Physical and mechanical properties of reconstructed bio-cemented sand

The application of bio-treatment techniques to soil improvement has received attention in recent years in terms of quantifying gains in strength and stiffness while considering the environmental impacts. This paper presents the development of a system for a bacterial bio-cementation process in reconstructed samples. Then, the changes in the properties of cemented sands are examined through a set of physical, chemical, and direct shear tests. The bio-cemented sands resulted in higher shear strength due to the presence of cementation bonds leading to increases in cohesion and the friction angle. Furthermore, the effects of both the mechanical disturbance and the temperature-induced disturbance on the strength characteristics of cemented soils were investigated. The sheared specimens that were reconstructed by repeating the cementation process regained their shear strength. In addition, freeze-thaw cycles induced small amounts of disturbance and strength loss to the specimens where the highest disturbance occurred after the first cycle and during the largest temperature gradient.