013 American Association of Anatomists.

  11. Clays in natural and engineered barriers for radioactive waste confinement - 4. International meeting. Book of abstracts

    International Nuclear Information System (INIS)

    2010-01-01

    proposed within the Strategic Research Agenda, elaborated through the Implementing Geological Disposal of Radioactive Waste Technology Platform (IGD-TP). The conference offers a particular opportunity to present the more recent developments and main outputs of research carried out within the framework of national and international cooperative experiments and dedicated European projects. Contributions coming from fields other than radioactive waste disposal; like geological storage of natural gas, sequestration of CO 2 , energy storage in underground, chemical waste isolation, etc., also taking advantage of the properties of the clay material, were encouraged. This conference covers all topics concerning the natural argillaceous geological barriers and the clay-based engineered barrier systems, investigated by means of: laboratory experiments on clay samples (new analytical developments), in situ experiments in underground research laboratories, mock-up demonstrations, natural analogues, as well as numerical modelling and global integration approaches (including up-scaling processes and treatment of uncertainties) and monitoring. General strategy for clay based repository concepts Examples of research programmes (national or international) concerning the role of natural and engineered clay barriers for radioactive waste confinement including repository designs, safety assessment, full-scale demonstrations and implementations (e.g. heater tests). Geology and clay characterisation Clay mineralogy, sedimentology, paleo-environment, diagenesis, dating techniques, discontinuities in clay rock, fracturing, self-sealing processes, role of organic matters and microbiological processes, micro and nano characterisation of clay minerals and argillaceous rocks. Geochemistry Pore water geochemistry, clay thermodynamics, chemical retention, geochemical modelling, advanced isotopic geochemistry. Mass transfer Water status and hydraulic properties in low permeability media, pore space

  12. Mars, clays and the origins of life

    Science.gov (United States)

    Hartman, Hyman

    1989-01-01

    To detect life in the Martian soil, tests were designed to look for respiration and photosynthesis. Both tests (labeled release, LR, and pyrolytic release, PR) for life in the Martian soils were positive. However, when the measurement for organic molecules in the soil of Mars was made, none were found. The interpretation given is that the inorganic constituents of the soil of Mars were responsible for these observations. The inorganic analysis of the soil was best fitted by a mixture of minerals: 60 to 80 percent clay, iron oxide, quartz, and soluble salts such as halite (NaCl). The minerals most successful in simulating the PR and LR experiments are iron-rich clays. There is a theory that considers clays as the first organisms capable of replication, mutation, and catalysis, and hence of evolving. Clays are formed when liquid water causes the weathering of rocks. The distribution of ions such as aluminum, magnesium, and iron play the role of bases in the DNA. The information was stored in the distribution of ions in the octahedral and tetrahedral molecules, but that they could, like RNA and DNA, replicate. When the clays replicated, each sheet of clay would be a template for a new sheet. The ion substitutions in one clay sheet would give rise to a complementary or similar pattern on the clay synthesized on its surface. It was theorized that it was on the surface of replicating iron-rich clays that carbon dioxide would be fixed in the light into organic acids such as formic or oxalic acid. If Mars had liquid water during a warm period in its past, clay formation would have been abundant. These clays would have replicated and evolved until the liquid water was removed due to cooling of Mars. It is entirely possible that the Viking mission detected life on Mars, but it was clay life that awaits the return of water to continue its evolution into life based on organic molecules.

  13. Project Opalinus clay Zuercher Weinland of Nagra. Evaluation of the geo-scientific data base and of the construction engineering aspects

    International Nuclear Information System (INIS)

    2005-02-01

    In this report the Commission for Nuclear Waste Management (KNE) assesses the geological and engineering aspects of the project Opalinus Clay, in which Nagra demonstrates the postclosure safety of geological disposal of spent fuel (SF), vitrified high-level wastes (HLW) and intermediate-level wastes (ILW) in a repository in the Opalinus Clay of the Zuercher Weinland in northern Switzerland. After in-depth examination of the geological database, KNE concludes that the demonstration of a suitable geological site for final disposal of SF, HLW and ILW in the Opalinus Clay of the Zuercher Weinland has been achieved. The geological assumptions Nagra uses for the assessment of long-term safety are based on data that have been carefully collected and interpreted. KNE acknowledges that Nagra interpreted the geological data correctly and adequately using state-of-the-art techniques. In case of lacking information, Nagra has used conservative or worst-case assumptions. The information documented by Nagra represents a good synthesis of field, laboratory and literature data. The tectonic situation of the Zuercher Weinland was examined in great details by Nagra. In the centre of the investigated region, where the Opalinus Clay occurs at 600 to 750 meters depth, the 3D-seismic data confirm its undisturbed stratification in an area of about 15 km 2 . Analysis and interpretation of the available information on the geological evolution provides no indication that erosion would expose the confining units above the Opalinus Clay within the next million years. The Opalinus Clay in the Zuercher Weinland is quite homogeneous and about 110 m thick. The properties of this rock are examined and found to be favourable for a repository. The dominance of the fine grain size and the high clay content indicate a very low hydraulic conductivity suitable for the isolation of radioactive wastes. Pore water extracted from drill-core samples is saline and has remained trapped for millions of years

  14. Novel environment friendly corrosion inhibitor pigments based on naturally occurring clay minerals

    Energy Technology Data Exchange (ETDEWEB)

    Bohm, S.; McMurray, H.N.; Worsley, D.A. [University of Wales, Swansea (United Kingdom). Dept. of Materials Engineering; Powell, S.M. [University of Wales, Swansea (United Kingdom). Engineering Doktorate Centre

    2001-12-01

    Novel, ceramic, corrosion inhibitor pigments consisting of cerium (III) and calcium (II) cation exchanged bentonites have been shown to provide effective cut-edge corrosion resistance in organic coated galvanised steel. The bentonite pigments were prepared from a naturally occurring (Wyoming) bentonite with a cation-exchange-capacity of 0.7 milli-equivalents per gram. Cation exchange was carried out by repeated washing with aqueous solutions of cerium (III) chloride and calcium (II) chloride to produce bentonites containing 31500 ppm exchangeable cerium (III) and 13500 ppm exchangeable calcium (II) respectively. The resulting bentonite pigments were dispersed in a polyester-resin based primer paint system to give a pigment volume concentration of 19%. For comparison, two similar primer systems were prepared containing a commercial calcium (II) exchanged silica pigment Shieldex: 60 000 ppm calcium (II) and a strontium chromate dispersion, both with a 19% pigment volume concentration. All three primer systems were applied (5 {mu}m) to the zinc surface of galvanised 0.7 mm gauge sheet steel and overcoated with an architectural polyester topcoat (18 {mu}m). The performance of the inhibitor pigments was compared by measuring the rate of corrosion-driven organic coating delamination from the cut edge of samples during 1000 h of salt-spray testing. The calcium (II) bentonite pigment exhibited an anti-delamination performance similar to that of strontium chromate but superior to that of Shieldex. However, the cerium (III) bentonite pigment was superior in performance to both strontium chromate and Shieldex. Thus, the bentonite pigments represent promising, environmentally friendly, ion-exchange corrosion inhibitors which exhibit good anti-delamination performance by comparison with current commercial systems. (orig.)

  15. Removal of bulk contaminants from radioactive waste water at Bruce A using a clay based flocculent system

    International Nuclear Information System (INIS)

    Davloor, R.; Harper, B.

    2011-01-01

    implement a clay-based flocculation Pre-Treatment System. In-service since late 2000, the system has been able to reliably treat a broad range of contaminants in the waste water before being sent to the downstream ROS. This clay-based system is unique in its application; it is able to remove bulk oil and grease, suspended solids, and metal contaminants in a waste stream that contains a high amount of surfactants originating from the laundering of plastic suits (personal protective equipment for working in radioactive environments) and other waste waters from the station. The treated water from the PTS consistently meets the strict requirements for subsequent treatment by the system RO membranes. This paper describes the laboratory and pilot scale testing that led to the development of the process, as well as the full scale implementation of this unique Pre-Treatment System. (author)

  16. Removal of bulk contaminants from radioactive waste water at Bruce A using a clay based flocculent system

    Energy Technology Data Exchange (ETDEWEB)

    Davloor, R.; Harper, B. [Bruce Power, Tiverton, ON (Canada)

    2011-07-01

    implement a clay-based flocculation Pre-Treatment System. In-service since late 2000, the system has been able to reliably treat a broad range of contaminants in the waste water before being sent to the downstream ROS. This clay-based system is unique in its application; it is able to remove bulk oil and grease, suspended solids, and metal contaminants in a waste stream that contains a high amount of surfactants originating from the laundering of plastic suits (personal protective equipment for working in radioactive environments) and other waste waters from the station. The treated water from the PTS consistently meets the strict requirements for subsequent treatment by the system RO membranes. This paper describes the laboratory and pilot scale testing that led to the development of the process, as well as the full scale implementation of this unique Pre-Treatment System. (author)

  17. Organo-clay/anthracite filtration for oil removal

    International Nuclear Information System (INIS)

    Moazed, H.; Viragahavan, T.

    1999-01-01

    An advantage of organo-clay compared to other sorbents is that it can selectively remove organic pollutants from contaminated waters. An investigation was conducted to determine the potential of an organo-clay/anthracite mixture as a filter media for the removal of oil from synthetic and real oily waters. Also included in the study were column filtration studies using synthetic and real waste waters to determine the sorptive capacity of the material. In general, oil removal efficiencies in a 300 mm organo-clay/anthracite bed decreased with an increase in flow rates. Results of eight hour studies indicated that the depth of an organo-clay/anthracite bed has a direct effect on oil removal efficiency. The Thomas equation provides a reasonable fit of the data based on breakthrough studies. The model can be used to determine the parameters needed to design full-scale filtration columns. The uptake of oil by an organo-clay/anthracite mixture is well described by an equation including time such as the Weber or Moris model. The maximum solid-phase concentration of the solute values obtained from the Thomas equation were comparable to the values found by a mass balance approach. 12 refs., 8 figs., 4 tabs

  18. The release of organic material from clay based buffer materials and its potential implications for radionuclide transport

    International Nuclear Information System (INIS)

    Vilks, P.; Stroes-Gascoyne, S.; Goulard, M.; Haveman, S.A.; Bachinski, D.B.

    1998-01-01

    In the Canadian nuclear fuel waste disposal concept used fuel would be placed in corrosion resistant containers which would be surrounded by clay-based buffer and backfill materials in an engineered vault excavated at 500 to 1000 m depth in crystalline rock formations in the Canadian shield. Organic substances could affect radionuclide mobility due to the effects of redox and complexation reactions that increase solubility and alter mobility. The purpose of this study was to determine whether the buffer and backfill materials, proposed for use in a disposal vault, contain organics that could be leached by groundwater in large enough quantities to affect radionuclide mobility within the disposal vault and surrounding geosphere complex. Buffer material, made from a mixture of 50 wt.% Avonlea sodium bentonite and 50 wt.% silica sand, was extracted with deionized water to determine the release of dissolved organic carbon (DOC), humic acid and fulvic acid. The effect of radiation and heat from the used fuel was simulated by treating samples of buffer before leaching to various amounts of heat (60 and 90 C) for periods of 2, 4 and 6 weeks, and to ionizing radiation with doses of 25 kGy and 50 kGy. The results showed that groundwater would leach significant amounts of organics from buffer that complex with radionuclides such as the actinides, potentially affecting their solubility and transport within the disposal vault and possibly the surrounding geosphere. In addition, the leached organics would likely stimulate microbial growth by several orders of magnitude. Heating and radiation affect the amount and nature of leachable organics. (orig.)

  19. Poly(N-isopropylacrylamide)–clay based hydrogels controlled by the initiating conditions: evolution of structure and gel formation

    Czech Academy of Sciences Publication Activity Database

    Strachota, Beata; Matějka, Libor; Zhigunov, Alexander; Konefal, Rafal; Spěváček, Jiří; Dybal, Jiří; Puffr, Rudolf

    2015-01-01

    Roč. 11, č. 48 (2015), s. 9291-9306 ISSN 1744-683X R&D Projects: GA ČR(CZ) GAP108/12/1459; GA ČR(CZ) GA13-23392S Institutional support: RVO:61389013 Keywords : thermoresponsive hydrogel * hybrid nanocomposite * polymer clay hydrogel Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.798, year: 2015

  20. Hygrothermal behavior for a clay brick wall

    Science.gov (United States)

    Allam, R.; Issaadi, N.; Belarbi, R.; El-Meligy, M.; Altahrany, A.

    2018-06-01

    In Egypt, the clay brick is the common building materials which are used. By studying clay brick walls behavior for the heat and moisture transfer, the efficient use of the clay brick can be reached. So, this research studies the hygrothermal transfer in this material by measuring the hygrothermal properties and performing experimental tests for a constructed clay brick wall. We present the model for the hygrothermal transfer in the clay brick which takes the temperature and the vapor pressure as driving potentials. In addition, this research compares the presented model with previous models. By constructing the clay brick wall between two climates chambers with different boundary conditions, we can validate the numerical model and analyze the hygrothermal transfer in the wall. The temperature and relative humidity profiles within the material are measured experimentally and determined numerically. The numerical and experimental results have a good convergence with 3.5% difference. The surface boundary conditions, the ground effect, the infiltration from the closed chambers and the material heterogeneity affects the results. Thermal transfer of the clay brick walls reaches the steady state very rapidly than the moisture transfer. That means the effect of using only the external brick wall in the building in hot climate without increase the thermal resistance for the wall, will add more energy losses in the clay brick walls buildings. Also, the behavior of the wall at the heat and mass transfer calls the three-dimensional analysis for the whole building to reach the real behavior.

  1. Hygrothermal behavior for a clay brick wall

    Science.gov (United States)

    Allam, R.; Issaadi, N.; Belarbi, R.; El-Meligy, M.; Altahrany, A.

    2018-01-01

    In Egypt, the clay brick is the common building materials which are used. By studying clay brick walls behavior for the heat and moisture transfer, the efficient use of the clay brick can be reached. So, this research studies the hygrothermal transfer in this material by measuring the hygrothermal properties and performing experimental tests for a constructed clay brick wall. We present the model for the hygrothermal transfer in the clay brick which takes the temperature and the vapor pressure as driving potentials. In addition, this research compares the presented model with previous models. By constructing the clay brick wall between two climates chambers with different boundary conditions, we can validate the numerical model and analyze the hygrothermal transfer in the wall. The temperature and relative humidity profiles within the material are measured experimentally and determined numerically. The numerical and experimental results have a good convergence with 3.5% difference. The surface boundary conditions, the ground effect, the infiltration from the closed chambers and the material heterogeneity affects the results. Thermal transfer of the clay brick walls reaches the steady state very rapidly than the moisture transfer. That means the effect of using only the external brick wall in the building in hot climate without increase the thermal resistance for the wall, will add more energy losses in the clay brick walls buildings. Also, the behavior of the wall at the heat and mass transfer calls the three-dimensional analysis for the whole building to reach the real behavior.

  2. Iodide uptake by negatively charged clay interlayers?

    Science.gov (United States)

    Miller, Andrew; Kruichak, Jessica; Mills, Melissa; Wang, Yifeng

    2015-09-01

    Understanding iodide interactions with clay minerals is critical to quantifying risk associated with nuclear waste disposal. Current thought assumes that iodide does not interact directly with clay minerals due to electrical repulsion between the iodide and the negatively charged clay layers. However, a growing body of work indicates a weak interaction between iodide and clays. The goal of this contribution is to report a conceptual model for iodide interaction with clays by considering clay mineral structures and emergent behaviors of chemical species in confined spaces. To approach the problem, a suite of clay minerals was used with varying degrees of isomorphic substitution, chemical composition, and mineral structure. Iodide uptake experiments were completed with each of these minerals in a range of swamping electrolyte identities (NaCl, NaBr, KCl) and concentrations. Iodide uptake behaviors form distinct trends with cation exchange capacity and mineral structure. These trends change substantially with electrolyte composition and concentration, but do not appear to be affected by solution pH. The experimental results suggest that iodide may directly interact with clays by forming ion-pairs (e.g., NaI(aq)) which may concentrate within the interlayer space as well as the thin areas surrounding the clay particle where water behavior is more structured relative to bulk water. Ion pairing and iodide concentration in these zones is probably driven by the reduced dielectric constant of water in confined space and by the relatively high polarizability of the iodide species. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Removal of Phenol in Aqueous Solution Using Kaolin Mineral Clay

    International Nuclear Information System (INIS)

    Sayed, M.S.

    2008-01-01

    Kaolin clay were tested for phenol removal as toxic liquid waste from aqueous waste water. Several experimental conditions such as weight and particle size of clay were investigated to study batch kinetic techniques, also the ph and concentration of the phenol solution were carried out. The stability of the Langmuir adsorption model of the equilibrium data were studied for phenol sorbent clay system. Infrared spectra, thermogravimetric and differential thermal analysis techniques were used to characterize the behavior of kaolin clay and kaolin clay saturated with phenol. The results obtained showed that kaolin clay could be used successfully as an efficient sorbent material to remove phenol from aqueous solution

  4. The influence of clay minerals on acoustic properties of sandstones

    Energy Technology Data Exchange (ETDEWEB)

    Hansen, Olav

    1997-12-31

    This thesis aims to provide better understanding of the relationship between the acoustic properties and the petrophysical/mineralogical properties in sand-prone rock. It emphasizes the influence of clay minerals. The author develops a method to deposit clay minerals/mineral aggregates in pore space of a rigid rock framework. Kaolinite aggregates were flushed into porous permeable Bentheimer sandstone to evaluate the effect of pore filling minerals on porosity, permeability and acoustic properties. The compressional velocity was hardly affected by the clay content and it was found that the effect of minor quantities of pore filling minerals may be acoustically modelled as an ideal suspension, where the pore fluid bulk modulus is modified by the bulk modulus of the clay minerals. The influence of clays on acoustic velocities in petroleum reservoir rocks was investigated through ultrasonic measurements of compressional- and shear-waves on core material from reservoir and non-reservoir units on the Norwegian Continental Shelf. The measured velocities decrease as the porosity increases, but are not strongly dependent on the clay content. The measured velocities are less dependent on the petrophysical and lithological properties than indicated by previous authors and published mathematical models, and stiffness reduction factors are introduced in two of the models to better match the data. Velocities are estimated along the wellbores based on non-sonic well logs and reflect well the actual sonic log well measurements. In some wells the compressional velocity cannot be modelled correctly by the models suggested. Very high compressional wave anisotropy was measured in the dry samples at atmospheric conditions. As the samples were saturated, the anisotropy was reduced to a maximum of about 30% and decreases further upon pressurization. Reservoir rocks retrieved from 2500 m are more stress dependent than those retrieved from less than 200 m depth. 168 refs., 117 figs., 24

  5. Sensitivity of the acid-base properties of clays to the methods of preparation and measurement. 2. Evidence from continuous potentiometric titrations.

    Science.gov (United States)

    Duc, Myriam; Gaboriaud, Fabien; Thomas, Fabien

    2005-09-01

    The effects of experimental procedures on the acid-base consumption titration curves of montmorillonite suspension were studied using continuous potentiometric titration. For that purpose, the hysteresis amplitudes between the acid and base branches were found to be useful to systematically evaluate the impacts of storage conditions (wet or dried), the atmosphere in titration reactor, the solid-liquid ratio, the time interval between successive increments, and the ionic strength. In the case of storage conditions, the increase of the hysteresis was significantly higher for longer storage of clay in suspension and drying procedures compared to "fresh" clay suspension. The titration carried out under air demonstrated carbonate contamination that could only be cancelled by performing experiments under inert gas. Interestingly, the increase of the time intervals between successive increments of titrant strongly emphasized the amplitude of hysteresis, which could be correlated with the slow kinetic process specifically observed for acid addition in acid media. Thus, such kinetic behavior is probably associated with dissolution processes of clay particles. However, the resulting curves recorded at different ionic strengths under optimized conditions did not show the common intersection point required to define point of zero charge. Nevertheless, the ionic strength dependence of the point of zero net proton charge suggested that the point of zero charge of sodic montmorillonite could be estimated as lower than 5.

  6. Experimental investigation of virus and clay particles cotransport in partially saturated columns packed with glass beads.

    Science.gov (United States)

    Syngouna, Vasiliki I; Chrysikopoulos, Constantinos V

    2015-02-15

    Suspended clay particles in groundwater can play a significant role as carriers of viruses, because, depending on the physicochemical conditions, clay particles may facilitate or hinder the mobility of viruses. This experimental study examines the effects of clay colloids on the transport of viruses in variably saturated porous media. All cotransport experiments were conducted in both saturated and partially saturated columns packed with glass beads, using bacteriophages MS2 and ΦX174 as model viruses, and kaolinite (KGa-1b) and montmorillonite (STx-1b) as model clay colloids. The various experimental collision efficiencies were determined using the classical colloid filtration theory. The experimental data indicated that the mass recovery of viruses and clay colloids decreased as the water saturation decreased. Temporal moments of the various breakthrough concentrations collected, suggested that the presence of clays significantly influenced virus transport and irreversible deposition onto glass beads. The mass recovery of both viruses, based on total effluent virus concentrations, was shown to reduce in the presence of suspended clay particles. Furthermore, the transport of suspended virus and clay-virus particles was retarded, compared to the conservative tracer. Under unsaturated conditions both clay particles facilitated the transport of ΦX174, while hindered the transport of MS2. Moreover, the surface properties of viruses, clays and glass beads were employed for the construction of classical DLVO and capillary potential energy profiles, and the results suggested that capillary forces play a significant role on colloid retention. It was estimated that the capillary potential energy of MS2 is lower than that of ΦX174, and the capillary potential energy of KGa-1b is lower than that of STx-1b, assuming that the protrusion distance through the water film is the same for each pair of particles. Moreover, the capillary potential energy is several orders of

  7. Wetland eco-engineering: Measuring and modeling feedbacks of oxidation processes between plants and clay-rich material

    NARCIS (Netherlands)

    Saaltink, R.; Dekker, S.C.; Griffioen, J.; Wassen, M.J.

    2016-01-01

    Interest is growing in using soft sediment as a foundation in eco-engineering projects. Wetland construction in the Dutch lake Markermeer is an example: here, dredging some of the clay-rich lake-bed sediment and using it to construct wetland will soon begin. Natural processes will be utilized during

  8. Experimental and modeling study of flash calcination of kaolinite rich clay particles in a gas suspension calciner

    DEFF Research Database (Denmark)

    Gebremariam, Abraham Teklay; Yin, Chungen; Rosendahl, Lasse

    2015-01-01

    gas suspension calciner, with the aim to derive useful guidelines on smart calcination for obtaining products of the best pozzolanic properties. Calcination tests are performed in the calciner under six different operation conditions. The raw feed and the calcined clay samples are all characterized...

  9. Human Clay Models versus Cat Dissection: How the Similarity between the Classroom and the Exam Affects Student Performance

    Science.gov (United States)

    Waters, John R.; Van Meter, Peggy; Perrotti, William; Drogo, Salvatore; Cyr, Richard J.

    2011-01-01

    This study examined the effect of different anatomic representations on student learning in a human anatomy class studying the muscular system. Specifically, we examined the efficacy of using dissected cats (with and without handouts) compared with clay sculpting of human structures. Ten undergraduate laboratory sections were assigned to three…

  10. Constitutive relationships for elastic deformation of clay rock: Data Analysis

    International Nuclear Information System (INIS)

    Liu, H.H.; Rutqvist, J.; Birkholzer, J.T.

    2011-01-01

    Geological repositories have been considered a feasible option worldwide for storing high-level nuclear waste. Clay rock is one of the rock types under consideration for such purposes, because of its favorable features to prevent radionuclide transport from the repository. Coupled hydromechanical processes have an important impact on the performance of a clay repository, and establishing constitutive relationships for modeling such processes are essential. In this study, we propose several constitutive relationships for elastic deformation in indurated clay rocks based on three recently developed concepts. First, when applying Hooke's law in clay rocks, true strain (rock volume change divided by the current rock volume), rather than engineering strain (rock volume change divided by unstressed rock volume), should be used, except when the degree of deformation is very small. In the latter case, the two strains will be practically identical. Second, because of its inherent heterogeneity, clay rock can be divided into two parts, a hard part and a soft part, with the hard part subject to a relatively small degree of deformation compared with the soft part. Third, for swelling rock like clay, effective stress needs to be generalized to include an additional term resulting from the swelling process. To evaluate our theoretical development, we analyze uniaxial test data for core samples of Opalinus clay and laboratory measurements of single fractures within macro-cracked Callovo-Oxfordian argillite samples subject to both confinement and water reduced swelling. The results from this evaluation indicate that our constitutive relationships can adequately represent the data and explain the related observations.

