Effects of Microbial Induced Calcite Precipitation on Bentonite Cracking Remediation

摘要

This paper describes a preliminary study of the effects of microbial induced calcite precipitation (MICP) on the desiccation cracking behaviors of bentonite. The drying shrinkage of bentonite mixed with bacteria and cementation medium is monitored in the petri dish under controlled temperature and relative humidity conditions. Three control groups are also monitored, in which bentonites are mixed with live bacteria + cementation medium without CaCl_2, dead bacteria + cementation medium, and dead bacteria + cementation medium without CaCl_2, in order to study the influence of MICP process and microbial activity on soil desiccation cracking. Scanning electron microscope images show bacteria survive on the surface of bentonite after dried. The MICP occurred at the early stage after mixing bentonite with cementation medium changes soil's property and leads to more intact cracking polygons while drying. Bentonite mixed with live bacteria tends to form larger cracking polygons due to the increase of soil's mechanical strength. It shows the MICP process as well as the microbial activity have a positive influence on bentonite's cracking potential remediation.