Effectiveness of microbial induced carbonate precipitation treatment strategies for sand

Microbial induced carbonate precipitation (MICP) is a sustainable and environmentally protectable technique in geotechnical engineering. Treatment uniformity and convenience of application are crucial considerations in laboratory and field tests. This study focuses on the exploration of three treatment strategies using the surface percolation method. A rapid MICP process may lead to uneven distribution issues. By lowering the pH of the bacterial solution to delay the reaction time, the accumulation of calcium carbonate at the injection point can be minimized, thereby enhancing the treatment effectiveness. The results suggest that single-phase treatment under undrained conditions at the bottom of specimen, utilizing a lower pH bacterial solution, effectively improves the uniformity of the treatment. It was observed that flocculated calcium carbonate deposited and solidified over the curing time. The morphology of calcium carbonate under scanning electron microscopic (SEM) that forms as a bonding agent between sand particles displays the cubic crystalline structure characteristic of calcite, as reflected in the shear strength observed during triaxial consolidated drained (CD) tests. • Three treatment strategies were evaluated • A method was proposed to lower the bacterial solution pH • Single-phase treatment with non-drainage at the bottom is the optimum treatment • SEM images and triaxial results show the effectiveness of calcite precipitation