  11. Constitutive relationships for elastic deformation of clay rock: Data Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Liu, H.H.; Rutqvist, J.; Birkholzer, J.T.

    2011-04-15

    Geological repositories have been considered a feasible option worldwide for storing high-level nuclear waste. Clay rock is one of the rock types under consideration for such purposes, because of its favorable features to prevent radionuclide transport from the repository. Coupled hydromechanical processes have an important impact on the performance of a clay repository, and establishing constitutive relationships for modeling such processes are essential. In this study, we propose several constitutive relationships for elastic deformation in indurated clay rocks based on three recently developed concepts. First, when applying Hooke's law in clay rocks, true strain (rock volume change divided by the current rock volume), rather than engineering strain (rock volume change divided by unstressed rock volume), should be used, except when the degree of deformation is very small. In the latter case, the two strains will be practically identical. Second, because of its inherent heterogeneity, clay rock can be divided into two parts, a hard part and a soft part, with the hard part subject to a relatively small degree of deformation compared with the soft part. Third, for swelling rock like clay, effective stress needs to be generalized to include an additional term resulting from the swelling process. To evaluate our theoretical development, we analyze uniaxial test data for core samples of Opalinus clay and laboratory measurements of single fractures within macro-cracked Callovo-Oxfordian argillite samples subject to both confinement and water reduced swelling. The results from this evaluation indicate that our constitutive relationships can adequately represent the data and explain the related observations.

  12. Concrete-Opalinus clay interaction

    International Nuclear Information System (INIS)

    Jenni, A.; Maeder, U.; Lerouge, C.; Gaboreau, S.; Schwyn, B.

    2012-01-01

    Document available in extended abstract form only. Designs for deep geologic disposal of radioactive waste foresee cementitious materials as structural elements, backfill or waste matrix. Therefore, studies of interactions between cement and all other materials involved are important. Interactions are mostly driven by chemical gradients in pore water and might lead to mineralogical alterations in the barrier system, which in turn influence properties like swelling pressure, permeability, or specific retention in case of clay materials. Existing laboratory and in-situ studies using clay-stone revealed significant alteration in both cement and clay-stone. Phase dissolution, precipitation, and carbonation, were found to cause an overall porosity increase in the cement with a possible decrease close to the interface, and clogging in the clay-stone [2]. Most of the work was done on cement pastes rather than concretes to avoid analytical complications caused by aggregates, and the scale of investigation was chosen in the range of centimetres rather than micrometers. The Cement-Clay Interaction (CI) experiment at the Mont Terri Underground Laboratory (St. Ursanne, Switzerland) aims at replicating some of the processes at interfaces to be expected.For this purpose, two vertical cylindrical boreholes (384 mm diameter, up to 10 m length) in Opalinus Clay (OPA) were filled with layers of three different concretes and bentonite. The concrete formulations are based on common aggregate content and grain size distributions, combined with three different cements: Portland cement (OPC), ESDRED cement especially designed for repository applications (40% of cement substituted with silica fume), and low alkali cement (LAC, containing slag and nano-silica).In this study, we present a characterisation of the three concrete-OPA interfaces after two years of alteration and deduce possible mechanisms. Backscattered electron (BE) imaging and energy dispersive spectrum (EDX) element mapping

  13. Modelling the evolution of compacted bentonite clays in engineered barrier systems: process model development of the bentonite-water-air system

    International Nuclear Information System (INIS)

    Bond, A.E.; Wilson, J.C.; Maul, P.R.; Robinson, P.C.; Savage, D.

    2010-01-01

    Document available in extended abstract form only. An adequate understanding of the short- and long-term evolution of compacted bentonite clays in engineered barrier systems (EBS) for radioactive waste based on the KBS-3 disposal concept is an essential requirement for demonstrating the safe performance of the system. Uncertainties in the way that the re-saturation process occurs are intrinsically tied to the thermal and mechanical evolution of the bentonite buffer and its interaction with the disposal canister and host-rock. Furthermore, the evolution of bentonite in the presence of changing ambient saturation states, groundwater chemistry and stress states could cause the bentonite re-saturation and long-term stability (including the so-called 'buffer erosion scenario') to deviate from the behaviour required by the safety case; this has emphasised the need to consider adequately coupled thermal (T), hydraulic(H), mechanical (M) and chemical (C) processes. Historically, there have been fundamental differences in the representation of porosity and water disposition between geochemical modelling and coupled THM modelling studies. In this paper, a model for the porosity and water disposition in bentonite is presented that is more detailed than models used to date in most THM modelling studies under variably saturated conditions. The new model moves away from the conventional THM soils approach which treats bentonite as an elasto-plastic porous medium with water or air occupying a notional porosity with the inclusion of additional process models to take into account the very high observed water suctions, intrinsic permeability variation and macroscopic swelling of partially saturated compacted bentonite. It replaces the empirical parameterisation usually employed in THM models with a direct representation of the water disposition, pore structure and relevant processes, albeit at an abstracted level. The new model differentiates between water which can be

  14. Thermal and mechanical properties of palm oil-based polyurethane acrylate/clay nanocomposites prepared by in-situ intercalative method and electron beam radiation

    International Nuclear Information System (INIS)

    Salih, A. M.; Ahmad, Mansor Bin; Ibrahim, Nor Azowa; Dahlan, Khairul Zaman Hj Mohd; Tajau, Rida; Mahmood, Mohd Hilmi; Yunus, Wan Md. Zin Wan

    2014-01-01

    Palm oil based-polyurethane acrylate (POBUA)/clay nanocomposites were prepared via in-situ intercalative polymerization using epoxidized palm oil acrylate (EPOLA) and 4,4' methylene diphenyl diisocyante (MDI). Organically modified Montmorillonite (ODA-MMT) was incorporated in EPOLA (1, 3 and 5%wt), and then subjected to polycondensation reaction with MDI. Nanocomposites solid films were obtained successfully by electron beam radiation induced free radical polymerization (curing). FTIR results reveal that the prepolymer was obtained successfully, with nanoclay dispersed in the matrix. The intercalation of the clay in the polymer matrix was investigated by XRD and the interlayer spacing of clay was found to be increased up to 37 Å, while the structure morphology of the nanocomposites was investigated by TEM and SEM. The nanocomposites were found to be a mixture of exfoliated and intercalated morphologies. The thermal stability of the nanocomposites was significantly increased by incorporation of nanoclay into the polymer matrix. DSC results reveal that the Tg was shifted to higher values, gradually with increasing the amount of filler in the nanocomposites. Tensile strength and Young's modulus of the nanocomposites showed remarkable improvement compared to the neat POBUA

  15. Thermal and mechanical properties of palm oil-based polyurethane acrylate/clay nanocomposites prepared by in-situ intercalative method and electron beam radiation

    Energy Technology Data Exchange (ETDEWEB)

    Salih, A. M. [Department of Chemistry, Faculty of Science, University Putra Malaysia 43400, UPM, Serdang, Selangor, Malaysia and Department of Radiation Processing, Sudan Atomic Energy Commission, Khartoum 1111 (Sudan); Ahmad, Mansor Bin; Ibrahim, Nor Azowa [Department of Chemistry, Faculty of Science, University Putra Malaysia 43400, UPM, Serdang, Selangor (Malaysia); Dahlan, Khairul Zaman Hj Mohd [Polycomposite Sdn Bhd, No.75-2, Jalan TKS 1, Taman Kajang Sentral, 43000 Kajang, Selangor (Malaysia); Tajau, Rida [Radiation Processing Technology Division, Nuclear Malaysia, Bangi, 43000 Kajang, Selangor (Malaysia); Mahmood, Mohd Hilmi [No. 107, Jalan 2, Taman Kajang Baru, Sg Jelok, 43000 Kajang, Selangor (Malaysia); Yunus, Wan Md. Zin Wan [Department of Chemistry, Centre for Defence Foundation Studies, National Defence University of Malaysia, 57000, Sungai Besi Camp, Kuala Lumpur (Malaysia)

    2014-02-12

    Palm oil based-polyurethane acrylate (POBUA)/clay nanocomposites were prepared via in-situ intercalative polymerization using epoxidized palm oil acrylate (EPOLA) and 4,4' methylene diphenyl diisocyante (MDI). Organically modified Montmorillonite (ODA-MMT) was incorporated in EPOLA (1, 3 and 5%wt), and then subjected to polycondensation reaction with MDI. Nanocomposites solid films were obtained successfully by electron beam radiation induced free radical polymerization (curing). FTIR results reveal that the prepolymer was obtained successfully, with nanoclay dispersed in the matrix. The intercalation of the clay in the polymer matrix was investigated by XRD and the interlayer spacing of clay was found to be increased up to 37 Å, while the structure morphology of the nanocomposites was investigated by TEM and SEM. The nanocomposites were found to be a mixture of exfoliated and intercalated morphologies. The thermal stability of the nanocomposites was significantly increased by incorporation of nanoclay into the polymer matrix. DSC results reveal that the Tg was shifted to higher values, gradually with increasing the amount of filler in the nanocomposites. Tensile strength and Young's modulus of the nanocomposites showed remarkable improvement compared to the neat POBUA.

  16. A Damage Constitutive Model for the Effects of CO2-Brine-Rock Interactions on the Brittleness of a Low-Clay Shale

    Directory of Open Access Journals (Sweden)

    Qiao Lyu

    2018-01-01

    Full Text Available CO2 is a very promising fluid for drilling and nonaqueous fracturing, especially for CO2-enhanced shale gas recovery. Brittleness is a very important characteristic to evaluate the drillability and fracability. However, there is not much relevant research works on the influence of CO2 and CO2-based fluids on shale’s brittleness been carried out. Therefore, a series of strength tests were conducted to obtain the stress-strain characteristics of shale soaked in different phases of CO2 including subcritical or supercritical CO2 with formation of water for different time intervals (10 days, 20 days, and 30 days. Two damage constitutive equations based on the power function distribution and Weibull distribution were established to predict the threshold stress for both intact and soaked shale samples. Based on the results, physical and chemical reactions during the imbibition cause reductions of shales’ peak axial strength (20.79%~61.52% and Young’s modulus (13.14%~62.44%. Weibull distribution-based constitutive model with a damage threshold value of 0.8 has better agreement with the experiments than that of the power function distribution-based constitutive model. The energy balance method together with the Weibull distribution-based constitutive model is applied to calculate the brittleness values of samples with or without soaking. The intact shale sample has the highest BI value of 0.9961, which is in accordance with the high percentage of brittleness minerals of the shale samples. The CO2-NaCl-shale interactions during the imbibition decrease the brittleness values. Among the three soaking durations, the minimum brittleness values occur on samples with 20 days’ imbibition in subcritical and supercritical CO2 + NaCl solutions and the reductions of which are 2.08% and 2.49%, respectively. Subcritical/supercritical CO2 + NaCl imbibition has higher effect on shale’s strength and Young’s modulus than on the brittleness. The

  17. Iodide uptake by negatively charged clay interlayers?

    International Nuclear Information System (INIS)

    Miller, Andrew; Kruichak, Jessica; Mills, Melissa; Wang, Yifeng

    2015-01-01

    Understanding iodide interactions with clay minerals is critical to quantifying risk associated with nuclear waste disposal. Current thought assumes that iodide does not interact directly with clay minerals due to electrical repulsion between the iodide and the negatively charged clay layers. However, a growing body of work indicates a weak interaction between iodide and clays. The goal of this contribution is to report a conceptual model for iodide interaction with clays by considering clay mineral structures and emergent behaviors of chemical species in confined spaces. To approach the problem, a suite of clay minerals was used with varying degrees of isomorphic substitution, chemical composition, and mineral structure. Iodide uptake experiments were completed with each of these minerals in a range of swamping electrolyte identities (NaCl, NaBr, KCl) and concentrations. Iodide uptake behaviors form distinct trends with cation exchange capacity and mineral structure. These trends change substantially with electrolyte composition and concentration, but do not appear to be affected by solution pH. The experimental results suggest that iodide may directly interact with clays by forming ion-pairs (e.g., NaI (aq) ) which may concentrate within the interlayer space as well as the thin areas surrounding the clay particle where water behavior is more structured relative to bulk water. Ion pairing and iodide concentration in these zones is probably driven by the reduced dielectric constant of water in confined space and by the relatively high polarizability of the iodide species. - Highlights: • Iodide sorption experiments were completed with a diverse array of clay minerals. • Iodide uptake trended with CEC and swamping electrolyte identity and concentration. • Results can be explained by considering the formation of ion pairs in clay interlayers

  18. Characterization of groundwater dynamics in landslides in varved clays

    NARCIS (Netherlands)

    Van der Spek, J.E.; Bogaard, T.A.; Bakker, M.

    2013-01-01

    Groundwater dynamics may play a significant role in landslides. A detailed model is developed of the groundwater dynamics in landslides in varved clays in the Trièves area in the French Alps. The varved clays consist of a sequence of alternating silt and clay layers, covered by a colluvium layer and

  19. Characterization of groundwater dynamics in landslides in varved clays

    NARCIS (Netherlands)

    Van der Spek, J.E.; Bogaard, T.A.; Bakker, M.

    2013-01-01

    Groundwater dynamics may play a significant role in landslides. A detailed model is developed of the groundwater dynamics in landslides in varved clays in the Trieves area in the French Alps. The varved clays consist of a sequence of alternating silt and clay layers, covered by a colluvium layer and

  20. Water and clay based drilling fluids: rheologic, filtration and lubricity behavior; Fluidos hidroargilosos: comportamento reologico, de filtracao e lubricidade

    Energy Technology Data Exchange (ETDEWEB)

    Amorim, Luciana V.; Pereira, Melquesedek S.; Ferreira, Heber C. [Universidade Federal de Campina Grande (UFCG), PB (Brazil)

    2008-07-01

    The aim of this work is to provide continuity for UFCG studies presenting results of rheological, filtration and the lubricity behaviors obtained with fluids prepared with bentonite clays from Paraiba, in binary compositions, after treatment with lubricants agents. It was selected two samples of bentonite clays and four lubricants (Lub 1, Lub 2, Lub 3 and Lub 4). The results showed that: depending on the composition, the drilling fluids presented bingham and pseudo plastic rheological behaviors, and with the additives bingham behavior; among the rheological and filtration properties evaluated, the apparent viscosity, yield limiting and the water loss are the have changes with the addition of lubricants; the values of the lubricity coefficient (LC) of fluids without additives were next of 0.50, independent of the composition of the bentonite clay mixture; after addition of the lubricants, the LC of fluids reduced for values next to 0,11, independent of its concentration and lubricants the best-performing are the Lub 2 and Lub 4. (author)

  1. Effect of addition of organo clay on mechanical properties and dynamic-mechanical based TPV; Preparacao de termoplasticos vulcanizados dinamicamente (TPV) de NBR/PP com nanocargas de argila

    Energy Technology Data Exchange (ETDEWEB)

    Honorato, Luciana R.; Silva, Adriana A.; Soares, Bluma G. [Universidade Federal do Rio de Janeiro - UFRJ, Instituto de Macromoleculas Professora Eloisa Mano, Rio de Janeiro, RJ (Brazil); Soares, Ketly P. [Centro Universitario do Leste de Minas Gerais (UNILESTEMG) - Coronel Fabriciano, MG (Brazil)

    2011-07-01

    The effect of organophilic clay on the mechanical and dynamical-mechanical properties of thermoplastic elastomers based on polypropylene (PP) and nitrile rubber (NBR) was investigated. The addition of clay was performed from a master batch prepared by a solution intercalation of NBR inside the clay galleries. Since the PP/NBR blend is highly incompatible, PP functionalized with maleic anhydride (PP-g-MA) and carboxylated NBR (XNBR) were employed as compatibilizing system together with triethylene-tetramine (TETA) used as coupling agent. The addition of Clay inside the elastomeric phase of the TPV resulted in a significant decrease of the elongation at break without changes on the tensile strength. The presence of clay also promoted a slight increase of the storage modulus and the glass transition temperature. The small angle X ray scattering confirmed the high dispersion of clay inside the TPV. Analysis of light scattering small angle (SAXS) confirmed the high dispersion of clay in the matrix of the TPV. (author)

  2. Common clay and shale

    Science.gov (United States)

    Virta, R.L.

    2000-01-01

    Part of the 1999 Industrial Minerals Review. The clay and shale market in 1999 is reviewed. In the U.S., sales or use of clay and shale increased from 26.4 million st in 1998 to 27.3 million st in 1999, with an estimated 1999 value of production of $143 million. These materials were used to produce structural clay products, lightweight aggregates, cement, and ceramics and refractories. Production statistics for clays and shales and for their uses in 1999 are presented.

  3. Modelling Aqueous Solubility of Sodium Chloride in Clays at Thermodynamic Conditions of Hydraulic Fracturing by Molecular Simulations.

    Czech Academy of Sciences Publication Activity Database

    Moučka, Filip; Svoboda, Martin; Lísal, Martin

    2017-01-01

    Roč. 19, JUL 7 (2017), s. 16586-16599 ISSN 1463-9076 R&D Projects: GA ČR(CZ) GA16-12291S EU Projects: European Commission(XE) 640979 - ShaleXenvironmenT Institutional support: RVO:67985858 Keywords : molecular simulation * Monte Carlo (GCMC) technique * clay pores Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 4.123, year: 2016

  4. Enrichment and activation of smectite-poor clay

    Energy Technology Data Exchange (ETDEWEB)

    Sarcevica, Inese; Kostjukovs, Juris; Actint, Andris, E-mail: inese.sarcevicha@gmail.com [Department of Chemistry, University of Latvia, Kr. Valdemara street 48, Riga (Latvia)

    2011-06-23

    A new method of smectite clay enrichment has been developed. The method is based on dispersing clay in a phosphate solution and sequential coagulation. The product of enrichment is characterized with X-ray powder diffraction, wavelength dispersive X-ray fluorescence spectrometry, differential thermal analysis and thermogravimetry. Sorption of methylene blue and hexadecylpyridinium bromide on raw and purified clays was studied.

  5. Clay nanoparticles for regenerative medicine and biomaterial design: A review of clay bioactivity.

    Science.gov (United States)

    Mousa, Mohamed; Evans, Nicholas D; Oreffo, Richard O C; Dawson, Jonathan I

    2018-03-01

    Clay nanoparticles, composites and hydrogels are emerging as a new class of biomaterial with exciting potential for tissue engineering and regenerative medicine applications. Clay particles have been extensively explored in polymeric nanocomposites for self-assembly and enhanced mechanical properties as well as for their potential as drug delivery modifiers. In recent years, a cluster of studies have explored cellular interactions with clay nanoparticles alone or in combination with polymeric matrices. These pioneering studies have suggested new and unforeseen utility for certain clays as bioactive additives able to enhance cellular functions including adhesion, proliferation and differentiation, most notably for osteogenesis. This review examines the recent literature describing the potential effects of clay-based nanomaterials on cell function and examines the potential role of key clay physicochemical properties in influencing such interactions and their exciting possibilities for regenerative medicine. Copyright © 2018 Elsevier Ltd. All rights reserved.

  6. Discrete analysis of clay layer tensile strength

    International Nuclear Information System (INIS)

    Le, T.N.H.; Ple, O.; Villard, P.; Gourc, J.P.

    2010-01-01

    The Discrete Element Method is used to investigate the tensile behaviour and cracks mechanisms of a clay material submitted to bending loading. It is the case of compacted clay liners in landfill cap cover application. Such as the soil tested in this study is plastic clay, the distinct elements model was calibrated with previous data results by taking into account cohesive properties. Various contact and cohesion laws are tested to show that the numerical model is able to reproduce the failure mechanism. Numerical results are extending to simulate a landfill cap cover and comparing to experimental large scale field bending tests achieved in a real site of storage. (authors)

  7. Physicochemical analysis of clays and ceramics of the regional state of Calakmul: production models, distribution and consumption; Analisis fisicoquimico de arcillas y ceramicos del estado regional de Calakmul: modelos de produccion, distribucion y consumo

    Energy Technology Data Exchange (ETDEWEB)

    Dominguez C, M.R.; Folan, W.J. [Centro de Investigaciones Historicas y Sociales, Universidad Autonoma de Campeche, Campeche (Mexico); Espinosa P, M.E. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico); Rodriguez L, V. [CUV, BUAP, 72000 Puebla (Mexico)

    2005-07-01

    This work presents the final results of the research project 'Sources, production and consumption of ceramics in the regional state of Calakmul: a socio-political approach', with the proposal of models of production and ceramic specialization as well as of distribution and consumption of these goods in the territory that occupied the regional state of Calakmul, with base in the typological analysis of the ceramics of Calakmul and 72 sites registered in its environs as well as in comparative studies with ceramics of other greater sites near Calakmul and complemented with the application of analytical techniques in the study of clays and sherds diagnoses of the Mayan Classic period. These models were proposed also, according to a socio-political approach based on the social and political relations that Calakmul maintained with other political entities of diverse ranks derived from the obtained epigraphic evidences. (Author)

  8. Clay Portrait Boxes

    Science.gov (United States)

    Wilbert, Nancy Corrigan

    2009-01-01

    In an attempt to incorporate sculptural elements into her ceramics program, the author decided to try direct plaster casting of the face to make a plaster mold for clay. In this article, the author shares an innovative ceramics lesson that teaches students in making plaster casts and casting the face in clay. This project gives students the…

  9. Columns in Clay

    Science.gov (United States)

    Leenhouts, Robin

    2010-01-01

    This article describes a clay project for students studying Greece and Rome. It provides a wonderful way to learn slab construction techniques by making small clay column capitols. With this lesson, students learn architectural vocabulary and history, understand the importance of classical architectural forms and their influence on today's…

  10. pillared and un-pillared bentonite clays

    African Journals Online (AJOL)

    BARTH EKWUEME

    2011-07-29

    Jul 29, 2011 ... A pseudo-second order kinetic model was used to characterize the metal ion transport ... may endanger human health through consumption of sea food and ... widely reported. The pillared clays are two – dimensional zeolite.

  11. Organoclay hybrid materials as precursors of porous ZnO/silica-clay heterostructures for photocatalytic applications

    Directory of Open Access Journals (Sweden)

    Marwa Akkari

    2016-12-01

    Full Text Available In this study, ZnO/SiO2-clay heterostructures were successfully synthesized by a facile two-step process applied to two types of clays: montmorillonite layered silicate and sepiolite microfibrous clay mineral. In the first step, intermediate silica–organoclay hybrid heterostructures were prepared following a colloidal route based on the controlled hydrolysis of tetramethoxysilane in the presence of the starting organoclay. Later on, pre-formed ZnO nanoparticles (NP dispersed in 2-propanol were incorporated under ultrasound irradiation to the silica–organoclay hybrid heterostructures dispersed in 2-propanol, and finally, the resulting solids were calcinated to eliminate the organic matter and to produce ZnO nanoparticles (NP homogeneously assembled to the clay–SiO2 framework. In the case of montmorillonite the resulting materials were identified as delaminated clays of ZnO/SiO2-clay composition, whereas for sepiolite, the resulting heterostructure is constituted by the assembling of ZnO NP to the sepiolite–silica substrate only affecting the external surface of the clay. The structural and morphological features of the prepared heterostructures were characterized by diverse physico-chemical techniques (such as XRD, FTIR, TEM, FE-SEM. The efficiency of these new porous ZnO/SiO2-clay heterostructures as potential photocatalysts in the degradation of organic dyes and the removal of pharmaceutical drugs in water solution was tested using methylene blue and ibuprofen compounds, respectively, as model of pollutants.

