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|Title:||Effect of dissolved NaCl on freezing curves of kaolinite, montmorillonite, and sand pastes|
|Authors:||United States. Department of Energy.|
Strategic Environmental Research and Development Program (U.S.)
Grant, Steven A.
Boitnott, Ginger E.
Tice, Andrew R.
Soil freezing curve
|Publisher:||Cold Regions Research and Engineering Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
|Series/Report no.:||Special report (Cold Regions Research and Engineering Laboratory (U.S.)) ; 99-2.|
Abstract: We developed a chemical-thermodynamic procedure for calculating the capillary pressures of aqueous NaCl solutions in a porous medium at temperatures below 0°C by extending the treatment by Brun et al. (1977). Ice in the porous medium was assumed to be a pure phase with thermophysical properties identical to bulk hexagonal ice. The thermophysical properties (and the attendant derivative and integral properties) of the electrolyte solutions were calculated with the Pitzer model as parameterized by Archer (1992). Experiments were conducted to test this procedure. Pastes of kaolinite clay, montmorillonite, and quartz sand were prepared by washing repeatedly with aqueous solutions of 0.1-, 0.01-, and 0.001-mol kg^–1 NaCl. The molar unfrozen water contents of these pastes were measured by pulsed nuclear magnetic resonance (NMR) in the temperature range –0.14°C to -66.6°C. The relationships between ice-solution capillary pressures and specific solution volumes for frozen pastes of each mineral were plotted for all initial solution molalities. While some systemic errors were evident, these plots indicated that the capillary pressure-volume relationships were consistent for pastes of the three minerals and, as expected from theory, unaffected by initial equilibrating solution molality.
|Rights:||Approved for public release; distribution is unlimited.|
|Appears in Collections:||Special Report|