A Laboratory-Scale Study on the Bio-cementation Potential of Distinct River Sediments Infused with Microbes

Abstract

Microbially induced calcite precipitation (MICP) is a novel ground stabilization technique. In this technical research, a microbe, Bacillus subtilis, was incorporated into two different soils to prompt calcite precipitation along with the aid of a cementation blend of urea and calcium chloride. Compaction of the soil was done in fabricated moulds along with the mixing of microbe at three optical densities of 1.0, 1.3 and 1.5, respectively. The cementation solution (CS) with various molarities (0.5 M and 1 M) was injected into the moulds at a steady head of 1.5 m, keeping a constant flow at the entrance from the base to the top of the mould so as to restrict piping. The extruded soil samples were cured for 7 and 14 days individually in desiccators and unconfined compressive strength tests (UCS) were done on each sample. Direct shear tests (DST) and California bearing ratio (CBR) tests were similarly carried out on the preferred variable combinations. The outcome of the experimental results illustrated that an increased concentration of the microbe and curing time increased the calcite precipitate for both the soils, further increasing the mechanical properties of the weak river sediments. The micro-structural analysis confirmed the experimental results. The principle objective of this investigation was to balance out weak soil deposits for mass utilization in different geotechnical applications.