Effect of chemical action on the volume change characteristics of Lake Agassiz clay

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Smith, John Philip.
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The effects of various inorganic chemicals on the volume change characteristics of the expansive clay soil of the Winnipeg area have been investigated. Chloride, sulphate and hydroxide salts were used as immersing solutions for standard one-dimensional consolidation tests. These results were compared to those using distilled water as a swelling solution. Differential Thermal Analyses revealed that, for each salt, exchange took place between the exchangeable cations held in the interlayer water of the clay minerals and the cations in the solution. It was found that the amount of swelling of the soil was partially dependent on the valence of the exchangeable cation; a monovalent ion like sodium absorbed more water and thus produced greater swelling than the trivalent ion aluminum. The chloride salts tended to reduce the swelling of the soil while the sulphates and hydroxides generally increased the amount of swelling. Calcium hydroxide, which had a considerable stabilizing effect, was an exception to the rule. The effect of the ions upon the compressibility of the soil was small in comparison to the effect on the swelling characteristics.