No abstract

Soil improvement techniques of granular soils via Enzyme Induced Calcite Precipitation (EICP) have attracted an increasing attention as bio-based ground improvement technique. This technique uses biogeochemical reactions to precipitate calcium carbonate (CaCO3). Calcium carbonate precipitate introduced into soil pores help bind soil particles and result in increased soil shear strength. The multiple-phase injection and percolation methods are currently adopted for EICP treatment to reach the desired soil shear strength. However, this method is rather complex and not feasible for practical applications. In this study, one-phase low-pH all-in-one solution (i.e. a mixture of urease enzyme, urea, CaCl2 and organic stabilizer) mixed with sand soil to enhance the soil shear strength has been proposed. Three different EICP cementing solutions have been investigating. A key factor that facilitated this approach is decrease the pH of the cementing solution to facilitate longer period and slower reaction of the precipitation of calcium. Unconfined compressive strength of 3.0 MPa was achieved by mixing cementing solution with soil without multiple treatment cycles.