Effect of freezing and thawing processes on soil aggregate stability

The effect of freezing and thawing on wet aggregate stability of soils formed on different parent materials was determined for different aggregate size groups (0.0–1.0; 1.0–2.0; and 2.0–4.0 mm), different water contents and for various freezing and thawing cycles (three, six and nine times) and freezing temperatures (−4 and −18 °C). The initial wet aggregate stability decreased with freeze–thaw treatments by 28.6–51.7% depending on soil type, and was more pronounced with increased moisture contents at freezing. The percent decrease in wet aggregate stability for different aggregate size groups ranged from 13.8% to 57.7%. Wet aggregate stability generally increased when the number of freezing and thawing cycles increased from 3 to 6, but decreased after that point. The percentage of water-stable aggregates in all soils at −18 °C was less than that at −4 °C.