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CYCLIC FREEZING AND THAWING EFFECTS ON ATTERBERG LIMITS OF CLAY SOILS Session: Laboratory Testing in Cold Regions / Essais en laboratoire en ingénierie nordique Daryl Dagesse, Brock University (Canada) Several previous studies suggest Atterberg limits may change as a result of mechanical disruption. This study tests the hypothesis that liquid and plastic limits may be altered by the cyclic freezing and thawing process. Four soils with different clay contents were used. In one group of samples initial structure was maintained while a second group were ultrasonically dispersed at a high water content. Cyclic freezing at -15°C for 6 hr and thawing at +15°C for 6 hr was performed for 1, 5, 10, and 25 cycles at 25% gravimetric water content. Both liquid limits and plastic limits showed increases with an increasing number of freeze/thaw cycles for the structured soils but decreases in both limits for the unstructured soils. However, regression analysis revealed that the slopes of these relationships did not significantly differ from zero suggesting no effect of cyclic freezing and thawing on soil plasticity.
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