REDUCTION OF FROST HEAVING BY TETRAALKYLAMMONIUM IONS

Abstract

The extent to which tetramethylammonium and tetrabutylammonium ions are capable of reducing frost heaving in a loam soil has been investigated in the laboratory. Frost heaving was reduced exponentially with respect to concentration of ions on the soil colloid. The adsorption of about 100 μg N/g soil was capable of reducing the extent of frost heave after 12 h by 50%. The effects of tetraalkylammonium ions on the water release curve, the saturated hydraulic conductivity, the low temperature differential thermogram, and the freezing point (the temperature at which freezing commenced in a sample) were evaluated to determine the mechanism whereby these ions reduced frost heave. Both the water release curves and the low temperature differential thermograms indicated that these ions did not influence the capillary or "adsorbed" water content. The freezing point remained the same for all treatments. However, saturated hydraulic conductivity decreased linearly with increasing concentration of adsorbed cations, suggesting that this was the mechanism principally responsible for the reduction in frost heaving.