  12. Primordial clays on Mars formed beneath a steam or supercritical atmosphere.

    Science.gov (United States)

    Cannon, Kevin M; Parman, Stephen W; Mustard, John F

    2017-12-06

    On Mars, clay minerals are widespread in terrains that date back to the Noachian period (4.1 billion to 3.7 billion years ago). It is thought that the Martian basaltic crust reacted with liquid water during this time to form hydrated clay minerals. Here we propose, however, that a substantial proportion of these clays was formed when Mars' primary crust reacted with a dense steam or supercritical atmosphere of water and carbon dioxide that was outgassed during magma ocean cooling. We present experimental evidence that shows rapid clay formation under conditions that would have been present at the base of such an atmosphere and also deeper in the porous crust. Furthermore, we explore the fate of a primordial clay-rich layer with the help of a parameterized crustal evolution model; we find that the primordial clay is locally disrupted by impacts and buried by impact-ejected material and by erupted volcanic material, but that it survives as a mostly coherent layer at depth, with limited surface exposures. These exposures are similar to those observed in remotely sensed orbital data from Mars. Our results can explain the present distribution of many clays on Mars, and the anomalously low density of the Martian crust in comparison with expectations.

  13. Feasibility study of development a pressuremeter for use in stiff to hard clays for land based site investigations

    International Nuclear Information System (INIS)

    1983-03-01

    Existing borehole pressuremeters and jacks have been reviewed for suitability in light of the requirements for testing to depths of 350 metres in hard clays and soft rocks to provide geotechnical information for repository design. Since no currently available device is suitable for immediate use in this application, recommendations have been made for the development work necessary to achieve a satisfactory pressuremeter instrument. Drilling and instrument insertion procedures have also been reviewed and it has been concluded that a wireline system is the most appropriate. Development costs are detailed for the provision of a prototype high pressure pressuremeter testing package. (author)

  14. Mechanical interaction between swelling compacted clay and fractured rock, and the leaching of clay colloids

    NARCIS (Netherlands)

    Grindrod, P.; Peletier, M.A.; Takase, H.

    1999-01-01

    We consider the interaction between a saturated clay buffer layer and a fractured crystalline rock engineered disturbed zone. Once saturated, the clay extrudes into the available rock fractures, behaving as a compressible non-Newtonian fluid. We discuss the modelling implications of published

  15. LOUIS I. KAHN, EL PAISAJE TELÚRICO Y LAS MAQUETAS DE ARCILLA / Louis I. Kahn, the telluric landscape and clay models

    Directory of Open Access Journals (Sweden)

    José María Jové Sandoval

    2016-11-01

    Full Text Available RESUMEN Kahn siempre mantuvo una especial conexión con el paisaje reconociéndose desde muy temprano en sus dibujos y pinturas, especialmente en sus bocetos de viaje. Él forjó una idea de un paisaje telúrico, formado por el moldeado del suelo en conjunción con la arquitectura; para trabajarlo y transmitirlo encontraría un instrumento muy eficaz: las maquetas de arcilla. Estos peculiares modelos surgieron a partir del año 1961, cuando se produjo la colaboración con el escultor Isamu Noguchi en el Levy Memorial Playground. A partir de aquel momento la arcilla será el material omnipresente en la producción de maquetas a gran escala en la oficina de Kahn; en ellas se abordaban y se concretaban las ideas generales. Estos modelos de arcilla hablan del vínculo de sus propuestas con el paisaje, con la orografía y con el orden subyacente que su arquitectura establece con el sitio, expresada a través de lo que podríamos denominar protoedificios. Este trabajo con la arcilla será reflejo también de un significado más profundo experimentado en sus viajes a la India que lo vinculan al sentido más atávico de aquellas culturas con el trabajo de sustracción y acumulación de la tierra, un paisaje telúrico donde el hombre impone la huella de su presencia. SUMMARY Kahn always had a special connection with landscape, recognizable in his drawings and paintings from early on, especially in his travel sketches. He forged the idea of a telluric landscape, formed by terrain sculpting along with architecture; to work on this and transmit it, he would find a most effective tool: clay models. These distinctive models came into existence in 1961, when he collaborated with the sculptor Isamu Noguchi on the Levy Memorial Playground. From then on, clay would be ubiquitous in the large-scale models in Kahn's office; he approached and materialized his general ideas in them. These clay mock-ups reflect how he linked his purposes to landscape, to orography

  16. Clay particles as binder for earth buildings materials: a fresh look into rheology of dense clay suspensions

    Directory of Open Access Journals (Sweden)

    Landrou Gnanli

    2017-01-01

    Full Text Available In the ceramic industry and in many sectors, clay minerals are widely used. In earthen construction technique, clay plays a crucial role in the processing. The purpose of this research is to understand and modify the clay properties in earth material to propose an innovative strategy to develop a castable earth-based material. To do so, we focused on the modification of clay properties at fresh state with inorganic additives. As the rheological behaviour of clays is controlled by their surface charge, the addition of phosphate anion allows discussing deep the rheology of concentrated clay suspensions. We highlighted the thixotropic and shear thickening behaviour of a dispersed kaolinite clay suspensions. Indeed, by adding sodium hexametaphosphate the workability of clay paste increases and the behaviour is stable during time after a certain shear is applied. Moreover, we stress that the aging and the shift in critical strain in clay system are due to the re-arrangement of clay suspension and a decrease of deformation during time. The understanding of both effect: thixotropy and aging are crucial for better processing of clay-based material and for self-compacting clay concrete. Yet, studies need to pursue to better understand the mechanism.

  17. Clay particles as binder for earth buildings materials: a fresh look into rheology of dense clay suspensions

    Science.gov (United States)

    Landrou, Gnanli; Brumaud, Coralie; Habert, Guillaume

    2017-06-01

    In the ceramic industry and in many sectors, clay minerals are widely used. In earthen construction technique, clay plays a crucial role in the processing. The purpose of this research is to understand and modify the clay properties in earth material to propose an innovative strategy to develop a castable earth-based material. To do so, we focused on the modification of clay properties at fresh state with inorganic additives. As the rheological behaviour of clays is controlled by their surface charge, the addition of phosphate anion allows discussing deep the rheology of concentrated clay suspensions. We highlighted the thixotropic and shear thickening behaviour of a dispersed kaolinite clay suspensions. Indeed, by adding sodium hexametaphosphate the workability of clay paste increases and the behaviour is stable during time after a certain shear is applied. Moreover, we stress that the aging and the shift in critical strain in clay system are due to the re-arrangement of clay suspension and a decrease of deformation during time. The understanding of both effect: thixotropy and aging are crucial for better processing of clay-based material and for self-compacting clay concrete. Yet, studies need to pursue to better understand the mechanism.

  18. EPR monitoring of the bioavailability of an organic xenobiotic (4-hydroxy-TEMPO) in model clay suspensions and pastes

    Energy Technology Data Exchange (ETDEWEB)

    Dumestre, Alain [Laboratory of Geoenvironmental Science and Engineering, Bradfield Hall, Cornell University, Ithaca, NY 14853 (United States); Spagnuolo, Matteo [Dipartimento di Biologia e Chimica Agro-forestale ed Ambientale, Universita degli Studi di Bari, via Amendola 165/a, 70126 Bari (Italy); Bladon, Rebecca [158 Kottinger Drive, Pleasanton, CA (United States); Berthelin, Jacques [CNRS-LIMOS Laboratoire des Interactions Microorganismes-Mineraux-Matieres Organiques, UMR 7137 du CNRS, Universite Henri Poincare, B.P. 239, F-54506 Vandoeuvre les Nancy (France); Baveye, Philippe [Laboratory of Geoenvironmental Science and Engineering, Bradfield Hall, Cornell University, Ithaca, NY 14853 (United States)]. E-mail: philippe.baveye@cornell.edu

    2006-09-15

    Electron paramagnetic resonance spectroscopy is used to monitor the bioavailability of a nitroxide spin probe, 4-hydroxy-Tempo or Tempol, in Ca-hectorite suspensions and pastes, to bacteria capable of degrading this probe co-metabolically. In nutrient solutions with an initial probe concentration of 1.2 mM and in the absence of hectorite, bacteria are able to denature Tempol and eliminate its paramagnetic signal within 48 h. In the presence of hectorite and after flocculation, the effect of bacteria is significantly delayed, but almost complete denaturation still occurs, after roughly 120 h. When hectorite is added but the bacterial/clay suspension is not centrifuged, Tempol denaturation levels off after about 24 h and reaches a plateau with approximately 45% of Tempol remaining. This plateau does not constitute evidence of limited bioavailability, as is widely assumed, since subsequent addition of nutrients causes the denaturation reaction to proceed to a second plateau, with merely 10% of Tempol remaining. - Spectroscopic data demonstrate that the bioavailability of an organic compound in clay suspensions and pastes strongly depends on conditions that affect bacterial metabolism.

  19. Thermomechanical behaviour of boom clay

    International Nuclear Information System (INIS)

    Sultan, N.; Delage, P.; Cui, Y.J.

    2000-01-01

    Special attention has been recently paid on temperature effects on the behaviour of deep saturated clays, in relation with nuclear deep waste storage. However, few experimental data are presently available, and existing constitutive models need to be completed. This note is aimed at completing, both experimentally and theoretically, the understanding of the effects of the over-consolidation ration on the thermal volume changes of Boom clay (Belgium). The experimental data obtained here are in a good agreement with existing data. As a complement to existing data, they are used to develop a new elastoplastic model. The adoption of a second coupled plastic mechanism provides good simulations on a complex thermo-mechanical path. (authors)

  20. Physical and numerical modelings of lateral drag in a pipeline in very soft clay; Modelagens fisica e numerica de arraste lateral de duto em argila mole

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Jose Renato M.S.; Almeida, Maria C.F.; Almeida, Marcio S.S. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia; Borges, Ricardo G.; Amaral, Claudio S. [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil). Centro de Pesquisas

    2005-07-01

    This paper discusses some results from a joint research project undertaken by COPPE/UFRJ and CENPES/PETROBRAS about soil-structure interaction applied to thermal snaking of shallowly buried pipelines embedded in very soft clay. At this phase, the lateral soil reaction due to pipeline horizontal displacements was studied by means of physical and numerical modeling. In that way, a set of comprehensive centrifuge tests has been undertaken using a 1:30 scaled pipe dragged laterally, varying the burial depth condition. The soil used for the tests is a very soft clay sample collected at the Duque de Caxias Refinery area in Rio de Janeiro. The vertical and horizontal displacements of the pipe were imposed by computer-controlled actuators, with soil reaction forces being measured on both directions. The physical modeling results were compared with numerical simulations of the same centrifuge scenarios using the software AEEPECD, developed by PETROBRAS, showing good agreement in terms of horizontal and vertical soil reactions. (author)

  1. Characterization of clay minerals

    International Nuclear Information System (INIS)

    Diaz N, C.; Olguin, M.T.; Solache R, M.; Alarcon H, T.; Aguilar E, A.

    2002-01-01

    The natural clays are the more abundant minerals on the crust. They are used for making diverse industrial products. Due to the adsorption and ion exchange properties of these, a great interest for developing research directed toward the use of natural clays for the waste water treatment has been aroused. As part of such researches it is very important to carry out previously the characterization of the interest materials. In this work the results of the mineral and elemental chemical composition are presented as well as the morphological characteristics of clay minerals from different regions of the Mexican Republic. (Author)

  2. Coupled modelling (transport-reaction) of the fluid-clay interactions and their feed back on the physical properties of the bentonite engineered clay barrier system; Modelisation couplee (transport - reaction) des interactions fluides - argiles et de leurs effets en retour sur les proprietes physiques de barrieres ouvragees en bentonite

    Energy Technology Data Exchange (ETDEWEB)

    Marty, N

    2006-11-15

    The originality of this work is to process feed back effects of mineralogical and chemical modifications of clays, in storage conditions, on their physical properties and therefore on their transport characteristics (porosity, molecular diffusion, permeability). These feed back effects are modelled using the KIRMAT code (Kinetic of Reaction and MAss Transfer) developed from the kinetic code KINDIS by adding the effect of water renewal in the mineral-solution reactive cells. KIRMAT resolves mass balance equations associated with mass transport together with the geochemical reactions in a 1D approach. After 100 000 years of simulated interaction at 100 C, with the fluid of the Callovo-Oxfordian geological level (COX) and with iron provided by the steel overpack corrosion, the montmorillonite of the clay barrier is only partially transformed (into illite, chlorite, saponite...). Only outer parts of the modelled profile seem to be significantly affected by smectite dissolution processes, mainly at the interface with the geological environment. The modifications of physical properties show a closure of the porosity at the boundaries of the barrier, by creating a decrease of mass transport by molecular diffusion, essentially at the interface with the iron. Permeability laws applied to this system show a decrease of the hydraulic conductivity correlated with the porosity evolution. Near the COX, the swelling pressure of the clays from the barrier decreases. In the major part of the modelled profile, the engineered clay barrier system seems to keep its initial physical properties (porosity, molecular diffusion, permeability, swelling pressure) and functionalities. (author)

  3. Technetium migration in Boom Clay - Assessing the role of colloid-facilitated transport in a deep clay formation

    International Nuclear Information System (INIS)

    Bruggeman, C.; Martens, E.; Maes, N.; Jacops, E.; Van Gompel, M.; Van Ravestyn, L.

    2010-01-01

    independent study on the migration of natural organic matter was used to extract migration parameters. This independent study relied on both lab-scale and in situ large-scale migration experiments with 14 C-labelled NOM which were performed over a period of 15 years. A classic diffusion-advection equation, including a colloid filtration term and/or non-linear sorption, simulated the experimental data quite well and could also account for the anisotropy of the Boom Clay formation. By using information from independent experiments on processes that were assumed to occur upon transport of Tc through the Boom Clay formation, the degree of freedom of the model was seriously constrained. All parameters used in the reactive transport model (Tc solubility, complexation with inorganic ligands, stability constant for the 'colloid-colloid' interaction process, solid-solution distribution coefficient of aqueous inorganic Tc species) were either taken from established thermodynamic data sources, or from published data of batch experiments. Only the first-order kinetic rate that accounted for slow decoupling of the Tc colloid and the organic matter colloids was fitted. An accurate model simulation could be obtained both for the Tc concentration in the outflowing solution, and the Tc tracer profile across the clay cores used in the setup. The good accuracy between the reactive transport model, batch experimental data and the experimental percolation data shows that the conceptual model is strong enough to handle different types of experimental setups, and allows to make interpolations for different geochemical conditions. Moreover, the model was adapted to make predictions of Tc migration as a NOM-associated colloid over the entire height of the overlying formation. Based on these predictions, we are now able to assess the potential for colloid-facilitated transport of radionuclides by dissolved NOM in Boom Clay. (authors)

  4. Modelling of the physico-chemical behaviour of clay minerals with a thermo-kinetic model taking into account particles morphology in compacted material.

    Science.gov (United States)

    Sali, D.; Fritz, B.; Clément, C.; Michau, N.

    2003-04-01

    Modelling of fluid-mineral interactions is largely used in Earth Sciences studies to better understand the involved physicochemical processes and their long-term effect on the materials behaviour. Numerical models simplify the processes but try to preserve their main characteristics. Therefore the modelling results strongly depend on the data quality describing initial physicochemical conditions for rock materials, fluids and gases, and on the realistic way of processes representations. The current geo-chemical models do not well take into account rock porosity and permeability and the particle morphology of clay minerals. In compacted materials like those considered as barriers in waste repositories, low permeability rocks like mudstones or compacted powders will be used : they contain mainly fine particles and the geochemical models used for predicting their interactions with fluids tend to misjudge their surface areas, which are fundamental parameters in kinetic modelling. The purpose of this study was to improve how to take into account the particles morphology in the thermo-kinetic code KINDIS and the reactive transport code KIRMAT. A new function was integrated in these codes, considering the reaction surface area as a volume depending parameter and the calculated evolution of the mass balance in the system was coupled with the evolution of reactive surface areas. We made application exercises for numerical validation of these new versions of the codes and the results were compared with those of the pre-existing thermo-kinetic code KINDIS. Several points are highlighted. Taking into account reactive surface area evolution during simulation modifies the predicted mass transfers related to fluid-minerals interactions. Different secondary mineral phases are also observed during modelling. The evolution of the reactive surface parameter helps to solve the competition effects between different phases present in the system which are all able to fix the chemical

  5. Numerical simulation of the time-dependent deformation behaviour of clay-stone rock mass at the Tournemire site with 2D and 3D models

    International Nuclear Information System (INIS)

    Rutenberg, M.; Lux, K.H.

    2010-01-01

    Document available in extended abstract form only. Modern repository research foregrounds physico-chemical processes (mechanical, hydraulic, thermal, chemical) and their interactions taking place in the near field and the far field of the geological system being explored. With regard to load bearing behaviour and preservation of barrier integrity, and with the general objective of complete confinement of the waste in the isolating rock zone, the focus is especially on geomechanical processes induced by excavation - including the influences on and by hydraulic, thermal, and chemical processes - as well as on thermal processes induced by heat generation of the deposited radioactive waste and their effects on mechanical and hydraulic processes. In order to improve assessments of the mechanical stability and, in case of a water saturated rock formation, of the hydraulic effects on the host rock of the repository, suitable physical models for numerical simulations of rock and rock mass behaviour have to be found and to be validated. Because of their radionuclide retention capacity, their low water permeability, and their resistance to water, clay-stone rock masses form a reasonable alternative to e.g. salt rock masses as a host rock for deep geological repositories. In past decades, various working groups at an international level have elaborated a broad experimental and theoretical understanding of the geomechanical and geo-hydraulic behaviour of clay-stones and applied this know-how to geologic repository components, e.g. in the context of engineering studies, or in the back-analysis of field tests. In this context, measurement results revealed a continuing convergence of drift walls lasting for a few years after completion of excavation. Possible reasons for this time-dependent deformation behaviour of the clay-stone rock mass might be: - viscous properties of the material from a phenomenological point of view, meaning a constant stress state leading to increasing

  6. Effect of the addition of expanded vermiculite in the technological properties of ceramic materials of clay base

    International Nuclear Information System (INIS)

    Lins, R.R.F.; Peixoto, R.S. Dutra; Macedo, D.A.; Nascimento, R.M.; Oliveira, G.V.M.; Universidade Federal da Paraiba

    2016-01-01

    This paper discusses the effects of adding expanded vermiculite ceramic block made from two different types of clay and analysis of the properties for three compositions at different sintering temperatures. Samples pressed at 40 MPa were sintered between 800 and 1100 ° C. The technological properties were determined according to the sintering temperature. The evaluation of the crystalline phases and microstructure was carried out by X-ray diffraction results indicated that with the addition of expanded vermiculite in the specimens there was an increase in porosity of the blocks together with the water absorption, therefore a reduction in apparent density, as well as the breakdown voltage of the three-point bending. This study demonstrates the possibility of formulating ceramic blocs order to improve the insulating properties of these materials. (author)

  7. Compressibility characteristics of Sabak Bernam Marine Clay

    Science.gov (United States)

    Lat, D. C.; Ali, N.; Jais, I. B. M.; Baharom, B.; Yunus, N. Z. M.; Salleh, S. M.; Azmi, N. A. C.

    2018-04-01

    This study is carried out to determine the geotechnical properties and compressibility characteristics of marine clay collected at Sabak Bernam. The compressibility characteristics of this soil are determined from 1-D consolidation test and verified by existing correlations by other researchers. No literature has been found on the compressibility characteristics of Sabak Bernam Marine Clay. It is important to carry out this study since this type of marine clay covers large coastal area of west coast Malaysia. This type of marine clay was found on the main road connecting Klang to Perak and the road keeps experiencing undulation and uneven settlement which jeopardise the safety of the road users. The soil is indicated in the Generalised Soil Map of Peninsular Malaysia as a CLAY with alluvial soil on recent marine and riverine alluvium. Based on the British Standard Soil Classification and Plasticity Chart, the soil is classified as a CLAY with very high plasticity (CV). Results from laboratory test on physical properties and compressibility parameters show that Sabak Bernam Marine Clay (SBMC) is highly compressible, has low permeability and poor drainage characteristics. The compressibility parameters obtained for SBMC is in a good agreement with other researchers in the same field.

  8. Cross flow microfiltration of oil-water emulsions using clay based ceramic membrane support and TiO2 composite membrane

    Directory of Open Access Journals (Sweden)

    Kanchapogu Suresh

    2017-09-01

    Full Text Available The main objective of this work is to study the effect of cross flow filtration conditions on the separation of oily wastewater using ceramic support and TiO2 membrane. Firstly, the low cost clay based ceramic membrane support was prepared by uniaxial compaction method using combination of pyrophyllite, quartz, feldspar, kaolin, ball clay and calcium carbonate along with PVA as a binder. Subsequently, TiO2 composite membrane was fabricated via hydrothermal route employing TiO2 sol derived from TiCl4 and NH4OH solution. Cross flow microfiltration investigations were carried out by utilizing oil-water emulsion concentration of 200 mg/L at three distinct applied pressures (69–207 kPa and three cross flow velocities (0.0885, 0.1327, and 0.1769 m/s. Compared to ceramic support, TiO2 composite membrane demonstrates better performance in terms of flux and removal efficiency of oil and also the rate of flux decline during filtration operation is lower due to highly hydrophilic surface of the TiO2 membrane. TiO2 membrane displays the oil removal efficiency of 99% in the entire range of applied pressures investigation, while ceramic support shows 93–96% of oil removal.

  9. Mass Transfer Behavior of Perfluorinated Chemicals in Saturated Clay-rich Sands: A Laboratory-based Study on Fate and Transport in Groundwater and Sediments

    Science.gov (United States)

    Greenberg, R. R.; Tick, G. R.; Abbott, J. B., III; Carroll, K. C.

    2017-12-01

    Perfluoroalkyl substances (PFAS) are a class of emerging contaminants that pose a threat to the human health and the quality of groundwater, surface water, and drinking water supplies. This study aims to elucidate the primary physicochemical factors controlling the fate and transport of the PFAS contaminants, perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), in groundwater. Physicochemical processes of intercalation, adsorption, and desorption were investigated for the retention of PFAS at different initial aqueous-phase concentrations in modified-natural sediments composed of sand (40/50 accusand; foc = 0.04% unmodified) with low, medium, and high organic carbon contents (foc = 10, 20, and 50%) and various pre-conditioned clay-fractions. Diffusional mass-transfer limitations were evaluated based on initial PFAS concentration, specific clay structure, and resulting contaminant intercalation (d-spacing changes). A series of short- (48 hr), medium- (7 day) and long-term (30 day) batch and column experiments were conducted to determine physicochemical processes as a function of compound chemistry, sediment geochemistry, sorbent crystalline structure, and contaminant/sediment contact-time. Physicochemical parameters, PFAS concentrations, and sediment characterization were conducted using high performance liquid chromatography (HPLC), X-ray diffraction (XRD), and furnace combustion analytical techniques. The results of PFAS contaminant transport, under the different conditions tested, provide a scientific contribution with application to the development of improved risk assessments, predictions of fate and transport, and more effective remediation strategies for emerging perfluorinated contaminants in soil and groundwater.

  10. Processes of cation migration in clay-rocks: Final Scientific Report of the CatClay European Project

    International Nuclear Information System (INIS)

    Altmann, S.; Aertsens, M.; Appelo, T.; Bruggeman, C.; Gaboreau, S.; Glaus, M.; Jacquier, P.; Kupcik, T.; Maes, N.; Montoya, V.; Rabung, T.; Robinet, J.-C.; Savoye, S.; Schaefer, T.; Tournassat, C.; Van Laer, L.; Van Loon, L.

    2015-07-01

    illite and clay rocks, even though some assumptions made have to be verified. In parallel, actual 3D geometrical pore size distributions of compacted illite, and in less extent, clay rock samples, were successfully determined by combining TEM and FIB-nt analyses on materials maintained in a water-like saturation state by means of an extensive impregnation step. Based on this spatial distribution of pores, first numerical diffusion experiments were carried at the pore scale through virtual illite, enabling a better understanding of how transfer pathways are organized in the porous media. Finally, the EC CatClay project allowed a better understanding of the migration of strongly sorbing tracers through low permeability 'clay rock' formations, increasing confidence in our capacity to demonstrate that the models used to predict radionuclide migration through these rocks are scientifically sound. (authors)

  11. Hydro-mechanical properties of the red salt clay (T4) - Natural analogue of a clay barrier

    International Nuclear Information System (INIS)

    Minkley, W.; Popp, T.; Salzer, K.; Gruner, M.; Boettge, V.

