Letteratura scientifica selezionata sul tema "Clay"
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Articoli di riviste sul tema "Clay"
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Refai Kassab, Alaa El-Hosani, Azza Hassan Moubark, Waleed Hamdy Elkamash, and Kamal Mohamed Hafez Ismail. "Shear Strength of Unsaturated Soils with Different Plasticity." Journal of University of Shanghai for Science and Technology 23, no. 11 (November 9, 2021): 197–217. http://dx.doi.org/10.51201/jusst/21/11887.
Testo completoAbstract (sommario):
A series of shear box tests were conducted on four different types of soils in this study. The first set , (clay1) is the host clay, Middle Delta Nile clay “MDNC” which was obtained from Mid Delta Nile zone, Qalyubiyya Governorate, Egypt. The second set, (clay2) consists of the host clay MDNC but mixed with 40% sand. The third set of tests (clay3) was carried out on natural low plastic clay samples brought from El-Tal El-Kbeer area in Ismailia Governorate. The fourth set (clayey sand -SC) consists of 25% of the host clay MDNC mixed with 75% sand. The purpose is to predict the unsaturated shear strength for various soil types. The results illustrate that for clay1, clay2, and clay3, the relationships between the unsaturated shear strength and matric suction are approximated to two linear failure envelopes intersected at matric suction equals to plastic limit. Each segment has an angle of internal friction due to matric suction b ranging from 1.80 o to 2.90o for the first zone and b ranging from 0.28 o to 0.20o for the second zone. Meanwhile, for SC soil it appears to have one linear failure envelope for all saturation levels with angle of internal friction due to matric suction; b=1.19 o.. Design- Expert® software applied the least square method (LSM) to fit a mathematical model for the experimental data. The Response Surface Methodology (RSM) of the program is used to predict the required model. The paper proposed two general equations to calculate the shear strength of unsaturated clays and one equation for granular soils, which are presented at the end of the paper with their coefficients.
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Korolev, V. A. "BIOTIC COMPONENT OF CLAYSOILS." Gruntovedenie 1, no. 16 (January 2021): 7–15. http://dx.doi.org/10.53278/2306-9139-2021-1-16-7-15.
Testo completoAbstract (sommario):
All kinds of micro- and macroorganisms live in the massifs of clay soils: plants living in (or on) clay soils are called pelitophytes (from the Greek πηλός - “clay” and phyton - “plant”), micro- and macroorganisms living in clays, or associated with clays, they are called pelitophiles (from the Greek πηλός - "clay" and φιλία - "love"), that is, "loving clays" or "prone to clays." The article analyzes these groups of organisms and describes their role in the formation of the properties of clay soils and ecological-geological systems.
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Lescinskis, Oskars, Ruta Švinka, and Visvaldis Švinka. "Common and Different in Latvian Clay Minerals." Key Engineering Materials 762 (February 2018): 268–72. http://dx.doi.org/10.4028/www.scientific.net/kem.762.268.
Testo completoAbstract (sommario):
Clays are materials consisting of clay minerals and non-clay minerals. Some applications allow to use raw clay others require to separate clay minerals from non-clay minerals. Clay mineral fraction is considered to be a nanofraction. Description and characterization of 3 different Latvian clay nanosized minerals from 3 different geological periods (clay Liepa from Devonian period, clay Vadakste from Triassic period and clay Apriki from Quaternary period) are summarized. The main mineral in these clays is illite, however the presence of kaolinite is observed and its quantity depends on geological period in which clays formed. Nanosized clay mineral particles were obtained using sedimentation method. Comparison of mineralogical composition, BET nitrogen adsorption, zeta potential, DTA/TG analysis and FTIR spectra is given. XRD phase analysis results were very close to each other and shows that mineral of illite is more than that of kaolinite. BET nitrogen adsorption data shows that clay minerals of Apriki has the highest specific surface area (81 m2/g), whereas clay minerals of Vadakste has it the lowest (43 m2/g). Zeta potential values for clay minerals Apriki, Liepa and Vadakste are-40.9 mV, -49.6 mV and-43.0 mV, respectively. DTA analysis and FTIR spectra show similar tendencies for all 3 clay minerals.
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Chorom, M., P. Rengasamy, and RS Murray. "Clay dispersion as influenced by pH and net particle charge of sodic soils." Soil Research 32, no. 6 (1994): 1243. http://dx.doi.org/10.1071/sr9941243.
Testo completoAbstract (sommario):
The effect of changing pH on the dispersion of clay from sodic soils was investigated in relation to changes in net charge on clay particles. A positive relationship was obtained between pH and the percentage of dispersible clay for each soil clay. The percentage increase in net negative charge was also positively correlated with pH. However, the slopes of these relationships varied between soil clays. In general, the net negative charge was the primary factor in clay dispersion and the pH affected clay dispersion by changing the net charge on clay particles. In comparing the values for pure clay minerals quoted in the literature with soil clays having similar mineralogy, it was found that soil clays had higher flocculation values. This is shown to be due to higher net negative charge on soil clays than the corresponding values for pure clay minerals found in the literature. The effect of soil organic matter in enhancing the net negative charge probably contributes to the higher charge on soil clays. The critical dispersion concentration for clay dispersion from soil aggregates was lower than the flocculation values observed for the separated soil clays. The separated soil clays had high negative charge due to exposure of surfaces which were originally bonded in the aggregates. The dispersive potential of a number of Alfisols, Oxisols, Aridisols (calcareous soils) and Vertisols collected from different parts of Australia was highly correlated with soil pH. The relationship with CEC was poor because CEC was estimated at a pH different to the natural pH of the soil. This study has brought out the importance of pH in the management of dispersive soils.
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Lefebvre, Guy, Karol Rohan, and Serge Douville. "Erosivity of natural intact structured clay: Evaluation." Canadian Geotechnical Journal 22, no. 4 (November 1, 1985): 508–17. http://dx.doi.org/10.1139/t85-071.
