Kliknij ten link, aby zobaczyć inne rodzaje publikacji na ten temat: Clay volume.
Artykuły w czasopismach na temat „Clay volume”
Utwórz poprawne odniesienie w stylach APA, MLA, Chicago, Harvard i wielu innych
Sprawdź 50 najlepszych artykułów w czasopismach naukowych na temat „Clay volume”.
Przycisk „Dodaj do bibliografii” jest dostępny obok każdej pracy w bibliografii. Użyj go – a my automatycznie utworzymy odniesienie bibliograficzne do wybranej pracy w stylu cytowania, którego potrzebujesz: APA, MLA, Harvard, Chicago, Vancouver itp.
Możesz również pobrać pełny tekst publikacji naukowej w formacie „.pdf” i przeczytać adnotację do pracy online, jeśli odpowiednie parametry są dostępne w metadanych.
Przeglądaj artykuły w czasopismach z różnych dziedzin i twórz odpowiednie bibliografie.
1
Baldi, G., T. Hueckel i R. Pellegrini. "Thermal volume changes of the mineral–water system in low-porosity clay soils". Canadian Geotechnical Journal 25, nr 4 (1.11.1988): 807–25. http://dx.doi.org/10.1139/t88-089.
Pełny tekst źródłaStreszczenie:
The effect of temperature on the volumetric strains of the clay skeleton and clay – water system has been examined experimentally. Heating tests at (various) constant effective stress and isotropic loading tests at (various) constant temperatures were performed on low-porosity clays under drained conditions. The results indicate that the thermal expansion of adsorbed water in these clays is significantly lower than that of free water. Depending on the effective pressure, the clay skeleton may undergo either compression or expansion. Key words: nuclear waste isolation, clay, low porosity, thermal strain, adsorbed water.
2
Barbour, S. L., i D. G. Fredlund. "Mechanisms of osmotic flow and volume change in clay soils". Canadian Geotechnical Journal 26, nr 4 (1.11.1989): 551–62. http://dx.doi.org/10.1139/t89-068.
Pełny tekst źródłaStreszczenie:
The mechanical behavior of compressible clay soils may be strongly influenced by physicochemical effects when concentrated pore fluids are introduced to the soil. Conceptual models have been used to explain the influence of pore fluid chemistry on the mechanical behavior of clays in a qualitative way. In this paper an alternate macroscopic description of the osmotic volume change behavior of a clay soil undergoing changes in pore fluid chemistry is provided.Theoretical descriptions of two potential mechanisms of osmotic volume change (osmotic consolidation and osmotically induced consolidation) are presented. Osmotic consolidation occurs as a result of a change in the electrostatic repulsive-minus-attractive stresses, R — A, between clay particles. Osmotically induced consolidation occurs because of fluid flow out of the clay in response to osmotic gradients.A numerical simulation is used to demonstrate the characteristic behavior of a clay soil undergoing either of these volume change processes. The results of a laboratory testing program on two clay soils exposed to concentrated NaCl solutions are used to illustrate that the dominant mechanism of osmotic volume change in surficial clay soils is osmotic consolidation. Key words: physicochemical, osmosis, volume change, NaCl salt, montmorillonite, clay, stress state variables, R – A.
3
Abuel-Naga, H. M., D. T. Bergado, A. Bouazza i G. V. Ramana. "Volume change behaviour of saturated clays under drained heating conditions: experimental results and constitutive modeling". Canadian Geotechnical Journal 44, nr 8 (sierpień 2007): 942–56. http://dx.doi.org/10.1139/t07-031.
Pełny tekst źródłaStreszczenie:
One of the essential features of thermomechanical behaviour of saturated fine-grained soils is the thermally induced volume change occurring under a drained heating condition. In this study, a modified oedometer apparatus, able to handle temperatures up to 100 °C, was used to investigate the thermally induced volume change behaviour of soft Bangkok clay. The results of this experimental study provide additional experimental evidence and insights that may enhance the understanding of volume change behaviour of saturated clays at elevated temperatures. This paper also introduces an isotropic thermoelastoplastic constitutive model that closely predicts the thermally induced volume change behaviour of saturated clay specimens under normally consolidated conditions as well as overconsolidated conditions obtained by unloading process in the temperature range of 20–95 °C. Two yield limits, namely: loading yield limit and thermal yield limit, each of which can be measured from simple experimental results, are proposed to capture the volumetric plastic strain behaviour induced either by mechanical or thermal loading (or any combination thereof). The capability of the proposed model has been verified against experimental results obtained on soft Bangkok clay as well as on two other clays (Boom clay and MC clay) as reported in the literature.
4
Matteson, A., J. P. Tomanic, M. M. Herron, D. F. Allen i W. E. Kenyon. "NMR Relaxation of Clay/Brine Mixtures". SPE Reservoir Evaluation & Engineering 3, nr 05 (1.10.2000): 408–13. http://dx.doi.org/10.2118/66185-pa.
Pełny tekst źródłaStreszczenie:
Summary Effective interpretation of nuclear magnetic resonance (NMR) logs in shaly sands requires an understanding of the NMR contribution of clays. Of particular importance is the role of clays in the rapidly relaxing part of the NMR signal. In this study we measured the transverse relaxation time spectrum T2 of brine mixed with four clays (illite, smectite, kaolinite and glauconite) as a function of compaction. The Larmor frequency was 2 MHz and the echo spacing 0.16 ms. Mild compaction was achieved by centrifuging the clay slurry at three successive pressures ranging from 1 to 125 psi. Highly compacted samples were produced in a uniaxial press at six sequential pressures ranging from 500 to 16,000 psi. Each clay/brine slurry and its associated compacted sample showed a single peak in the T2 distribution spectrum. A second peak, which could be interpreted as the "clay-bound water," was never observed. The T2 peak position shifted to faster relaxation times as compaction increased, in proportion to the pore volume-to-surface ratio, Vp/As. The single peak and Vp/As proportionality are consistent with fast diffusion between the pore water and the monolayer of water on the clay surface. Surface relaxivity varied among the four clay minerals; glauconite, the clay with the highest magnetic susceptibility and iron content had the largest surface relaxivity. These results have important implications for the interpretation of NMR logs in shaly sands. Because of the effects of compaction and to a lesser extent the iron content on a clay's T2 peak position, it is not possible to independently determine clay type from some characteristic relaxation time. These data also imply that it is not feasible to estimate the cation exchange capacity from a single time cutoff of the T2 distribution without additional information such as laboratory measurements or other log data. Introduction Nuclear magnetic resonance logging has become an important tool in evaluating a formation's petrophysical properties. The unique and valuable advantage that NMR provides is pore size distribution information. No other logging method provides these data, which are the key component of log-based estimates of capillary-bound water volume, and permeability to flow.1 It has been proposed that NMR logging can be extended to estimate clay-bound water volumes, and identify clay minerals. Clay-bound water volume, important in determining water saturation from resistivity, has been correlated with the short-T2 less than 3 ms, porosity of 45 oilfield sandstones.2 Prammer et al.'s3 NMR clay/brine study found that the T2 distribution of clay-bound water associated with kaolinite and chlorite was greater than 3 ms, for illite it ranged between 1 and 2 ms and for smectite it was less than 1 ms. Observed T2 's were then used as an indicator of cation exchange capacity (CEC) because the number of available exchange sites is proportional to a clay's specific surface area. CEC is fundamental to converting bulk resistivity measurements into water saturation. The ability to estimate clay-bound water, and to identify the clay type, from NMR T2 distributions is not compatible with the ability to determine pore size distribution from the same data. In the first two cases the molecular diffusion rate of water in the pores must be slow, whereas in the latter case it is assumed to be fast. For example, consider a monolayer of water on the surface of room-dry clay. The monolayer has a short relaxation time, less than a millisecond, because of its interaction with the solid rock. Now fill the void space between the clay particles with water and consider the two extreme cases. In the first case, there is no molecular diffusion (exchange) between the surface-monolayer water and bulk water. Thus, the T2 spectrum will contain two separate peaks, one associated with the surface-monolayer water at less than a millisecond and one associated with the bulk water. In the opposite case, molecular diffusion is highly effective, and both the surface monolayer and bulk water have a common relaxation time, a single peak in the T2 spectrum with time constant: 1 T 2 = ρ s ( A s V p ) . ( 1 ) In this equation, which provides the fundamental connection between T2 and pore size, the term ?2 is the surface relaxivity parameter that indicates the capacity of the rock to cause the decay of magnetization in the water. Fig. 1 is a conceptual drawing of a T2 distribution for a sandstone that includes fluid in small pores that are typically associated with clays, capillary-bound and producible fluid. The objective of this study was to determine whether it is possible to infer a clay-bound water volume (peak or T2 cutoff), or clay type, and a pore size distribution from a NMR distribution spectrum. To achieve this goal we designed a set of experiments that examined the NMR relaxation of clay/brine mixtures at various compaction states. In contrast to shaly sands, the clay/brine mixtures provided the means to minimize the pore volume-to-surface ratio, so that any water-monolayer-related signal might be detected. The pore volume-to-surface ratio was easily varied through compaction, and the monomineralic samples enable the NMR response of individual clay types to be evaluated. We chose to study four clays commonly found in oil-bearing sedimentary environments: kaolinite, illite, smectite and glauconite. Experimental Procedures Samples of illite and glauconite were obtained from Wards Natural Science Establishment. Kaolinite and smectite (Ca Montmorillonite) were procured from ECC Intl., Georgia Kaolin Co. and the Source Clay Minerals Repository, respectively. Various physical properties of the clays were measured. Prior to the surface area and magnetic susceptibility measurements, the clays were dried overnight in a vacuum oven at 100°C. Surface area measurements were collected using the Micromeritics Gemini 2360 with nitrogen gas as adsorbate, and magnetic susceptibilities were measured on a Johnson Matthey MSB-AUTO magnetic susceptibility balance. CEC measurements were taken using the ammonium acetate/ammonium ion-specific electrode method by David K. Davies & Assoc., Inc. Table 1 is a summary of clay type, clay origin and clay physical properties. The samples were analyzed for mineralogy using dual-range Fourier transform infrared (FTIR) spectroscopy.4 In addition, the samples were sent to X-Ray Assay Laboratories for chemical analyses (Table 2). The mineralogy data indicate the presence of quartz in the illite sample. Consequently, a <2 ?m fraction of the sample was extracted by centrifuging the illite and drying the supernatant. The physical properties for these clays are in good agreement with those in the literature.5 The clay samples used for the room-dry and clay/brine mixture NMR experiments were kept at room temperature and at typical laboratory humidity conditions of 50%. To evaluate whether clay samples have a measurable NMR signal at room-dry conditions, samples were prepared by placing the clay in a test tube and sealing it off with a stopper and Teflon tape.
