Thermal analysis of selected illite and smectite clay minerals. Part II. Smectite clay minerals

Earnest, Charles M.

doi:10.1007/bfb0010272

Cited by 15 publications

(10 citation statements)

References 6 publications

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“…The thermogravimetric analysis indicates ~12% weight loss at ~240°C, demonstrating that the initial water content specified by the provider was accurate (Figure b). The TG curve and its time‐derivative (DTG) were also in agreement with the literature [ Earnest , ]. DTG indicates that the dehydration rate is maximal at ~132°C (i.e., 1.16% weight loss per minute).…”

Section: Resultssupporting

confidence: 87%

Laboratory measurements of the longitudinal and transverse wave velocities of compacted bentonite as a function of water content, temperature, and confining pressure

Tisato

Marelli

2013

JGR Solid Earth

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[1] Bentonite is a material commonly included in the design of the sealing liners of radioactive waste repositories. Understanding the evolution of its elastic properties during the repository lifetime could provide a powerful aid to the development of nonintrusive monitoring techniques based on tomographic methods. In this contribution, we present the results of a series of laboratory experiments aimed at measuring the elastic properties of a compacted bentonite at different water contents, temperatures, and hydrostatic confining pressures similar to those expected in a realistic radioactive waste repository. We prepared four sets of samples at different water contents (10, 20, 35, and 52%); we measured that V P and V s (and the derived bulk and shear moduli) (i) increase significantly (up to 60%) with increasing water content, (ii) decrease up to 15% with increasing temperature in the range of 30 to 80°C, and (iii) increase significantly with confining pressure following different paths highly dependent on the water content (with drier samples showing stronger dependence on confining pressure). Further, we provide empirical relations between ultrasonic velocities and temperature, and ultrasonic velocities and pressure. We also measured the effects of dehydration at temperatures up to 160°C, which led to the structural failure of samples. Finally, we modeled our results according to two widespread effective elastic media models, Hashin-Shtrikman bounds and modified Voigt average, achieving only partial success in describing our results. In the light of these results, the increase of seismic wave speeds as function of increasing confining pressure is interpreted as an effect of the pore collapse.Citation: Tisato, N., and S. Marelli (2013), Laboratory measurements of the longitudinal and transverse wave velocities of compacted bentonite as a function of water content, temperature, and confining pressure,

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Section: Resultssupporting

confidence: 87%

Laboratory measurements of the longitudinal and transverse wave velocities of compacted bentonite as a function of water content, temperature, and confining pressure

Tisato

Marelli

2013

JGR Solid Earth

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“…Determining water content by oven drying remains a somewhat arbitrary measure, as Gardner (1986) pointed out. Thermogravimetric analysis of clays demonstrated that 105°C is not a significant point (Earnest, 1991a,b). The choice of 105°C is a compromise between identifying water loss and preventing excessive weight loss due to oxidation and decomposition of organic materials.…”

Section: Physical Properties Used To Determine Water Contentmentioning

confidence: 99%

Soil Moisture Measurement for Ecological and Hydrological Watershed‐Scale Observatories: A Review

Robinson

Campbell

Hopmans

et al. 2008

Vadose Zone Journal

893

620

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Over the oceans, approximately 90% of net radiation produces evaporation (Budyko, 1974), primarily in the tropics. Over continents, net radiation heats the surface, evaporates water from water bodies or moist soils, or provides plants with energy to remove water from soils (Pitman, 2003; Istanbulluoglu and Bras, ANALYSISAt the watershed scale, soil moisture is the major control for rainfall-runoff response, especially where saturation excess runoff processes dominate. From the ecological point of view, the pools of soil moisture are fundamental ecosystem resources providing the transpirable water for plants. In drylands particularly, soil moisture is one of the major controls on the structure, function, and diversity in ecosystems. In terms of the global hydrological cycle, the overall quantity of soil moisture is small, ∼0.05%; however, its importance to the global energy balance and the distribution of precipitation far outweighs its physical amount. In soils it governs microbial activity that aff ects important biogeochemical processes such as nitrifi cation and CO 2 production via respiration. During the past 20 years, technology has advanced considerably, with the development of diff erent electrical sensors for determining soil moisture at a point. However, modeling of watersheds requires areal averages. As a result, point measurements and modeling grid cell data requirements are generally incommensurate. We review advances in sensor technology, particularly emerging geophysical methods and distributed sensors, aimed at bridging this gap. We consider some of the data analysis methods for upscaling from a point to give an areal average. Finally, we conclude by off ering a vision for future research, listing many of the current scientifi c and technical challenges.

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“…Pristine layered silicates has been known for more than 60 years 6–11. They possess the same structural characteristics as the well‐known minerals talc and mica (2:1 phyllosilicate), and are comprised of hydrated aluminum silicate.…”

Section: Introductionmentioning

confidence: 99%

The characterization of organic modified clay and clay‐filled PMMA nanocomposite

Hwu

Jiang

Gao

et al. 2001

J of Applied Polymer Sci

125

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ABSTRACT:Recently, polymer-clay hybrid materials have received considerable attention from both a fundamental research and application point of view.1-3 This organicinorganic hybrid, which contains a nanoscale dispersion of the layered silicates, is a material with greatly improved physical and mechanical characteristics. These nanocomposites are synthesized through in situ polymerization or direct intercalation of the organically modified layered silicate (OLS) into the polymer matrix. Thus, understanding the relationship between the molecular structure and the thermal stability (decomposition temperature, rate, and the degradation products) of the OLS is critical. In this study, modern thermal analysis techniques combined with infrared spectroscopy and mass spectrometry (TGA-FTIR-MS) were used to obtain information on the thermal stability and degradation products of organic modified clay. Furthermore, the thermal and mechanical properties of clay-filled PMMA nanocomposites were determined by using TGA and DSC.

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Thermal analysis of selected illite and smectite clay minerals. Part II. Smectite clay minerals

Cited by 15 publications

References 6 publications

Laboratory measurements of the longitudinal and transverse wave velocities of compacted bentonite as a function of water content, temperature, and confining pressure

Laboratory measurements of the longitudinal and transverse wave velocities of compacted bentonite as a function of water content, temperature, and confining pressure

Soil Moisture Measurement for Ecological and Hydrological Watershed‐Scale Observatories: A Review

The characterization of organic modified clay and clay‐filled PMMA nanocomposite

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