MACKENZIE MALISHER. An Investigation on the Strength and Moisture Density Relationships of Soils Treated with Organo Silanes as a Function of Moisture and Salt Content. (Under the direction of Dr. John Daniels)Organo silanes (OS) are chemical agents that can be mixed with soil to induce water repellency by coating the surfaces of particles. As a means to mitigate the effect of frost heaving, the current research has been conducted to determine the effectiveness of using chemical agents to make soil water-repellent. The effect of salt, known to lower the temperature at which the surrounding water freezes has also been investigated. Both of these treatment processes are expected to change the mechanical properties of soil. Laboratory tests were carried out to determine the compaction properties, shear strength, and penetration resistance of the untreated and treated soils, with and without the addition of salt. TerraSil (from Zydex industries) was used as the OS in the treatment process at a ratio of 1:100 (OS: Water) batched gravimetrically. It was determined that a reduction in moisture content occurred in all soils treated with OS, ranging from 0.20 to 2.70%. Additionally, when comparing soils with increased salinity, the difference in optimum moisture content was less for treated and untreated soils, ranging from 0 to 0.9%. The change in shear strength for treated soils was found to be dependent on soil. For the Fairbanks, Alaska (AK-F) soil, changes in maximum shear strength were minimal at optimum moisture content. For the Hanover, New Hampshire (NH-H) soil, the peak shear stress for the sample treated with TerraSil dropped to approximately 6 kPa. For the pocket penetrometer tests, the maximum drop in penetration resistance when considering treated and untreated soils at a particular moisture content was 1.83 kg/cm2 .