Sustainability of EICP treated sand: Permeated water and sequential loading

The Enzyme Induced Carbonate Precipitation (EICP) is used to stabilize the soil in a less burden to the environment. Since the CaCO3 by-product of the EICP reaction is susceptible to the acidic water and external forces, the permeability test with different pH values of the water and the sequential loading test are conducted for evaluating the sustainability. Before applying to the soil, the optimal EICP solution is measured with different urea-CaCl2 molar ratio and urease concentration. The urease concentration of 0.5 g/L and 0.9 g/L with 1.5 urea-CaCl2 molar ratio is the optimal condition for the 0.5M CaCl2 and 1M CaCl2, respectively. The CaCO3 resists not only to the water with only 2.4% loss in stiffness by flushing, but also to the acidic water, showing similar permeability regardless of pH values. Also, the debonding induced stress is constant regardless of CaCl2 molar concentration in dense soil while it increases as the increment of the CaCl2 molar concentration in loose soil. The volume collapse in soil skeleton does not appear near the debonding induced stress.