5
Journal, Baghdad Science. "Investigation of the Porosity of Certain Iraqi Clay Deposits by Mercury Porosimeter". Baghdad Science Journal 6, nr 1 (1.03.2009): 163–72. http://dx.doi.org/10.21123/bsj.6.1.163-172.
Pełny tekst źródłaStreszczenie:
Pore volume, pore diameter, and pore volume distribution of three of Iraqi natural clay deposites were measured using mercury intrusion porosimetry .The clays are white kaolin, colored kaolin, and bentonite .The results showed that the variation of the pore area of the clay deposites followed the following order :- Coloured Kaolin > White Kaolin > Bentonite While the pore volume may be arranged as in the following sequence:- White Kaolin > Coloured Kaolin >Bentonite Also , Bentonite exhibits the narrow range pore size distribution than the white and coloured kaolin.
6
Tall, Andrej, Branislav Kandra, Milan Gomboš i Dana Pavelková. "The influence of soil texture on the course of volume changes of soil". Soil and Water Research 14, No. 2 (5.04.2019): 57–66. http://dx.doi.org/10.17221/217/2017-swr.
Pełny tekst źródłaStreszczenie:
Volume changes of soil associated with soil moisture changes are caused by the presence of clay minerals from illite and montmorillonite groups. Clay minerals are found in the so-called clay soil component which can be quantified by laboratory analysis of the soil particle-size distribution. Consequently, the potential for volume changes in soil can be assessed from soil texture. In our study, 172 soil samples with different textures were used to measure dependencies between volume changes in soil and changes in soil moisture under laboratory conditions. The samples were collected from 11 sites in the Eastern Slovak Lowland. On the basis of the measurements, 10 mathematical models were created to compute the correlation between volume changes of soil and soil moisture content and texture. The highest accuracy was obtained with the model which assumes the content of particles < 0.002 mm. When comparing the clay particles < 0.001 mm (colloidal clay) with the particles < 0.002 mm (colloidal + physical clay) it was also found that the particles < 0.002 mm have a larger impact on the volume changes of soil than the particles < 0.001. The inclusion of particles > 0.002 mm (silt + sand) into the models resulted in either no or only negligible refinement of the soil volume change calculations.
7
Casarella, Angela, Alessandro Tarantino i Alice Di Donna. "Micromechanical interpretation of thermo-plastic behaviour of clays". E3S Web of Conferences 205 (2020): 09003. http://dx.doi.org/10.1051/e3sconf/202020509003.
Pełny tekst źródłaStreszczenie:
The effect of temperature on mechanical behaviour of clay-based geomaterials is relevant in a number of geotechnical applications (e.g. low enthalpy geothermal systems and energy geostructures, nuclear waste disposal, and heating in rapid shear deformation). Mechanical response of (saturated) clays upon heating is not always intuitive as volume changes may occur due to both thermal expansion of clay constituents and temperature-induced changes of clay microstructure. This paper first revisits the macroscopic thermally-induced mechanical behaviour of saturated clays available in the literature via an advanced thermo-elastoplastic constitutive model and then elucidates the dependence on clay mineralogy of the two key parameters of the model (mechanical hardening and thermal softening respectively) by inspecting differences in clay inter-particle electro-chemical forces occurring in kaolinitic, illitic, and smectitic clays. The micromechanically-based interpretation of constitutive parameters can serve as a guidance for soil parameter selection in the design of energy geostructures.
8
Dagesse, D. F. "Freezing-induced bulk soil volume changes". Canadian Journal of Soil Science 90, nr 3 (1.08.2010): 389–401. http://dx.doi.org/10.4141/cjss09054.
Pełny tekst źródłaStreszczenie:
The volumetric expansion accompanying the phase transition from water to ice does not always cause structural deterioration in soil, as at low water contents the empty pore volume of the soil may be sufficient to contain this expansion. The objective of this study was to investigate the volume change in soils of varying clay contents and initial water contents during the freezing process. Volume change upon freezing was measured for seven soils with clay contents ranging from 0.11 to 0.75 kg kg–1. Curve fitting revealed percent saturation levels corresponding to maximum shrinkage, zero volume change and maximum expansion. Curves for all soils exhibited similar shapes, composed of zones dominated by volumetric decreases at values less that 63 to 70% saturation, and expansion at percent saturations above this level. Zero volume change occurred at percent saturations of 74 to 90%. Clay content was found to control the maximum amount of shrinkage, with greater shrinkage in soils with higher clay contents. Bulk soil volume decreases occur in non-rigid clay containing soils due to desiccation and shrinkage when frozen at low water contents.Key words: Volume change, soil freezing, cla
9
Nascimento, J. J. S., F. A. Belo i Antônio Gilson Barbosa de Lima. "Experimental Drying of Ceramics Bricks Including Shrinkage". Defect and Diffusion Forum 365 (lipiec 2015): 106–11. http://dx.doi.org/10.4028/www.scientific.net/ddf.365.106.
Pełny tekst źródłaStreszczenie:
This work presents an experimental study on the behavior of clays during the drying process. Experimental tests were carried out with clay material for the production of red ceramics and white ceramic (ball clay). Different dimensions and the material initial moisture content plus temperature and relative air-drying humidity were taken into account. Drying kinetics and volume changes of parallelepiped-shaped samples were shown and analyzed. It has been verified that air-drying temperatures and body shape have an enormous influence on the drying rate process. The drying process occurs during the falling drying period and the volume changes display two linear periods.
10
Ohtsubo, Masami, Kazuhiko Egashira i Masateru Takayama. "Properties of a low-swelling smectitic marine clay of interest in soil engineering". Canadian Geotechnical Journal 22, nr 2 (1.05.1985): 241–45. http://dx.doi.org/10.1139/t85-033.
Pełny tekst źródłaStreszczenie:
Smectite is generally a high-swelling clay. However, the smectite found in marine quick clays in the Ariake Bay area of Japan is a low-swelling clay like illite and kaolinite. The low swelling properties of an Ariake marine clay are investigated here in terms of consolidation, swelling, and shrinkage characteristics. The void ratios in compression curves of soils containing sodium are lower at 0.01 N than at 1.0 N NaCl concentration, and the slopes of swelling curves are independent of salt concentration in the pore water and cation valency. These tendencies are contrary to those observed for montmorillonite and a paddy soil containing high-swelling smectite. Measurements of swelling pressure suggest that the smectite in the Ariake marine clay exhibits little intracrystalline swelling even after saturation with Na. The volume shrinkage of the Ariake marine clay by air-drying is smaller than that of the paddy soil. Key words: compressibility, marine clays, smectite, swelling.
11
Ghadiri, H., D. Connell i R. Parker. "Sorption-desorption and column leaching of strychnine with soil". Soil Research 38, nr 3 (2000): 603. http://dx.doi.org/10.1071/sr99056.