Testo completoAbstract (sommario):
Previous studies on erodibility of cohesive soil are briefly reviewed and it is concluded that experimental observations have been mainly concerned with remolded and reconsolidated or weathered clays. The structure effect, which is considered important in the behaviour of natural intact clay, especially for Eastern Canadian clays, has not up to now been really considered in the evaluation of clay erodibility. This paper proposes a new laboratory technique for the study of the erodibility of natural intact clays and presents results of a testing program on three Canadian clays. The results indicate that Canadian structured clays are very resistant to erosion if intact and unweathered. Erosion is not taking place at the clay particle level but rather by the pulling out of larger elements composed of sand or silt grains or of clay aggregates. The pulling out of clay aggregates appears related to defects in the clay matrix, such as microfissures or planes of weakness associated with bedding. Key words: erosivity, intact clay, rate of erosion, tractive force, erosivity test, microstructure, macrostructure.
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Lakevičs, Vitālijs, Valentīna Stepanova, Santa Niedra, Inga Dušenkova, and Augusts Ruplis. "Thixotropic Properties of Latvian Illite Containing Clays." Environment. Technology. Resources. Proceedings of the International Scientific and Practical Conference 1 (August 6, 2015): 133. http://dx.doi.org/10.17770/etr2013vol1.813.
Testo completoAbstract (sommario):
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 decreases. It was found that the solid phase concentration and mineralogical composition make an impact on the thixotropy of clays. Decreasing the solid phase concentration in the clay suspensions from 50% to 25%, dynamic viscosity decreases proportionally to the solid phase concentration. It was found that modifying clay suspensions with carboxymethyl cellulose (0,1g) increases concentration of structure forming. In the same time, modifying of clay suspensions with calcified soda (0,1g) decreases the structure forming concentration. Dependence of pH value from the solid phase concentration slightly decreases with the clay phase concentration increasing in the suspension.
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Bekee, D., Edori, and E.S. "Geochemical Properties of Clays and Clay Pots from Kono Boue and Ara-Ekiti Communities in Nigeria." Pharmaceutical and Chemical Journal 8, no. 1 (January 31, 2021): 53–60. https://doi.org/10.5281/zenodo.13957746.
Testo completoAbstract (sommario):
Clays and clay pots samples from two Southern Nigeria communities, Ara-Ekiti and Kono-Boue were studied to ascertain their mineralogical content and physicochemical parameters. The cation exchange capacity (CEC)were12.06, 5.97, 4.88 and 5.44 Cmol/Kg; bulk density, were 0.94, 1.20, 0.2 and 1.00 g/cm3, organic matter were 8.88, 3.29, 0.74 and 1.48% for Ara-Ekiti clay (AER), Kono-Boue clay (KBR), Ara-Ekiti clay pot (AEP) and Kono-Boue clay pot (KBP) respectively. The percentages of silt, clay and sand were 12.40, 30.00 and 57.60% for AER; 17.40, 24.00 and 58.60% for KBR; 9.40, 14.00 and 76.60% for AEP and 7.40, 12.00 and 80.60% for KBP. The mineralogical content of the clays and clay pots were studied using X-ray diffraction (XRD) instrument. The mineralogy of AER and KBR by XRD analysis showed the presence of kaolinite, quartz, berthierine and almandine while for AEP and KBP XRD results showed the presence of microcline, kaolinite and quartz. The resultant differences in the mineralogy of the clays from the two communities might have resulted due to geological and anthropogenic factors, while the differences between the clays and the clay pots were due to the firing temperature during the clay pots production processes.
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Saaedifar, D., A. Casarella, and J. Dijkstra. "Genesis of Quick Clay: A Nanometric Experimental Investigation on Geological Environment." IOP Conference Series: Earth and Environmental Science 1480, no. 1 (April 1, 2025): 012098. https://doi.org/10.1088/1755-1315/1480/1/012098.
Testo completoAbstract (sommario):
Abstract Quick clays are fine-grained soils with high sensitivity that transform into a liquid when remoulded. The deposition history directly impacts the composition and microstructure of natural clays. This study examines the morphology at the nanoscale of two different sensitive Swedish clays (Lödöse and Kärra clay) to establish a connection between the microscopic features and the macroscopic mechanical behaviour observed at their intact and remoulded state. Using in-line holotomography, the nano-scale imaging instrument at the ID16B beamline of ESRF is employed to capture nano-level features in the natural clay specimens. The results illustrate that the size of the silt grains and the macroporosity are smaller for Lödöse clay than for Kärra clay. This might indicate the higher sensitivity of Lödöse clay. Although the macroporosity of Kärra clay reduces by 32% after remoulding, the difference in macropores recorded after remoulding Lödöse clay is negligible.
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Incledion, Alexander, Megan Boseley, Rachael L. Moses, Ryan Moseley, Katja E. Hill, David W. Thomas, Rachel A. Adams, Tim P. Jones, and Kelly A. BéruBé. "A New Look at the Purported Health Benefits of Commercial and Natural Clays." Biomolecules 11, no. 1 (January 5, 2021): 58. http://dx.doi.org/10.3390/biom11010058.
Testo completoAbstract (sommario):
Clays attributed to have medicinal properties have been used since prehistoric times and are still used today as complementary medicines, which has given rise to unregulated “bioceutical” clays to treat skin conditions. Recently, clays with antibacterial characteristics have been proposed as alternatives to antibiotics, potentially overcoming modern day antibiotic resistance. Clays with suggested antibacterial properties were examined to establish their effects on common wound-infecting bacteria. Geochemical, microscopical, and toxicological characterization of clay particulates, their suspensions and filtered leachates was performed on THP-1 and HaCaT cell lines. Cytoskeletal toxicity, cell proliferation/viability (MTT assays), and migration (scratch wounds) were further evaluated. Clays were assayed for antibacterial efficacy using minimum inhibitory concentration assays. All clays possessed a mineral content with antibacterial potential; however, clay leachates contained insufficient ions to have any antibacterial effects. All clay leachates displayed toxicity towards THP-1 monocytes, while clay suspensions showed less toxicity, suggesting immunogenicity. Reduced clay cytotoxicity on HaCaTs was shown, as many leachates stimulated wound-healing responses. The “Green” clay exhibited antibacterial effects and only in suspension, which was lost upon neutralization. pH and its interaction with clay particle surface charge is more significant than previously understood to emphasize dangers of unregulated marketing and unsubstantiated bioceutical claims.
