Improvement of Peat Soil Settlement Parameter Using Soybean Crude Urease Calcite Precipitation (SCU-CP) Method

The characteristics of peat soil with high organic and moisture content, also high compressibility can cause structural failure due to excessive settlement. Improvement of peat soil settlement parameters can be conducted using calcite precipitation method with soybean as bio-catalyst, namely Soybean Crude Urease-Calcite Precipitation (SCU-CP). SCU-CP is one of the grouting methods to improve soil consistency so that the bearing capacity of the soil increases. The purpose of this study was to analyze the increase in the parameters of the settlement parameter (R90) and the time at 90% degree of compression (t90). This study was conducted using a density of 90% Proctor standard compaction and the variation of untreated and treated samples. The optimum combination SCU-CP solution was used in the treated samples with a concentration of reagents (Urea and CaCl2) of 1 mol/L and soybean concentration of 20 g/L. The results proved that using the optimum combination of SCU-CP method, it could significantly improved soil settlement parameter of R90 and t90. The R90 values for untreated samples (UT) at each pressure of 2.0 kg/cm2, 4.0 kg/cm2, and 8.0 kg/cm2 obtained 39 mm, 86.7 mm, and 162 mm respectively. The improvement on R90 values of treated samples (TE) obtained 16.4 mm, 28.1 mm, and 57.5 mm respectively after being treated with the SCU-CP method. In the treated samples (TE) the t90 value is lower than untreated samples which indicates that the time to reach 90% consolidation is getting faster.