Pełny tekst źródłaStreszczenie:
Sorption–desorption of rodenticide strychnine by soil and its leaching through soil columns were studied on 4 typical soils of south-east Queensland. All 4 soils showed a high tendency to sorb strychnine, with the sorption rate higher for clay soils. The sorption capacities of the 4 soils are in the order Kingsthorpe > Warra > Oakey > Roma, which is also the order of decline in their clay contents. The desorption process also closely followed the clay content of the 4 soils. The 2 clay soils of Kingsthorpe and Warra not only sorbed a higher proportion of the applied strychnine at any application rate, they also showed a greater resistance to releasing their sorbed strychnine compared with the 2 silty clay loam soils. The effects of pH and organic matter content on the sorption–desorption of strychnine were inconclusive due to the dominant influence of clay content and the narrow range of these characteristics provided by the soils under investigation. The 2 clay soils of Kingsthorpe and Warra required a significantly higher number of pore volumes of leaching solution to pass through their respective columns for the concentration of strychnine in the effluent to approach that of the leaching solution, compared with the 2 silty clay soils of Oakey and Roma. The pore volumes of the leaching solution necessary for this point to be reached were not in the order of their clay contents, but when the cumulative volume of solution was used instead of the pore volume, the trend followed the clay content of the soils closely. Pore volume may not be an appropriate characteristic for assessing the leachability of strychnine through soil columns when the soil’s clay fraction is of an expanding type, as it is the case for Kingsthorpe soil. No desorption or leaching of strychnine took place in any of the 4 soils aged with a range of strychnine concentrations.
12
Chia, Julian Y. H., Kais Hbaieb i Q. X. Wang. "Finite Element Modelling Epoxy/Clay Nanocomposites". Key Engineering Materials 334-335 (marzec 2007): 785–88. http://dx.doi.org/10.4028/www.scientific.net/kem.334-335.785.
Pełny tekst źródłaStreszczenie:
A full 3D finite element method has been used to understand how nano-clay particles affect the mechanical properties of an epoxy/clay nanocomposite. The epoxy/clay nanocomposite has been modelled as a representative volume element (RVE) containing intercalated clay platelets that internally delaminates at the gallery layer upon satisfying an energy criterion, and an epoxy matrix that is elastic-plastic. A cohesive traction-displacement law is used to model the clay gallery behaviour until failure. For clay volume fractions >1%, clay particle interaction is observed to develop during uniaxial tension, the nanocomposite stiffness becomes non-linearly dependent on the clay volume fraction, and the Mori-Tanaka model overestimates the stiffness. Failure of the clay gallery is not observed and is believed to have no influence on the ultimate tensile strength of the nanocomposite.
13
Sridharan, A., i K. Prakash. "Influence of clay mineralogy and pore-medium chemistry on clay sediment formation". Canadian Geotechnical Journal 36, nr 5 (23.11.1999): 961–66. http://dx.doi.org/10.1139/t99-045.
Pełny tekst źródłaStreszczenie:
The responses of the two common clay minerals in soils, namely kaolinite and montmorillonite, to varying physicochemical factors are quite drastic and opposite. The effect of variation in the physicochemical factors is phenomenal at very high water contents of the sediments, as the electrical forces of attraction and repulsion play a decisive role in controlling the structure of the sediment formed. This note discusses through detailed illustrations the effect of dielectric constant and electrolyte concentration as well as the effect of valency and hydrated size of the exchangeable cations on the sediment volume of clayey soils as governed by the clay mineralogy. Key words: clays, kaolinite, montmorillonite, pore-medium contamination, sediment formation.
14
Pervukhina, Marina, Pavel Golodoniuc, Boris Gurevich, Michael B. Clennell, Dave N. Dewhurst i Hege M. Nordgård-Bolås. "Prediction of sonic velocities in shale from porosity and clay fraction obtained from logs — A North Sea well case study". GEOPHYSICS 80, nr 1 (1.01.2015): D1—D10. http://dx.doi.org/10.1190/geo2014-0044.1.
Pełny tekst źródłaStreszczenie:
Prediction of sonic velocities in shales from well logs is important for seismic to log ties if the sonic log is absent for a shaly section, for pore pressure anomaly detection, and for data quality control. An anisotropic differential effective medium (DEM) was used to simulate elastic properties of shales from elastic properties and volume fractions of silt and wet clay (a hypothetical composite material that includes all clay minerals and water). Anisotropic elastic coefficients of the wet clay were assumed as a first-order approximation to be linearly dependent on wet clay porosity (WCP). Here, by WCP we mean a ratio of a pore volume occupied by water to a total volume of the wet clay. Effects of silt inclusions on elastic coefficients of shales were taken into account by using the anisotropic differential effective medium model. Silt inclusions were modeled as spherical quartz particles. Simulated elastic coefficients of shales were used to calculate compressional and shear velocities, and these were in a good agreement with the sonic velocities observed on a test data set from an offshore Mid-Norway well penetrating a 500-m vertical section of shale. To further study the elastic properties of wet clays, elastic coefficients calculated from compressional and sonic velocities measured in shales were inverted for vertical profiles of wet clay elastic coefficients. Analysis of these coefficients found that in the well considered, the increase in elastic coefficients of shales was controlled by the increase of silt fraction with depth. Elastic coefficients of wet clay found no increase with depth. The inverted elastic moduli of wet clay found much stronger correlation with WCP than do the moduli of shale. This confirmed the hypothesis that silt fraction is one of the key parameters for the modeling of elastic properties of shale.
15
Graham, J., N. Tanaka, T. Crilly i M. Alfaro. "Modified Cam-Clay modelling of temperature effects in clays". Canadian Geotechnical Journal 38, nr 3 (1.06.2001): 608–21. http://dx.doi.org/10.1139/t00-125.
Pełny tekst źródłaStreszczenie:
The Cam-Clay model for isothermal mechanical behaviour of clays has been extended to take account of the effects of temperature on stressstrain behaviour. The assumptions used in constructing the new model are based on published results and on new data presented in the paper. The model allows prediction of how heating and cooling affect volume changes, pore-water pressures, and strengths for both normally consolidated and overconsolidated saturated clays. It permits modelling of observed reductions in the overconsolidation ratio with increasing temperature. The model provides accessible qualitative explanations for temperature effects that were previously difficult to understand. It will also allow easy implementation for quantitative modelling in triaxial stress fields. Results predicted by the model are compared with data collected by the authors at temperatures up to 100°C. The model does not account for changes that occur in clay minerals at higher temperatures, for example, in bentonites at temperatures higher than about 150°C.Key words: clay, triaxial, temperature, modelling, elasticplastic, Cam-Clay.
16
XU, YONGFU. "SURFACE FRACTAL DIMENSION OF SWELLING CLAY MINERALS". Fractals 11, nr 04 (grudzień 2003): 353–62. http://dx.doi.org/10.1142/s0218348x03002245.
Pełny tekst źródłaStreszczenie:
A simple method is proposed to determine the surface fractal dimension of swelling clay minerals. When swelling clay mineral is immersed into the water solution, swelling deformation and swelling pressure will occur. The swelling deformation and swelling pressure are proportional to the amount of water volume absorbed by swelling clay minerals. The water volume absorbed by swelling clay minerals is related to its surface fractality. The correlation of the normalized water volume by the volume of swelling clay minerals (Vw/Vm) to vertical overburden pressure (p) is obtained as Vw/Vm = KpDs-3, from which the surface fractal dimension of swelling clay minerals can be estimated. The surface fractal dimension (Ds) of Wyoming bentonite is 2.64, obtained from the swelling tests. The surface fractal dimension of Wyoming bentonite determined from the swelling tests nearly equals to that obtained from the nitrogen adsorption isotherms, and is larger than that measured using the mercury intrusion porosimetry.
17
Chowdhury, Uraching, i Xiang-Fa Wu. "Cohesive Zone Modeling of the Elastoplastic and Failure Behavior of Polymer Nanoclay Composites". Journal of Composites Science 5, nr 5 (14.05.2021): 131. http://dx.doi.org/10.3390/jcs5050131.
