Effect of MICP treatment on the mechanical properties of clay soils

The presence of drying cracks can significantly affect soil hydromechanical behavior, which has effects on soil performance in civil engineering. One innovative approach that has received much interest in the last decade is using microbially induced calcium carbonate precipitation (MICP) for soil reinforcement and stabilization. A series of clay specimens with varying moisture levels and concentrations of cementation solution were carefully prepared. All these samples were subjected to a series of mechanical tests to assess the improvement in the clay’s mechanical characteristics. These tests covered various conditions, ranging from unsaturated to saturated states of the clays. The results showed that the strength of clays was significantly improved, and the most significant increase in mechanical strength was observed with the 1.4 M MICP solution. The precipitation of CaCO3 was quantified using a calcimeter. In addition, composition analysis by X-ray diffraction and attenuated total reflectance infrared spectroscopy confirmed the presence of calcium carbonate crystals and indicated residual urea and calcium acetate.