Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Solute Diffusion in Bentonite Pastes
AbstractSodium bentonite (Na-bentonite) is a high-swelling clay with low hydraulic conductivity (k) that is commonly used for hydraulic and chemical containment applications (e.g., engineered barriers, seals, and grouts) to limit advective (hydraulic) flow and chemical transport. In Na-bentonite pastes and other paste-like substances (e.g., high slump backfills, filter cakes, well seals, and slurried mine tailings) that exhibit low values of k (<10−9 m/s), diffusion can be a significant chemical transport process such that measurement of diffusion properties of these materials may be necessary. Based on these considerations, diffusion of NaCl from Na-bentonite pastes with porosities ranging from 0.96 to 0.98 was evaluated by adapting standardized test methods for diffusive leaching of contaminants from stabilized/solidified waste to a dialysis procedure commonly used for clay purification. The apparent diffusion coefficients (Da) measured with the proposed dialysis-leaching test method ranged from 2.26×10−10 to 1.37×10−9 m2/s for initial NaCl concentrations ranging from 1.0 to 0.1 M, respectively. Values of Da decreased as the exchangeable sodium percentage of the bentonite increased and as the average concentration of NaCl remaining in the bentonite decreased. The diffusion results were in agreement with expectations based on the literature and diffuse double layer theory. The dialysis-leaching test method may offer a simple, fast (≤2 weeks), and inexpensive (<$300 per setup) approach to measure diffusion in bentonite pastes and other paste-like substances.
Solute Diffusion in Bentonite Pastes
AbstractSodium bentonite (Na-bentonite) is a high-swelling clay with low hydraulic conductivity (k) that is commonly used for hydraulic and chemical containment applications (e.g., engineered barriers, seals, and grouts) to limit advective (hydraulic) flow and chemical transport. In Na-bentonite pastes and other paste-like substances (e.g., high slump backfills, filter cakes, well seals, and slurried mine tailings) that exhibit low values of k (<10−9 m/s), diffusion can be a significant chemical transport process such that measurement of diffusion properties of these materials may be necessary. Based on these considerations, diffusion of NaCl from Na-bentonite pastes with porosities ranging from 0.96 to 0.98 was evaluated by adapting standardized test methods for diffusive leaching of contaminants from stabilized/solidified waste to a dialysis procedure commonly used for clay purification. The apparent diffusion coefficients (Da) measured with the proposed dialysis-leaching test method ranged from 2.26×10−10 to 1.37×10−9 m2/s for initial NaCl concentrations ranging from 1.0 to 0.1 M, respectively. Values of Da decreased as the exchangeable sodium percentage of the bentonite increased and as the average concentration of NaCl remaining in the bentonite decreased. The diffusion results were in agreement with expectations based on the literature and diffuse double layer theory. The dialysis-leaching test method may offer a simple, fast (≤2 weeks), and inexpensive (<$300 per setup) approach to measure diffusion in bentonite pastes and other paste-like substances.
Solute Diffusion in Bentonite Pastes
Shackelford, Charles D (Autor:in) / Sample-Lord, Kristin M
2016
Aufsatz (Zeitschrift)
Englisch
BKL:
56.20
Ingenieurgeologie, Bodenmechanik
Solute diffusion in bentonite pastes
| Online Contents | 2016
Solute Diffusion in Bentonite Pastes
| British Library Online Contents | 2016
Solute Diffusion in Bentonite Pastes
| Online Contents | 2016
Solute Diffusion in Bentonite Pastes
| ASCE | 2016