Pełny tekst źródłaStreszczenie:
Cohesive zone model (CZM) is commonly used to deal with the nonlinear zone ahead of crack tips in materials with elastoplastic deformation behavior. This model is capable of predicting the behavior of crack initiation and growth. In this paper, CZM-based finite element analysis (FEA) is performed to examine the effects of processing parameters (i.e., the clay nanoparticle volume fraction and aspect ratio) in the mechanical behaviors of a polymeric matrix reinforced with aligned clay nanoparticles. The polymeric matrix is treated as an ideal elastoplastic solid with isotropic hardening behavior, whereas the clay nanoparticles are simplified as stiff, linearly elastic platelets. Representative volume elements (RVEs) of the resulting polymer nanoclay composites (PNCs) are adopted for FEA with the clay nanoparticle distributions to follow both stack and stagger configurations, respectively. In the study, four volume fractions (Vf = 2.5%, 5%, 7.5% and 10%) and four aspect ratios (ρ = 5, 7.5, 10, and 20) of the clay nanoparticles in the PNCs are considered. Detailed computational results show that either increasing volume fraction or aspect ratio of the clay nanoparticles enhances the effective tensile strength and stiffness of the PNCs. The progressive debonding process of the clay nanoparticles in the polymeric resin was predicted, and the debonding was initiated in the linearly elastic loading range. The numerical results also show that PNCs with stagger nanoparticle configuration demonstrate slightly higher values of the engineering stress than those based on the stack nanoparticle configuration at both varying volume fractions and aspect ratios of the clay nanoparticles. In addition, CZM-based FEA predicts a slightly lower stress field around the clay particles in PNCs than that without integration of CZM. The present computational studies are applicable for processing PNCs with controllable mechanical properties, especially the control of the key processing parameters of PNCs, i.e., the volume fraction and aspect ratio of the clay nanoparticles.
18
Choo, Hyunwook, Youngmin Choi, Woojin Lee i Changho Lee. "Effect of pH Variations on the Yield Stress of Calcium Bentonite Slurry Treated with pH-Responsive Polymer". Materials 13, nr 11 (1.06.2020): 2525. http://dx.doi.org/10.3390/ma13112525.
Pełny tekst źródłaStreszczenie:
The pH-responsive polymers, such as polyacrylamide (PAM), show distinct conformational states according to the pH of their environmental groundwater. Therefore, the interactions between clay–polymer and polymer–water molecules, which determine the yield stress of bentonite–polymer composites, can be affected by the pH of groundwater. This study aims to evaluate the effect of pH variation on the yield stress of calcium bentonite treated with PAM. The yield stresses (τy) of untreated and PAM treated clays were measured with varying volume fractions of solid (VF = 10–23%) and under varying pH conditions (pH = 7.6–9.6). In addition, the zeta potential was measured for both untreated and treated clays to figure out the change in the surface charge of the mineral surface due to PAM treatment. The results of this study demonstrate that τy for treated clay is higher than that for untreated clay at a given VF, because van der Walls attraction dominates electrostatic repulsion in the case of treated clay. Due to the change in conformational states of PAM and the consequent change in surface charge that comes with varying pH, the pH-dependent change in τy of treated clay is significantly different from that of untreated clay.
19
Srithammaraj, K., Rathanawan Magaraphan i H. Manuspiya. "Surfactant-Templated Synthesis of Modified Porous Clay Heterostructure (PCH)". Advanced Materials Research 55-57 (sierpień 2008): 317–20. http://dx.doi.org/10.4028/www.scientific.net/amr.55-57.317.
Pełny tekst źródłaStreszczenie:
Porous Clay Heterostructures (PCHs) have been prepared by the surfactant-directed assembly of mesostructured silica within the two-dimensional interlayer galleries of clays. The PCH is an interesting material to use as entrapping system such as ethylene scavenger, owing to its high surface area with uniform and specific pore size. In the present work, the PCH was synthesized within the galleries of Na-bentonite clay by the polymerization of tetraethoxysilane (TEOS) in the presence of surfactant micelles. In addition, a mesoporous clay with organic-inorganic hybrid (HPCH) is modified via co-condensation reaction of TEOS with methyltriethoxysilane (MTS) to enhance hydrophobicity of PCH material for entrapping system. According to pore characterization, PCHs have surface areas of 421-551 m2/g, an average pore diameter in the supermicropore to small mesopore range of 4.79-5.02 nm, and a pore volume of 0.57-0.66 cc/g while HPCHs have surface areas of 533-966 m2/g, an average pore diameter of 4.28-6.38 nm, and a pore volume of 0.42-0.77cc/g.
20
Nadeau, P. H. "The physical dimensions of fundamental clay particles". Clay Minerals 20, nr 4 (grudzień 1985): 499–514. http://dx.doi.org/10.1180/claymin.1985.020.4.06.
Pełny tekst źródłaStreszczenie:
AbstractThe thickness, length, width, area and perimeter of 575 particles from 16 aqueously dispersed samples of a variety of interstratified clays, smectites and illite have been recorded using TEM techniques. Complete dispersion of the clay material was achieved by saturating the clay with either Na+ or Li+, removal of excess ions by dialysis, and isolation of the <0·1 or <0·2 µm fraction by centrifugation. The samples have mean maximum dimensions of 1900 to 90 nm and the dispersed system can be considered as colloidal in nature. The mean thickness of the clays is about 1 nm for smectites, corresponding to that of elementary 2:1 silicate layers, from 1·9 to 4·9 nm for the interstratified clays, and 9 nm for illite. From these data the volume, total surface area and other parameters have been calculated and compared with independent determinations of surface area and CEC. The total surface area by TEM, assuming a density of 2·6 g/cm3, varies from ∼675 m2/g for smectites to 86 m2/g for illite, and is inversely proportional to the mean particle thickness. The charge density of monovalent cation exchange sites on the surface of the particles as determined for nine of the samples varies from 0·54 to 1·16 nm2/site. The particle-thickness distribution data can be used to calculate interstratified XRD layer-sequence probabilities and composition parameters, and agree with XRD data for interstratified clay with <60% illite layers. The thickness data also provide a rationale for the interpretation of TEM lattice-fringe images. Relationships between the particle area, length, thickness and volume are shown to be potentially useful in assessing the mechanism(s) of crystal growth of these extremely small phyllosilicate particles.
21
Adesokan, Hamid, i Yuefeng Sun. "Rock-physics-based estimation of critical-clay-volume fraction and its effect on seismic velocity and petrophysical properties". GEOPHYSICS 79, nr 3 (1.05.2014): D175—D185. http://dx.doi.org/10.1190/geo2012-0510.1.
Pełny tekst źródłaStreszczenie:
Knowledge of the clay content in clastic reservoirs is important for predicting reservoir quality and properties. We used a microgeometrical model for shaly sand and sandy shale to define the critical-clay-volume fraction and explain the dependence of the bulk modulus on clay content. We found that the concept of the pore-aspect ratio relating to the critical-clay-volume fraction was important to interpret the elastic behavior of shaly sandstone. An abrupt decrease in pore-aspect ratio from about 0.23 to about 0.04 was observed where the clay-volume fraction was greater than the critical value of 32% for the studied data set. At the critical-clay-volume fraction of 32%, an increase in pore compressibility also occurred from about 0.6 to about [Formula: see text]. Results revealed that the microgeometrical model compared to other models can better explain the existence of highly scattered compressional velocity-porosity crossplots when the clay content is close to the critical amount. We discovered that the model can be applied in well-logging interpretations of shaly formations for determining shale cut-off and mapping of reservoir pore shape from velocity measurements.
22
STONE, J. A., i K. C. WIRES. "WATER CONTENT AND SOIL CORE VOLUME ON BROOKSTON CLAY LOAM". Canadian Journal of Soil Science 70, nr 2 (1.05.1990): 255–58. http://dx.doi.org/10.4141/cjss90-026.
Pełny tekst źródłaStreszczenie:
Soil core volumes, from a long-term fertility experiment on Brookston clay loam, were adjusted for soil water content at sampling to explain large year-to-year fluctuations in bulk density and porosity. Adjusting the long-term soil core data decreased values of bulk density, total porosity, and air-filled porosity and reduced the variation between years. However, the year-to-year variation remained highly significant. Year-to-year fluctuations in bulk density and porosity on Brookston clay loam soil do not appear to be solely the result of changes in soil volume due to differences in soil water content at the time of sampling. Key words: Shrinkage, bulk density, porosity
23
Marcial, Duilio, Pierre Delage i Yu Jun Cui. "On the high stress compression of bentonites". Canadian Geotechnical Journal 39, nr 4 (1.08.2002): 812–20. http://dx.doi.org/10.1139/t02-019.
