The 2nd Badong International Geohazards Symposium (BIGS2019)

65 / 2019-07-23 21:31:03

Remediation of Desiccation Cracking in Clayey Soils through Microbially Induced Calcite Precipitation (MICP)

Microbially Induced Calcite Precipitation; Desiccation cracking remediation; Clayey soil; Crack Image Analysis; Cyclic wetting-drying treatment

Prevention and Control of Reservoir Geohazards and Ecological Environmental Protection > Technologies of geohazards Prevention and Control

Abstract: Desiccation cracking is a common natural phenomenon in clayey soils, considerably degrading their mechanical and hydraulic properties. Traditional remediation methods are associated with high labor costs, high maintenance costs, or the usage of environment-unfriendly chemicals. Microbially induced calcite precipitation (MICP) has emerged as a green and sustainable soil improvement technique. In this study, the cyclic wetting-drying tests were carried out to investigate the effect of MICP on the desiccation cracking behaviors of clayey soils. Four groups of soil samples sprayed with deionized water, bacteria solution, cementation solution, and both bacteria and cementation solutions were prepared respectively. Soil desiccation cracking behaviors captured by a high-resolution camera are quantified using image processing. The optical microscopy and scanning electron microscopy were resorted to obtain microstructural characterizations. Experimental results reveal the effects of fluid type and treatment cycle number on the crack evolution and volumetric deformation of soils. Comparatively, the MICP treatment involving both bacteria and cementation solutions work most effectively in lowering the soil cracking potential. Geometrical parameters featuring the crack pattern such as surface crack ratio, average crack width, total crack length, crack width distribution range and the most probable value of crack width decrease significantly with the increasing treatments. This study is expected to improve the fundamental understanding of desiccation cracking mechanisms in the MICP-treated soils and provide insights into the potential application of MICP for cracking remediation in clayey soils.