    2010-01-01

    Document available in extended abstract form only. Long-term storage of high-level radioactive waste in deep geologic formations is worldwide the only accepted solution to warranty long term safety. Besides clay and crystalline rocks, salt is one of the potential host-rock candidates, mainly favored in Germany. As salts rocks are highly soluble their barrier integrity against water inflow from the cap rock is questionable. Argillaceous cap rocks or intercalated clay layers may act as protective shield in the hanging wall above a repository, thus providing a multi-barrier system. The aims of our study are twofold: 1) to characterize the mineralogical, hydraulic and rock-mechanical properties of the so-called Red Salt Clay (T4) as natural analogue of a clay barriers represented by different states of induration corresponding to various depth of burial diagenesis; 2) to demonstrate the favoured barrier properties of an argillaceous layer in the top of a salt formation undergoing dynamic processes such as rock bursts. The so-called Red Salt Clay (T4) is deposited as clay rich clastic sediment at the base of the Aller-series forming a persistent lateral layer above the lower Zechstein-series. The thickness of the clay-formation becomes smaller with decreasing distance from the border of the basin, i.e. from ∼15 m at Rossleben, over 7 m at Bernburg to 3.5 m at Zielitz, all in Saxony-Anhalt, D). The mineralogical composition of the Red Salt Clay varies, e.g. average composition for the Teutschenthal area: clay minerals 54% (Chlorite: 8%; Illite/Muscovite: 46%); quartz: 22%; anhydrite: 15%; accessory gypsum; Halite: 6%, Hematite: ∼ 2%). The geochemical and mineralogical composition of the Red Salt Clay represents a final state of natural salt-clay-systems, thus standing as a natural analogue for bentonite-based sealing systems in contact with high-saline solutions (e.g. saturated NaCl-solution, solutions with various Mg 2+ -, K + -, SO 4 2- - concentrations). The

  12. Sorption of Pu onto some kinds of clay

    International Nuclear Information System (INIS)

    Jia Haihong; Si Gaohua; Liu Wei; Yu Jing

    2010-01-01

    There are rich clay mines holding in one area, so it's necessary to know about these clays' sorption capacity to Pu, for building radioactive waste repository in the area. Distribution coefficients of Pu onto different clays were acquired in static method, with the result about 104. The size of clay is different, but the result of Kds is near. In addition, it's estimated how far Pu moves in the most rapid speed in the clay based on these Kids', disregarding the influence of Pu-colloid. In a word, as a kind of backfilling material clays in the area can effectively prevent Pu from moving to environment, and when designing the backfilling layer, it's not necessary to catch clays through NO.200 sieve, if only considering the influence of Kd. (authors)

  13. Impact of operating variables on re-refining of vehicle waste oil to base-oil by acid-clay process

    International Nuclear Information System (INIS)

    Durrani, H.A.; Panhwar, M.I.; Kazi, R.A.

    2009-01-01

    A large volume of waste oil is generated each year as the number of vehicles in the country is increasing every day. This used lubricant oil constitutes a serious pollution problem. It easily be converted as a resource depending on the manners of utilization and management. This paper compares various end uses of waste oil and develops technology by which basic properties of the base oil can be regained. An experimental setup (Experimental rig) of acid-clay method was used to regain waste oil collected and number of experiments were conducted by varying different process variables. The impacts of the operating variables on the quality of re-refined oil are also discussed. The recovery of re-refined base oil was found in between 44-49%. (author)

  14. Thixotropic Properties of Latvian Clays

    OpenAIRE

    Lakevičs, Vitālijs; Stepanova, Valentīna; Ruplis, Augusts

    2015-01-01

    This research studies Latvia originated Devon (Tūja, Skaņkalne), quaternary (Ceplīši), Jurassic, (Strēļi) and Triassic (Vadakste) deposit clays as well as Lithuania originated Triassic (Akmene) deposit clays. Thixotropic properties of clay were researched by measuring relative viscosity of clay in water suspensions. Relative viscosity is measured with a hopper method. It was detected that, when concentration of suspension is increased, clay suspension’s viscosity also increases. It happens un...

  15. Influence of Polymer-Clay Interfacial Interactions on the Ignition Time of Polymer/Clay Nanocomposites.

    Science.gov (United States)

    Zope, Indraneel S; Dasari, Aravind; Yu, Zhong-Zhen

    2017-08-11

    Metal ions present on smectite clay (montmorillonite) platelets have preferential reactivity towards peroxy/alkoxy groups during polyamide 6 (PA6) thermal decomposition. This changes the decomposition pathway and negatively affects the ignition response of PA6. To restrict these interfacial interactions, high-temperature-resistant polymers such as polyetherimide (PEI) and polyimide (PI) were used to coat clay layers. PEI was deposited on clay by solution-precipitation, whereas PI was deposited through a solution-imidization-precipitation technique before melt blending with PA6. The absence of polymer-clay interfacial interactions has resulted in a similar time-to-ignition of PA6/PEI-clay (133 s) and PA6/PI-clay (139 s) composites as neat PA6 (140 s). On the contrary, PA6 with conventional ammonium-based surfactant modified clay has showed a huge drop in time-to-ignition (81 s), as expected. The experimental evidences provided herein reveal the role of the catalytic activity of clay during the early stages of polymer decomposition.

  16. Influence of clay environment and of corroding canister on the long-term behaviour of nuclear glasses

    International Nuclear Information System (INIS)

    GIn, St.

    1997-01-01

    This article reviews the current state of knowledge of R77 glass alteration mechanisms in the presence of the clay materials under consideration for use in an engineered barrier, and in the presence of metal canister corrosion products. These issues are addressed by a phenomenological approach and by modeling. In most cases, the codes are unable to account for the glass alteration data obtained in clay media. The main reason for this discrepancy lies in the glass alteration kinetics (a first-order law based exclusively on silicon) that do not take into account other elements including aluminum, zirconium or the rare earths, which are strongly mobilized in clay media. (author)

  17. Analysis of cement-treated clay behavior by micromechanical approach

    OpenAIRE

    Zhang , Dong-Mei; Yin , Zhenyu; Hicher , Pierre Yves; Huang , Hong-Wei

    2013-01-01

    International audience; Experimental results show the significant influence of cement content on the mechanical properties of cement-treated clays. Cementation is produced by mixing a certain amount of cement with the saturated clay. The purpose of this paper is to model the cementation effect on the mechanical behavior of cement-treated clay. A micromechanical stress-strain model is developed considering explicitly the cementation at inter-cluster contacts. The inter-cluster bonding and debo...

  18. The geochemical behaviour of selenium in the Boom Clay system - a XANES and EXAFS study

    International Nuclear Information System (INIS)

    2S, KULeuven, B-3001Leuven (Belgium))" data-affiliation=" (Center for surface Chemistry and Catalysis - M2S, KULeuven, B-3001Leuven (Belgium))" >Breynaert, Eric; 2S, KULeuven, B-3001Leuven (Belgium))" data-affiliation=" (Center for surface Chemistry and Catalysis - M2S, KULeuven, B-3001Leuven (Belgium))" >Dom, Dirk; 2S, KULeuven, B-3001Leuven (Belgium))" data-affiliation=" (Center for surface Chemistry and Catalysis - M2S, KULeuven, B-3001Leuven (Belgium))" >Vancluysen, Jacqueline; 2S, KULeuven, B-3001Leuven (Belgium))" data-affiliation=" (Center for surface Chemistry and Catalysis - M2S, KULeuven, B-3001Leuven (Belgium))" >Kirschhock, Christine E.A.; 2S, KULeuven, B-3001Leuven (Belgium))" data-affiliation=" (Center for surface Chemistry and Catalysis - M2S, KULeuven, B-3001Leuven (Belgium))" >Maes, Andre; Scheinost, Andreas C.

    2010-01-01

    Document available in extended abstract form only. In Belgium, the Boom Clay formation is studied as a reference host formation for the geological disposal of high-level and long-lived radioactive waste for more than 30 years. This formation mainly consists of mixed clay minerals (illite, inter-stratified illite-smectite), pyrite and immobile and dissolved natural organic matter. Since it provides good sorption capacities, very low permeability, and chemically reducing conditions due to the presence of pyrite (FeS 2 ), the Boom clay formation itself is considered to be the main barrier preventing radionuclide migration from the geological repository. Within this concept for geological storage Se 79 has been identified as one of the critical elements contributing to the final dose to man. Although the sorption and migration behaviour of Se in the Boom Clay system has been thoroughly studied, the speciation of Se in the Boom Clay system has never been identified spectroscopically. In all previous studies, the interpretation of the behaviour of Se in Boom Clay conditions has always been based on circumstantial evidence such as solubility measurements or comparison with the spectroscopically identified speciation of Se in model systems. Based on the XANES analysis, selenite is transformed into Se 0 confirming the previously proposed reduction of selenite in the Boom Clay system. Combination of the mass-balance for Se with the results from linear combination analysis of the XANES spectra provided new evidence for the sorption-reduction mechanism proposed to explain the interaction between Se(IV) and the BC solid phase. In addition, evidence was found that that the fate of Se(IV) in the BC system is completely dominated by its interaction with pyrite present in the Boom Clay. The combined EXAFS analysis of Se in Se 0 reference phases (hexagonal, monoclinic, Se-loaded pyrite) allowed to elucidate further details on the short-range structure of the reaction products formed

  19. Aspects of clay/concrete interactions

    International Nuclear Information System (INIS)

    Oscarson, D.W.; Dixon, D.A.; Onofrei, M.

    1997-01-01

    In the Canadian concept for nuclear fuel waste management, both clay-based materials and concrete are proposed for use as barriers, seals or supporting structures. The main concern when clays and concrete are in proximity is the generation of a high-pH environment by concrete since clay minerals are relatively unstable at high pH. Here we examine the OH - -generating capacity of two high-performance concretes when in contact with several solutions. We also investigate various aspects of claylconcrete interactions. They are: (1) the alkalimetric titration of clay suspensions, (2) the effect of Ca(OH) 2 (portlandite) on the swelling and hydraulic properties of compacted bentonite, and (3) the influence of cement grout on a backfill clay retrieved from the 900-d Buffer/Container Experiment at the Underground Research Laboratory of AECL. The results indicate that although high-performance concretes establish significantly lower poresolution pH (9 to 10) than does ordinary portland cement, the pH is still somewhat higher than that of clay/groundwater systems of about pH 8. Hence, even if high-performance concrete is used in a disposal vault, the potential still exists for clay minerals to alter over long periods of time if in contact with this concrete. The data show, however, that clays have a substantial buffering capacity, and clay-based barriers can thus neutralize much of the OH - potentially released from concrete in a vault. Moreover, even after reacting for 120 d at 85 o C with up to 5 wt.% Ca(OH) 2 , compacted bentonite (dry density = 1.2 Mg/m 3 ) retains much of its swelling capacity and has a permeability low enough (hydraulic conductivity ≤ 10 -11 m/s) to ensure that molecular diffusion will be the main transport mechanism through compacted clay-based barriers. Furthermore, according to X-ray diffractometry, the clay mineral component of backfill was not altered by contact with a cement grout for 900 d in the Buffer/Container Experiment

  20. PHREEQC modelling of concrete/clay interactions in a 2D geometry with explicit effect of porosity evolution on transport properties due to mineralogical changes

    International Nuclear Information System (INIS)

    Claret, F.; Marty, N.C.M.; Tournassat, C.; Gaboreau, S.; Burnol, A.; Chiaberge, C.; Gaucher, E.C.; Munier, I.; Cochepin, B.; Michau, N.

    2010-01-01

    Document available in extended abstract form only. In the context of deep repository for radioactive waste, significant use of concrete will be made. This material constitutes a compromise between properties, technical uses and costs. Within the French concepts, concrete will be used to build access structures, drifts as well as waste disposal cells and waste packages for Intermediate Level Wastes (ILW). With this design, concrete will be at the interface with either/both the host rock, Callovo-Oxfordian argillites in our case, and/or the clay plug built with swelling clay such as bentonite. Due to the chemical disequilibrium between concrete and clay, chemical reactions can modify both chemical and physical properties of these materials (e.g. mineralogical composition, diffusion coefficient...). In order to assess the long term behaviour of concrete/clay interfaces and the evolution of their properties with time, predictive modelling have to be performed. The high chemical contrast (e.g. pH or pe at the interface) often leads to problems of numerical convergence. Our own experience showed that PHREEQC is very successful in handling such difficulties in 1D geometry. PHREEQC is also able to handle 2D geometries as presented hereafter thanks to the MIX option as well as feedback on porosity thanks to the MCD option (multi component diffusion). Indeed, 2D simulation of a drift sealing concept developed by Andra was attempted using PHREEQC with the MIX option which allows the use of different transport properties in the different cells. A basic program was developed to generate this complex 2D mesh and another one to treat the outputs under TECPLOT R . The mesh is composed of 3081 cells with a refinement of 3 cm at each interface. Such a simulation was already conducted under ALLIANCES geochemistry transport tools, but in our cases the mesh refinement and the chemistry of the system are extended and the feedback on porosity is now considered. Furthermore, the new multi

  1. Phase modification and dielectric properties of a cullet-paper ash-kaolin clay-based ceramic

    Science.gov (United States)

    Samah, K. A.; Sahar, M. R.; Yusop, M.; Omar, M. F.

    2018-03-01

    Novel ceramics from waste material made of ( x) paper ash-(80 - x) cullet-20 kaolin clay (10wt% ≤ x ≤ 30wt%) were successfully synthesized using a conventional solid-state reaction technique. Energy-dispersive X-ray analysis confirmed the presence of Si, Ca, Al, and Fe in the waste material for preparing these ceramics. The influence of the cullet content on the phase structures and the dielectric properties of these ceramics were systematically investigated. The impedance spectra were verified in the range from 1 Hz to 10 MHz at room temperature. The phase of the ceramics was found to primarily consist of wollastonite (CaSiO3), along with minor phases of γ-dicalcium silicate (Ca2SiO4) and quartz (SiO2). The sample with a cullet content of 55wt% possessed the optimum wollastonite structure and exhibited good dielectric properties. An increase of the cullet content beyond 55wt% resulted in a structural change from wollastonite to dicalcium silicate, a decrease in dielectric constant, and an increase in dielectric loss. All experimental results suggested that these novel ceramics from waste are applicable for electronic devices.

  2. Simulation of field scale water flow and bromide transport in a cracked clay soil

    NARCIS (Netherlands)

    Dam, van J.C.

    2000-01-01

    Single domain models may seriously underestimate leaching of nutrients and pesticides to groundwater in clay soils with shrinkage cracks. Various two-domain models have been developed, either empirical or physically based, which take into account the effects of cracks on water flow and solute

  3. Base Station Performance Model

    OpenAIRE

    Walsh, Barbara; Farrell, Ronan

    2005-01-01

    At present the testing of power amplifiers within base station transmitters is limited to testing at component level as opposed to testing at the system level. While the detection of catastrophic failure is possible, that of performance degradation is not. This paper proposes a base station model with respect to transmitter output power with the aim of introducing system level monitoring of the power amplifier behaviour within the base station. Our model reflects the expe...

  4. Preparation of nanocomposites polyurethane water bone with clay montmorillonite sodica and organophilic clay

    International Nuclear Information System (INIS)

    Garcia, Claudia P.; Delpech, Marcia C.; Coutinho, Fernanda M.B.; Mello, Ivana L.

    2009-01-01

    Nanocomposites based on water bone polyurethane (NWPU's) were synthesized based on poli(propylene glycol), dimethylolpropionic acid (DMPA), isophorone diisocyanate (IPDI) and hydrazine (HYD), as chain extender. Two kinds of clays were employed: hydrophilic and organophilic. The nanocomposites were characterized by infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electronic microscopy (SEM) and the mechanical properties were evaluated. The FTIR results showed the presence of specific groups of clay and the XRD suggested that occurred their intercalation/exfoliation through polyurethane matrix. The mechanical resistance of the systems showed significant increase when compared to water dispersions synthesized without clay. (author)

  5. Ab-Initio Modelling Of Surface Site Reactivity And Fluid Transport In Clay Minerals Case Study: Pyrophyllite

    International Nuclear Information System (INIS)

    Churakov, S.V.

    2005-01-01

    Pyrophyllite, Al 2 [Si 4 O 10 ](OH) 2 , is the simplest structural prototype for 2:1 dioctahedral phyllosilicate. Because the net electric charge in pyrophyllite is zero, it is the best candidate for investigating the non electrostatic contribution to sorption and transport phenomena in clays. Using ab-initio simulations, we have investigated the reactivity and structure of the water-solid interface on the basal plane and edge sites of pyrophyllite. The calculations predict slightly hydrophobic behaviour of the basal plane. For the high water coverage (100), (110) and (-110), lateral facets have a lower energy than for the (010), (130) and (-130) surfaces. Analysis of the surface reactivity reveals that the =Al-OH groups are most easily protonated on the (010), (130) and (-130) facets. The =Al-O-Si= sites will be protonated on the (100), (130), (110), (-110) and (-130) surfaces. The =Al-OH 2 complexes are more easily de-protonated than the =Si-OH and =Al-OH sites. A spontaneous, reversible exchange of the protons between the solution and the edge sites has been observed in ab-initio molecular dynamics simulations at 300 K. Such near-surface proton diffusion may result in a significant contribution to the diffusion coefficients measured in neutron scattering experiments. (author)

  6. Thermal/fluid modeling of the response of saturated marine red clays to emplacement of nuclear waste

    International Nuclear Information System (INIS)

    McVey, D.F.; Gartling, D.K.; Russo, A.J.

    1980-01-01

    In this report, we discuss heat and mass transport in marine red clay sediments being considered as a nuclear waste isolation medium. Development of two computer codes, one to determine temperature and convective velocity fields, the other to analyze the nuclide migration problem, is discussed and preliminary results from the codes reviewed. The calculations indicate that for a maximum allowable sediment/canister temperature range of 200 0 C to 250 0 C, the sediment can absorb about 1.5 kW initial power from waste in a 3 m long by 0.3 m diameter canister. The resulting fluid displacement due to convection is found to be small, less than 1 m. The migration of four nuclides, 239 Pu, 137 Cs, 129 I and 99 Tc were computed for a canister buried 30 m deep in 60 m thick sediment. It was found that the 239 Pu and 137 Cs, which migrate as cations and have relatively high distribution coefficients, are essentially completely contained in the sediment. The anionic species, 129 I and 99 Tc, which have relatively low distribution coefficients, broke through the sediment in about 5000 years. The resultant peak injection rates which occur at about 15,000 years were extremely small (0.5 μCi/year for 129 I and 180 μCi/year for 99 Tc)

  7. Geosynthetic clay liners shrinkage under simulated daily thermal cycles.

    Science.gov (United States)

    Sarabadani, Hamid; Rayhani, Mohammad T

    2014-06-01

    Geosynthetic clay liners are used as part of composite liner systems in municipal solid waste landfills and other applications to restrict the escape of contaminants into the surrounding environment. This is attainable provided that the geosynthetic clay liner panels continuously cover the subsoil. Previous case histories, however, have shown that some geosynthetic clay liner panels are prone to significant shrinkage and separation when an overlying geomembrane is exposed to solar radiation. Experimental models were initiated to evaluate the potential shrinkage of different geosynthetic clay liner products placed over sand and clay subsoils, subjected to simulated daily thermal cycles (60°C for 8 hours and 22°C for 16 hours) modelling field conditions in which the liner is exposed to solar radiation. The variation of geosynthetic clay liner shrinkage was evaluated at specified times by a photogrammetry technique. The manufacturing techniques, the initial moisture content, and the aspect ratio (ratio of length to width) of the geosynthetic clay liner were found to considerably affect the shrinkage of geosynthetic clay liners. The particle size distribution of the subsoil and the associated suction at the geosynthetic clay liner-subsoil interface was also found to have significant effects on the shrinkage of the geosynthetic clay liner. © The Author(s) 2014.

  8. Novel organo soluble poly imides and polyimide nano composites based on 1,4-bis(4-aminophenyl)-1,3,4-oxadiaz olyl)benzene, BAOB, via BAOB-modified organo clay

    International Nuclear Information System (INIS)

    Mansoori, Y.; Darvishi, K.

    2014-01-01

    New, thermally stable poly imides (PI) containing a 1,3,4-oxadiazole ring in the polymer backbone based on 1,4-bis((4-aminophenyl)-1,3,4-oxadiaz olyl)benzene, BAOB, were synthesized. The prepared polymers were soluble in polar and aprotic solvents. The obtained results reveal that within the prepared polymers, polyimide which has been obtained from BAOB and 4,4-oxy diphthalic dianhydride, ODPA, has the most improved thermal properties. In the next part, thermally stable organophilic clay was obtained via cation exchange reaction between sodium montmorillonite (Na-MMT) and the hydrochloride salt of BAOB. Then, a series of PI/clay nano composite materials (PCNs) were synthesized from the in situ polymerization reaction of BAOB and ODPA via thermal imidization, BAOB-MMT was used as the filler at different concentrations. Intercalation of polymer chains within the organo clay galleries was confirmed by W XRD. The glass transition temperature is increased with respect to pristine PI for PCNs 1-3 wt %. At high clay loadings, the aggregation of organo clay particles results in a decrease in T g . In the Sem images of the pure polymer too many micro-cracks were observed in the background, while surface homogeneity of PCN 1 wt % is increased and micro-cracks are reduced. (Author)

  9. Novel organo soluble poly imides and polyimide nano composites based on 1,4-bis(4-aminophenyl)-1,3,4-oxadiaz olyl)benzene, BAOB, via BAOB-modified organo clay

    Energy Technology Data Exchange (ETDEWEB)

    Mansoori, Y.; Darvishi, K., E-mail: ya_mansoori@yahoo.com [University of Mohaghegh Ardabili, Faculty of Science, Department of Applied Chemistry, Daneshgah, Ardabil (Iran, Islamic Republic of)

    2014-10-01

    New, thermally stable poly imides (PI) containing a 1,3,4-oxadiazole ring in the polymer backbone based on 1,4-bis((4-aminophenyl)-1,3,4-oxadiaz olyl)benzene, BAOB, were synthesized. The prepared polymers were soluble in polar and aprotic solvents. The obtained results reveal that within the prepared polymers, polyimide which has been obtained from BAOB and 4,4-oxy diphthalic dianhydride, ODPA, has the most improved thermal properties. In the next part, thermally stable organophilic clay was obtained via cation exchange reaction between sodium montmorillonite (Na-MMT) and the hydrochloride salt of BAOB. Then, a series of PI/clay nano composite materials (PCNs) were synthesized from the in situ polymerization reaction of BAOB and ODPA via thermal imidization, BAOB-MMT was used as the filler at different concentrations. Intercalation of polymer chains within the organo clay galleries was confirmed by W XRD. The glass transition temperature is increased with respect to pristine PI for PCNs 1-3 wt %. At high clay loadings, the aggregation of organo clay particles results in a decrease in T{sub g}. In the Sem images of the pure polymer too many micro-cracks were observed in the background, while surface homogeneity of PCN 1 wt % is increased and micro-cracks are reduced. (Author)

  10. Analytical Expressions for Thermo-Osmotic Permeability of Clays

    Science.gov (United States)

    Gonçalvès, J.; Ji Yu, C.; Matray, J.-M.; Tremosa, J.

    2018-01-01

    In this study, a new formulation for the thermo-osmotic permeability of natural pore solutions containing monovalent and divalent cations is proposed. The mathematical formulation proposed here is based on the theoretical framework supporting thermo-osmosis which relies on water structure alteration in the pore space of surface-charged materials caused by solid-fluid electrochemical interactions. The ionic content balancing the surface charge of clay minerals causes a disruption in the hydrogen bond network when more structured water is present at the clay surface. Analytical expressions based on our heuristic model are proposed and compared to the available data for NaCl solutions. It is shown that the introduction of divalent cations reduces the thermo-osmotic permeability by one third compared to the monovalent case. The analytical expressions provided here can be used to advantage for safety calculations in deep underground nuclear waste repositories.

