Adsorbed cation effects on the frost susceptibility of natural soils

To investigate the effects of adsorbed cations on the frost susceptibility of soil, a comprehensive suite of laboratory experiments was conducted on five natural heterogeneous soils. Cation treatments, which included Ca2+, Mg2+, Na+, and K+ treatments, were prepared by exchanging the soil's adsorbed cations in saturated salt solutions. Laboratory experiments included measuring unfrozen water contents, zeta potentials, and frost heave ratios. Results from frost heave tests indicate that exchanging the predominately adsorbed cation in a natural soil greatly affects the soil's physicochemical properties and frost susceptibility. Statistical analysis results indicate that frost heaving is most dependent on adsorbed cations, the unfrozen water content, and the amount of smectite, kaolinite, and chlorite present in the soil. The results also indicate that the frost heave response of a given soil to a salt treatment may not be predictable and systematic.