Soil improvement to enhance resistance parameters using bacterial precipitation and nanosilica

Soil has an important role in the structure of every building. Although there are different methods available to improve the mechanical properties of soil (adhesion, friction, and rigidity), some, such as chemical methods, despite their limited advantages, will harm the environment. The present study examined the use of microbiologically induced calcite precipitation, which is good for the environment and is a stable improvement method. An experimental study was conducted to study the influence of different factors on the resistance parameters of improved sandy soil. These parameters were the concentration of reactive materials (0.25, 0.5, 0.75 M), curing time (3, 7, 14 days), and compatibility of the bacteria with the nanoparticle. The results showed that the shear strength parameters improved and the soil adhesion rate increased from 0.1 to 186. The soil friction angle reached 35.6 degrees, indicating a 12% increase compared to that of unimproved sand. Nano silica as an additive compatible with bacteria has the ability to improve soil resistance.The effect of cementation solution concentration and curing time on the performance of treated samples hasbeen explained.An increase in the cementation concentration had a limited effect on improving the effectiveness ofmicrobially induced calcite precipitation.