Application of calcite precipitation method to increase the shear strength of peat soil

The organic elements in the peat soil promote the fibrous texture and high moisture content. As a result, it has high compressibility density, shear strength, and low bearing capacity. Several methods of peat soil improvement have been implemented but are less environmentally friendly. The calcite precipitation method is one of the alternative sustainable methods by depositing calcium carbonate (CaCO₃). Soybean flour is used for the hydrolysis of urea, which causes the supply of calcium ions to precipitate calcium carbonate. The optimum composition of grouting solution consisting of 1 mol/L of reagent and 15 g/L and soybean is mixed into the soil. The shear strength parameters, namely the undrained shear strength (Cu) and internal friction angle, were evaluated by direct shear test. Soil with the treated solutions obtains Cu and internal friction angle of 49 kPa and 34°, respectively. On the other hand, Cu and internal friction angle have increased from the soil untreated soil by 34 kPa and 19°. This study elucidated that the calcite precipitated method have a great potential to improve the shear strength of organic soil.