Effect of Bio-enzyme on Strength and Microstructure of Banda Clay Soil, India

The present study presents the stabilisation of clay soil (expansive soil) collected from Banda, India with bio-enzyme. The bio-enzyme has been mixed with Banda clay in different dosages to obtain the optimum soil enzyme mix (OSEM). The laboratory experiments have been performed on Banda clay and OSEM specimens to determine material strength, consolidation characteristics, and shear strength parameters. The cyclic triaxial tests (strain-controlled) have been conducted on Banda clay and OSEM specimens to study the dynamic characteristics considering different cyclic strain rates and confining pressures at a frequency of 1 Hz. The microstructural analysis including X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS) have been conducted on Banda clay and OSEM specimens to study microstructure and stabilisation mechanism. The OSEM is found to be Soil + 100 ml/m(3) bio-enzyme. The bio-enzyme significantly improves the compressive strength and shear strength of Banda clay. In addition, it effectively reduces the expansiveness of the clay soil. The cyclic triaxial results show increase of 19-45% in shear modulus and decrease of 15-33% in damping ratio of OSEM, representing substantial improvement in its dynamic properties. The XRD spectrum of OSEM specimen indicates development of cementitious product, such as calcium silicate hydrate. The SEM images of OSEM specimen show modification in soil texture due to cementation and aggregation of particles. This study describes the applicability of Banda clay stabilised with bio-enzyme as subgrade material in pavement.