Pełny tekst źródłaStreszczenie:
High stress consolidation tests (up to 30 MPa) were carried out on slurries made up of three bentonites considered as possible constituents for engineered clay barriers used for nuclear waste disposal at great depth (Na Kunigel, Na-Ca MX80 Wyoming clay, and Ca Fourges clay). Water retention curves (WRCs) were determined for a wide range of suctions (up to 305 MPa). A bilinear shape for the compression curves and the WRCs was observed in the three clays, with significant changes occurring in the 0.41 MPa suctionstress range. The permeability and the coefficient of consolidation were also determined during the compression tests. In the WRCs and compression curves, the two clays containing Na+ exhibited a similar behaviour, which was different from that of the Ca2+ clay. The coefficient of consolidation for the three clays was decreasing in the 0.41 MPa stress range and increasing at higher stresses. Data were interpreted in the light of existing experimental observations on the microstructural changes of similar swelling clays carried out by various authors, which obtained compatible and coherent results. The diffuse double theory, often used in the interpretation of the volume change behaviour of swelling clays, was also considered. Under higher stresses (> 2 MPa), the compressive behaviour appeared to be linked to the expulsion water molecules that form the hydration shells around exchangeable cations inside the domains formed of staked clay plates. The permeability properties of the Ca2+ and Na+ clays were linked to the microstructure features and to the WRCs, whereas the changes in the coefficients of consolidation during compression were linked to the changes in soil stiffness.Key words: consolidation, swelling clay, permeability, exchangeable cations, diffuse double layer, adsorbed water.
24
El-Sheikhy, Refat, i Mosleh Al-Shamrani. "Size Effect on Volume-Shape Change of both Micro and Nano Aluminum-Silicate Minerals". Advanced Materials Research 214 (luty 2011): 430–33. http://dx.doi.org/10.4028/www.scientific.net/amr.214.430.
Pełny tekst źródłaStreszczenie:
Both conventional and nano silicate minerals have importance for several fields of advanced technological research and industries. Nano clay can be used as filler material or reinforcement for other materials to produce nanocomposite as the case of clay based-polymer nanocomposite. Nowadays there is worldwide interest of these materials which may be synthesized or natural. In current paper, shrinkage phenomenon has been studied and cracks of this material using natural Saudi Arabian smectite type MMT. The three dimensional changes of cubic samples of nano clay are studied and compared to conventional clay, semi conventional-semi nano clay and another cementous type of clay based nanocomposite. It is found that nano clay changes are very sensitive and high without cracking while conventional clay type has less change accompanied by cracks. On the other hand semi conventional-semi nano clay mineral composite has intermediate resuls of volume change with cracks but less than the pure conventional type. SEM, EDAX and XRD characterizations are made. Both volume and length changes are recorded. The study can be considered as the base of proposing of new swelling – shrinkage theory.
25
Al-Abduljabbar, Abdulhamid. "A Permeability Model for Polymer-Clay Nanocomposites with Varying Clay Platelets Thickness". Materials Science Forum 916 (marzec 2018): 3–9. http://dx.doi.org/10.4028/www.scientific.net/msf.916.3.
Pełny tekst źródłaStreszczenie:
Polymer-clay nanocomposites (PCNC), are characterized by the high ratio of surface area to volume of the clay nanoparticles which are in the form of clay platelets with very high aspect ratio. This feature provides superior gas barrier properties at very low volume fraction of the nanofiller. Clay platelets introduce discontinuity to flows through the bulk polymer matrix material. The extent of this improvement depends on the success of separation of clay layers during processing which would produce single-layer particles (exfoliation) or several-layer particles (intercalation) through the bulk polymer matrix. This paper discusses the common permeability models used to capture the effects of the clay nanofillers in PCNC. Since these models assume a state of full exfoliation of clay platelets; that is a single phase of the nanofiller, they fall short of representing the actual state as evidenced by experimental works, which confirm the presence of both the intercalated phase and the exfoliated phase. A model that incorporates clay inclusions with different sizes (different thicknesses) is proposed and its implications are assessed.
26
Tariq, Ata-ur-Rehman, i Deanna S. Durnford. "Analytical Volume Change Model for Swelling Clay Soils". Soil Science Society of America Journal 57, nr 5 (wrzesień 1993): 1183–87. http://dx.doi.org/10.2136/sssaj1993.03615995005700050003x.
Pełny tekst źródła
27
Jones, L. D., i R. Terrington. "Modelling Volume Change Potential in the London Clay". Quarterly Journal of Engineering Geology and Hydrogeology 44, nr 1 (luty 2011): 109–22. http://dx.doi.org/10.1144/1470-9236/08-112.
Pełny tekst źródła
28
Bell, F. G., i C. A. Jermy. "Building on Clay Soils which Undergo Volume Changes". Architectural Science Review 37, nr 1 (marzec 1994): 35–43. http://dx.doi.org/10.1080/00038628.1994.9697327.
Pełny tekst źródła
29
Favero, Valentina, Alessio Ferrari i Lyesse Laloui. "Thermo-mechanical volume change behaviour of Opalinus Clay". International Journal of Rock Mechanics and Mining Sciences 90 (grudzień 2016): 15–25. http://dx.doi.org/10.1016/j.ijrmms.2016.09.013.
Pełny tekst źródła
30
Thian, Siaw Yin, i Choon Yong Lee. "Simplified Constant Volume Simple Shear Tests on Clay". KSCE Journal of Civil Engineering 22, nr 8 (10.04.2018): 2834–42. http://dx.doi.org/10.1007/s12205-018-0467-y.
Pełny tekst źródła
31
Ferber, Valéry, Jean-Claude Auriol, Yu-Jun Cui i Jean-Pierre Magnan. "Wetting-induced volume changes in compacted silty clays and high-plasticity clays". Canadian Geotechnical Journal 45, nr 2 (luty 2008): 252–65. http://dx.doi.org/10.1139/t07-081.
Pełny tekst źródłaStreszczenie:
Wetting-induced deformations of compacted fine-grained soils are of particular interest in earthworks engineering, where embankment design needs to take into account potential future water-content variations. The influence of compaction rate on swelling potential and, more generally, wetting-induced deformations are analyzed in this paper on the basis of an original physical microstructural model. The interpretation of macroscopic experimental results obtained on a high-plasticity clay and a silty clay shows that the model enables quantitative description of intra- and inter-aggregate pore volume changes due to wetting. Using this approach, a fundamental difference was observed between the high-plasticity clay and the silty clay in wetting tests under vertical stress: tests performed on the high-plasticity clay can be analyzed using a microstructural model, whereas this model is not relevant for the analysis of silty clay behaviour, which is better interpreted in the framework of a conventional elastoplastic model. The interpretations were compared to microstructure observations, which support the main tendencies deduced from the model.
32
Lomic, Gizela, Erne Kis, Etelka Dimic i Ranko Romanic. "Investigation of activated Al-pillared clay efficiency in vegetable oil purification". Acta Periodica Technologica, nr 35 (2004): 31–36. http://dx.doi.org/10.2298/apt0435031l.
Pełny tekst źródłaStreszczenie:
This paper represents a contribution to the applicability of natural clays and their derivates as adsorbents in the process of purification of vegetable oil. Investigation of textural properties of raw and purified clay samples reveals that during acid activation and Al-pillaring, BET and micropore surface area increases significantly. However, bleaching capacity of clay and its derivates is not determined by using sample surface area, but rather sample total pore volume. Surface area, especially micropore surface area contributes to removal of smaller molecules. This was confirmed by successful elimination of moisture and volatile materials by samples with an appropriate micropore structure. Used samples of clay and its derivates do not significantly influence acid and peroxide values of raw sunflower oil during its treatment.
33
Katti, Dinesh R., i Vijayakumar Shanmugasundaram. "Influence of swelling on the microstructure of expansive clays". Canadian Geotechnical Journal 38, nr 1 (1.02.2001): 175–82. http://dx.doi.org/10.1139/t00-079.
Pełny tekst źródłaStreszczenie:
The focus of this work is to elucidate the changes in microstructure during swelling in expansive clays. A new device to enable controlled swelling of clay samples was designed and fabricated. This controlled uniaxial swelling device when integrated with a closed loop mechanical testing load frame allowed for the measurement of swelling pressure at a controlled and predetermined extent of swelling of the expansive clay samples. Further, this cell offered ease of removal of samples for microanalytical testing in a scanning electron microscope. Microstructural analysis was performed on the bentonite samples after the saturated samples were allowed to swell 0, 50, and 75% beyond their original volume. The void and particle gray scales were identified in the images using energy-dispersive X-ray analysis. Digital analysis of the images using custom-developed macros and Scion ImageTM software shows that the increase in swelling and reduction of swelling pressure due to swelling in the clay samples result in appreciable reduction in particle size. Thus, the swelling results in a breakdown of the clay agglomerates into smaller sized particles. These effects of swelling on microstructure of swelling clays could have a significant impact on stress deformation and the hydraulic properties of the clay.Key words: expansive clays, swelling, swelling pressure, microstructure, image analysis, scanning electron microscopy.
34
Phanikumar, B. R. "Volume change behaviour of an expansive clay blended with lime and pond ash – controlling swell". Quarterly Journal of Engineering Geology and Hydrogeology 54, nr 1 (18.06.2020): qjegh2020–046. http://dx.doi.org/10.1144/qjegh2020-046.
