Improvement of Soil Physico-Mechanical Properties with Biological Techniques Utilizing Ureolytic Bacteria

The biological soil stabilization process can be done by utilizing the concept of biogrouting. The concept of biogrouting by urea-producing microbes (ureolytic bacteria) can help control permeability and strengthen soil. This research aimed to study the effect of different concentrations and incubation periods of ureolytic bacteria related to the effectiveness of ureolytic bacteria for foundation-soil structure reinforcement. Fine-grained soil and lumajang sand as soil samples were dried before being incubated together with the bacteria and the mixed media. After 14th days of incubation, soil samples were direct-shear tested. The moisture content and the density were determined afterward. The result of this study is cohesion values increased in soil with bacterial densities of 105
cells/mL and 106 cells/mL, and in the sand with bacterial densities of 106 cells/mL and 107 cells/mL. There was a decrease in the cohesion value in the soil with a bacterial density of 107 cells/mL and sand with a bacterial density of 105 cells/mL. An increase in cohesion indicates an increase in soil binding capacity. So it can be concluded that the best density to increase soil strength is the addition of bacteria with a density of 105 cells/mL and 106 cells/mL.