Healing of biologically induced cemented sands

Microbial-induced calcite precipitation (MICP) is a novel bio-mediated ground improvement method that can be used to increase the shear strength and stiffness of sand. One of the benefits of the MICP treatment process is the ability to heal degraded calcite bonds post-shearing. The healed bonds can then improve the sand properties (small strain stiffness and peak strength) compared with those of the pre-shearing condition. The MICP healing process was evaluated using monotonic undrained shearing and dynamic centrifuge tests, and comparing the sand behaviour before and after the healing process. Similar or improved behaviour was observed after the healing process. This healing ability implies that degraded MICP-treated sands can be healed after loading (e.g. in an earthquake) to their original level of treatment to prevent additional settlements or damage from subsequent loading (e.g. aftershocks).