On the functional dependence of the freezing point of soils on the composition of water soluble salts in an interstitial solution

• Main Authors: Velli, Y. Y., Grishin, P. A.
• Format: Report
• Language: English
• Published: National Research Council of Canada 1983
• Subjects: permafrost; soils; freezing point; frozen soils; moisture content; salinity; ground water; pergélisol; sol; point de congélation; sol gelé; degré hygrométrique; salinité; eaux souterraines; Arctic
• Online Access: https://dx.doi.org/10.4224/20358589; https://nrc-publications.canada.ca/eng/view/object/?id=f8ba5d45-8997-480d-b3a3-3b10b7311001

The freezing point of soils is the boundary of change of physical state from a thawed to frozen condition. A paramount factor which affects the transition zone is the quantity and composition of the dissolved salt in the pore water. The marine soils used in the experiments were from the arctic coast with a range in the granulometric composition. The clay fraction consisted of 40% kaolinite, 30% montmorillonite, 25% chlorite and 5% quartz. Salts used were from soil extractions or from sea water. NaCl and CaCl[ 2] solutions were also used for artificial salination of the soil samples. The salt content used ranged from 0.2 to 1% by weight or in terms of the pore water was from 0.006 to 0. 055. Three stages were observed; a supercooling stage, a phase of comparatively constant temperature, and a gradual fall of temperature. The supercooling temperature was from 1.5 to 2 times the freezing point. Conclusions are as follows: (a) the grain size characteristics of the soil do not influence the freezing point when the moisture content is in excess of the liquid limit; and (b) when there are equal concentrations of the interstitual solution only the qualitative composition of the salts influences the freezing point. Within the range investigated the freezing point of the soil is inversely proportional to the molecular weight of the soluble salts.