Pełny tekst źródłaStreszczenie:
This paper presents the influence of lime content on free swell index (FSI) of an expansive clay powder passing through a 425 µm sieve and on some significant swell-compressibility characteristics of oven-dry, expansive clay with grains of a size <4.75 mm. One-dimensional swell-consolidation tests were conducted on the expansive clay passing through a 4.75 mm sieve to which lime powder (CaOH2) was added at 0, 1, 2 and 4% by dry weight of the clay. Swell potential, swelling pressure, coefficient of compressibility (av), compression index (Cc) and linear shrinkage (LS) were evaluated. While av, Cc and LS decreased significantly with increasing lime content, swelling pressure increased. Heave and swell potential also decreased with increasing lime content but only up to 2% and were found to have increased at 4% lime content. The paper also compares the swell-compressibility behaviour of 2% lime-blended expansive clay lumps and powders. Heave and swell potential were higher for clay powder than for clay lumps at 2% lime. However, swelling pressure (ps) was found to be more for clay lumps than clay powder. Furthermore, the paper also presents the variation of FSI and swell-compressibility characteristics of another expansive clay powder (of different properties) blended with pond ash contents of 0, 5, 10, 15 and 20%. One-dimensional swell-consolidation tests were conducted on clay–pond ash blends in an oedometer. Swell potential and swelling pressure decreased up to 15% of pond ash content and increased thereafter, when pond ash content was increased to 20%. FSI of the ash-blended clay specimens was also determined. FSI continuously decreased with increase in pond ash content.
35
Becker, D. E., J. H. A. Crooks, K. Been i M. G. Jefferies. "Work as a criterion for determining in situ and yield stresses in clays". Canadian Geotechnical Journal 24, nr 4 (1.11.1987): 549–64. http://dx.doi.org/10.1139/t87-070.
Pełny tekst źródłaStreszczenie:
A method of interpreting conventional oedometer test data using work per unit volume as a criterion for determining both in situ effective and yield stresses in clay is presented. This technique was applied to the results of oedometer tests carried out on samples of natural clay deposits and on specimens consolidated anisotropically from a slurry to a known effective stress state. The work per unit volume – effective stress relationship, using arithmetic scales, can be approximated or fitted using linear relationships. The intersections of these fitted lines are demonstrated to provide accurate values for in situ current and yield (preconsolidation) stresses. The yield stress is defined as the intersection of the initial fitted line and the linear relationship observed at higher stresses. The current effective stress is indicated by the first significant divergence of the data from the initial fitted line. These relationships apply to both conventionally (horizontally) trimmed specimens and to vertically trimmed oedometer samples. It is hypothesized that the in situ effective and yield stresses (in both the vertical and horizontal directions) in a natural clay can be determined by the work per unit volume interpretation of oedometer tests carried out on horizontally and vertically trimmed specimens. Key words: in situ, stress, yield, oedometer, interpretation, clays, work, state, K0, preconsolidation pressure.
36
Abdideh, Mohammad. "STUDY OF DEPENDENCE BETWEEN CLAY MINERAL DISTRIBUTION AND SHALE VOLUME IN RESERVOIR ROCKS USING GEOSTATISTICAL AND PETROPHYSICAL METHODS". Geodesy and Cartography 41, nr 2 (25.10.2015): 92–100. http://dx.doi.org/10.3846/20296991.2015.1051333.
Pełny tekst źródłaStreszczenie:
Identify and obtain a detailed understanding of shale and its clay minerals in three segments; exploration, drilling and reservoir in the oil industry are very important. The study of the formation clay minerals in terms of depth and layers of earth is done through X-ray tests on samples taken from the reservoir which in comparison with logging requires a lot more time and cost and also can't provide continuous results because continuous sampling from the whole well is not possible. NGS (Gamma-ray Spectrometry) log is used to identify formation clay minerals that is an indicator of three radioactive elements thorium, uranium and potassium and the amount of each of these elements and according to amount of each of these elements and their ratio gives a description of clay minerals of each zone. CGR log represents the sum of two elements Thorium and potassium that are present in the shale and uranium has no effect on it. The CGR log is usually used as a shale indicator and it is an essential tool for determining the Shale volume in well logging operation. In this study the relationship between shale volume shown by the CGR log and the type of formation clay mineral was investigated. A very clear relationship between the shale volume and formation clay minerals was observed. In intervals with low shale volume the amount of active clay minerals, especially montmorillonite was higher and in intervals with high shale volume, inactive clay minerals were more. In order to investigate the spatial relation between the logging data, frequency distribution and correlation between logging data was studied. By using logging data and identifying the type of clay minerals in each zone and also the spatial correlation between logging data a suitable program for drilling and exploitation of oil fields in different areas can be proposed.
37
Arsenovic, Milica, Lato Pezo i Zagorka Radojevic. "Response surface method as a tool for heavy clay firing process optimization: Roofing tiles". Processing and Application of Ceramics 6, nr 4 (2012): 209–14. http://dx.doi.org/10.2298/pac1204209a.
Pełny tekst źródłaStreszczenie:
Heavy clay samples collected in close vicinity of Toplicka Mala Plana, Serbia, were surveyed to examine their possible use in heavy clay industry. The representative raw material, which contained the lowest content of clay minerals and the highest content of carbonates, was enriched with two more plastic clays. Chemical and mineralogical composition, as well as particle size distribution, were determined to distinct the samples. The samples in the form of tiles, hollow blocks and cubes were prepared following the usual practice in ceramic laboratories. The effect of process parameters, such as temperature (850-950 ?C) and concentration of the added clays (both in the range of 0-10 wt.%), were investigated in terms of compressive strength, water ab?sorption, firing shrinkage, weight loss during firing and volume mass of cubes. The optimal conditions were determined by the response surface method, coupled with the fuzzy synthetic evaluation algorithm, using mem?bership trapezoidal function, and showed that these materials can be used for roofing tiles production.
38
Rath, Sangram K., Manoranjan Patri, Priya Maheshwari, Kathi Sudarshan, Pradeep K. Pujari i Devang V. Khakhar. "Depth Profile of Chemical Composition and Free Volume of Polyurethane-Urea/Clay Nanocomposite". Materials Science Forum 733 (listopad 2012): 175–78. http://dx.doi.org/10.4028/www.scientific.net/msf.733.175.
Pełny tekst źródłaStreszczenie:
Depth profile of subsurface chemical composition and free volume in segmented polyurethane-urea/clay nanocomposites was studied by angle resolved X-ray photoelectron spectroscopy (ARXPS) and Doppler broadening energy spectroscopy (DBES) using slow positron beam. The ARXPS studies revealed increasing N/C atomic ratio (hard segment to soft segment ratio) at any given depth for the clay loaded samples compared to the neat polymer. DBES study revealed significant microstructure modification with clay loading. Self segregation of hard and soft segments in neat polymer and their interspersing with clay loading was observed from DBES measurements.
39
Delage, Pierre, Nabil Sultan i Yu Jun Cui. "On the thermal consolidation of Boom clay". Canadian Geotechnical Journal 37, nr 2 (1.04.2000): 343–54. http://dx.doi.org/10.1139/t99-105.
Pełny tekst źródłaStreszczenie:
When a mass of saturated clay is heated, as in the case of host soils surrounding nuclear waste disposal at great depth, the thermal expansion of the constituents generates excess pore pressures. The mass of clay is submitted to gradients of pore pressure and temperature, hydraulic and thermal flows, and changes in its mechanical properties. In this work, some of these aspects were experimentally studied in the case of Boom clay to help predict the response of the soil, in relation to investigations in the Belgian underground laboratory at Mol. Results of slow-heating tests with careful volume change measurements showed that a reasonable prediction of the thermal expansion of the clay-water system was obtained by using the thermal properties of free water. Despite the density of Boom clay, no significant effect of water adsorption was observed. The thermal consolidation of Boom clay was studied through fast-heating tests. A simple analysis shows that the hydraulic and thermal transfers are uncoupled. Experimental results from fast-heating tests showed that the consolidation coefficient does not change significantly with increased temperature, due to the opposite effect of increasing permeability and decreasing porosity. The changes of permeability with temperature were investigated by running constant head measurements at various temperatures. An indirect analysis, based on estimation of the coefficient of volume change mv, showed that the indirect method of estimating the permeability from consolidation tests should be considered carefully. Intrinsic permeability values were derived by considering the change of the viscosity of free water with temperature. A unique relationship between the intrinsic permeability and the porosity was observed, with no dependence on temperature, confirming that the flow involved in the permeability test only concerns free water.Key words: clays, thermal consolidation, adsorbed water, permeability, temperature effects, radioactive waste disposal.
40
Eigenbrod, K. D., i T. Issigonis. "Pore-water pressures in soft to firm clay during driving of piles into underlying dense sand". Canadian Geotechnical Journal 33, nr 2 (8.05.1996): 209–18. http://dx.doi.org/10.1139/t96-001.
