Thaw Settlement and Mechanical Properties of Admixture-Stabilized Frozen Soil

Roads and other infrastructure in Western Alaska are difficult to design and build owing to the high cost of construction materials and the ice-rich permafrost foundation. The present study explores methods to treat locally available frozen materials for satisfactory engineering applications. Stabilizing agents including cement, perlite, nanosilica, and polypropylene fiber (PP-fiber) were used at various mix ratios to treat pulverized frozen silty sand. Subsequently, a suite of laboratory tests was performed on thawed and/or cured specimens to assess the thaw strain, shear-strength parameters, elastic wave velocities, and thermal conductivity of the treated soil. Scanning electron microscopy images were obtained to reveal the microstructure of the stabilized frozen soil. It was found that the addition of cement, perlite, nanosilica, and PP-fiber greatly reduces the thaw strain and improves the shear strength of the stabilized soil. A combination of cement and perlite at 3% each can be very effective and economical in reducing the thaw strain, enhancing the shear strength, and decreasing the thermal conductivity, and is recommended for field trial.