  11. Poly(vinyl acetate-Based Block Copolymer/Clay Nanocomposites Prepared by In Situ Atom Transfer Radical Polymerization

    Directory of Open Access Journals (Sweden)

    M.A. Semsarzadeh

    2009-12-01

    Full Text Available Atom transfer radical polymerization of styrene (St and methyl methacrylate (MMA was performed at 90oC in the absence and presence of nanoclay (Cloisite 30B. Trichloromethyl-terminated poly(vinyl acetate telomerand CuCl/ PMDETA were used as a macroinitiator and catalyst system, respectively. The experimental results showed that the atom transfer radical polymerization of St and MMA in the absence or presence of nanoclay proceeds via a controlled/living mode. It was observed that nanoclay significantly enhances the homopolymerization rate of MMA, which was attributed to the activated conjugated C=C bond of MMA monomer via interaction between the carbonyl group of MMA monomer and the hydroxyl moiety (Al-O-H of nanoclay as well as the effect of nanoclay on the dynamic equilibrium between the active (macro radicals and dormant species.Homopolymerization rate of St (a non-coordinative monomer with nanoclay decreased slightly in the presence of nanoclay. This could be explained by insertion of a portion of macroinitiator into the clay galleries, where no sufficient St monomer exists due to the low compatibility or interaction of St monomer with nanoclay to react with the macroinitiator. The results obtained from XRD, TEM and TGA analyses were fully in agreement with the kinetic data. Structure of the poly(vinyl acetate-bpolystyrene nanocomposite was found to be a combination of stacking layers and exfoliated structures while poly(vinyl acetate-b-poly(methyl methacryale nanocomposite had an exfoliated structure. This difference in the structure of nanocomposites was attributed to the different capability of the monomers (styrene and methyl methacrylate to react with the hydroxyl moiety (Al-O-H of nanoclay.

  12. Sorption Energy Maps of Clay Mineral Surfaces

    International Nuclear Information System (INIS)

    Cygan, Randall T.; Kirkpatrick, R. James

    1999-01-01

    A molecular-level understanding of mineral-water interactions is critical for the evaluation and prediction of the sorption properties of clay minerals that may be used in various chemical and radioactive waste disposal methods. Molecular models of metal sorption incorporate empirical energy force fields, based on molecular orbital calculations and spectroscopic data, that account for Coulombic, van der Waals attractive, and short-range repulsive energies. The summation of the non-bonded energy terms at equally-spaced grid points surrounding a mineral substrate provides a three dimensional potential energy grid. The energy map can be used to determine the optimal sorption sites of metal ions on the exposed surfaces of the mineral. By using this approach, we have evaluated the crystallographic and compositional control of metal sorption on the surfaces of kaolinite and illite. Estimates of the relative sorption energy and most stable sorption sites are derived based on a rigid ion approximation

  13. A new and improved methodology for qualitative and quantitative mineralogical analysis of Boom Clay

    International Nuclear Information System (INIS)

    Zeelmaekers, E.; Vandenberghe, N.; Honty, M.; De Craen, M.; Derkowski, A.; Van Geet, M.

    2010-01-01

    Document available in extended abstract form only. A good knowledge of the mineralogy of any host formation studied for geological disposal of high-level radioactive waste, is a prerequisite for understanding the geochemical environment which will determine the migration and retention behaviour of radionuclides. In this respect, the Boom Clay mineralogical composition has been extensively studied last decades as reference host formation (e.g. ARCHIMEDEARGILE project, OECD-NEA clay catalogue report) with the aim to provide reliable data for a safety assessment. However, a comparison of the available literature data clearly showed a serious discrepancy among studies, not only in the quantitative, but also in the qualitative mineralogical composition of the Boom Clay (SAFIR II). The reason for such a huge disagreement could be related, among others, to variable grain size distributions of the studied samples (sample heterogeneity) and differences in the methodological approaches. In particular, the unambiguous characterisation of clay minerals and the quantification of mixed-layer phases appeared as an everlasting problem. This study is aimed at achieving a consensus on the qualitative and quantitative mineralogical data of the Boom Clay using the most advanced techniques currently available in the clay science. A new sampling campaign was performed in such a way that samples are (20 in total) more or less regularly distributed over Boom Clay Formation, ensuring that variations in the grain size distributions due to silty clay-clayey silt layers alternations are accounted for. The novel concept based on an analysis at two levels was applied: (1) bulk rock and (2) clay fraction analysis. (1) A bulk rock analysis consists of conventional XRD analysis with the identification of the principal mineral phases. As a next step, the bulk rock was mixed with a ZnO internal standard and experimental diffraction patterns of randomly oriented powders were analyzed using &apos

  14. Absorption characteristics of Kupravas deposit clays modified by phosphoric acid

    International Nuclear Information System (INIS)

    Ruplis, A.; Mezinskis, G.; Chaghuri, M.

    1998-01-01

    Literature data suggested that clays may be used as sorbents for waste water treatment. The surface and sorption properties of minerals changes due to the influence of acid rains. The process of recession of clay properties has been modeled in laboratory by treatment of clays with mineral acids at higher temperature that in natural conditions. The present paper is devoted to the study of influence of phosphoric acid on the sorption properties of Kupravas deposit clays. Natural clay samples and samples treated with phosphoric acid were characterized by means of x-ray diffraction an differential thermal analysis (DTA) methods These methods were used also to identify the sample of Lebanese clays. X-ray diffraction analysis data show that the samples of clays from the deposit of Kuprava contain illite and kaolinite while sample of Lebanese clay contains quartz, calcite, and montmorillonite. DTA results show characteristic features of Kuprava clays described in reference with DTA of Lebanese clay clearly demonstrate the presence of large quantity of calcite

  15. Web Based VRML Modelling

    NARCIS (Netherlands)

    Kiss, S.; Sarfraz, M.

    2004-01-01

    Presents a method to connect VRML (Virtual Reality Modeling Language) and Java components in a Web page using EAI (External Authoring Interface), which makes it possible to interactively generate and edit VRML meshes. The meshes used are based on regular grids, to provide an interaction and modeling

  16. Accurate control testing for clay liner permeability

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, R J

    1991-08-01

    Two series of centrifuge tests were carried out to evaluate the use of centrifuge modelling as a method of accurate control testing of clay liner permeability. The first series used a large 3 m radius geotechnical centrifuge and the second series a small 0.5 m radius machine built specifically for research on clay liners. Two permeability cells were fabricated in order to provide direct data comparisons between the two methods of permeability testing. In both cases, the centrifuge method proved to be effective and efficient, and was found to be free of both the technical difficulties and leakage risks normally associated with laboratory permeability testing of fine grained soils. Two materials were tested, a consolidated kaolin clay having an average permeability coefficient of 1.2{times}10{sup -9} m/s and a compacted illite clay having a permeability coefficient of 2.0{times}10{sup -11} m/s. Four additional tests were carried out to demonstrate that the 0.5 m radius centrifuge could be used for linear performance modelling to evaluate factors such as volumetric water content, compaction method and density, leachate compatibility and other construction effects on liner leakage. The main advantages of centrifuge testing of clay liners are rapid and accurate evaluation of hydraulic properties and realistic stress modelling for performance evaluations. 8 refs., 12 figs., 7 tabs.

  17. 3D Numerical Modeling of Pile Group Responses to Excavation-Induced Stress Release in Silty Clay

    Directory of Open Access Journals (Sweden)

    M. A. Soomro

    2018-02-01

    Full Text Available Development of underground transportation systems consists of tunnels, basement construction excavations and cut and cover tunnels which may encounter existing pile groups during their construction. Since many previous studies mainly focus on the effects of excavations on single piles, settlement and load transfer mechanism of a pile group subjected to excavation-induced stress release are not well investigated and understood. To address these two issues, three-dimensional coupled-consolidation numerical analysis is conducted by using a hypoplastic model which takes small-strain stiffness into account. A non-linear pile group settlement was induced. This may be attributed to reduction of shaft resistance due to excavation induced stress release, the pile had to settle substantially to further mobilise end-bearing. Compared to the Sp of the pile group, induced settlement of the single pile is larger with similar settlement characteristics. Due to the additional settlement of the pile group, factor of safety for the pile group can be regarded as decreasing from 3.0 to 1.4, based on a displacement-based failure load criterion. Owing to non-uniform stress release, pile group tilted towards the excavation with value of 0.14%. Due to excavation-induced stress release and dragload, head load of rear piles was reduced and transferred to rear piles. This load transfer can increase the axial force in front piles by 94%.

  18. Clay and concrete brick

    CSIR Research Space (South Africa)

    Dlamini, MN

    2014-03-01

    Full Text Available Brick is one of the most used and versatile building materials in use today. Bricks can be defined as modular units connected by mortar in the formation of a building system or product. Commonly the word brick is used to refer to clay bricks, which...

  19. Performance of polymeric films based thermoplastic starch and organophilic clay; Efeito da incorporacao de argila no desempenho de filmes de amido termoplastico/PEBD

    Energy Technology Data Exchange (ETDEWEB)

    Cipriano, P.B.; Costa, A.N.M.; Araujo, S.S.; Araujo, A.R.A.; Canedo, E.L.; Carvalho, L.H., E-mail: pamufcg@gmail.co [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Dept. de Engenharia de Materiais

    2010-07-01

    The aim of this work was the development and investigation of the properties of flat films of LDPE/corn thermoplastic starch (TPS). A bentonite clay (Argel) was organophilized and characterized by XRD. This clay (1%) in both pristine and organophilic forms was added to the matrix (LDPE) and to LDPE/TPS systems with TPS contents varying from 5-20% w/w. The films manufactured (LDPE, LDPE/Clay, LDPE/TPS, LDPE/TPS/Clay) were characterized. Results indicate that water vapor permeability is dependent and increases with TPS content which was attributed to the higher affinity of water by TPS. TPS and Clay addition to LDPE led to significant changes in film properties with respect to the neat LDPE. In general,tensile and perforation forces increased with clay and TPS contents; the strength of thermo sealed films lowered with natural clay addition and increased with TPS and organoclay incorporation and, in general, dynamic friction coefficient decrease with organoclay and TPS addition. Best overall properties were obtained for the systems containing the organoclay and optimal properties were achieved for the 5%TPS10 LDPE1% ANO system. (author)

  20. Modelling of acid-base titration curves of mineral assemblages

    Directory of Open Access Journals (Sweden)

    Stamberg Karel

    2016-01-01

    Full Text Available The modelling of acid-base titration curves of mineral assemblages was studied with respect to basic parameters of their surface sites to be obtained. The known modelling approaches, component additivity (CA and generalized composite (GC, and three types of different assemblages (fucoidic sandstones, sedimentary rock-clay and bentonite-magnetite samples were used. In contrary to GC-approach, application of which was without difficulties, the problem of CA-one consisted in the credibility and accessibility of the parameters characterizing the individual mineralogical components.

  1. Clay matrix voltammetry

    International Nuclear Information System (INIS)

    Perdicakis, Michel

    2012-01-01

    Document available in extended abstract form only. In many countries, it is planned that the long life highly radioactive nuclear spent fuel will be stored in deep argillaceous rocks. The sites selected for this purpose are anoxic and satisfy several recommendations as mechanical stability, low permeability and low redox potential. Pyrite (FeS 2 ), iron(II) carbonate, iron(II) bearing clays and organic matter that are present in very small amounts (about 1% w:w) in soils play a major role in their reactivity and are considered today as responsible for the low redox potential values of these sites. In this communication, we describe an electrochemical technique derived from 'Salt matrix voltammetry' and allowing the almost in-situ voltammetric characterization of air-sensitive samples of soils after the only addition of the minimum humidity required for electrolytic conduction. Figure 1 shows the principle of the developed technique. It consists in the entrapment of the clay sample between a graphite working electrode and a silver counter/quasi-reference electrode. The sample was previously humidified by passing a water saturated inert gas through the electrochemical cell. The technique leads to well-defined voltammetric responses of the electro-active components of the clays. Figure 2 shows a typical voltammogram relative to a Callovo-Oxfordian argillite sample from Bure, the French place planned for the underground nuclear waste disposal. During the direct scan, one can clearly distinguish the anodic voltammetric signals for the oxidation of the iron (II) species associated with the clay and the oxidation of pyrite. The reverse scan displays a small cathodic signal for the reduction of iron (III) associated with the clay that demonstrates that the majority of the previously oxidized iron (II) species were transformed into iron (III) oxides reducible at lower potentials. When a second voltammetric cycle is performed, one can notice that the signal for iron (II

  2. Structures and mechanisms in clay nanopore trapping of structurally-different fluoroquinolone antimicrobials.

    Science.gov (United States)

    Okaikue-Woodi, Fanny E K; Kelch, Sabrina E; Schmidt, Michael P; Enid Martinez, Carmen; Youngman, Randall E; Aristilde, Ludmilla

    2018-03-01

    Smectite clay nanoparticles are implicated in the retention of antimicrobials within soils and sediments; these clays are also inspected as drug carriers in physiological systems. Cation exchange is considered the primary adsorption mechanism of antimicrobials within smectite nanopores. However, a dual role of acid-base chemistry and adsorptive structures is speculated by recent studies. Using the prototypical smectite clay montmorillonite, we employed a combination of X-ray diffraction (XRD), nuclear magnetic resonance, attenuated total reflectance-Fourier transform infrared spectroscopy, and molecular dynamics simulations to investigate the interlayer nanopore trapping of two structurally-different fluoroquinolone (FQ) antimicrobials with similar acid-base chemistry: ciprofloxacin (a first-generation FQ) and moxifloxacin (a third-generation FQ). Greater sorption at pH 5.0 than at pH 7.0 for both FQs was consistent with cation-exchange of positively-charged species. However, the clay exhibited a near twofold higher sorption capacity for moxifloxacin than for ciprofloxacin. This difference was shown by the XRD data to be accompanied by enhanced trapping of moxifloxacin within the clay interlayers. Using the XRD-determined nanopore sizes, we performed molecular dynamics simulations of thermodynamically-favorable model adsorbates, which revealed that ciprofloxacin was adsorbed parallel to the clay surface but moxifloxacin adopted a tilted conformation across the nanopore. These conformations resulted in more slowly-exchanged than quickly-exchanged Na complexes with ciprofloxacin compared with moxifloxacin. These different Na populations were also captured by 23 Na nuclear magnetic resonance. Furthermore, the simulated adsorbates uncovered different complexation interactions that were corroborated by infrared spectroscopy. Therefore, beyond acid-base chemistry, our findings imply that distinct adsorbate structures control antimicrobial trapping within clay nanopores

  3. Migration of uranium in the presence of clay colloids in a sandy aquifer

    International Nuclear Information System (INIS)

    Le Cointe, P.; Grambow, B.; Piscitelli, A.; Montavon, G.; Van der Lee, J.; Giffaut, E.; Schneider, V.

    2010-01-01

    polystyrene standards on different sediment samples (core sample, reconsolidated auger sample and clay-free reconsolidated auger sample). The filtration threshold has been defined between 70 and 100 nm, except for the clay-free sample, for which it is above 500 nm. Laboratory column experiments were performed with 70 nm clay colloids, U(VI) and clay colloids + U(VI). To make the system simpler, the clay fraction was removed from the sediment and the experiments were carried out at a low ionic strength, to avoid clay colloids flocculation. The breakthrough behaviour of clay colloids and U(VI) was monitored and compared to conservative tracers (HTO and 36 Cl). The data were modelled with the HYTEC reactive transport code developed at the Paris School of Mines, considering both hydrodynamic properties of the porous system (porosity of 30%, Darcy velocity fixed to 3.10 -6 m/s, close to the one measured in situ) and the parameters quantifying U(VI)-Quartz and U(VI)-Clay interactions. An in situ tracing experiment was also conducted with both conservative (D 2 O, H 2 18 O) and colloidal (polystyrene nanoparticles) tracers. The objective is to ensure the reactive transport model, based on laboratory experiments, can be extended to a parcel of the site, and finally to the whole site, using experimental and modelling data collected by Andra. (authors)

  4. Migration of uranium in the presence of clay colloids in a sandy aquifer

    Energy Technology Data Exchange (ETDEWEB)

    Le Cointe, P. [Laboratoire SUBATECH, UMR 6457 Ecole des Mines/CNRS/Universite, 4 rue A. Kastler, BP 20722, 44307 Nantes Cedex 03 (France); Centre de Geosciences, Ecole des Mines de Paris, 35 rue St-Honore, 77305 Fontainebleau Cedex (France); ANDRA 1/7 rue Jean Monnet - 92298 Chatenay Malabry Cedex (France); Grambow, B.; Piscitelli, A.; Montavon, G. [Laboratoire SUBATECH, UMR 6457 Ecole des Mines/CNRS/Universite, 4 rue A. Kastler, BP 20722, 44307 Nantes Cedex 03 (France); Van der Lee, J. [EDF R ete D, Site des Renardieres, Route de Sens - Ecuelles, 77250 Moret sur Loing (France); Giffaut, E.; Schneider, V. [ANDRA 1/7 rue Jean Monnet - 92298 Chatenay Malabry Cedex (France)

    2010-07-01

    polystyrene standards on different sediment samples (core sample, reconsolidated auger sample and clay-free reconsolidated auger sample). The filtration threshold has been defined between 70 and 100 nm, except for the clay-free sample, for which it is above 500 nm. Laboratory column experiments were performed with 70 nm clay colloids, U(VI) and clay colloids + U(VI). To make the system simpler, the clay fraction was removed from the sediment and the experiments were carried out at a low ionic strength, to avoid clay colloids flocculation. The breakthrough behaviour of clay colloids and U(VI) was monitored and compared to conservative tracers (HTO and {sup 36}Cl). The data were modelled with the HYTEC reactive transport code developed at the Paris School of Mines, considering both hydrodynamic properties of the porous system (porosity of 30%, Darcy velocity fixed to 3.10{sup -6} m/s, close to the one measured in situ) and the parameters quantifying U(VI)-Quartz and U(VI)-Clay interactions. An in situ tracing experiment was also conducted with both conservative (D{sub 2}O, H{sub 2}{sup 18}O) and colloidal (polystyrene nanoparticles) tracers. The objective is to ensure the reactive transport model, based on laboratory experiments, can be extended to a parcel of the site, and finally to the whole site, using experimental and modelling data collected by Andra. (authors)

  5. Physical Properties of Latvian Clays

    OpenAIRE

    Jurgelāne, I; Stepanova, V; Ločs, J; Mālers, J; Bērziņa-Cimdiņa, L

    2012-01-01

    Physical and chemical properties of clays mostly depends on its mineral and chemical composition, particle size and pH value. The mutual influence of these parameters is complex. Illite is the most abundant clay mineral in Latvia and usually used in building materials and pottery. The viscosity and plasticity of Latvian clays from several deposits were investigated and correlated with mineral composition, particle size and pH value. Fractionated and crude clay samples were used. The p...

  6. A framework for the behaviour of unsaturated expansive clays

    International Nuclear Information System (INIS)

    Gens, A.; Alonso, E.E.

    1992-01-01

    The paper presents a framework for describing the mechanical behaviour of unsaturated expansive clays. It is an extension of an existing formulation developed for unsaturated soils of low activity. The extended framework is based on the distinction within the material of a microstructural level where the basic swelling of the active minerals takes place, and a macrostructural level responsible for major structural rearrangements. Bu adopting simple assumptions concerning the coupling between the two levels, it is possible to reproduce major features of the behaviour of unsaturated expansive clays. Some selected qualitative comparisons between model predictions and experimental results reported in the literature are presented. Despite the simplified hypotheses made, a very encouraging agreement is obtained

  7. Clay Animals and Their Habitats

    Science.gov (United States)

    Adamson, Kay

    2010-01-01

    Creating clay animals and their habitats with second-grade students has long been one of the author's favorite classroom activities. Students love working with clay and they also enjoy drawing animal homes. In this article, the author describes how the students created a diorama instead of drawing their clay animal's habitat. This gave students…

  8. Prediction of the residual strength of clay using functional networks

    Directory of Open Access Journals (Sweden)

    S.Z. Khan

    2016-01-01

    Full Text Available Landslides are common natural hazards occurring in most parts of the world and have considerable adverse economic effects. Residual shear strength of clay is one of the most important factors in the determination of stability of slopes or landslides. This effect is more pronounced in sensitive clays which show large changes in shear strength from peak to residual states. This study analyses the prediction of the residual strength of clay based on a new prediction model, functional networks (FN using data available in the literature. The performance of FN was compared with support vector machine (SVM and artificial neural network (ANN based on statistical parameters like correlation coefficient (R, Nash--Sutcliff coefficient of efficiency (E, absolute average error (AAE, maximum average error (MAE and root mean square error (RMSE. Based on R and E parameters, FN is found to be a better prediction tool than ANN for the given data. However, the R and E values for FN are less than SVM. A prediction equation is presented that can be used by practicing geotechnical engineers. A sensitivity analysis is carried out to ascertain the importance of various inputs in the prediction of the output.

  9. Clay facial masks: physicochemical stability at different storage temperatures.

    Science.gov (United States)

    Zague, Vivian; de Almeida Silva, Diego; Baby, André Rolim; Kaneko, Telma Mary; Velasco, Maria Valéria Robles

    2007-01-01

    Clay facial masks--formulations that contain a high percentage of solids dispersed in a liquid vehicle--have become of special interest due to specific properties presented by clays, such as particle size, cooling index, high adsorption capacity, and plasticity. Although most of the physicochemical properties of clay dispersions have been studied, specific aspects concerning the physicochemical stability of clay mask products remain unclear. This work aimed at investigating the accelerated physicochemical stability of clay mask formulations stored at different temperatures. Formulations were subjected to centrifuge testing and to thermal treatment for 15 days, during which temperature was varied from -5.0 degrees to 45.0 degrees C. The apparent viscosity and visual aspect (homogeneity) of all formulations were affected by temperature variation, whereas color, odor, and pH value remained unaltered. These results, besides the estimation of physicochemical stability under aging, can be useful in determining the best storage conditions for clay-based formulations.

  10. Clay membrane made of natural high plasticity clay

    DEFF Research Database (Denmark)

    Foged, Niels; Baumann, Jens

    1998-01-01

    Leachate containment in Denmark has through years been regulated by the DIF Recommendation for Sanitary Landfill Liners (DS/R 466). It states natural clay deposits may be used for membrane material provided the membrane and drainage system may contain at least 95% of all leachate created throughout...... ion transport as well as diffusion.Clay prospection for clays rich in smectite has revealed large deposits of Tertiary clay of very high plasticity in the area around Rødbyhavn on the Danish island Lolland. The natural clay contains 60 to 75% smectite, dominantly as a sodium-type. The clay material...... has been evaluated using standardised methods related to mineralogy, classification, compaction and permeability, and initial studies of diffusion properties have been carried out. Furthermore, at a test site the construction methods for establishing a 0.15 to 0.3m thick clay membrane have been tested...

  11. Clay membrane made of natural high plasticity clay:

    DEFF Research Database (Denmark)

    Foged, Niels; Baumann, Jens

    1999-01-01

    Leachate containment in Denmark has throughout the years been regulated by the DIF Recommendation for Sanitary Landfill Liners (DS/R4669. It states that natural clay deposits may be used as membrane material provided the membrane and drainage system contains at least 95% of all leachate created...... into account advective ion transport as well as diffusion. Clay prospecting for clays rich in smectite has revealed large deposits of Tertiary clay of very high plasticity in the area around Rødbyhavn on the Danish island of Lolland. The natural clay contains 60-75% smectite, dominantly as a sodium......-type. The clay material has been evaluated using the standardized methods related to mineralogy, classification, compaction and permeability, and initial studies of diffusion properties have been carried out. Furthermore, at a test site the construction methods for establishing a 0.15-0.3 m thick clay membrane...

  12. Cementitious Near-Field Sorption Data Base for Performance Assessment of an ILW Repository in Opalinus Clay

    Energy Technology Data Exchange (ETDEWEB)

    Wieland, E.; Van Loon, L. R

    2003-08-01

    The present report describes a cement sorption database (SDB) for the safety-relevant radionuclides to be disposed of in the planned Swiss repository for long-lived intermediate-level radioactive wastes (ILW). This report is an update on earlier SDBs, which were compiled for the cementitious near field of a repository for low- and intermediate-level radioactive wastes (L/ILW) by BRADBURY + SAROTT (1995) and BRADBURY + VAN LOON (1998). The radionuclide inventories are determined by the waste streams to be disposed of in the ILW repository. A list of the safety-relevant radionuclides was provided based on the currently available information on ILW inventories. The compositions of the cement porewaters in the near fields of the L/ILW and ILW repositories, which had been calculated using well-established codes for modelling cement degradation, were compared to identify any differences in the near-field conditions and to assess their influence on radionuclide sorption. Sorption values were selected based on the previously reported SDBs for the near field of the L/ILW repository. Sorption values were revised if new information and/or data were available which allowed changes to or re-appraisals of the data to be made. The sorption values recommended in this report were either selected on the basis of data from in-house experimental studies or from literature data. For some key radioelements, i.e., Cs(l), Sr(II), Ni(II), Eu(lll), Th(IV) and Sn(IV), new data were available from in-house measurements. These elements had been selected for experimental studies due to their relevance to safety assessment and/or their importance as appropriate chemical analogues. Degradation products of bitumen and cellulose, concrete admixtures and cement-derived near-field colloids were taken into account as the main potential perturbations, which could reduce radionuclide sorption in the near field. Possible impacts of the perturbing factors on radionuclide mobility were considered and

  13. Selective Clay Placement within a Silicate Clay-Epoxy Blend Nanocomposite and the Effect on Physical Properties

    Science.gov (United States)

    Miller, Sandi G.; Scheiman, Daniel A; Kohlmman, Lee W.

