Effectiveness of the Calcite Precipitation Method Examined Through Variations in Sand Soil Density

Abstract

The soybean crude urease-calcite precipitation (SCU-CP) method utilizes soybean extract as a natural urease source to hydrolyze urea into ammonium and carbonate ions, which subsequently react with calcium ions from calcium chloride to form calcium carbonate that binds the soil particles. This study to evaluate its effectiveness at varying relative densities of sand, specifically 50, 70, and 90%. The results indicated that the permeability coefficient decreased as the relative density of sand increased. The sample with a relative density of 50% exhibited the most uniform calcite distribution, with the lowest standard deviation of 0.43. The highest unconfined compressive strength of the sand sample occurred at a density of 1.625 g/cm3, measuring 23.58 kPa. However, even at high relative densities, achieving a uniform distribution of calcite throughout the sample is essential to ensure that the increase in strength is consistent across all layers. The presence of sediment layers resulting from residual organic matter left over from the soybean extract filtration process remains a challenge for achieving a uniform calcite distribution. These findings indicate that optimizing the SCU-CP solution preparation and application, such as minimizing residual solids and enhancing penetration, is critical for achieving uniform bio-cementation and maximizing soil-strengthening efficiency