Pełny tekst źródłaStreszczenie:
During driving of steel piles through soft, sensitive clay into very dense sand and gravel, pore-water pressure responses were monitored. As a result of the large length of the piles and also because of the high sensitivity of the soft clays, the piles were driven in two stages. During the initial stage of driving in the soft clay, only very small pore-water pressure increases were recorded together with very low pile driving resistances; however, during the second stage of driving, high pore-water pressure increases were observed in the clay as soon as the piles penetrated into the underlying very dense sand and gravel. It was concluded that the clay deposit was loaded from below, as the piles were driven into very dense sand. The total stress changes and the resulting pore-water pressure changes in the clay were analyzed, assuming that the pile driving load was equivalent to a flexible load acting on the surface of an elastic half-space, which represents the soft clay deposit. This interpretation of the pore-water pressure increases is important for the assessment of the bearing capacity of engineering structures affected by piles driven through soft soils into very dense deposits. The potential for high pore-water pressure increases in the clay during undrained loading as well as for volume increases in the dense sand due to pile driving can be predicted from piezocone test data. Key words: pile driving, pore-water pressure, piezocone testing, soft sensitive clays, dense sand deposits.
41
Catanzaro, C., S. Bhatti i B. T. Jordan. "(72) Effects of Clay-amended Substrates on Production of Nursery and Greenhouse Crops". HortScience 41, nr 4 (lipiec 2006): 1019C—1019. http://dx.doi.org/10.21273/hortsci.41.4.1019c.
Pełny tekst źródłaStreszczenie:
The U.S. Environmental Protection Agency limits the amount of nitrate and phosphate, yet these nutrients are applied in relatively large amounts during crop production. The objective of greenhouse studies conducted in 2002–05 was to determine the effects of calcined, attapulgite-type clays used as substrate amendments during production of containerized poinsettias, chrysanthemums, and ornamental grasses. Crops were grown with recommended rates of controlled-release fertilizers and irrigation volumes set to achieve a leaching fraction around 0.2. Results with poinsettias grown in substrates amended with clays were as follows: EC of leachate from poinsettia was reduced by up to 39% in the first few weeks after potting; orthophosphate concentration in leachate was reduced by up to 74% in peat-based substrate; cumulative irrigation volume required to produce plants in 16.5-cm containers was reduced by 11%. With two chrysanthemum cultivars, clays reduced EC of leachate and increased plant growth. A non-calcined clay reduced growth of poinsettia and `Oborozuki' Japanese sweetflag grass, but not `Karl Foerster' feather reed grass. Results from these studies suggest that, with controlled irrigation volumes, calcined clays added to a peat-based substrate can reduce leachate nutrient concentrations and reduce crop water requirements without negatively affecting crop growth or quality.
42
V A Alexander, Damian, Kyung Ho Park i Derek Anthony Gay. "An estimation of the soil water characteristics curves of Trinidad's expansive clays". E3S Web of Conferences 195 (2020): 03009. http://dx.doi.org/10.1051/e3sconf/202019503009.
Pełny tekst źródłaStreszczenie:
Volume change behaviour of expansive clays has been one of the leading causes of damage to civil infrastructures worldwide. Contributing factors that lead to failures relate to changes in water content within the soil. Variations of water content can vary significantly based on an area’s climate regime. Trinidad has two seasons, the dry season (January to June) and the wet season (July to December). This variation leads to volume changes of expansive clay, where they exist mainly within the central and south regions of Trinidad. These areas are densely populated by residential and commercial buildings, which can be susceptible to damages from unsaturated expansive clays. The Soil Water Characteristic Curve (SWCC) for expansive clays is critical to estimate their unsaturated properties for the analysis of water flow movement. This study investigates the SWCCs for two expansive clay soil types in Trinidad. A WP4-T (Water Potential Measurement) is used to measure soil suction. The shrinkage curve (SC) test is conducted to consider the volume change of soil. The Fredlund and Xing (1994) SWCC equation and Fredlund and Zhang (2013) SC equation are used to fit the measured data. The SWCCs in terms of gravimetric and volumetric water contents and degree of saturation are compared. It is found that the normalised degree of saturation SWCC can provide a better display of the SWCC and estimation of the air-entry value.
43
Pereira, I. D. S., V. N. F. Lisboa, I. A. Silva, J. M. R. Figueirêdo, G. A. Neves i R. R. Menezes. "Bentonite Clays Characterization in the Town of Sossego – Paraiba State". Materials Science Forum 820 (czerwiec 2015): 65–70. http://dx.doi.org/10.4028/www.scientific.net/msf.820.65.
Pełny tekst źródłaStreszczenie:
Bentonite exhibt a range of industrial applications moving millions of dollars on the market per year. Among several applications if highlights it is use for petroleum drilling fluids. Thus, this work aims to characterize physical, mineralogical and technologically, the bentonitics clays of Sossego County, Paraíba, Brazil. Mineralogical characterization of clays was done through the following techniques: particle size analysis by laser diffraction, thermogravimetric and differential thermal analysis, chemical analysis and x-ray diffraction. The clays were turned in by treatment with sodium in Na2CO3 and then determined whether the apparent viscosity, plastic and volume of filtrate of clay-water dispersions. The results showed that the samples are of polycationic, showing levels of MgO, CaO and K2O, similar to those from Boa Vista County, Paraíba, Brazil, and consist of clay mineral kaolinite, quartz and esmec. The clays showed rheological properties that indicate potential for use in drilling fluids.
44
ARHIN, Emmanuel, Mahamuda ABU i Musah Saeed ZANGO. "Environmental and Affordable Housing Material - The Use of Bricks and Tiles in Reducing Housing Deficits in Developing Countries: A Case Study at Bongo District, Ghana". Ghana Journal of Science, Technology and Development 7, nr 1 (8.08.2020): 13–25. http://dx.doi.org/10.47881/218.967x.
Pełny tekst źródłaStreszczenie:
Many factors such as inadequate mortgage finance, defective land tenure system, and high cost of land are speculated to influence the housing deficit in Ghana. Rarely do the housing deficit challenges include unavailability of construction materials as a factor. Evidence of clays used in building are common mostly in Great Britain, Italy, Japan and sparsely in developing countries and was used in building in ancient Ghana. Clay is considered as an eco- friendly building material available on earth. The abundance of intrusive rocks in Bongo District led to the exploration and evaluation of clay for bricks and tiles in Balungu and Apamtaga areas. Six pits were dug at these two areas for clay mineralogy studies. The predominant minerals found were quartz, kaolinite, smectite and those present but in trace amounts were dolomite, amphibolite, microcline, plagioclase and muscovite. The predominant minerals also vary in mineral compositions with respect to the characteristics of the underlying geology. The results showed over 50% quartz, 11.8 % kaolinite and 6 .7% smectite clay minerals occur in most samples analysed. Additional investigation to aid in the determination of the clays suitability for bricks and tiles involved 85 auger drill holes that assessed the clay thickness at Balungu River catchment. An average clay thickness of 4.5 m was calculated from the 85 drill holes drilled over 382 m of core drilled. This drill activity identified 2840000 m2 area with significant clay thickness of 4.5 m averagely. The product of the prospective clay area and the average thickness led to the estimation of clay volume of 12, 78000.00 m3. Using dimensions of standard solid bricks of 0. 222 m × 0.106 m ×0.076 m, an equivalent of 0.00172 m3 60000 bricks can be produced in a day. A total of 38 or 41 production years will be required to exhaust the discovered clay for bricks and tiles. The utilization of clay that are readily abundant in Ghana may significantly provide solutions to the Ghana’s housing deficits and make housing affordable as the product will be cheap.
45
Wang, Yongsheng, Yuheng Li i Yurui Li. "Land Engineering Consolidates Degraded Sandy Land for Agricultural Development in the Largest Sandy Land of China". Land 9, nr 6 (17.06.2020): 199. http://dx.doi.org/10.3390/land9060199.
Pełny tekst źródłaStreszczenie:
Sandification has become a major obstacle to China’s regional farmland protection, economic development, and ecological civilization construction. It is urgent to adopt advanced ideas and practical actions to reverse the sandy land. Structural consolidation theory was introduced to rehabilitate sandy land into farmland by soil body building, soil layer reconstruction, and soil quality improvement. A field experiment was conducted in Mu Us Sandy Land to explore the effects of blended guest materials (red clay and loess) with sand at four volume ratios (1:1, 1:2, 1:3 and 1:5) on crop yields, soil properties, and root growth. Red clay and loess significantly increased clay and silt contents and regulated the soil total nitrogen concentration and organic matter content during the critical growth stage of maize. Red clay and loess had a significant promotion of maize and soybean yields at a volume ratio of 1:3. The maximum potato yield was 42,501 and 37,332 kg ha−1 in red clay treatment at a volume ratio of 1:5 and in loess treatment at a volume ratio of 1:3, respectively. Lowest root biomass in surface soil and surface/subsoil root biomass ratio mediated maize growth in red clay treatment. Red clay was considered as the better material to rehabilitate sandy land and develop agriculture in the long-term according to the engineering costs and crop yields. Water sustainable utilization strategies and potential popularization areas of sandy land structural consolidation should be enhanced in the future.