    2009-01-01

    Many epoxy systems under consideration for composite pressure vessels are composed of toughened epoxy resins. In this work, epoxy blends containing both rigid aromatic and flexible aliphatic components were prepared, to model toughened systems, and determine the optimum route of silicate addition. Compositions were chosen such that both glassy and rubbery resins were obtained at room temperature. The physical properties of the nanocomposites varied with T(g) and silicate placement, however, nanocomposite T(g)s were observed which exceeded that of the base resin by greater than 10 C. The tensile strength of the glassy resin remained constant or decreased on the dispersion of clay while that of the rubbery material doubled. Selectively placing the clay in the aliphatic component of the rubbery blend resulted in a greater than 100% increase in material toughness.

  14. Model Based Temporal Reasoning

    Science.gov (United States)

    Rabin, Marla J.; Spinrad, Paul R.; Fall, Thomas C.

    1988-03-01

    Systems that assess the real world must cope with evidence that is uncertain, ambiguous, and spread over time. Typically, the most important function of an assessment system is to identify when activities are occurring that are unusual or unanticipated. Model based temporal reasoning addresses both of these requirements. The differences among temporal reasoning schemes lies in the methods used to avoid computational intractability. If we had n pieces of data and we wanted to examine how they were related, the worst case would be where we had to examine every subset of these points to see if that subset satisfied the relations. This would be 2n, which is intractable. Models compress this; if several data points are all compatible with a model, then that model represents all those data points. Data points are then considered related if they lie within the same model or if they lie in models that are related. Models thus address the intractability problem. They also address the problem of determining unusual activities if the data do not agree with models that are indicated by earlier data then something out of the norm is taking place. The models can summarize what we know up to that time, so when they are not predicting correctly, either something unusual is happening or we need to revise our models. The model based reasoner developed at Advanced Decision Systems is thus both intuitive and powerful. It is currently being used on one operational system and several prototype systems. It has enough power to be used in domains spanning the spectrum from manufacturing engineering and project management to low-intensity conflict and strategic assessment.

  15. Semianalytical Solutions for Transport in Aquifer and Fractured Clay Matrix System

    Science.gov (United States)

    A three-dimensional mathematical model that describes transport of contaminant in a horizontal aquifer with simultaneous diffusion into a fractured clay formation is proposed. A group of analytical solutions is derived based on specific initial and boundary conditions as well as ...

  16. Water drilling fluids: evaluation of lubricity and clay swelling control; Fluidos de perfuracao a base de agua: avaliacao de lubricidade e controle de inchamento de argilas

    Energy Technology Data Exchange (ETDEWEB)

    Felix, Thiago de Freitas; Arruda, Jefferson Teixeira; Medeiros, Ana Catarina; Garcia, Rosangela Balaban [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil)

    2008-07-01

    During the oil well drilling, drilling fluids are used in order to transport the cuttings until the surface. This fluid is also responsible for the mechanical sustentation of the well walls, the control of undesirable production of fluids in the formation, the lubricity and the cooling of the bit. The drilling fluids based on water are extensively applied due to their lower cost, thermal stability, biodegradability, easiness of pumping and treatment, resulting in smaller environmental impacts. However, some situations, such as hydrophilic shale drilling, request the use of additives to avoid the hydration of them and, consequently, the tool imprisonment or migration (filtration) of the drilling fluids into the rock. The goal of this work was to develop and test formulations of water-base drilling fluids with high capacity of inhibition of clay swelling and lubricity, obtaining drillings with larger penetration rate and calipers without enlargements. The results showed that the appropriate combination of commonly used commercial products can promote the obtaining of fluids with equal or better performance than those used by world companies. (author)

  17. Insightful understanding of the role of clay topology on the stability of biomimetic hybrid chitosan-clay thin films and CO2-dried porous aerogel microspheres

    OpenAIRE

    Frindy, Sana; Primo Arnau, Ana Maria; Qaiss, Abou el Kacem; Bouhfid, Rachid; Lahcini, Mohamed; García Gómez, Hermenegildo; Bousmina, Mosto; El Kadib, Abdelkrim

    2016-01-01

    [EN] Three natural clay-based microstructures, namely layered montmorillonite (MMT), nanotubular halloysite (HNT) and micro-fibrillar sepiolite (SP) were used for the synthesis of hybrid chitosan-clay thin films and porous aerogel microspheres. At a first glance, a decrease in the viscosity of the three gel forming solutions was noticed as a result of breaking the mutual polymeric chains interaction by the clay microstructure. Upon casting, chitosan-clay films displayed enhanced hydrophilicit...

  18. Experimental Study on Unconfined Compressive Strength of Basalt Fiber Reinforced Clay Soil

    Directory of Open Access Journals (Sweden)

    Lei Gao

    2015-01-01

    Full Text Available In order to study the mechanism and effect of basalt fiber reinforced clay soil, a series of unconfined compressive strength tests conducted on clay soil reinforced with basalt fiber have been performed under the condition of optimum water content and maximum dry density. Both the content and length of basalt fiber are considered in this paper. When the effect of content is studied, the 12 mm long fibers are dispersed into clay soil at different contents of 0.05%, 0.1%, 0.15%, 0.20%, 0.25%, 0.30%, and 0.35%. When the effect of length is researched, different lengths of basalt fibers with 4 mm, 8 mm, 12 mm, and 15 mm are put into soil at the same content of 0.05%. Experimental results show that basalt fiber can effectively improve the UCS of clay soil. And the best content and length are 0.25% and 12 mm, respectively. The results also show that the basalt fiber reinforced clay soil has the “poststrong” characteristic. About the reinforcement mechanism, the fiber and soil column-net model is proposed in this paper. Based on this model and SEM images, the effect of fiber content and length is related to the change of fiber-soil column and formation of effective fiber-soil net.

  19. Calcination of kaolinite clay particles for cement production

    DEFF Research Database (Denmark)

    Gebremariam, Abraham Teklay; Yin, Chungen; Rosendahl, Lasse

    2014-01-01

    Kaolinite rich clay particles calcined under certain conditions can attain favorable pozzolanic properties and can be used to substitute part of the CO2 intensive clinker in cement production. To better guide calcination of a clay material, a transient one-dimensional single particle model...

  20. Squeezed Interstitial Water and Soil Properties in Pleistocene Blue Clays under Different Natural Environments

    Directory of Open Access Journals (Sweden)

    Maria Dolores Fidelibus

    2018-03-01

    Full Text Available Studies dating almost a century relate clay properties with the structure of the diffuse double layer (DDL, where the charged surfaces of clay crystal behave like an electric capacitor, whose dielectric is the interstitial fluid. The intensity of the inner electric field relates to the concentration and type of ions in the DDL. Other important implications of the model are less stressed: this part of the clay soil system, energetically speaking, is conservative. External contribution of energy, work of overburden or sun driven capillarity and long exposure to border low salinity waters can modify the concentration of pore-waters, thus affecting the DDL geometry, with electric field and energy storage variations. The study of clay soils coming from various natural geomorphological and hydrogeological contexts, determining a different salinity of interacting groundwater, shows how the clay interaction with freely circulating waters at the boundaries produces alterations in the native pore water salinity, and, at the nano-scale, variations of electric field and stored energy from external work. The swelling and the shrinkage of clay soil with their volumetric and geotechnical implications should be regarded as variations of the electrostatic and mechanical energy of the system. The study is based on tests on natural clay soil samples coming from a formation of stiff blue clays, widespread in southern Italy. Geotechnical identification and oedometer tests have been performed, and pore waters squeezed out from the specimens have been analyzed. Tested samples have similar grain size, clay fraction and plasticity; sorted according to the classified geomorphological/hydrogeological contexts, they highlight good correlations among dry density, mechanical work performed in selected stages of the oedometric test, swelling and non-swelling behaviour, and electrical conductivity of the squeezed pore waters. The work performed for swelling and non

  1. Organic or organometallic template mediated clay synthesis

    Science.gov (United States)

    Gregar, Kathleen C.; Winans, Randall E.; Botto, Robert E.

    1994-01-01

    A method for incorporating diverse Varieties of intercalants or templates directly during hydrothermal synthesis of clays such as hectorite or montmorillonite-type layer-silicate clays. For a hectorite layer-silicate clay, refluxing a gel of silica sol, magnesium hydroxide sol and lithium fluoride for two days in the presence of an organic or organometallic intercalant or template results in crystalline products containing either (a) organic dye molecules such as ethyl violet and methyl green, (b) dye molecules such as alcian blue that are based on a Cu(II)-phthalocyannine complex, or (c) transition metal complexes such as Ru(II)phenanthroline and Co(III)sepulchrate or (d) water-soluble porphyrins and metalloporphyrins. Montmorillonite-type clays are made by the method taught by U.S. Pat. No. 3,887,454 issued to Hickson, Jun. 13, 1975; however, a variety of intercalants or templates may be introduced. The intercalants or templates should have (i) water-solubility, (ii) positive charge, and (iii) thermal stability under moderately basic (pH 9-10) aqueous reflux conditions or hydrothermal pressurized conditions for the montmorillonite-type clays.

  2. Toxicity assessment of organomodified clays used in food contact materials on human target cell lines

    NARCIS (Netherlands)

    Houtman, J.; Maisanaba, S.; Puerto, M.; Gutierrez-Praena, D.; Jorda, M.; Aucejo, S.; Jos, A.

    2014-01-01

    Nowadays, the incorporation of organomodified clays based on montmorillonite into polymers intended for packaging industry is a reality. The final result is a polymer nanocomposite with enhanced barrier properties. Different organomodified clays are already commercially available and others new ones

  3. A conceptual model linking functional gene expression and reductive dechlorination rates of chlorinated ethenes in clay rich groundwater sediment

    DEFF Research Database (Denmark)

    Bælum, Jacob; Chambon, Julie Claire Claudia; Scheutz, Charlotte

    2013-01-01

    We used current knowledge of cellular processes involved in reductive dechlorination to develop a conceptual model to describe the regulatory system of dechlorination at the cell level; the model links bacterial growth and substrate consumption to the abundance of messenger RNA of functional gene...

  4. ATLAS IV in situ heating test in Boom Clay

    International Nuclear Information System (INIS)

    Chen, Guangjing; Li, Xiangling; Verstricht, Jan; Sillen, Xavier

    2012-01-01

    Document available in extended abstract form only. The small scale in-situ ATLAS (Admissible Thermal Loading for Argillaceous Storage) tests are performed to assess the hydro-mechanical effects of a thermal transient on the host Boom clay at the HADES underground research facility in Mol, Belgium. The initial test set-up, consisting of a heater borehole and two observation boreholes, was installed in 1991-1992. The first test (later named 'ATLAS I') was then performed from July 1993 to June 1996; during this time, the heater dissipated a constant power of 900 W. During the second phase ('ATLAS II'), the heating power was doubled (1800 W) and maintained constant from June 1996 to May 1997. This was followed by shutdown and natural cooling starting from June 1997 on. To broaden the THM characterization of the Boom clay at a larger scale and at different temperature levels, the test set-up was extended in 2006 by drilling two additional instrumented boreholes (AT97E and AT98E). The heater was switched on again from April 2007 to April 2008 with a stepwise power increase, followed by an instantaneous shutdown. This phase is called 'ATLAS III'. The above tests have provided a large set of good quality and well documented data on temperature, pore water pressure and total stress; these data allowed to make several interesting observations regarding the thermal anisotropy and THM coupling in the Boom clay. The straightforward geometry and well defined boundary conditions of the tests facilitate the comparison between measurement and numerical modeling studies. Based on the three dimensional coupled THM modeling of the ATLAS III test, the good agreement between measurement and numerical modeling of temperature and pore water pressure yields a set of THM parameters and confirms the thermo-mechanical anisotropy of the Boom clay. To get a better insight in the anisotropic THM behavior of the Boom clay, a new upward instrumented borehole was drilled above the ATLAS heater at

  5. Strong discontinuity with cam clay under large deformations

    DEFF Research Database (Denmark)

    Katic, Natasa; Hededal, Ole

    2008-01-01

    The work shows simultaneous implementation of Strong discontinuity approach (SDA) by means of Enhanced Assumed Strain (EAS) and Critical State Soil Mechanics CSSM) in large strain regime. The numerical model is based on an additive decomposition of the displacement gradient into a conforming and ...... and an enhanced part. The localized deformations are approximated by means of a discontinuous displacement field. The applied algorithm leads to a predictor/corrector procedure which is formally identical to the returnmapping algorithm of classical (local and continuous) Cam clay model....

  6. Quick clay and landslides of clayey soils.

    Science.gov (United States)

    Khaldoun, Asmae; Moller, Peder; Fall, Abdoulaye; Wegdam, Gerard; De Leeuw, Bert; Méheust, Yves; Otto Fossum, Jon; Bonn, Daniel

    2009-10-30

    We study the rheology of quick clay, an unstable soil responsible for many landslides. We show that above a critical stress the material starts flowing abruptly with a very large viscosity decrease caused by the flow. This leads to avalanche behavior that accounts for the instability of quick clay soils. Reproducing landslides on a small scale in the laboratory shows that an additional factor that determines the violence of the slides is the inhomogeneity of the flow. We propose a simple yield stress model capable of reproducing the laboratory landslide data, allowing us to relate landslides to the measured rheology.

  7. A Study of Clay-Epoxy Nanocomposites Consisting of Unmodified Clay and Organo Clay

    Directory of Open Access Journals (Sweden)

    Graham Edward

    2006-04-01

    Full Text Available Clay-epoxy nanocomposites were synthesized from DGEBA resin and montmorillonite clay with an in-situ polymerization. One type of untreated clay and two types of organo clay were used to produce the nanocompsoites. The aims of this study were to examine the nanocomposite structure using different tools and to compare the results between the unmodified clay and modified clays as nanofillers. Although diffractogram in reflection mode did not show any apparent peak of both types of materials, the transmitted XRD (X-Ray Difraction graphs, DSC (Differential Scanning Calorimeter analysis and TEM (Transmission Electron Microscope images revealed that the modified clay-epoxy and unmodified clay-epoxy provides different results. Interestingly, the micrographs showed that some of the modified clay layers possessed non-exfoliated layers in the modified clay-epoxy nanocomposites. Clay aggregates and a hackle pattern were found from E-SEM images for both types of nanocomposite materials. It is shown that different tools should be used to determine the nanocomposite structure.

  8. Clays in natural and engineered barriers for radioactive waste confinement

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    Andra organised an International Symposium on the use of Natural and Engineered Clay-based Barriers for the Containment of Radioactive Waste hold at the Congress Centre of Tours, France, in March 2005. The symposium provided an opportunity to take stock of the potential properties of the clay-based materials present in engineered or natural barriers in order to meet the containment specifications of a deep geological repository for radioactive waste. It was intended for specialists working in the various disciplines involved with clays and clay based minerals, as well as scientists from agencies and organisations dealing with investigations on the disposal of high-level and long-lived radioactive waste. The themes of the Symposium included geology, geochemistry, transfers of materials, alteration processes, geomechanics, as well as the recent developments regarding the characterisation of clays, as well as experiments in surface and underground laboratories. The symposium consisted of plenary sessions, parallel specialized sessions and poster sessions. (author)

  9. The Role of Clay Swelling and Mineral Neoformation in the Stabilization of High Plasticity Soils Treated with the Fly Ash- and Metakaolin-Based Geopolymers

    Directory of Open Access Journals (Sweden)

    Mahmoud A. Mahrous

    2018-04-01

    Full Text Available In the southern U.S. states, expansive soils are frequently encountered, presenting an important hazard in geotechnical engineering. This research relies on mineralogical and geochemical clues to explain the swelling behavior of smectite-rich, high-plasticity soils, documented in a series of geomechanical swelling tests that were performed on the soils stabilized with the metakaolin (MKG and fly ash (FAG based geopolymers. These geopolymers were mixed with the soil at several concentration levels. The lowest swelling percentage was shown to correspond to the sample stabilized with 12% FAG and was attributed to the neoformation of calcium silicate hydrates that acted as a cementitious material, preventing the soil from expanding by occupying the pore space, thus binding the clay particles together. Conversely, the 12% MKG-stabilized soil exhibited enormous expansion, which was explained by montmorillonite swelling to the point that it gradually began to lose its structural periodicity. The relatively high abundance of the newly formed feldspathoids in MKG-treated samples is believed to have greatly contributed to the overall soil expansion. Finally, the cation exchange capacity tests showed that the percentage of Na+ and Ca2+, as well as the pH value, exercised strong control on the swelling behavior of smectitic soils.

  10. Modelling of the mechanical behaviour and damage of clay-stones: application to the East argillite; Modelisation du comportement mecanique des argiles raides avec prise en compte de l'endommagement: application aux argilites de l'Est

    Energy Technology Data Exchange (ETDEWEB)

    Aublive-Conil, N

    2003-03-15

    The storage in deep geological formation is one of the solutions retained by France for the management of highly long life radioactive waste. The retained host rock is a clay-stone named East argillite located in the departments of Meuse and Haute-Marne. A thermodynamic formulation is used to propose a rheological model, which reproduces the mechanical behavior of clay-stones. Initially, an anisotropic damage plastic model was formulated in order to describe material degradations. Then, the damage plastic model is reformulated in order to taken into account the damage influence on the hydraulic behavior of porous material. The numerical simulations correctly reproduce the mechanical behavior of East Argillites but also the anisotropy of the hydraulic behavior introduced by the damage effect. (author)

  11. Modelling of the mechanical behaviour and damage of clay-stones: application to the East argillite; Modelisation du comportement mecanique des argiles raides avec prise en compte de l'endommagement: application aux argilites de l'Est

    Energy Technology Data Exchange (ETDEWEB)

    Aublive-Conil, N

    2003-03-15

    The storage in deep geological formation is one of the solutions retained by France for the management of highly long life radioactive waste. The retained host rock is a clay-stone named East argillite located in the departments of Meuse and Haute-Marne. A thermodynamic formulation is used to propose a rheological model, which reproduces the mechanical behavior of clay-stones. Initially, an anisotropic damage plastic model was formulated in order to describe material degradations. Then, the damage plastic model is reformulated in order to taken into account the damage influence on the hydraulic behavior of porous material. The numerical simulations correctly reproduce the mechanical behavior of East Argillites but also the anisotropy of the hydraulic behavior introduced by the damage effect. (author)

  12. NOAA Office for Coastal Management Coastal Inundation Digital Elevation Model: Jacksonville (FL) WFO - Duval, Clay, and Nassau Counties

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This digital elevation model (DEM) is a part of a series of DEMs produced for the National Oceanic and Atmospheric Administration Office for Coastal Management's Sea...

  13. Skull base tumor model.

    Science.gov (United States)

    Gragnaniello, Cristian; Nader, Remi; van Doormaal, Tristan; Kamel, Mahmoud; Voormolen, Eduard H J; Lasio, Giovanni; Aboud, Emad; Regli, Luca; Tulleken, Cornelius A F; Al-Mefty, Ossama

    2010-11-01

    Resident duty-hours restrictions have now been instituted in many countries worldwide. Shortened training times and increased public scrutiny of surgical competency have led to a move away from the traditional apprenticeship model of training. The development of educational models for brain anatomy is a fascinating innovation allowing neurosurgeons to train without the need to practice on real patients and it may be a solution to achieve competency within a shortened training period. The authors describe the use of Stratathane resin ST-504 polymer (SRSP), which is inserted at different intracranial locations to closely mimic meningiomas and other pathological entities of the skull base, in a cadaveric model, for use in neurosurgical training. Silicone-injected and pressurized cadaveric heads were used for studying the SRSP model. The SRSP presents unique intrinsic metamorphic characteristics: liquid at first, it expands and foams when injected into the desired area of the brain, forming a solid tumorlike structure. The authors injected SRSP via different passages that did not influence routes used for the surgical approach for resection of the simulated lesion. For example, SRSP injection routes included endonasal transsphenoidal or transoral approaches if lesions were to be removed through standard skull base approach, or, alternatively, SRSP was injected via a cranial approach if the removal was planned to be via the transsphenoidal or transoral route. The model was set in place in 3 countries (US, Italy, and The Netherlands), and a pool of 13 physicians from 4 different institutions (all surgeons and surgeons in training) participated in evaluating it and provided feedback. All 13 evaluating physicians had overall positive impressions of the model. The overall score on 9 components evaluated--including comparison between the tumor model and real tumor cases, perioperative requirements, general impression, and applicability--was 88% (100% being the best possible

  14. Diffusion in Clay Layers and Groundwater Remediation

    Science.gov (United States)

    In a collaborative SERDP-funded study, researchers from the Air Force Institute of Technology, the U.S. Environmental Protection Agency, and the University of Michigan developed a numerical model that simulates the enhanced transport of CAHs into and out of low permeability clay ...

  15. Mud peeling and horizontal crack formation in drying clays

    KAUST Repository

    Style, Robert W.

    2011-03-01

    Mud peeling is a common phenomenon whereby horizontal cracks propagate parallel to the surface of a drying clay. Differential stresses then cause the layer of clay above the crack to curl up to form a mud peel. By treating the clay as a poroelastic solid, we analyze the peeling phenomenon and show that it is caused by the gradient in tensile stress at the surface of the clay, analogously to the spalling of thermoelastic materials. For a constant water evaporation rate at the clay surface we derive equations for the depth of peeling and the time of peeling as functions of the evaporation rate. Our model predicts a simple relationship between the radius of curvature of a mud peel and the depth of peeling. The model predictions are in agreement with the available experimental data. Copyright 2011 by the American Geophysical Union.

  16. Satellite based radar interferometry to estimate large-scale soil water depletion from clay shrinkage: possibilities and limitations

    NARCIS (Netherlands)

    Brake, te B.; Hanssen, R.F.; Ploeg, van der M.J.; Rooij, de G.H.

    2013-01-01

    Satellite-based radar interferometry is a technique capable of measuring small surface elevation changes at large scales and with a high resolution. In vadose zone hydrology, it has been recognized for a long time that surface elevation changes due to swell and shrinkage of clayey soils can serve as

  17. Investigation of isothermal water infiltration into fired clay brick by scattered neutrons

    International Nuclear Information System (INIS)

    El Abd, A.; Abdel-Monem, A.M.; Kansouh, W.A.

    2012-01-01

    A method based on neutron scattering was proposed to investigate isothermal water infiltration in porous media. Two different kinds of fired clay bricks were investigated. While the sample absorb water, scattered neutrons from the different wetted regions, along the flow direction were continuously recorded. The results were discussed in terms of the theory of water infiltration in unsaturated porous media as well as by an anomalous diffusion approach. It was shown that the infiltration process in the Canadian clay brick (CCB) is Fickian and the water diffusivity was analytically determined, while it is non-Fickian in the Egyptian clay brick (ECB). The infiltration process in ECB can be modeled as a two stage Fickian process, at the low and high absorption times. The anomalous diffusion approach failed to describe the diffusion process in the ECB at all water contents. (author)

  18. 1,2'-Bis(4-aminophenoxy)benzene based designed fluoro-poly(ether-imide)/MMT clay nanocomposites: Synthesis and properties for high performance applications

    International Nuclear Information System (INIS)

    Vora, Rohitkumar H.; Vora, Mayur

    2006-01-01

    In an effort to develop structure-property understanding of fluoro-polymer/inorganic clay nanocomposite (i.e., Ceramer) technology, two series of fluoro-poly(ether amic acid) (6F-PEAA)/organosoluble Montmorillonite (MMT) clay nanocomposite formulations containing varying percentage of diamine modified (ion-exchanged) organosoluble-MMT clay were prepared from the partially fluorinated fluoro poly(ether-amic acid)s (6F-PEAA) synthesized by reacting on 2,2'-bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) and di-ether-containing diamines, such as 1,2'-bis(4-aminophenoxy) benzene (o-BAPOB) and 4,4'-bis(4-aminophenoxy) diphenyl sulfone (p-SED), respectively. Self supporting films were cast from these formulations and cured at elevated temperatures. XRD data, indirectly confirmed the exfoliation of organosoluble-MMT clay at molecular level in the nanocomposite. The solubility, chemical resistance, morphology, thermo-oxidative stability, thermal degradation kinetics, mechanical behavior, and moisture absorption of these [(6F-PEI)/MMT clay] nanocomposite films were systematically studied

  19. Modified effective medium model for gas hydrate bearing,clay-dominated sediments in the Krishna-Godavari Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Sriram, G.; Dewangan, P.; Ramprasad, T.

