Unconfined compressive strength and freeze-thaw behavior of silty clay soils treated with bio-enzyme

The engineering properties of soils are considerably affected by freeze and thaw cycles in colder regions. Repeated cycles of freeze and thaw reduce the strength of soil by damaging soil structure. Therefore, soil subjected to frost action shows settlement and reduction in compressive strength. In this research work, the variation in the compressive strength with the freeze-thaw cycle is evaluated and improved by using terrazyme. The present research work investigated its usage for ground improvement. Samples of silty clays were extracted from two sites in Pakistan, i.e., Murree and Shangla, due to their unique climate resulting from high elevation and cold temperature. After performing a series of tests, it was observed that after seven cycles of freeze and thaw, the strength of Murree and Shangla soils reduced by 82% and 61% respectively in an untreated condition. Optimization of terrazyme showed that the maximum amount of terrazyme for Murree and Shangla should be 0.015 ml and 0.017 ml respectively. An increase of 36% in unconfined compressive strength for Murree soil and 18% in Shangla soil was observed with the addition of bio-enzyme. A considerable reduction in the moisture content was observed, along with a significant increase in the compressive strength of the soil.