Plasticity properties and undrained strength of bio-enzyme treated black-cotton soils

For Black cotton (B.C.) soils many alternate stabilization techniques are being suggested by researchers from time to time, which partially address the problem of volumetric instability with moisture changes. Of late, with the success of the enzymatic stabilization of kaolinitic soils, researchers have tried to extend the application of enzymatic stabilization to B.C. soils. The reported information in the literature on index properties of enzyme treated B.C. soils is very intriguing. In this study, two different formulations of a commercially available TerraZyme (TZ 5X and TZ 11X) with four selected dosages were used to understand the changes in index as well as undrained strength properties with ageing of two B.C. soils selected from different geological locations. Contrasting changes in plasticity properties on enzymatic treatment using TZ 5X with ageing are observed for the two B.C. soils used in the present study. However, TZ 11X has shown to have a slight reduction in liquid limit and an increase in shrinkage limit. As index properties are inferential properties of soils, changes in plasticity properties by using enzymes may not be the only indication of the effectiveness of enzymatic stabilization. Enzyme treated soils yielded a marked improvement in undrained strength indicating a better parameter to assess the effectiveness of enzymatic stabilization of B.C Soils.