    .D., 1990. Nonlinear elasticity and pressure-dependent wave speeds in granular media. Proc. R. Soc. London. Ser. A Math. Phys. Sci. 430, 105–131. Guerin, G., Goldberg, D., 2005. Modeling of acoustic wave dissipation in gas hydrate-bearing sediments...

  20. Particle and solute migration in porous media. Modeling of simultaneous transport of clay particles and radionuclides in a salinity gradient

    International Nuclear Information System (INIS)

    Faure, M.H.

    1994-03-01

    Understanding the mechanisms which control the transient transport of particles and radionuclides in natural and artificial porous media is a key problem for the assessment of safety of radioactive waste disposals. An experimental study has been performed to characterize the clayey particle mobility in porous media: a laboratory- made column, packed with an unconsolidated sand bentonite (5% weight) sample, is flushed with a salt solution. An original method of salinity gradient allowed us to show and to quantify some typical behaviours of this system: threshold effects in the peptization of particles, creation of preferential pathways, formation of immobile water zones induce solute-transfer limitation. The mathematical modelling accounts for a phenomenological law, where the distribution of particles between the stagnant water zone and the porous medium is a function of sodium chloride concentration. This distribution function is associated with a radionuclide adsorption model, and is included in a convective dispersive transport model with stagnant water zones. It allowed us to simulate the particle and solute transport when the salt environment is modified. The complete model has been validated with experiments involving cesium, calcium and neptunium in a sodium chloride gradient. (author). refs., figs., tabs

  1. Studies on thermal reactions and sintering behaviour of red clays by irreversible dilatometry

    Science.gov (United States)

    Anil, Asha; Misra, S. N.; Misra, N. M.

    2018-05-01

    Thermal behavior of clays strongly influences that of ceramic bodies made thereof and hence, its study is must for assessing its utility in ceramic products as well as to set the body composition. Irreversible dilatometry is an effective thermal analysis tool for evaluating thermal reactions as well as sintering behavior of clays or clay based ceramic bodies. In this study, irreversible dilatometry of four red clay samples (S, M, R and G) of Gujarat region, which vary in their chemical and mineralogical compositions was carried out using a Dilatometer and compared. Chemical analysis and XRD of red clays were carried out. XRD showed that major clay minerals in S, M and R clays are kaolinite. However, clay marked R and G showed presence of both kaolinite and illite and /muscovite. Presence of non-clay minerals such as hematite, quartz, anatase were also observed in all clays. XRD results were in agreement with chemical analyses results. Rational analyses showed variation in amount of clay and non-clay minerals in red clay samples. Evaluation of dilatometric curves showed that clay marked as S, M and R exhibit patterns typical for kaolinitic clays. Variation in linear expansion (up to 550°C) and shrinkage (above 550°C) between these three clays was found to be related to difference in amount of quartz and kaolinite respectively. However, dilatometric curve of G exhibit a pattern similar to that for an illitic clay. This study confirmed that sintering of investigated kaolinitic and illitic and / muscovitic red clays initiates at above 1060°C and 860°C respectively and this behaviour strongly depends upon type and amount of minerals and their chemical compositions.

  2. Hydroxyapatite clay for gap filling and adequate bone ingrowth.

    Science.gov (United States)

    Maruyama, M; Terayama, K; Ito, M; Takei, T; Kitagawa, E

    1995-03-01

    In uncemented total hip arthroplasty, a complete filling of the gap between femoral prosthesis and the host bone is difficult and defects would remain, because the anatomy of the reamed intramedullary canal cannot fit the prosthesis. Therefore, it seems practical to fill the gap with a clay containing hydroxyapatite (HA), which has an osteoconductive character. The clay (HA clay) is made by mixing HA granules (size 0.1 mm or more) having a homogeneous pore distribution and a porosity of 35-48 vol%, and a viscous substance such as a saline solution of sodium alginate (SSSA). In the first experiment, the ratio of HA granules and sodium alginate in SSSA is set for the same handling properties of HA clay and polymethylmethacrylate bone cement (standard viscosity) before hardening. As a result, the ratio is set for 55 wt% of HA in the clay and 12.5 wt% of sodium alginate in SSSA (i.e., HA:sodium alginate:saline solution = 9.8:1:7). In the second study, the gap between the femoral stem and bone model is completely filled with HA clay. However, the gap is not filled only with HA granules or HA granules mixed with saline solution. In the third animal experiment, using an unloaded model, histology shows that HA clay has an osteoconductive property bridging the gap between the implant and the cortical bone without any adverse reaction. HA clay is considered a useful biomaterial to fill the gap with adequate bone ingrowth.

  3. Long-term performance of geosynthetic clay liners in cappings

    International Nuclear Information System (INIS)

    Maubeuge, K.P. von; Fricke, A.

    1998-01-01

    Geosynthetic clay liners (GCLs) are relatively thin composite materials combining bentonite clay and geosynthesis (usually geotextiles). GCLs have been employed by the waste industry for well over a decade now, and their level of usage is rapidly increasing world-wide. In landfill facilities, GCLs are generally used to replace or augment compacted clay liners. Until recently, the decision to do so has primarily been based on the availability of clay material on site (i.e., economic considerations). However, the advantages in using a GCL over other sealing elements such as compacted clay are not only economic but technically based, and the economic benefits extend beyond the construction phase, as a thin GCL can increase the revenue earning potential of a facility. This paper will highlight the shear behaviour of GCLs and demonstrate the long-term stability. (orig.)

  4. Impact-Induced Clay Mineral Formation and Distribution on Mars

    Science.gov (United States)

    Rivera-Valentin, E. G.; Craig, P. I.

    2015-01-01

    Clay minerals have been identified in the central peaks and ejecta blankets of impact craters on Mars. Several studies have suggested these clay minerals formed as a result of impact induced hydrothermalism either during Mars' Noachian era or more recently by the melting of subsurface ice. Examples of post-impact clay formation is found in several locations on Earth such as the Mjolnir and Woodleigh Impact Structures. Additionally, a recent study has suggested the clay minerals observed on Ceres are the result of impact-induced hydrothermal processes. Such processes may have occurred on Mars, possibly during the Noachian. Distinguishing between clay minerals formed preor post-impact can be accomplished by studying their IR spectra. In fact, showed that the IR spectra of clay minerals is greatly affected at longer wavelengths (i.e. mid-IR, 5-25 micron) by impact-induced shock deformation while the near-IR spectra (1.0-2.5 micron) remains relatively unchanged. This explains the discrepancy between NIR and MIR observations of clay minerals in martian impact craters noted. Thus, it allows us to determine whether a clay mineral formed from impact-induced hydrothermalism or were pre-existing and were altered by the impact. Here we study the role of impacts on the formation and distribution of clay minerals on Mars via a fully 3-D Monte Carlo cratering model, including impact- melt production using results from modern hydrocode simulations. We identify regions that are conducive to clay formation and the location of clay minerals post-bombardment.

  5. Black clay. Domestic stove based on counter current combustion, a principle used during the Iron Age and utilized in a baking oven from the Middle Ages; Sortemuld; Braendovn med modstroemsforbraending et princip fra jernalderen anvendt i bageovne fra middelalderen

    Energy Technology Data Exchange (ETDEWEB)

    Lund, E.

    1994-01-01

    Sortemuld (Black clay) ovens, based on the counter-current combustion principle, were used during the Iron Age and throughout the following centuries. It is claimed that the use of this technique results in the wood fuel being burnt so quickly that the oven temperature remains so high and for such a long time that the heat will be retained in the walls of such clay ovens. Prototype ovens were constructed, based on this principle, and various types of wood fuel were burnt in them. About 20 - 40 kg of fuel was combusted with each firing which lasted from 2-4 hours, answering to 20 - 40 kW/hrs. The carbon dioxide content reached 0.1% at times. The designs and construction of the prototypes ovens are described in detail and their performance documented. The text is illustrated with diagrams and the results of the performance testing are given in detail. (AB)

  6. Fe(0)-clays interactions at 90°C under anoxic conditions: a comparative study between clay fraction of Callovo-Oxfordian and other purified clays

    International Nuclear Information System (INIS)

    Rivard, C.; Pelletier, M.; Villieras, F.; Barres, O.; Galmiche, M.; Ghanbaja, J.; Kohler, A.; Michau, N.

    2010-01-01

    separated by centrifugation. For the liquid phase, pH and Eh measurements as well as chemical analyses were carried out. The solid fraction was characterized using a combination of classical techniques (chemical analyses, X-ray diffraction, Fourier Transform Infrared spectroscopy, scanning and transmission electron microscopy, nitrogen adsorption and XPS and Moessbauer analyses). Additional observation tools, based on the use of synchrotron radiation (Scanning Transmission X-ray Microscopy (STXM) and Micro-X-ray Absorption Spectroscopy (μ-XAS)) were used to obtain more detailed data on the status of iron and location in individualized clay particles. The combination of all these experimental techniques and comparison between reference clays and Callovo-Oxfordian clay fraction provides information about the evolution of pristine iron and clay minerals and newly formed phases. In a second step, quartz, calcite or pyrite were added to Callovo-Oxfordian clay fraction and the same experimental procedure was applied in order to evaluate the impact of these accessory minerals on the evolution of clays fraction and iron. In addition, two other physicochemical parameters were investigated: the role of physical contact between metallic iron grains and clay particles, and the influence of gas exchanges. Indeed, these parameters can modify the kinetics of the reaction between iron and clay, and consequently, change the nature of newly formed minerals. (authors)

  7. Research of Deformation of Clay Soil Mixtures Mixtures

    OpenAIRE

    Romas Girkontas; Tadas Tamošiūnas; Andrius Savickas

    2014-01-01

    The aim of this article is to determine clay soils and clay soils mixtures deformations during drying. Experiments consisted from: a) clay and clay mixtures bridges (height ~ 0,30 m, span ~ 1,00 m); b) tiles of clay and clay, sand and straw (height, length, wide); c) cylinders of clay; clay and straw; clay, straw and sand (diameter; height). According to the findings recommendations for clay and clay mixtures drying technology application were presented. During the experiment clay bridge bear...

  8. Project Opalinus clay Zuercher Weinland of Nagra. Evaluation of the geo-scientific data base and of the construction engineering aspects; Projekt Opalinuston Zuercher Weinland der Nagra. Beurteilung der erdwissenschaftlichen Datengrundlagen und der bautechnischen Machbarkeit

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-02-15

    In this report the Commission for Nuclear Waste Management (KNE) assesses the geological and engineering aspects of the project Opalinus Clay, in which Nagra demonstrates the postclosure safety of geological disposal of spent fuel (SF), vitrified high-level wastes (HLW) and intermediate-level wastes (ILW) in a repository in the Opalinus Clay of the Zuercher Weinland in northern Switzerland. After in-depth examination of the geological database, KNE concludes that the demonstration of a suitable geological site for final disposal of SF, HLW and ILW in the Opalinus Clay of the Zuercher Weinland has been achieved. The geological assumptions Nagra uses for the assessment of long-term safety are based on data that have been carefully collected and interpreted. KNE acknowledges that Nagra interpreted the geological data correctly and adequately using state-of-the-art techniques. In case of lacking information, Nagra has used conservative or worst-case assumptions. The information documented by Nagra represents a good synthesis of field, laboratory and literature data. The tectonic situation of the Zuercher Weinland was examined in great details by Nagra. In the centre of the investigated region, where the Opalinus Clay occurs at 600 to 750 meters depth, the 3D-seismic data confirm its undisturbed stratification in an area of about 15 km{sup 2}. Analysis and interpretation of the available information on the geological evolution provides no indication that erosion would expose the confining units above the Opalinus Clay within the next million years. The Opalinus Clay in the Zuercher Weinland is quite homogeneous and about 110 m thick. The properties of this rock are examined and found to be favourable for a repository. The dominance of the fine grain size and the high clay content indicate a very low hydraulic conductivity suitable for the isolation of radioactive wastes. Pore water extracted from drill-core samples is saline and has remained trapped for millions of

  9. Groundwater flow reference model of the Meuse/Haute-Marne region: implications on performance analysis of high and intermediate level and long lived radwaste repository in clay formation

    International Nuclear Information System (INIS)

    Benabderrahmane, H.; Plas, F.; Yven, B.; Cornaton, F.; Perrochet, P.; Kerrou, J.; Stucki, J.; Caloz, P.

    2010-01-01

    Document available in extended abstract form only. An integrated multi-scale hydrogeological conceptual model of the Paris basin and the Meuse/Haute-Marne sector was developed to study the groundwater flow and solute transport behaviour in the multi-layered aquifer system and around the Callovo-Oxfordian clay formation as potential host for the French high and intermediate level and long lived radioactive waste. The Paris basin system (200000 km 2 ) consists of 27 aquiferous and semi-permeable (aquitard) hydrogeological units from Trias to Quaternary affected by 80 regional faults. It produces boundary conditions to the refined aquifer system of the 250 km 2 Meuse/Haute-Marne site, which includes 27 layers from Trias to Portlandian. The Callovo-Oxfordian clay formation is located at a mean depth of 500 m, with a minimum thickness of 130 m and hydraulic conductivity values of the order of 10-14 m/s. The numerical steady-state flow solution is calculated on a finite element mesh of about 3 million 2-D and 3-D linear elements (GEOS-CHYN 2009). At the top surface, the mesh refinement (250 m to 50 m) is locally constrained by the fault lineaments and the river network. At depth, it takes into account the 10 m to 500 m throw of the faults and the vertical flow through semi-permeable units. Triangular elements are used to represent a top surface layer that includes the weathered part of the outcropping formations, and quadrangular elements allow for the representation of the faults planes at depth. The layers are discretized into 6-nodded wedge elements, while 4-nodded tetrahedrons and 5-nodded pyramids are used to handle the pinching and the outcrop of the layers. The flow boundary conditions and source-sink terms are: - Specified hydraulic heads (Dirichlet) along the rivers and elsewhere on the top surface inflow fluxes (Neumann) derived from hydrological balance (with a mean inflow of 240 mm/year). - Specified hydraulic heads (Dirichlet) at the Manche coast side. - No

  10. Euroclay 95. Clays and clay materials sciences. Book of abstracts

    International Nuclear Information System (INIS)

    Elsen, A.; Grobet, P.; Keung, M.; Leeman, H.; Schoonheydt, R.; Toufar, H.

    1995-01-01

    The document contains the abstracts of the invited lecturers (18) and posters (247) presented at EUROCLAY '95. Clays and clay materials sciences. 13 items (4 from the invited lecturers and 12 from posters) have been considered within the INIS Subject Scope and indexed separately

  11. Euroclay 95. Clays and clay materials sciences. Book of abstracts

    Energy Technology Data Exchange (ETDEWEB)

    Elsen, A; Grobet, P; Keung, M; Leeman, H; Schoonheydt, R; Toufar, H [eds.

    1995-08-20

    The document contains the abstracts of the invited lecturers (18) and posters (247) presented at EUROCLAY `95. Clays and clay materials sciences. 13 items (4 from the invited lecturers and 12 from posters) have been considered within the INIS Subject Scope and indexed separately.

  12. Decantation time of evaluation on bentonite clays fractionation

    International Nuclear Information System (INIS)

    Gomes, J.; Menezes, R.R.; Neves, G.A.; Lira, H.L; Santana, L.N.L.

    2009-01-01

    Bentonite clays present a great number of industrial uses, from petroleum to pharmaceutics and cosmetic industry. The bentonite clay present particles with very fine particles that is responsible by the vast application of these materials. However, commercial clays present wide particle size distribution and a significant content of impurities, particularly quartz, in the form of silt and fine silt. So, the aim of this work is to analyze the effect of the stirring and decantation time in the deagglomeration, purification and size separation of the bentonite clay particles from Paraiba. The clays were characterized by X-ray diffraction and particle size distribution. Based on the results it was observed the decantation time give the elimination of the agglomerates formed by submicrometric particles. The uses of decantation column give separation of the fraction below 200nm. (author)

  13. Effect of Modified Red Pottery Clay on the Moisture Absorption Behavior and Weatherability of Polyethylene-Based Wood-Plastic Composites

    Directory of Open Access Journals (Sweden)

    Qingde Li

    2017-01-01

    Full Text Available Red pottery clay (RPC was modified using a silane coupling agent, and the modified RPC (mRPC was then used to enhance the performance of high-density polyethylene-based wood-plastic composites. The effect of the mRPC content on the performances of the composites was investigated through Fourier transform infrared spectrometry, differential mechanical analysis (DMA and ultraviolet (UV-accelerated aging tests. After adding the mRPC, a moisture adsorption hysteresis was observed. The DMA results indicated that the mRPC effectively enhanced the rigidity and elasticity of the composites. The mRPC affected the thermal gravimetric, leading to a reduction of the thermal degradation rate and a right-shift of the thermal degradation peak; the initial thermal degradation temperature was increased. After 3000 h of UV-accelerated aging, the flexural strength and impact strength both declined. For aging time between 0 and 1000 h, the increase in amplitude of ΔL* (luminescence and ΔE* (color reached a maximum; the surface fading did not became obvious. ΔL* and ΔE* increased more significantly between 1000 and 2000 h. These characterization results indicate that the chromophores of the mRPC became briefly active. However, when the aging times were higher than 2000 h, the photo-degradation reaction was effectively prevented by adding the mRPC. The best overall enhancement was observed for an mRPC mass percentage of 5%, with a storage modulus of 3264 MPa and an increase in loss modulus by 16.8%, the best anti-aging performance and the lowest degree of color fading.

  14. Toxic element composition of multani mitti clay for nutritional safety

    International Nuclear Information System (INIS)

    Waheed, S.; Faiz, Y.; Rahman, S.; Siddique, N.

    2013-01-01

    Geophagy of multani mitti (MM) clay is very common in central Pakistan especially amongst women. It was therefore mandatory to establish baseline levels of toxic elements in this clay for its safe dietary consumption by consumers of different genders, age groups and physical states. Instrumental neutron activation analysis and atomic absorption spectrometry techniques were used to determine the nutritional safety of MM clay for oral intake. All quantified toxic elements were detected at trace levels with composition in the descending order; Pb > Br > As > Sb > Hg > Cd. Comparison of these elements in MM clay with other clays shows that As, Cd, and Pb, are lowest in MM clay while its Br and Hg contents are high. Highest weekly dietary intakes of As, Br, Cd, Hg, and Sb were found to be 18, 0.05, 1.6, 9.2 and 1.1 % of the respective recommended provisional tolerable weekly intakes. The findings of this study show that As, Br, Cd, Hg and Sb in MM clay are well below the tolerance levels. However its Pb concentration is very high and may pose health concerns. The data presented in this study can be used as national base level guideline for geophagy of MM clay by men, women (normal, pregnant and lactating) and children. (author)

  15. Dynamics of confined reactive water in smectite clay-zeolite composites.

    Science.gov (United States)

    Pitman, Michael C; van Duin, Adri C T

    2012-02-15

    The dynamics of water confined to mesoporous regions in minerals such as swelling clays and zeolites is fundamental to a wide range of resource management issues impacting many processes on a global scale, including radioactive waste containment, desalination, and enhanced oil recovery. Large-scale atomic models of freely diffusing multilayer smectite particles at low hydration confined in a silicalite cage are used to investigate water dynamics in the composite environment with the ReaxFF reactive force field over a temperature range of 300-647 K. The reactive capability of the force field enabled a range of relevant surface chemistry to emerge, including acid/base equilibria in the interlayer calcium hydrates and silanol formation on the edges of the clay and inner surface of the zeolite housing. After annealing, the resulting clay models exhibit both mono- and bilayer hydration structures. Clay surface hydration redistributed markedly and yielded to silicalite water loading. We find that the absolute rates and temperature dependence of water dynamics compare well to neutron scattering data and pulse field gradient measures from relevant samples of Ca-montmorillonite and silicalite, respectively. Within an atomistic, reactive context, our results distinguish water dynamics in the interlayer Ca(OH)(2)·nH(2)O environment from water flowing over the clay surface, and from water diffusing within silicalite. We find that the diffusion of water when complexed to Ca hydrates is considerably slower than freely diffusing water over the clay surface, and the reduced mobility is well described by a difference in the Arrhenius pre-exponential factor rather than a change in activation energy.

  16. Clay-chitosan-gold nanoparticle nanohybrid: Preparation and application for assembly and direct electrochemistry of myoglobin

    International Nuclear Information System (INIS)

    Zhao Xiaojuan; Mai Zhibin; Kang Xinhuang; Dai Zong; Zou Xiaoyong

    2008-01-01

    A biocompatible nanohybrid material (clay/AuCS) based on clay, chitosan and gold nanoparticles was explored. The material could provide a favorable microenvironment for proteins to realize the direct electron transfer on glassy carbon electrodes (GCE). Myoglobin (Mb), as a model protein to investigate the nanohybrid, was immobilized between the clay/AuCS film and another clay layer. Mb in the system exhibited a pair of well-defined and quasi-reversible redox peaks at -0.160 V (vs. saturated Ag/AgCl electrode) in 0.1 M PBS (pH 7.0), corresponding to its heme Fe III /Fe II redox couples. UV-vis spectrum suggested that Mb retained its native conformation in the system. Basal plane spacing of clay obtained by X-ray diffraction (XRD) indicated that there was an intercalation-exfoliation-restacking process among Mb, AuCS and clay during the modified film drying. Excellent biocatalytic activity of Mb in the modified system was exemplified by the reduction of hydrogen peroxide and nitrite. The linear range of H 2 O 2 determination was from 3.9 x 10 -5 to 3.0 x 10 -3 M with a detection limit of 7.5 μM based on the signal to noise ratio of 3. The kinetic parameters such as α (charge transfer coefficient), k s (electron transfer rate constant) and K m (Michaelis-Menten constant) were evaluated to be 0.55, 2.66 ± 0.15 s -1 and 5.10 mM, respectively

  17. Effect of Water on Elastic and Creep Properties of Self-Standing Clay Films.

    Science.gov (United States)

    Carrier, Benoit; Vandamme, Matthieu; Pellenq, Roland J-M; Bornert, Michel; Ferrage, Eric; Hubert, Fabien; Van Damme, Henri

    2016-02-09

    We characterized experimentally the elastic and creep properties of thin self-standing clay films, and how their mechanical properties evolved with relative humidity and water content. The films were made of clay montmorillonite SWy-2, obtained by evaporation of a clay suspension. Three types of films were manufactured, which differed by their interlayer cation: sodium, calcium, or a mixture of sodium with calcium. The orientational order of the films was characterized by X-ray diffractometry. The films were mechanically solicited in tension, the resulting strains being measured by digital image correlation. We measured the Young's modulus and the creep over a variety of relative humidities, on a full cycle of adsorption-desorption for what concerns the Young's modulus. Increasing relative humidity made the films less stiff and made them creep more. Both the elastic and creep properties depended significantly on the interlayer cation. For the Young's modulus, this dependence must originate from a scale greater than the scale of the clay layer. Also, hysteresis disappeared when plotting the Young's modulus versus water content instead of relative humidity. Independent of interlayer cation and of relative humidity greater than 60%, after a transient period, the creep of the films was always a logarithmic function of time. The experimental data gathered on these mesoscale systems can be of value for modelers who aim at predicting the mechanical behavior of clay-based materials (e.g., shales) at the engineering macroscopic scale from the one at the atomistic scale, for them to validate the first steps of their upscaling scheme. They provide also valuable reference data for bioinspired clay-based hybrid materials.

