Hydraulic Conductivity of Cement-Treated Soils and Aggregates after Freezing

Improvements in the strength and durability of frost-susceptible soils and aggregates can be achieved through chemical stabilization using portland cement, where the efficacy of cement stabilization for improving durability generally depends on the degree to which hydraulic conductivity is reduced. Hydraulic conductivity is commonly estimated from basic soil properties using Moulton's empirical equation; however, the estimation does not consider the detrimental effects of freezing or the benefits of cement stabilization. The purpose of this research was to derive new equations relating hydraulic conductivity after freezing to specific material properties of cement-treated soils and aggregates stabilized with different cement concentrations. This research included material samples from two locations in Alaska and from single locations in Minnesota, Montana, Texas, and Utah, for a total of six material samples. The procedures used in this research included material characterization, determination of moisture-density relationships, selection of cement concentrations, hydraulic conductivity testing, and statistical analysis. Stepwise regression analyses of the data set produced four models to estimate hydraulic conductivity of cement-treated soils after freezing. While both the four- and six-parameter models can potentially be used for any soil or aggregate, the Unified Soil Classification System (USCS) and American Association of State Highway and Transportation Officials (AASHTO) classification models are valid only for the soil classifications included in this research. When applicable, use of the USCS model is recommended because it has the highest coefficient of determination. Further research is recommended to investigate the effects of cement on hydraulic conductivity for other USCS and AASHTO soil types.