Research on the feasibility of strengthening the soil structure by biomineralization

Abstract

ABSTRACT The objective of the present study is to explore the feasibility of strengthening soil structures using the microbe induced calcium carbonate precipitation (MICP) method. In the tests that have been conducted, the work has simulated soil structures using standard sand, producing test specimens with relative densities of Dr = 40%, 60% and 80%. The MICP test results indicate that Sporosarcina pasteurii induced the precipitation of calcium carbonate through a metabolic pathway, which enables the growth of calcium carbonate crystals between the sand particles to perform infilling and cementation. After conducting the MICP treatment, the originally non-cohesive standard-sand specimens could be consolidated into blocks, and the test specimens subjected to MICP treatment over longer durations exhibited better overall cementation. The unconfined compressive strengths of the specimens increased from 0 kPa (the compressive strength of a loose sand specimen) to become approximately 3 ~ 12 kPa. This result indicates that the MICP method can result in cohesion using a standard-sand test specimen and will strengthen the sand’s structure. The resonant column test results show that the shear-wave speed depicts a significant increase, which further demonstrates that the specimen structure is considerably strengthened using the MICP treatment.