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Chu, Chengfu, Zilong Wu, Yongfeng Deng, Yonggui Chen, and Qiong Wang. "Intrinsic compression behavior of remolded sand–clay mixture." Canadian Geotechnical Journal 54, no. 7 (July 2017): 926–32. http://dx.doi.org/10.1139/cgj-2016-0453.
Testo completoAbstract (sommario):
A series of incremental loading oedometer tests was conducted on pure clays and sand–clay mixtures with various sand/clay ratios and clay mineral compositions. The void indexes Iv and IvH were introduced to evaluate their intrinsic compressibility. Test results revealed that Iv was more suitable for depicting the compression behavior of pure clays than IvH; whereas, for the compressibility of sand–clay mixtures, the normalized compression line by using Iv was obviously different from that of pure clays and traditional soils due to the presence of sand particles. Therefore, a four-phase analysis framework of sand–clay mixtures was introduced to unify the intrinsic compression behavior of soils with and without sands. It was found that the updated clay void index Ivc parameter was effective to unify the soil’s compression behavior by excluding the influence of sand particles in clays before the sand skeleton formation. After the formation of the sand skeleton, the cluster particles change the stress distribution of mixtures, leading to less stress being applied on the clay matrix and thus the bifurcation of the intrinsic compression behavior.
Tesi sul tema "Clay"
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Taha, Ahmed M. "Interface Shear Behavior of Sensitive Marine Clays --Leda Clay." Thesis, University of Ottawa (Canada), 2010. http://hdl.handle.net/10393/28768.
Testo completoAbstract (sommario):
Leda clay, which is a type of sensitive marine clay in Canada, is a hazardous soil that could undergo sudden collapse and flow upon wetting and remolding. This type of soil causes many landslide disasters and foundation damage. The existence of Leda clay at or near the proximities of developed cities makes it challenging for infrastructure expansion, and therefore, challenging for geotechnical engineers. At the location where this sensitive marine clay exists, many foundation designers have adopted the use of deep foundations, such as pile foundations to support heavy structures. The shear behavior and strength parameters at the interface between the (friction) pile and soil are key design parameters. A sufficient knowledge of these interface shear behaviors and strength parameters is also essential for the safe and cost-effective design of several other geotechnical structures (e.g., retaining walls, reinforced soils, and buried structures). However, no studies have yet been implemented on the interface shear behavior between Leda clay and structural material. There is therefore, a need to generate more knowledge about the interface shear behavior of Leda clay.
This thesis deals with an experimental study of the shear behavior at the interface between Leda clay and structural material, such as steel and concrete. The effects of several factors, such as surface roughness of the construction material, Leda clay's overconsolidation ratio (OCR), saturation degree, density, and salt content on interface shear behavior are also investigated. Laboratory tests have been carried out by using an automatic direct shear machine connected to a linear variable differential transformer (LVDT), loading cell and a data logging system. The results of the interface shear tests show that under consolidated drained (CD) and saturated conditions, the interface friction angle increases with an increase in the clay's OCR. The results also indicate that increasing the salinity of Leda clay's pore water enhances its frictional resistance at the interface. Furthermore, the results reveal that Leda clay with a higher dry density shows higher interface shear resistance. On the other hand, the results also show that the interface shear resistance decreases as the degree of saturation of the Leda clay increases.
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Zhao, Feng. "Development of clay modifications for polymer/clay nanocomposites." Thesis, Loughborough University, 2010. https://dspace.lboro.ac.uk/2134/7620.
Testo completoAbstract (sommario):
Three commercial clays: Cloisite Na+ , Cloisite 30B and Cloisite 15A were used to melt compound with a number of polymer matrices, including polypropylene (PP), poly(butylene terephthalate) (PBT) and polyamides (PA). X-ray diffraction (XRD), contact angle measurement and thermogravimetric analysis (TGA) showed small interlayer space, poor compatibility and low thermal stability of these nanocomposites, resulting in poor mechanical properties in composites. A number of modifications of commercial clays were carried out, including silylation and introduction of thermally stable surfactants, e.g. alkyl quaternary phosphonium cations and polyhedral oligomeric silsesquioxane (POSS). It was found that poor compatibility between polymer matrices and organically modified clays, especially in those POSS modified clays, again restricted the formation of exfoliated structure in polymer matrices. A mode of dual-surfactant modification for clay was developed, and large interlayer spacing (>3.2 nm), good thermal stability (decomposed at ~300°C) and improved surface properties for those dual-surfactant modified clays promoted a better dispersion of clays in polymer matrices and consequently better mechanical properties. For example, the tensile moduli of PP, PBT and PA 12 were improved from 515 MPa, 1065 MPa and 490 MPa to 1020 MPa, 1470 MPa and 800 MPa of their nanocomposites containing 3 wt% dual-surfactant modified clays, respectively. However, the dispersion of these organoclays varied in different polymer matrices, due to the different compatibility and the existence of polar type interactions between organoclays and polymer matrices. In order to further address the effect of polymer matrix on clay dispersion, three polyamide matrices (PA 6, PA 11 and PA 12) were employed, and PA 6 based nanocomposites showed the most effective exfoliation and mechanical enhancements due to the strong polar type interactions between the polymer and the organoclays.
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Brow, Lawrence Michael. "Clay Chairs." Thesis, University of Iowa, 1989. https://ir.uiowa.edu/etd/2796.
Testo completo
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Gonzalez‐Blanco, Laura. "Gas migration in deep argillaceous formations : Boom clay and indurated clays." Doctoral thesis, Universitat Politècnica de Catalunya, 2017. http://hdl.handle.net/10803/406355.
