FREEZE-THAW PERFORMANCE OF LOW-CEMENT CONTENT STABILIZED SOILS FOR CONTAINMENT APPLICATIONS

Abstract

A laboratory-scale experimental study was performed to extend the available knowledge on the hydraulic and mechanical performance of cement-stabilized soils in cold regions. Experiments were performed on soil-cement (3 percent or 6 percent cement content by dry weight of soil) of different mix proportions before and after exposure to freeze/thaw cycles. For control specimens (i.e. no freeze-thaw), experiments showed more improvement in hydraulic conductivity when compacted at optimum and wet of optimum water content standard proctor conditions. Experiments showed increases in hydraulic conductivity after freeze/thaw cycling. Freeze/thaw damage related to hydraulic performance was observed to be more at optimum moisture content (i.e. maximum density) compared to dry and wet of optimum compaction water content conditions. Unconfined compressive strength also showed a decrease after exposure to three freeze/thaw cycles. To further study the mechanisms of freeze/thaw damage, thin sections were obtained from control and exposed soil-cement specimens. Thin sections were examined using an optical microscope to study the structural changes of soil cement specimens due to exposure to freeze/thaw cycles. Mercury Intrusion Porosimetry (MIP) test was also used to examine the changes in porous structure of the soil-cement due to changes in moisture and cement contents, as well as due to exposure to three freeze/thaw cycles. Thin section results showed a lack of ice lenses in the samples after freeze thaw and the formation of both cracks and matrix disruption after freeze thaw. MIP results comparing both before and after freeze thaw failed to show major changes in pore size distribution of the soil-cement samples which tends to agree with the hypothesis that most of the damage observed from hydraulic conductivity testing is likely due to cracking and macroscale pore changes.