Affectivity of biological cement's application to sandy soil for geotechnical engineering

In this research, the authors analyze the addition of bacterial producer of biological cement on sandy soil to increase its stability. Pseudomonas sp was injected into the soil to produce urease enzyme, which converts urea that reacted with water become ammonium and carbonate, causing calcite precipitation. Soil stability can be improved by the production of pore-filling materials and particle-binding materials through the calcite precipitation process. The aim of these applications is to improve the mechanical properties of soil that it will be more suitable for construction or environmental purposes. After bacterial inoculation, the experiment with variation of bacterial content concluded the best way to increase soil stability is inject 15% bacteria relative to total weight of soil. Highest permeability reduction is 73,73% and highest shear strength increation for cohesion is 6,84 with friction angle 44,46°. California Bearing Ratio test with 10 of hits generated that the treatment soil can proved a significant penetration stress changed. From Environmental Scanning Electron Microscopy test results of the inoculation sand test images and surface scan, the formed exopolysaccharide attached to the wall of the sand soil particles which expected will fill, patch, and close the pores between the sandy soil particles.