  18. Migration of leachate solution through clay soil

    Energy Technology Data Exchange (ETDEWEB)

    Abdel Warith, M M

    1987-01-01

    The problem of domestic solid wastes buried in landfill sites is viewed from the aspect of leachate contamination and migration in the substrate, and the efficiency of natural clay barriers as an expedient economic lining material is assessed. Various chemical constituents of the landfill leachate of an actual waste containment site at Lachenaie (35 km east of Montreal) were determined from samples collected from specially designed basins. Data for companion tests on laboratory columns are also presented. Chemical analysis on samples from the basins and leachates from the columns measured changes in the concentration of: (a) cations (Na, K, Ca, and Mg), (b) anions (Cl, HCO/sub 3/, and CO/sub 3/) (c) total organic carbon (TOC), and (d) heavy metals (Fe, Zn, Pb, and Cu). The physical parameters measured included: (a) pH, and (b) specific conductivity. Predictions, using a dispersion-convection model for concentration profile development for either adsorbed or retained contaminants, were compared with the experimentally determined profiles (both in leaching columns and landfill laboratory model). Another set of experiments was also conducted to evaluate the effect of some organic fluids on the geotechnical properties of different clay soils (natural clay and two reference clay soils: illite and kaolinite). The results from this study have demonstrated that the natural clay soil can be used to adequately contain the different contaminant species usually present in the leachate solutions. Furthermore, the data suggested that under favorable soil conditions, landfill leachates containing low levels of trace metals will not pose a substantial contamination threat to the subsurface environment, provided that a proper thickness of barrier is used.

  19. Encapsulation of Clay Platelets inside Latex Particles

    NARCIS (Netherlands)

    Voorn, D.J.; Ming, W.; Herk, van A.M.; Fernando, R.H.; Sung, Li-Piin

    2009-01-01

    We present our recent attempts in encapsulating clay platelets inside latex particles by emulsion polymerization. Face modification of clay platelets by cationic exchange has been shown to be insufficient for clay encapsulation, leading to armored latex particles. Successful encapsulation of

  20. Adsorptive Removal of Reactive Black 5 from Wastewater Using Bentonite Clay: Isotherms, Kinetics and Thermodynamics

    Directory of Open Access Journals (Sweden)

    Muhammad Tahir Amin

    2015-11-01

    Full Text Available The studies of the kinetics and isotherms adsorption of the Reactive Black 5 (RB5 onto bentonite clay were explored in a batch study in a laboratory. The maximum RB5 adsorption conditions of bentonite clay were optimized such as shaking speed (100 rpm, temperature (323 K, pH (10, contact time (40 min, initial dye concentration (170 mg·L−1, and particle size (177 µm. The adsorbent surface was characterized using Fourier Transform Infrared Spectroscopy spectroscopy. The mechanisms and characteristic parameters of the adsorption process were analyzed using two parameter isotherm models which revealed the following order (based on the coefficient of determination: Harkin-Jura (0.9989 > Freundlich (0.9986 and Halsey (0.9986 > Langmuir (0.9915 > Temkin (0.9818 > Dubinin–Radushkevich (0.9678. This result suggests the heterogeneous nature of bentonite clay. Moreover, the adsorption process was chemisorption in nature because it follows the pseudo-second order reaction model with R2 value of 0.9998, 0.9933 and 0.9891 at 25, 75 and 100 mg·L−1 RB5 dye in the solution, respectively. Moreover, based on the values of standard enthalpy, Gibbs free energy change, and entropy, bentonite clay showed dual nature of exothermic and endothermic, spontaneous and non-spontaneous as well as increased and decreased randomness at solid–liquid interface at 303–313 K and 313–323 K temperature, respectively.

  1. Heteroaggregation of titanium dioxide nanoparticles with natural clay colloids.

    Science.gov (United States)

    Labille, Jérôme; Harns, Carrie; Bottero, Jean-Yves; Brant, Jonathan

    2015-06-02

    To better understand and predict the fate of engineered nanoparticles in the water column, we assessed the heteroaggregation of TiO2 nanoparticles with a smectite clay as analogues for natural colloids. Heteroaggregation was evaluated as a function of water salinity (10(-3) and 10(-1) M NaCl), pH (5 and 8), and selected nanoparticle concentration (0-4 mg/L). Time-resolved laser diffraction was used, coupled to an aggregation model, to identify the key mechanisms and variables that drive the heteroaggregation of the nanoparticles with colloids. Our data show that, at a relevant concentration, nanoparticle behavior is mainly driven by heteroaggregation with colloids, while homoaggregation remains negligible. The affinity of TiO2 nanoparticles for clay is driven by electrostatic interactions. Opposite surface charges and/or high ionic strength favored the formation of primary heteroaggregates via the attachment of nanoparticles to the clay. The initial shape and dispersion state of the clay as well as the nanoparticle/clay concentration ratio also affected the nature of the heteroaggregation mechanism. With dispersed clay platelets (10(-3) M NaCl), secondary heteroaggregation driven by bridging nanoparticles occurred at a nanoparticle/clay number ratio of greater than 0.5. In 10(-1) M NaCl, the clay was preaggregated into larger and more spherical units. This favored secondary heteroaggregation at lower nanoparticle concentration that correlated to the nanoparticle/clay surface area ratio. In this latter case, a nanoparticle to clay sticking efficiency could be determined.

  2. Influence of clay organic modifier on morphology and performance of poly(ε-caprolactone/clay nanocomposites

    Directory of Open Access Journals (Sweden)

    Nikolić Marija S.

    2015-01-01

    Full Text Available Two series of poly(e-caprolactone nanocomposites with different organo-modified clays (1 to 8 wt% were prepared by the solution casting method. Organoclays with polar (Cloisite®C30B and nonpolar (Cloisite®C15A organic modifier and with different miscibility with poly(e-caprolactone matrix, were chosen. Exfoliated and/or intercalated nanocomposite’s structures were obtained by using high dilution and an ultrasonic treatment for the composite preparation. The effect of the surface modification and clay content on the morphology, mechanical and thermal properties of the nanocomposites was studied. Scanning electron microscopy excluded the formation of microcomposite. The wide-angle X-ray diffraction analysis revealed that the tendency toward exfoliated structure is higher for the Cloisite®C30B, which had better miscibility with poly(e-caprolactone matrix. Differences in spherulites’ sizes and morphology between two series of the nanocomposites were observed by the optical microscopy performed on as-casted films. Enthalpies of fusion and degrees of crystallinity were higher for nanocomposites than for neat poly(e-caprolactone and increase with the clay loading in both series, as a consequence of the clay nucleating effect. Decreased thermal stability of nanocomposites was ascribed to thermal instability of organic modifiers of the clays. The Halpin-Tsai model was used to compare the theoretically predicted values of the Young’s modulus with experimentally obtained ones in tensile tests.[Projekat Ministarstva nauke Republike Srbije, br. 172062

  3. Thixotropic Properties of Latvian Illite Containing Clays

    OpenAIRE

    Lakevičs, Vitālijs; Stepanova, Valentīna; Niedra, Santa; Dušenkova, Inga; Ruplis, Augusts

    2015-01-01

    Thixotropic properties of Latvian Devonian and Quaternary clays were studied. Dynamic viscosity of the water clay suspensions were measured with a rotating viscometer. Influence of concentration, pH and modifiers on the thixotropic clay properties was analyzed. It was found that Latvian clays have thixotropic properties. Stability of clay suspensions is described with the thixotropy hysteresis loop. Increasing the speed of the viscometer rotation, dynamic viscosity of the clay suspension decr...

  4. Viscosity and Plasticity of Latvian Illite Clays

    OpenAIRE

    Jurgelāne, I; Vecstaudža, J; Stepanova, V; Mālers, J; Bērziņa-Cimdiņa, L

    2012-01-01

    Due to viscosity and plasticity, clays and clay minerals are used in civil engineering, pottery and also in cosmetics and medicine as thickening agents and emulsion and suspension stabilizers. The rheological properties of clay suspensions are complex. Mostly it is an interaction between mineral composition, clay particle size and pH value and also depends on clay minerals. Clay-water suspension is non-Newtonian fluid showing thixotropic and pseudoplastic properties. Results showed that plast...

  5. Considering clay rock heterogeneity in radionuclide retention

    International Nuclear Information System (INIS)

    Grambow, B.; Montavon, G.; Tournassat, C.; Giffaut, E.; Altmann, S.

    2010-01-01

    Document available in extended abstract form only. The Callovo-Oxfordian clay rock formation has a strong retention capacity for radionuclides, a favorable condition for the implementation of a nuclear waste repository. Principal retaining minerals are illite, and inter-stratified illite/smectite (I/S). Radionuclide retention has been studied on illite, illite/smectite and on clay rock obtained from different locations and data for retention on bentonite (80% smectite) are available. Sorption depends on the type of mineral, composition of mineralogical assemblages, individual mineral ion exchange capacities, ion distribution on exchange sites, specific surface areas, surface site types and densities for surface complexation as well as on water/rock ratios, temperature etc. As a consequence of mineralogical and textural variations, radionuclide retention properties are expected to vary with depth in the Callovo-Oxfordian formation. Using a simple additivity approach for the case of sorption of Cs and Ni it is shown that models and databases for illite and bentonite can be used to describe sorption in heterogeneous clay rock systems. A surface complexation/ion-exchange model as proposed by Bradbury and Baeyens without electrostatic contributions, was used directly as far as acid base properties are concerned but was modified with respect to sorption constants, in order to describe Na-, Ca, and Cs montmorillonite and bentonite MX-80 with a single set of surface complexation constants and also to account for carbonate and sulphate concentrations in groundwater. The model is integrated into the geochemical code PHREEQC considering dissolution/ precipitation/solubility constraints of accessory minerals (calcite, illite, celestite, quartz). Site densities for surface complexation and ion exchange are derived from the mass fractions of illite and of smectite in illite/smectite obtained from an overall fit of measured CEC data from all samples of the EST205 drill core

  6. Influence of carbonate micro-fabrics on the failure strength of Callovo-Oxfordian clay stones and Opalinus Clay

    International Nuclear Information System (INIS)

    Klinkenberg, M.; Dohrmann, R.; Kaufhold, S.; Siegesmund, S.

    2010-01-01

    Document available in extended abstract form only. The potential use of clay stones as host rock for radioactive waste disposal is currently investigated. For this application, hydraulic conductivity, swelling properties, water uptake, rheological and mechanical properties are of great importance. The Opalinus Clay (Mont-Terri, Switzerland) and the Callovo- Oxfordian clay stone (France) are the most frequently studied clay stones. One goal is to develop a numerical model being able to predict the mechanical behaviour of clay stones under repository-like conditions. Experimental investigations reveal that Opalinus Clay and Callovo-Oxfordian clay stone behave different with respect to the dependence of mechanical strength on the carbonate content. The failure strength of Opalinus Clay decreases with increasing carbonate content, whereas it increases with increasing carbonate content when Callovo-Oxfordian clay stone is considered. To supply proper data and enable reliable model assumptions, the use of suitable experimental techniques for the description of the microstructure is indispensable. After mechanical testing, samples were taken perpendicular to the bedding and polished sections were prepared. The micro-fabrics were investigated using scanning electron microscopy (SEM) and image analysis. Backscattered electron (BSE) images were used for the image analysis because carbonates can be extracted by grey level analysis. The image analysis of the extracted particles provides the following parameters: area, longest and shortest axis of an ellipse (surrounding the particle), perimeter, the angle to horizontal (longest axis), and the aspect ratio (longest axis/shortest axis). Callovo-Oxfordian clay stone shows a homogenous distribution of fine-grained carbonates and dovetail connection of calcium carbonate with the clayey matrix. In contrast Opalinus Clay shows large elongated carbonate grains (high aspect ratios) of shell fragments. Cracks are mostly related to these

  7. Optimal factor evaluation for the dissolution of alumina from Azaraegbelu clay in acid solution using RSM and ANN comparative analysis

    Directory of Open Access Journals (Sweden)

    P.E. Ohale

    2017-12-01

    Full Text Available Artificial neural network (ANN and Response Surface Methodology based on a 25−1 fractional factorial design were used as tools for simulation and optimisation of the dissolution process for Azaraegbelu clay. A feedforward neural network model with Levenberg–Marquard back propagating training algorithm was adapted to predict the response (alumina yield. The studied input variables were temperature, stirring speed, clay to acid dosage, leaching time and leachant concentration. The raw clay was characterized for structure elucidation via FTIR, SEM and X-ray diffraction spectroscopic techniques and the result indicates that the clay is predominantly kaolinite. Leachant concentration and dosage ratio were found to be the most significant process parameter with p-value of 0.0001. The performance of the ANN and RSM model showed adequate prediction of the response, with AAD of 11.6% and 3.6%, and R2 of 0.9733 and 0.9568, respectively. A non-dominated optimal response of 81.45% yield of alumina at 4.6 M sulphuric acid concentration, 214 min leaching time, 0.085 g/ml dosage and 214 rpm stirring speed was established as a viable route for reduced material and operating cost via RSM. Keywords: Alumina dissolution, ANN modelling, Azaraegbelu, Clay, RSM

  8. Microbial diversity in opalinus clay and interaction of dominant microbial strains with actinides

    International Nuclear Information System (INIS)

    Moll, Henry; Luetke, Laura; Bachvarova, Velina; Steudtner, Robin; Geissler, Andrea; Krawczyk-Baersch, Evelyn; Selenska-Pobell, Sonja; Bernhardt, Gert

    2013-01-01

    For the first time microbial tDNA could be isolated from 50 g unperturbed Mont Terri Opalinus Clay. Based on the analysis of the tDNA the bacterial diversity of the unperturbed clay is dominated by representatives of Firmicutes, Betaproteobacteria, and Bacteriodetes. Firmicutes also dominate after treatment of the clay with R2A medium. Bacteria isolated from Mont Terri Opalinus Clay on R2A medium were related to Sporomusa spp., Paenibacillus spp., and Clostridium spp. All further investigations are concentrated on the unique isolates Sporomusa sp. MT-2 and Paenibacillus sp. MT-2. Cells of the type Sporomusa sp. MT-2 and Paenibacillus sp. MT-2 were comprehensively analyzed in terms of growing, morphology, functional groups of the cell envelope, and cell membrane structure. Strong actinide(An)/lanthanide(Ln)-interactions with the Opalinus Clay isolates and the Aespoe-strain Pseudomonas fluorescens (CCUG 32456) could be determined within a broad pH range (2-8). The metals bind as a function of pH on protonated phosphoryl, carboxyl and deprotonated phosphoryl sites of the respective cell membrane. The thermodynamic surface complexation constants of bacterial An/Ln-species were determined and can be used in modeling programs. Depending on the used An different interaction mechanisms were found (U(VI): biosorption, partly biomineralisation; Cm(III): biosorption, indications for embedded Cm(III); Pu: biosorption, bioreduction and indications for embedded Pu). Different strategies of coping with U(VI) were observed comparing P. fluorescens planktonic cells and biofilms under the chosen experimental conditions. An enhanced capability of the biofilm to form meta-autunite in comparison to the planktonic cells was proven. Conclusively, the P. fluorescens biofilm is more efficient in U(VI) detoxification. In conclusion, Mont Terri Opalinus Clay contains bacterial communities, that may influence the speciation and hence the migration behavior of selected An/Ln under

  9. Microbial diversity in opalinus clay and interaction of dominant microbial strains with actinides

    Energy Technology Data Exchange (ETDEWEB)

    Moll, Henry; Luetke, Laura; Bachvarova, Velina; Steudtner, Robin; Geissler, Andrea; Krawczyk-Baersch, Evelyn; Selenska-Pobell, Sonja; Bernhardt, Gert

    2013-07-01

    For the first time microbial tDNA could be isolated from 50 g unperturbed Mont Terri Opalinus Clay. Based on the analysis of the tDNA the bacterial diversity of the unperturbed clay is dominated by representatives of Firmicutes, Betaproteobacteria, and Bacteriodetes. Firmicutes also dominate after treatment of the clay with R2A medium. Bacteria isolated from Mont Terri Opalinus Clay on R2A medium were related to Sporomusa spp., Paenibacillus spp., and Clostridium spp. All further investigations are concentrated on the unique isolates Sporomusa sp. MT-2 and Paenibacillus sp. MT-2. Cells of the type Sporomusa sp. MT-2 and Paenibacillus sp. MT-2 were comprehensively analyzed in terms of growing, morphology, functional groups of the cell envelope, and cell membrane structure. Strong actinide(An)/lanthanide(Ln)-interactions with the Opalinus Clay isolates and the Aespoe-strain Pseudomonas fluorescens (CCUG 32456) could be determined within a broad pH range (2-8). The metals bind as a function of pH on protonated phosphoryl, carboxyl and deprotonated phosphoryl sites of the respective cell membrane. The thermodynamic surface complexation constants of bacterial An/Ln-species were determined and can be used in modeling programs. Depending on the used An different interaction mechanisms were found (U(VI): biosorption, partly biomineralisation; Cm(III): biosorption, indications for embedded Cm(III); Pu: biosorption, bioreduction and indications for embedded Pu). Different strategies of coping with U(VI) were observed comparing P. fluorescens planktonic cells and biofilms under the chosen experimental conditions. An enhanced capability of the biofilm to form meta-autunite in comparison to the planktonic cells was proven. Conclusively, the P. fluorescens biofilm is more efficient in U(VI) detoxification. In conclusion, Mont Terri Opalinus Clay contains bacterial communities, that may influence the speciation and hence the migration behavior of selected An/Ln under

  10. Clay squirt: Local flow dispersion in shale-bearing sandstones

    DEFF Research Database (Denmark)

    Sørensen, Morten Kanne; Fabricius, Ida Lykke

    2017-01-01

    Dispersion of elastic-wave velocity is common in sandstone and larger in shaly sandstone than in clean sandstone. Dispersion in fluid-saturated shaly sandstone often exceeds the level expected from the stress-dependent elastic moduli of dry sandstone. The large dispersion has been coined clay...... squirt and is proposed to originate from a pressure gradient between the clay microporosity and the effective porosity. We have formulated a simple model that quantifies the clay-squirt effect on bulk moduli of sandstone with homogeneously distributed shale laminae or dispersed shale. The model...... predictions were compared with the literature data. For sandstones with dispersed shale, agreement was found, whereas other sandstones have larger fluid-saturated bulk modulus, possibly due to partially load-bearing shales or heterogeneous shale distribution. The data that agree with the clay-squirt model...

  11. Repository tunnel construction in deep clay formations

    International Nuclear Information System (INIS)

    Clarke, B.G.; Mair, R.J.; Taylor, R.N.

    1992-01-01

    One of the objects of the Hades project at Mol, Belgium has been to evaluate the feasibility of construction of a deep repository in the Boom clay formation at depth of approximately 225 metres. The main objective of the present project was to analyse and interpret the detailed geotechnical measurements made around the Hades trial shaft and tunnel excavations and evaluate the safety of radioactive waste disposal in a repository facility in deep clay formations. Plasticity calculations and finite element analyses were used which gave results consistent with the in-situ measurements. It was shown that effective stress analysis could successfully predict the observed field behaviour. Correct modelling of the small-strain stiffness of the Boom clay was essential if reasonable predictions of the pore pressure response due to construction are to be made. The calculations undertaken indicated that, even in the long term, the pressures on the test drift tunnel lining are likely to be significantly lower than the overburden pressure. Larger long-term tunnel lining pressures are predicted for impermeable linings. A series of laboratory stress path tests was undertaken to determine the strength and stiffness characteristics of the Boom clay. The tests were conducted at appropriate effective stress levels on high-quality samples retrieved during construction of the test drift. The apparatus developed for the testing is described and the results discussed. The development of a self boring retracting pressure-meter is described. This novel in-situ testing device was specifically designed to determine from direct measurements the convergence/confinement curve relevant to tunnelling in clay formations. 44 refs., 60 figs., 3 tabs

  12. Evaluation of past and future alterations in tuff at Yucca Mountain, Nevada, based on the clay mineralogy of drill cores USW G-1, G-2, and G-3

    International Nuclear Information System (INIS)

    Bish, D.L.

    1989-03-01

    The tuffs at Yucca Mountain in south-central Nevada are being studied by the Yucca Mountain Project (YMP) to determine their suitability for a high-level radioactive waste repository. For predictive purposes, it is important to understand the alteration history of Yucca Mountain and to know how the minerals in Yucca Mountain tuffs respond to changing conditions such as elevated temperatures. The clay mineralogy of these tuffs has been examined using x-ray powder diffraction, and approximation temperatures of alteration have been determined using available clay mineral data and fluid inclusion analyses. Also, several illites from drill holes USW G-1 and G-2 have been dated using K/Ar techniques, yielding ages of about 11 Myr. The clay mineral in Yucca Mountain tuffs are predominantly interstratified illite/smectites, with minor amounts of chloride, kaolinite, and interstratified chlorite/smectite at depth in USW G-1 and G-2. The reactions observed for these illite/smectites are similar to those observed in pelitic rocks. With depths, the illite/smectites transform from random interstratifications (R = 0) through ordered intermediates (R = 1) to illite in USW G-2 and to Kalkberg (R ≥ 3) interstratifications in USW G-1. The illite/smectites in USW G-3 have not significantly transformed. It appears that the illites in deeper rock results from hydrothermal and diagenetic reactions of earlier-formed smectites. These data demonstrate that the rocks at depth in the northern end of Yucca Mountain were significantly altered about 11 Myr ago. Both clay mineralogy and fluid inclusions suggest that the rocks at depth in USW G-2 have been subjected to postdepositional temperatures of at least 275/degree/C, those in USW G-1 have reached 200/degree/C, and USW G-3 rocks probably have not exceeded 100/degree/C. 64 refs., 9 figs., 3 tabs

  13. Strength Properties of Aalborg Clay

    DEFF Research Database (Denmark)

    Iversen, Kirsten Malte; Nielsen, Benjaminn Nordahl; Augustesen, Anders Hust

    glacial time are characterised by the absence of this mussel. These deposits are named Aalborg Clay and Aalborg Sand. In the city of Aalborg, a fill layer superposes Aalborg Clay. This layer is at some places found to be 6m thick. This fill layer does not provide sufficient bearing capacity, which has...... resulted in many damaged buildings in Aalborg. To provide sufficient bearing capacity it is therefore necessary either to remove the fill or to construct the building on piles. Both methods imply that the strength of Aalborg Clay is important for the construction. This paper evaluates the strength...

  14. Processing and characterization of Polystyrene/cornstarch/organophilic clay hybrids

    International Nuclear Information System (INIS)

    Oliveira, Carlos Ivan R. de; Amorim, Ywrrenan C.; Andrade, Cristina T. de

    2011-01-01

    Polystyrene/cornstarch composite blends with organophilic Cloisite 15A were prepared in an internal mixer in the presence of maleic anhydride (MA). The contents of clay were 1, 3 and 5%, based on the weight of the blend. The results obtained by X-ray diffraction revealed significant intercalation and exfoliation of clay particles within the polymeric moiety, which indicate increased interaction between the components of the nanocomposites. Thermogravimetric analysis results revealed the increase in thermal stability for the compatibilized blends in relation to the noncompatibilized PS/starch blends. The composites showed better thermal stability with increasing clay content. (author)

  15. Assessment of the Effectiveness of Clay Soil Covers as Engineered Barriers in Waste Disposal Facilities with Emphasis on Modeling Cracking Behavior

    Science.gov (United States)

    2008-06-01

    standard proctor hammer (ASTM D698), which was dropped a sufficient number of times to achieve the desired dry density ERDC TR-08-7 34 Figure...using a standard proctor hammer to an equivalent dry density as was found in Experiment 1. ERDC TR-08-7 45 Figure 25. Sample container for...ER D C TR -0 8- 7 Assessment of the Effectiveness of Clay Soil Covers as Engineered Barriers in Waste Disposal Facilities with Emphasis

  16. Preparation and properties of biodegradable starch–clay nanocomposites

    KAUST Repository

    Chung, Yi-Lin

    2010-01-01

    Well-dispersed starch-clay nanocomposites were prepared by adding a dilute clay dispersion to a solution of starch followed by coprecipitation in ethanol. The cl