Influence of microbial geo-technology in the stabilization of dredged soils

Concern over environmental effects of dredging, disposal and the increasing unavailability of suitable disposal sites, has put pressure on engineers to improve dredged soils which are weak, have low bearing capacity and undergo excessive settlements over time. This study deals with improvement of such soils generated by dredging of the flood spill channel of River Jhelum, passing through world-renowned wetland, Hokersar. A recent introduction to the ground improvement techniques that utilizes microbes is known as microbial geo-technology. Both natural processes and laboratory investigations have shown that microorganisms can be used to improve the mechanical properties of soil. In this study, dredged soil is treated with microbes (Bacillus Subtilis) at different optical densities (1 and 1.3) and then supplemented with cementing agent solution of urea and calcium chloride at different molarities (0.25M and 1M). The samples are treated for a period of 48 h and then tested for shear strength. Curing for a period of 7 and 28 days is done in a temperature-controlled chamber (25–28°C). With increasing the optical density and molarity of cementing solution there is an increase in calcium carbonate precipitate which increases the strength parameters, the results are in-turn supported by SEM and XRD analysis. Treated dredged soil can be utilized in bulk as a resource for various engineering applications for eco-friendly and sustainable development of the environment.