Improving Poorly Graded Fine Sand with Microbial Induced Calcite Precipitation

Because of the rapid growth of cities in the present days, it has become the establishment of infrastructure in the lands previously was considered inappropriate an order cannot be avoided. Therefore, to improve the engineering properties of these lands, various techniques have been applied, such as vibroflotation, dynamic compaction, and composite foundations. Recently, an innovative and sustainable technique called Microbial Induced Calcite Precipitation (MICP) has emerged for soil improvement. This study aims to explore the effectiveness of the MICP technique for improving the engineering properties of the poor graded fine sandy soil. The influence of factors such as grain size distribution and initial water content of untreated sand on the effectiveness of the MICP technique was investigated.

A set of laboratory tests were conducted, including optical density (OD600), calcium carbonate content, unconfined compressive strength, and soil permeability. The results indicate that MICP is effective for this type of sand. The results also demonstrate that use of MICP is more effective for sand with initial water content of 0 (i.e., dry) with respect to increasing the strength, while the MICP is slightly better for sand with initial water content of 100 (i.e., saturated) for the purpose of decreasing the permeability.