||Effects of Drying Treatments on Porosity of Soil Materials.
Thompson, M. L. ;
McBridge, J. F. ;
Horton, R. ;
||Iowa Agricultural and Home Economics Experiment Station, Ames.;Environmental Protection Agency, Cincinnati, OH. Hazardous Waste Engineering Research Lab.
Freeze drying ;
Size determination ;
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The effects of three drying techniques on total porosity and pore size distribution of three soil materials were studied by Hg intrusion porosimetry. Some samples were dried in an oven at 40 C for 7 d; some samples were quick frozen in liquid N and lyophilized; some samples were dried by acetone vapor exchange and immersion, followed by evaporation of the acetone. Both undisturbed soils and soil samples compacted according to ASTM D-698 were investigated. The three drying techniques caused a reduction in sample total porosity ranging from 3 to 52%. Freeze drying usually caused the least change in total porosity, and resulted in the greatest volume of porosity in the 0.2 to 2 micrometers equivalent pore radius (epr) range. Acetone-dried samples had the greatest volume of porosity in the 0.02 to 0.2 and 0.2 to 2 micrometers epr ranges. Pore size distributions of oven-dried soil samples varied from soil to soil. The consistency of pore size distributions in freeze-dried materials strongly suggests that pores were deformed by ice crystals either during or after freezing of the soil samples. In the epr range of 0.002 to 0.02 micrometers, acetone-dried samples had porosities similar to oven-dried samples. (Copyright (c) 1985 Soil Science Society of America Journal.)