Testo completoAbstract (sommario):
Deep geological disposal remains the preferred option at present for the management of long-living and heat-emitting radioactive waste, which consists of confining the waste during a very long period (several hundreds of thousands of years) by placing them in a deep geological formation. Therefore, the understanding of the long-term behaviour of formations is becoming a key issue to ensure the feasibility of the geological disposal
facilities, particularly regarding the generation and migration of gases. The present PhD work aims at better understanding the complex hydro-mechanical response of different argillaceous formations to gas migration process. To this end, gas flow through Boom Clay (one of the potential candidate plastic Paleogene clay formations to host nuclear waste in Belgium) has been deeply investigated on the basis of laboratory experiments at different scales and their numerical modelling. This main study has been complemented by presenting tests on two indurated and deeper claystone Mesozoicformations, considered as candidate host rocks in the Swiss programme for deep geological disposal, namely Opalinus Clay and ‘Brauner Dogger’.
The different materials have been firstly characterised to evaluate mechanical (compressibility on loading) and two phase flow properties (water retention and permeability). Gas injection tests under oedometer and isotropic conditions have been performed following different testing protocols, in which boundary conditions have been carefully controlled. Major relevance has been given to restore the in situ stress state
and to ensure full saturation conditions before the gas tests. Special emphasis has been placed in measuring sample deformation along the gas injection and dissipation process. The anisotropy of Boom Clay has been studied by carrying out tests with bedding planes parallel and normal to flow. Air injections have been performed at three different controlled-volume rates. The dissipation stages after shut-off have been also analysed to study air intrinsic permeability changes. Microstructure of samples before and after air injection tests has been evaluated by different techniques: mercury intrusion porosimetry, field-emission scanning electron microscopy and micro-focus Xray computed tomography.
Gas migration turned out to be a fully coupled hydro-mechanical process. Air injection at constant stress induced expansion of the samples during pressure front propagation and compression during air pressure dissipation. The deformational behaviour was dependent on the injection rate. At slower injection rates expansion occurred during the injection while at higher rates it was delayed in time. Air intrinsic permeability resulted higher than water permeability suggesting that air flow took place along preferential pathways. Evaluation of the microstructural changes induced by air migration revealed the opening of fissures and allowed quantifying their apertures and separation, as well as their volume and connectivity. Air intrinsic permeability was found to be dependent on the fissured volume.
To complete and better understand the gas transport mechanisms, numerical simulations of the experimental results have been performed using a fully coupled hydro-mechanical finite element code, which incorporates an embedded fracture permeability model to account for the correct simulation of the gas flow along preferential pathways. Clay intrinsic permeability and its retention curve have been made depend on strains through fracture aperture changes. Numerical results not only accounted for the correct simulation of the recorded upstream pressures and outflow
volumes and pressures, but also for the volume change behaviour. The experimental and numerical information provided a good insight into the mechanisms of gas transport in deep clay formations and highlighted the role played by the deformational response on the air transport properties of argillaceous rock formations.<br>El almacenamiento geológico profundo es la solución actualmente aceptada para la gestión de los residuos radioactivos de alta actividad, que consiste en confinar dichos residuos durante un período muy largo de tiempo (varios cientos de miles de años) depositándolos en una formación geológica profunda. De ahí que el entendimiento del comportamiento a largo plazo se esté convirtiendo en una cuestión clave para asegurar la viabilidad de las instalaciones de almacenamiento de residuos, particularmente en lo que respecta a la generación y migración de gases. Este trabajo de doctorado tiene como objetivo mejorar la comprensión en lo que se refiere a la compleja respuesta hidro-mecánica de diferentes formaciones arcillosas frente a procesos de migración de gas. Con este objetivo, el flujo de gas a través de la arcilla Boom Clay (arcilla plástica del paleógeno candidata a alojar los residuos nucleares en Bélgica) se ha investigado en profundidad mediante experimentos de laboratorio a diferentes escalas y su modelación numérica. Este estudio principal se ha complementado con ensayos experimentales en dos formaciones arcillosas del mesozoico (más profundas y endurecidas),posibles candidatas a roca huésped en el programa suizo para el almacenamiento geológico profundo, llamadas Opalinus Clay y 'Brauner Dogger'.
Inicialmente, los diferentes materiales han sido caracterizados para evaluar sus propiedades mecánicas (compresibilidad en carga) e hidráulicas (retención de agua y permeabilidad). Los ensayos de inyección de gas, bajo condiciones edométricas e isótropas, se han realizado siguiendo diferentes protocolos de ensayo controlando
cuidadosamente las condiciones de contorno, así como, dando prioridad al hecho de restaurar el estado tensional in situ y las condiciones de saturación antes de los ensayos de gas. Además, se ha hecho especial hincapié en la medición de la deformación de las muestras a lo largo de los procesos de inyección y disipación de
gas. La anisotropía de la Boom Clay se ha tenido en cuenta realizando ensayos con los planos de estratificación dispuestos en paralelo y perpendicular al flujo. Las inyecciones de aire se han realizado a tres velocidades volumétricas diferentes. Las etapas de disipación se han analizado para evaluar los cambios en la permeabilidad intrínseca al aire. La microestructura de las muestras se ha evaluado antes y después de los ensayos de inyección de aire mediante tres técnicas diferentes: porosimetría de intrusión de mercurio, microscopía electrónica de barrido de emisión de campo y micro-tomografía computarizada La migración de gases en estas rocas arcillosas saturadas resultó ser un proceso hidro-mecánico totalmente acoplado. La inyección de aire a tensión constante produjo expansión de las muestras durante la propagación del frente de presión y compresión durante la disipación de la presión de aire. El comportamiento deformacional dependió de la velocidad de inyección. A velocidades de inyección más lentas, la expansión se
produjo durante la inyección, mientras que, a velocidades más altas, ésta se retrasó en el tiempo. La permeabilidad intrínseca al aire resultó ser más alta que la permeabilidad al agua medida, lo que sugiere que el flujo de aire tuvo lugar a lo largo de vías preferenciales. La evaluación de los cambios microestructurales inducidos por la migración de aire reveló la apertura de fisuras, cuantificando sus aperturas y separación, así como su volumen y conectividad, lo que permitió encontrar una relación de dependencia entre la permeabilidad intrínseca al aire y el volumen fisurado.
