An experimental investigation of dispersive soils treated by microbially induced calcium carbonate precipitation (MICP)

Dispersive soils are frequently employed as construction materials in projects such as drains and dams in western Jilin, China. However, their propensity to disperse upon contact with water presents a grave threat to construction projects if left unaddressed. Therefore, following the identification of the fundamental physical and chemical properties, as well as the dispersivity of soils in the western region of Jilin Province, Sporosarcina pasteurii was chosen to conduct laboratory experiments and mechanistic studies aimed at improving dispersive soils in the area through MICP. The treatment effect of the soil samples was quantitatively assessed through tests including comprehensive dispersivity identification, unconfined compressive strength (UCS) measurement, and determination of calcium carbonate content. Furthermore, scanning electron microscope (SEM) tests were conducted to examine the microstructural alterations of the soil samples before and after microbial treatment. The experimental results showed that soil dispersion can be significantly reduced under various conditions, and increase the soil strength under certain condition. MICP facilitates the replacement of exchangeable Na+ in soil and induces the formation of calcium carbonate, which fills pores and acts as a cementing agent. Treating dispersive soil in western Jilin is crucial to ensuring the safe and normal operation of its water conservancy projects.