Use of CO2-induced siderite and dolomite with nanoclay for soil improvement

We studied the precipitation of carbonate minerals used as cements for ground improvement. The carbonate minerals were prepared by combining divalent ions (Mg2+, Ca2+, and Fe2+) with carbonate ions (CO3 2-) induced by microbial activity. Scanning electron microscopy (SEM) and X-Ray Diffraction (XRD) analyses observed the shapes and sizes of the minerals and attested the formation of dolomite (CaMg (CO3)2) and siderite (FeCO3). Consolidated drained triaxial tests (CD) were performed on treated specimens of silica sand with the CO2-induced siderite and dolomite cements with and without the addition of nanoclay. Specimens treated with siderite had higher strengths than dolomite?treated specimens. The addition of nanoclay further increased the shear strength of the specimens and reduced their brittleness. Moreover, it was found that the shearing resistance of fully saturated specimens was not considerably reduced compared to that of dry specimens, as it only decreased by 5–15% compared to that of dry specimens.