Para completar la información experimental y comprender mejor los mecanismos de transporte de gas, se realizaron simulaciones numéricas de los resultados experimentales utilizando un código de elementos finitos acoplado, que incorpora un modelo de permeabilidad con fracturas embebidas para explicar el flujo de gas a lo largo de vías preferenciales. La permeabilidad intrínseca de la arcilla y su curva de retención dependen de la deformación a través de cambios en la apertura de la fractura. Los resultados numéricos no sólo reprodujeron de forma correcta las presiones registradas y los volúmenes de salida, sino también el comportamiento
deformacional. Esta información experimental y numérica proporcionó una buena visión de los mecanismos de transporte de gas en formaciones arcillosas profundas y en los que destacó el papel desempeñado por la respuesta deformacional sobre las propiedades de transporte de aire.
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Papargyris, Athanasios D. "Mechanical properties of clay and fibre reinforced clay-based ceramics." Thesis, University of Bath, 1994. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240685.
Testo completo
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Elder, Judith. "PMMA clay nanocomposites." Thesis, Durham University, 2009. http://etheses.dur.ac.uk/52/.
Testo completoAbstract (sommario):
Polymer clay nanocomposites (PCN) of poly(methyl methacrylate) (PMMA) and clay, were synthesised in-situ using a free radical suspension polymerisation technique. The weight fraction of clay in the PCN was systematically varied in order to understand the effect of clay on the physical properties of the resulting PCNs. However, unexpectedly it was found that the weight fraction of clay had a dramatic impact upon the molecular weight of the polymer matrix and a relationship between clay concentration and polymer molecular weight was established. Furthermore, it was also found that the change in molecular weight was dependent upon the clay type. Three different clay types were investigated; an organically modified montmorillonite (Cloisite 15a), a synthetic clay (Laponite RD) and a PEO modified Laponite RD. To produce the modified Laponite RD, mono amino PEO was synthesised via anionic polymerisation using dimethyl ethanol amine as an initiator. The modification of the Laponite RD clay took place in the reaction flask prior to the suspension polymerisation of the PCN. The PCN were characterised using size exclusion chromatography (SEC), X-ray diffraction (XRD), transmission electron microscopy (TEM) and oscillatory shear rheology. Morphological studies of the PCN showed that the extent of clay dispersion depended on the clay type. Within the PMMA/Laponite RD nanocomposites an unusual network structure was formed, which appeared to be continuous throughout the material. Thermal properties of the PCN were investigated using DSC, TGA and Microcalorimetry. From oscillatory shear rheology, the full master curves for the PCN were obtained by applying the time-temperature superposition (TTS) principle. To quantify the effect of the clay upon the rheology, the experimental data was compared to the time dependent diffusion model of Des Cloizeaux for polydisperse polymer melts, which enables polydispersity to be incorporated through the use of the molecular weight distribution obtained via SEC.
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Combs, Jasen Paul-Robert. "Altered clay vessels." Virtual Press, 2002. http://liblink.bsu.edu/uhtbin/catkey/1233190.
Testo completoAbstract (sommario):
The focus of the creative project was the artist exploration of altered forms and ash glaze techniques, as well as developing a new aesthetic of breaking free of old approaches, thus allowing him to express his emotions through the ceramic vessels. He developed and refined his technique of surface treatment on the vessels as he progressed through this project. His exploration into this new world of freedom helped him grow as an artist and emotionally.The artist desired to become a utilitarian potter at the beginning of his undergraduate studies but when he was introduced to the works of Paul Soldner, Peter Volkos, and Robert Piepenburg his interest in their works fueled his desire to expand his style of work. This lead to his exploration into altered vessels.<br>Department of Art
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Chen, Biqiong. "Polymer-clay nanocomposites." Thesis, Queen Mary, University of London, 2004. http://qmro.qmul.ac.uk/xmlui/handle/123456789/1854.
Testo completoAbstract (sommario):
Polymer-clay nanocomposites are attracting global interest principally because property enhancements are obtained at low clay particle loadings (1-5 wt%). However there is lack of fundamental understanding of such composites. The aim of this work is to provide an insight into the interaction between polymer and clay. This includes the driving force for intercalation, the reinforcement mechanisms and property-volume fraction relationships. Functionalised poly(ethylene glycol)-clay, poly(c-caprolactone)-clay and thermoplastic starch-clay nanocomposites with a range of polymer molecular weights, clay volume fractions and with different clays were prepared using solution methods, melt-processing methods, and in situ polymerisation. A reliable X-ray diffraction technique for low angle basal plane spacing of clay, the essential parameter for structure determination, was established obtaining ±0.005 Mn between three diffractometers. The basal plane spacing was found to be unaffected by polymer molecular weight and preparation method but was affected by the nature of the polymer and clay. Increasing clay loading could lead to a lower spacing. As a cautionary observation, poly(ethylene glycol) with high molecular weight (2: 10,000) was found to undergo degradation readily during preparation of nanocomposites with and without clay. Competitive sorption experiments for molecular weight showed that high molecular weight fractions of polymer intercalate preferentially into clay during solution preparation. Thermodynamic studies on the intercalation process found that significant enthalpic change occurred during intercalation, which is coincident with the observation that heat-treated clays without interlayer water can intercalate polymer. The calculation of true volume fraction against nominal volume fraction provided reasonable explanation of property enhancement and helps understand the relation between nanocomposites and conventional composites. At a given clay loading, nanocomposites with better dispersion gave more property enhancement than those with lower dispersion or conventional composites. The crystallinity of semicrystalline polymer was also affected by varying extents of dispersion of clay. The use of X-ray diffraction with an internal standard was explored for quantitative analysis of intercalation and exfoliation.
