Abstract:
: Microbial induced carbonate precipitation (MICP) is one of the foremost bio-inspired soil stabilization technique mediated by ureolytic microorganisms through a chain of chemical reactions, which leads to the formation of calcium carbonate bio-cement in soil matrix, and persuades the substantial bonds between the soil particles. This research aims to examine the achievability of embankment soil stabilization by mediating low-grade chemicals via different scales of preliminary laboratory investigations. Psychrobacillus sp., indigenous ureolytic bacteria, isolated from the embankment slope of Asari (Hokkaido, Japan), was employed in elementary-scale column and benchtop-scale slope model solidification tests performed at different physio-chemical conditions to optimize the bio-cementing performance. According to the column test results, a better stabilization (UCS of 0.82 MPa) was obtained for the specimen treated mediating low-grade chemicals (urea fertilizer, beer yeast and snow melting reagent), whereas specimen treated mediating pure chemicals resulted only 0.42 MPa. The benchtop-scale test reveals that the highest surface strength of 1.02 MPa was achieved with 0.5 M cementation solution at 30ºC. Sets of colorimeter measurements were undertaken on treated slope models to compare precipitation profile at different locations. The results have evidenced the acceptable level of solidifying possibility of surface layer while using low-grade chemicals, which would be adequate to be occupied as crust-layer for the natural embankments.
