Influence of ice segregation and solutes on soil structural stability

Abstract

The structural consequences of freezing in the presence of solutes was investigated. Nine 27-cm-diameter by 19-cm-high columns were packed with air-dry Conestogo silt loam soil (Gleyed Melanic Brunisol or Aquic Eutrochrept) and wetted with CaCl2 solutions. Slow freezing took place from the top down in an environmental chamber maintained at -3.4 ± 0.4°C. Depth of frost penetration, temperature, frost heave, and unfrozen water content were monitored within each column. After 20 d, the mean frost penetration was 107 ± 18 mm and the soil surface had heaved 9 ± 4 mm, indicating ice segregation. At the end of the experiment, samples which had been frozen had significantly more water and CaCl2 in the thawed state than those which had remained unfrozen. Soil that had been frozen and thawed had a more stable structure than the unfrozen soil. Wet-aggregate stability increased with decreasing water content for those aggregates which had been frozen and thawed, but not for those which had remained unfrozen. -from Authors