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Dugan, Moi. "Narratives on clay /." Online version of thesis, 1993. http://hdl.handle.net/1850/11769.
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Prendergast, Jean O'Dea. "Splinters and clay." View electronic thesis (PDF), 2009. http://dl.uncw.edu/etd/2009-1/rp/prendergastj/jeanprendergast.pdf.
Testo completoLibri sul tema "Clay"
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Newman, A. C. D., 1929-, ed. Chemistry of clays and clay minerals. New York: Wiley, 1987.
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Publishing, Newbridge Educational, ed. Clay. New York: Newbridge Educational Pub., 2003.
Cerca il testo completoCapitoli di libri sul tema "Clay"
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Bergaya, Faïza, Maguy Jaber, and Jean-François Lambert. "Clays and Clay Minerals." In Rubber-Clay Nanocomposites, 1–44. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2011. http://dx.doi.org/10.1002/9781118092866.ch1.
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Theng, Benny K. G. "Clays and Clay Minerals." In The Chemistry of Clay-Organic Reactions, 1–51. 2nd ed. Boca Raton: CRC Press, 2024. http://dx.doi.org/10.1201/9781003080244-1.
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Theng, Benny K. G. "Clays and Clay Minerals." In Clay Mineral Catalysis of Organic Reactions, 1–83. Boca Raton : CRC Press, Taylor & Francis Group, 2018.: CRC Press, 2018. http://dx.doi.org/10.1201/9780429465789-1.
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Manning, D. A. C. "Industrial clays: kaolin (china clay), ball clay and bentonite." In Introduction to Industrial Minerals, 35–71. Dordrecht: Springer Netherlands, 1995. http://dx.doi.org/10.1007/978-94-011-1242-0_3.
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Rothwell, R. G. "Clay." In Minerals and Mineraloids in Marine Sediments, 57–59. Dordrecht: Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-009-1133-8_7.
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Nandi, Arpita. "Clay." In Selective Neck Dissection for Oral Cancer, 1–2. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-12127-7_53-1.
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Nandi, Arpita. "Clay." In Selective Neck Dissection for Oral Cancer, 1–2. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-12127-7_53-2.
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Gooch, Jan W. "Clay." In Encyclopedic Dictionary of Polymers, 147. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_2433.
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Negrónk-Mendoza, Alicia. "Clay." In Encyclopedia of Astrobiology, 480–83. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-662-44185-5_303.
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Negrón-Mendoza, Alicia. "Clay." In Encyclopedia of Astrobiology, 316–19. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-11274-4_303.
Testo completoAtti di convegni sul tema "Clay"
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Jordan, M. M., K. S. Sorbie, P. Jiang, M. D. Yuan, A. C. Todd, and L. Thiery. "The Effect of Clay Minerals, pH, Calcium and Temperature on the Adsorption of Phosphonate Scale Inhibitor onto Reservoir Core and Mineral Separates." In CORROSION 1994, 1–24. NACE International, 1994. https://doi.org/10.5006/c1994-94049.
Testo completoAbstract (sommario):
Abstract During a scale inhibitor squeeze treatment, the dynamics of the inhibitor return is governed by the inhibitor/rock interaction. In the case of adsorption/desorption inhibitor treatments, this interaction is described through the inhibitor/rock adsorption isotherm. The rock mineralogy plays an important role in determining the nature of the adsorption isotherm and clays in particular are known to strongly affect the adsorption process. However, no previous work has (a) presented a systematic study of the effects of various clays on inhibitor adsorption and (b) clearly demonstrated the significance of this behaviour for the squeeze process. It is the central objective of the work in this paper to carry out these tasks. In this paper, an extensive series of results from static bulk adsorption tests using pure mineral separates (quartz, kaolinite, chlorite and muscovite) as adsorbent and using phosphonate (DETPMP) as model inhibitor is presented. These allow us to make a systematic study of the factors (e.g. pH, [Ca2+], temperature, etc) affecting inhibitor adsorption onto these substrates. The inhibitor adsorption (measured in mg/g) is found to be much higher on the clays than on quartz, consistent with their higher surface areas. Phosphonate adsorption shows a declining trend as solution pH increases from acidic to near neutral values, which is significant at ambient temperature. At weak acidic conditions (~ pH 4), the inhibitor adsorption is strongly affected(enhanced) by temperature rise from 25°C to 95°C. Calcium has been shown to be involved in the adsorption (or surface condensation) of phosphonate scale inhibitor onto quartz (at pH ~ 6 at 25°C and at pH ~4 at 95°C) and, indeed, it also plays a role in the binding of inhibitor onto the clay surface. However, for clays, no minimum in bulk adsorption level is seen at pH ~ 4 as is observed for quartz. From our results, the order of importance of factors governing the phosphonate inhibitor level onto clays appears to be Temperature &gt; pH &gt; [Ca2+]. Some supporting electrokinetic (electrophoretic) measurements on the quartz and clay mineral samples are reported from which the ζ-potential at the mineral surface has been determined as a function of pH under various solution conditions. It is found that the phosphonate adsorption behaviour onto both quartz and clays correlates very well with the surface charge measurements. To support the findings from the bulk adsorption tests, results from reservoir condition core floods are presented for reservoir rock from a North Sea field which contains significant quantities of clay (principally kaolinite). By comparing the inhibitor return curves with those from a relatively clean (low clay) outcrop sandstone, we demonstrate that this clay material strongly affects inhibitor adsorption during injection (adsorption) stage, which consequently produces considerably higher inhibitor return concentrations during early stage of seawater postflush (&lt; 400 pore volumes). However, in the long tail (&gt; ~ 800pv), low concentration (&lt; 6 ppm) region, the return curves are quite similar. Calcium was involved in the phosphonate adsorption mechanism in these high clay cores as well as in the outcrop sandstone cores. The dynamic adsorption isotherms for these inhibitor/core systems are derived and compared with similar isotherms from the low clay material. The field significance of these results for the inhibitor squeeze performance is demonstrated by using the field and outcrop isotherms in some model squeeze return calculations.
