On the Application of Microbially Induced Calcite Precipitation for Soils: A Multiscale Study

Two laboratory experiments are used to provide preliminary evidence towards upscaling the microbially induced calcite precipitation (MICP) for soils. Fine sand is packed and subsequently subjected to MICP treatment in 11-liter cylindrical tanks. Different conditions are tested regarding the bacteria injection source as well as their propagation in the porous medium. The goal is to associate the adopted application strategy with the final shape, size and total mass of precipitated calcite in the yielded bio-cemented soil volume. Observations carried out at the micro-scale reveal the presence of calcified biofilms as a distinct “habit” of CaCO3 precipitate. Finally, a series of drained triaxial shear tests is carried out on fine and medium MICP-treated sands. Results reveal a more pronounced enhancement in terms of strength for the medium sand, despite the same CaCO3 content.