Geotechnical Tests of Sands Following Bioinduced Calcite Precipitation Catalyzed by Indigenous Bacteria

Recent experiments have shown that exogenous bacteria can be introduced into soil for the purpose of inducing calcite precipitation. A series of tests are documented in this paper that demonstrate that natural indigenous bacteria can also be stimulated to induce calcite precipitation with measurable changes in geotechnical properties. Tests reported in this paper include a microcosm experiment with cone-penetration testing and cyclic triaxial shear tests. These experiments demonstrate that indigenous bacteria can induce significant quantities of calcite precipitation, that calcite precipitation can result in measurable changes to geotechnical soil properties, and that the cyclic resistance ratio can be increased substantially with moderate levels of calcite precipitation. Using indigenous bacteria to modify soil properties is a significant step in making biomodification of soils economically viable.