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Yu, Long, Hui Zhou, Wen Gao, Jun Liu, and Yuxia Hu. "Spudcan Penetration in Clay-Sand-Clay Soils." In ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2011. http://dx.doi.org/10.1115/omae2011-49316.
Testo completoAbstract (sommario):
Multi-layered soil conditions often exist in offshore practice. In some sites a thin layer of medium dense sand lays between firm to stiff clay layers. In these cases the ultimate bearing capacity of foundations can be increased due to the strong sand layer by comparing with foundations in uniform clay. However, there is also a potential of reduction in foundation capacity when the foundation punches through the sand layer. The punch-through failure can occur during either pre-loading or storm loading. In this study, the continuous penetration of spudcan foundations on clay-sand-clay soils was investigated by large deformation finite element analysis. The numerical simulation was carried out using Remeshing and Interpolation Technique with Small Strain (RITSS) model. The clays obey Tresca failure criterion for undrained analysis and the sands obey Mohr-Coulomb yield criterion for drained analysis. The friction angle of the sand was taken as φ = 32° and 40° with its dilation angle ψ = 2° and 10° respectively. The effects of the relative height of the top soft clay and the relative thickness of the middle sand layer on the load-displacement responses were investigated. The soil flow mechanisms at various penetration depths were also discussed.
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Mondol, Nazmul Haque. "Velocity anisotropy in experimentally compacted clay-silt and clay-clay mixtures." In SEG Technical Program Expanded Abstracts 2012. Society of Exploration Geophysicists, 2012. http://dx.doi.org/10.1190/segam2012-0125.1.
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Horvath, William, Michael T. Myers, and Lori A. Hathon. "Physics Based Permeability Models Based on Thomas-Stieber Plots." In 2023 SPWLA 64th Annual Symposium. Society of Petrophysicists and Well Log Analysts, 2023. http://dx.doi.org/10.30632/spwla-2023-0027.
Testo completoAbstract (sommario):
A Staged Differential Effective Medium (SDEM) model is applied to interpret the permeability in thin-bedded shaly sands. In this model, the permeability varies with the amount and distribution of clay minerals. The model allows continuous interpolation between a series and parallel distribution of the clay minerals. Dispersed clays are added before structural clays and matrix grains. The longest length scale, clay laminations, are the last phase added to the massive sand matrix. The resulting equations include the distribution parameters for each inclusion. The standard Thomas-Stieber (T-S) model is extended to allow for differing clay properties. This more accurate analysis allows a quantitative separation of clay types that are distributed at these different length scales using only density and gamma ray log data. The three endpoints of the Thomas-Stieber triangle (clean sand, clay-filled sand, and shale) are determined from log data, thin sections, and scanning electron microscope (SEM) observations. Dispersed clay porosity and shale laminae porosity were estimated using SEM imaging and image segmentation. The dispersed clays were observed to have substantially higher porosity than the laminar clays. Clay laminae and pore-filling dispersed clays are, therefore, given differing porosities and gamma ray responses in contrast to a standard T-S model. The SDEM model is then used to iteratively extract the clay properties according to their differing length scales. The initial regression determines the distribution parameter of the shale laminae. The properties of the clay-filled sand allow the impact of the dispersed clays on permeability to be determined. Core data are used to calibrate the permeability model. Dispersed clay is found to reduce the permeability much more rapidly than clay laminations; sand macroporosity is more strongly correlated to permeability than the net/gross (N/G). Macroporosity is defined as the total percent bulk volume of macropores, or sand porosity minus the bulk volume fraction of dispersed clay. Macroporosity ranges from the total porosity in clean sand to zero when the dispersed clay is completely pore filling. Using macroporosity as the control on permeability acknowledges the negligible contribution of the microporosity associated with dispersed clays. The standard Timur-Coates parameters are not appropriate for use in this reservoir. Both the NMR and the SDEM models have to be calibrated to the measured core data. The permeability estimations using the SDEM model have a comparable uncertainty to that of standard NMR permeability models. This work introduces the use of SDEM models applied in conjunction with the T-S plot for the estimation of permeability. This allows geology-based models incorporating the differing length scales of the clays to be built. Because the model performs as well as the NMR-based permeability models, the application of the SDEM model can result in significant financial savings. The use of the T-S plot means that varying N/G and volumes of dispersed clay are accounted for, giving increased accuracy and the ability to extrapolate the model.
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Di Emidio, G., W. F. Van Impe, and R. D. Verástegui Flores. "Advances in Geosynthetic Clay Liners: Polymer Enhanced Clays." In Geo-Frontiers Congress 2011. Reston, VA: American Society of Civil Engineers, 2011. http://dx.doi.org/10.1061/41165(397)197.
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A R, Sindhu, Minukrishna P, and B. M. Abraham. "Experimental Study on the Impact of Type of Sulphate in Lime Stabilised Clays." In International Web Conference in Civil Engineering for a Sustainable Planet. AIJR Publisher, 2021. http://dx.doi.org/10.21467/proceedings.112.14.
Testo completoAbstract (sommario):
Marine clays are distinguished by high compressibility and low shear strength. It has been reported that lime stabilisation is very much potent, and can be used as an ideal ground improvement technique in the case of marine clays. Cochin marine clays are sometimes abundant in primary and secondary sources of sulphates of sodium, lithium, potassium and calcium. Different types of sulphates may have different impact on lime stabilised clays. Present study investigates the effect of different types of sulphates in lime treated marine clays. Marine clay samples were collected by auger boring and all the physical properties were determined. Sulphate content in clay was also found. Clay samples were treated with 6% of lime and 4% of sodium sulphate, lithium sulphate and potassium sulphate and were kept for various curing periods of zero days, 1 week, 1 month, 3 months and 6 months. Atterberg limits, free swell index, unconfined compressive strength and pH of all samples were determined. It was found that the plasticity and swelling characteristics of lime treated clay were influenced by the addition of sulphates. It was also found that all the three types of sulphates had detrimental effect on the gain in strength of lime stabilised soil. But the effect varies significantly with the type of sulphate present in the clay. This necessitates the importance of determination of the type sulphate present in the marine clay, before planning the soil stabilisation using lime.