46
Jiao, Wencan, Dong Zhou i Yetian Wang. "Effects of Clay Content on Pore Structure Characteristics of Marine Soft Soil". Water 13, nr 9 (22.04.2021): 1160. http://dx.doi.org/10.3390/w13091160.
Pełny tekst źródłaStreszczenie:
This study investigates the pore structure characteristics of a marine soft soil of the Beibu Gulf, Guangxi Province, China and its variation with clay content. Pore-size distribution was measured by Mercury intrusion porosimetry (MIP) and analyzed based on fractal theory. The analysis of the results relies on the distinction of several types of pores: micropores, small pores, mesopores and macropores, separated by the critical pore diameters of 0.02 μm, 0.18 μm and 0.78 μm, respectively. Mesopores and small pores were dominant, accounting for more than 75% of the total pore volume. Small pore volume increases with clay content at the expense of the mesopore volume. Between 22.31% and 32.31% clay, the connectivity of pores improves with clay content, while the tortuosity of pores increases from 22.31% to 32.31% of clay and then decreases between 32.31% and 37.31% clay. Marine soft soil in the Beibu Gulf is characterized by multiple fractal dimensions. Macropores had a large (close to 3) fractal dimension, independent of clay content. Mesopores and small pores had a smaller fractal dimension comprised between 2.1 and 2.4, while the fractal dimension of micropores did not exceed 1.5. The fractal dimension of mesopores and micropores are influenced significantly by the clay content. The study of the porosity of the marine soft soil of the Beibu Gulf could serve as a useful basis for the prediction of its hydraulic properties.
47
Wang, Gui Fang, Xian Jun Lu, Shuai Zhang, Shao Jian Ma, Jun Qiu i Jin Lin Yang. "Study on Microstructure Variation Laws of Al-Pillared Montmorillonite". Advanced Materials Research 158 (listopad 2010): 248–55. http://dx.doi.org/10.4028/www.scientific.net/amr.158.248.
Pełny tekst źródłaStreszczenie:
Al3+/clay ratio is one of the important factors influencing microstructure of Al-pillared montmorillonite. Microstructure variation laws of Al-pillared montmorillonite prepared under the condition of different Al3+/clay ratio are systematically studied by XRD, FTIR, specific surface area and pore size analysis. The results show that the interlayer spacing and BET specific surface area of Al-pillared montmorillonite are remarkably affected by the Al3+/clay ratio. The interlayer spacing d(001) value and BET specific surface area of Al-pillared montmorillonite increase firstly and then decrease with the increases of the Al3+/clay ratio, and they reach to maximum when the Al3+/clay ratio is 10mmol/g. Besides, the BJH porous volume distribution of Al-pillared montmorillonite is the most probable distribution, and the most probable pore size is about 2 nm, which is attributed to mesopore. The porous structure of hydroxy-Al pillared montmorillonite is characterized as parallel plate slit or “house-of-cards” wedge-shaped pore which is formed by novel meso-microporous delaminated structure and fragments. With the increase of the Al3+/clay ratio, BJH total porous volume and mesoporous volume of hydroxy-Al pillared montmorillonite decreases, while the proportion of microporous volume in the total porous volume increases. The proportion of microporous specific surface area of all the hydroxy-Al pillared montmorillonite samples is about 62% and is much larger than that of Na-M and those of mesopore and macropore, indicating the main action of intercalation of hydroxy-Al pillaring solution into montmorillonite interlayer is to increase the micropore amount.
48
RYASHCHENKO, T. G., N. N. UKHOVA, S. I. SHTELMAKH, N. I. BELYANINA i P. S. BELYANIN. "COMPOSITION, MICROSTRUCTURE AND PROPERTIES OF QUATERNARY CLAYS OF THE PRIKHANKAYSKAYA DEPRESSION (PRIMORYE)". Engineering Geology World 14, nr 1 (15.06.2019): 20–34. http://dx.doi.org/10.25296/1993-5056-2019-14-1-20-34.
Pełny tekst źródłaStreszczenie:
The article considers the study results of composition, microstructure and physical-chemical properties of the quaternary clays of the Prikhankayskaya depression in district of the lake Khanka (Primorye) on the example of air-dry samples of geological borehole 45-b in the range of 18–62 m. The objective of research was to obtain new information about the properties of widespread clay sediments in this area using geologic-lithological materials and laboratory data. The schematic geologic-lithological column was composed with the selection of various zones in the quaternary clay sediments section and the border with sediments of the Neogene System. The methodological scheme of laboratory studies of clays was proposed. This scheme includes the determination of chemical and microelement composition, clay minerals, contents of carbonates, water-soluble salts, mobile forms of aluminum oxide, humus, as well as microstructural parameters (method «Microstructure») and some physical-chemical properties. Geochemical coefficients (Kz, CIA, CIW, ICV) determined the degree of chemical maturity of clays and confirmed the results of palynological studies reflecting the fluctuations of the climatic conditions of their formation. For the group of toxic microelements for the first time the special indicator (Zc) was calculated. Which was the criterion for a degree of pollution of the clay sediments section. Clay minerals of the quaternary clays are represented by smectite and hydromica. The clear change in the mineral association was found when passing to the Neogene sediments (kaolinite prevails). The method «Microstructure» revealed the aggregated type of clays microstructure, the domination of the particles of coarse dust fraction among the primary (free) particles and the almost complete absence of the particles of fine-grained sand fraction, the participation of various fractions in the composition of aggregates. The variants of the formation of certain types of aggregates (on sizes) in the fluviolacustrine «khankayskiy» clays are presented. Solid part density, water resistance (soaking time), sedimentation volume, plasticity, relative swelling (samples-pastes) were determined using standard methods for clays. By special methods, the cation exchange capacity was measured and the calculated values of the plasticity index were obtained from forecasting formulas using the yield limit. The proposed methodological scheme of complex laboratory studies of clay sediments can be recommended for problematic geologic-lithological and engineering-geological sections.
49
Nascimento, R. C. A. M., A. C. A. Costa, L. A. Fernandes i Luciana Viana Amorim. "Evaluation of Filtration Properties of Clay Suspensions under Different Thermic Conditions". Materials Science Forum 881 (listopad 2016): 206–11. http://dx.doi.org/10.4028/www.scientific.net/msf.881.206.
Pełny tekst źródłaStreszczenie:
In clay suspensions designed for drilling, the sodic bentonite clay is commonly chosen for its better hydration capacity compared to the other kinds. The sodium bentonite clay is essentially composed by montmorilonite, a clay mineral that belongs to the group of smectites. This work aims to evaluate the behavior of clay suspensions under different thermic conditions. For that, were studied suspensions prepared with sodium bentonite clay, in concentrations varying between 2.5% and 6.4%, under different temperatures and also types of aging. The suspensions were tested based on a matrix of experimental planning. The filtration properties were determined by the filtrate volume, the relation of filtrate volume with time of filtration, the mudcake thickness and the permeability of the mudcake. The results exhibited that the high temperature promotes a gelification state of the suspensions, being therefore responsible for the high values of the filtration properties.
50
Dafalla, Muawia, Ahmed Al-Mahbashi i Mosleh Al-Shamrani. "Trends of Moisture and Electrical Conductivity in Clay Liners". Geofluids 2018 (1.08.2018): 1–7. http://dx.doi.org/10.1155/2018/8391830.
Pełny tekst źródłaStreszczenie:
This research is aimed at investigating the influence of ambient air temperature on the moisture content and electrical conductivity of clay sand mixtures. Volume changes as a result of shrinking or swelling are very much related to the moisture content and the electrical conductivity for liners consisting of sand and clays. The laboratory tests carried out for clay sand mixtures subjected to drying indicated a bilinear trend for 15, 20, 25, and 30% clay content. Moisture content measurements are influenced by the ambient temperature and exposure time. Watering a clay sand layer at a regular frequency in a field site revealed useful information on the trends of moisture gain and loss. Suction fluctuation associated with these changes is responsible for absorbing variable amounts of water. Moisture/Temp/EC sensors (5TE) were utilized to survey a sand clay liner section over 30 day’s period. A metrological station installed within the site was used to observe temperature, humidity, and rain fall. The drop of moisture and electrical conductivity was found to be nonlinear with temperature changes and reflecting the bimodal nature of the soil. The general trends of repeated wetting and drying were found similar in shape.