Comparative Study of Strength Characteristics (CBR) of Bio-enzymatically Treated Expansive Soil for Subgrade Stabilization

The subgrade stabilization using bio-enzymes becomes a revolutionary and most useful technique among all the available methods of soil stabilization. The previous research work shows that the use of bio-enzymes in field is soil specific and depends upon various factors such as clay content, type and dosages of bio-enzymes and curing period. Thus, present work aims to study the effect on both soaked and unsoaked CBR of expansive soil treated with varying dosages of different bio-enzymes (TerraZyme and DZ-2X) for curing period of 1, 7, 14, 21 and 28 days. The result shows that significant improvement in CBR values for all dosages of bio-enzymatic treatment. The maximum strength gain was achieved after 21 days of curing, and further increase in curing period shows marginal improvement. The precipitation formed on the surface of sealed soil samples results in improvement in CBR values. The comparative study helps in finding the maximum percentage increase in CBR values (soaked and unsoaked) for individual bio-enzymes and its optimum for the treatment of expansive soil. The treated soil can be effectively used as subgrade material for the construction of road pavement.