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Villarroel, Andres, Michael Myers, and Lori Hathon. "Integrating the Thomas-Stieber Analysis With a Staged Differential Effective Medium Model for Saturation Interpretation of Thin-Bedded Shaly Sands." In 2022 SPWLA 63rd Annual Symposium. Society of Petrophysicists and Well Log Analysts, 2022. http://dx.doi.org/10.30632/spwla-2022-0035.
Testo completoAbstract (sommario):
A Staged Differential Effective Medium (SDEM) model based on the Hanai-Bruggeman equation is applied to interpret water saturation in shaly sands. In this model, the conductivity of the formation changes when different volumes of clays, oil, and quartz (inclusions) are successively distributed in the host. The host continuously varies as the inclusions are added. The resulting equations require the conductivity and distribution parameters, which are assumed constant. A Thomas-Stieber analysis allows the separation of clay types that are distributed at different length scales. It allows estimating the fractional bulk volumes of clay laminations and dispersed clays using only the density and gamma ray log data. The three endpoints of the Thomas-Stieber triangle (clean sand, 100 percent clay-filled sand, and shale) are determined from log data, thin sections, and SEM (Scanning Electron Microscope) observations. Dispersed clay and shale laminae porosity were estimated using SEM imaging. The dispersed clays were observed to have substantially higher porosity than the laminar clays. For this reason, clay laminae, and pore-filling dispersed clays are allowed to have differing properties. This is a generalization of the conventional Thomas-Stieber model. Principal Component Analysis (PCA) was used to cluster the data, allowing the impact of clays and their occurrence to be assessed. The density, resistivity, acoustic, and gamma ray logs are employed for this analysis. The model is used to iteratively extract the clays, oil, and quartz properties according to their differing length scales. The initial regression determines the distribution parameter and resistivity of the shale laminae. Next, the properties of the clay-filled sand are determined. The clay-filled sand conductivity increases linearly with the amount of dispersed clay. The pore fluid salinity is then estimated and agrees well with produced water analyses. Finally, the water saturation in the shaly sand is estimated. Saturation estimations using the SDEM model differ from those obtained using conventional shaly sand resistivity models. The water saturation estimations using the SDEM model are in agreement with the resistivity model and capillary pressure estimate, unlike the conventional shaly sand models. This is consistent with the current understanding of column heights and free water levels in the formation.
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McDonnell, Kevin T., Hong Qin, and Robert A. Wlodarczyk. "Virtual clay." In the 2001 symposium. New York, New York, USA: ACM Press, 2001. http://dx.doi.org/10.1145/364338.364395.
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Takahashi, Nobuo. "Mathematical clay." In ACM SIGGRAPH ASIA 2010 Computer Animation Festival. New York, New York, USA: ACM Press, 2010. http://dx.doi.org/10.1145/1900264.1900275.
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Stricklin, Colin, and Michael Nitsche. "Primal Clay." In FDG '20: International Conference on the Foundations of Digital Games. New York, NY, USA: ACM, 2020. http://dx.doi.org/10.1145/3402942.3409786.
Testo completoRapporti di organizzazioni sul tema "Clay"
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Nagy, Kathryn L. DE-FG02-06ER15364: Final Technical Report Nanoscale Reactivity of Clays, Clay Analogues (Micas), and Clay Minerals. Office of Scientific and Technical Information (OSTI), July 2008. http://dx.doi.org/10.2172/934383.
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Beul, Jasmine. Design x Clay. Ames (Iowa): Iowa State University, August 2022. http://dx.doi.org/10.31274/cc-20240624-504.
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Deming, M. Elen, and Paul Littleton. Carmel Clay Central Park. Landscape Architecture Foundation, 2013. http://dx.doi.org/10.31353/cs0470.
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Johnston, Jeffery. Clay, roots, and coexistence. Portland State University Library, January 2000. http://dx.doi.org/10.15760/etd.2764.
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Columber, Christopher Eugene. Structural clay tile component behavior. Office of Scientific and Technical Information (OSTI), December 1994. http://dx.doi.org/10.2172/125406.
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Thomas, J. K. Photochemistry on, and Nature of Adsorbed Species on Colloidal Clay and Model Clay Systems. Fort Belvoir, VA: Defense Technical Information Center, September 1987. http://dx.doi.org/10.21236/ada186099.
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Keene, Thea. Throwing Up: A Self-Guided Study in Clay Bodies. Montana State University, 2022. https://doi.org/10.15788/s2022.curio1.
Testo completoAbstract (sommario):
Based on the demands of her upcoming thesis project, Studio Arts major Thea Keene delves into the reasoning and technicalities of her research in clay bodies. Keene explains the dilemma caused by the range of firing temperatures for different types of clay, and how it influences the decision to experiment with new ones. Her research includes the tedious process of mixing and curing the clay, and a bit on the physics of throwing on the wheel. After testing three low-fire clay mixtures, Keene ultimately decides to use an earthenware terracotta for its color and maneuverability on the wheel.
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Di Pietro, S. A., C. Joseph, and M. Zavarin. Neptunium(IV) Diffusion through Bentonite Clay. Office of Scientific and Technical Information (OSTI), October 2019. http://dx.doi.org/10.2172/1605055.
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Gilman, Jeffrey W., Takashi Kashiwagi, Alexander B. Morgan, Richard H. Jr Harris, Lori Brassell, Mark VanLandingham, and Catheryn L. Jackson. Flammability of polymer clay nanocomposites consortium:. Gaithersburg, MD: National Institute of Standards and Technology, 2000. http://dx.doi.org/10.6028/nist.ir.6531.
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Flanagan, R. D. Behavior of structural clay tile infilled frames. Office of Scientific and Technical Information (OSTI), December 1994. http://dx.doi.org/10.2172/130659.
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