Effect of cement anisotropy caused by MICP on the mechanical behaviours of bio-improved granular soils

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4. Effect of cement anisotropy caused by MICP on the mechanical behaviours of bio-improved granular soils

In recent years, microbial-induced calcium carbonate precipitation (MICP) has emerged as a promising ground improvement method for cementing sand particles together. This study focuses on investigating the anisotropy of bio-cement cohesion behavior at the macroscopic level and evaluates the treating effect on granular soils, specifically calcareous sand and quartz sand. The MICP procedure was performed on specimens of calcareous sand and quartz sand with varying delamination-load angles, treatment rounds, and particle sizes. Subsequently, splitting tensile strength and stiffness of the treated specimens were evaluated through a series of splitting tensile strength tests. Additionally, microstructure and component characterization of the bio-cemented sand were investigated using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The findings indicate that the mechanical behavior of bio-cemented sand is influenced by the gravity-induced bio-cement layer which formed during MICP treatment. Calcareous sand tends to produce more uniform and denser bio-cement compared to quartz sand. Moreover, the irregular particle shape of calcareous sand results in interlocking between particles, leading to higher splitting tensile strength compared to quartz sand specimens that underwent the same MICP treatments.

9th International Congress on Environmental Geotechnics (ICEG2023)

Biogeotechnics and Bioremediation