Evaluation of Engineering properties of problematic soils using Bacillus pasteurii

摘要

Soil improvement method using enzymatic activity from bacteria Bacillus pasteurii that able to catalyse urea and calcium chloride enabling cementation solution has become an emerging approach to increase the shear strength of sand. The production of urease enzyme of B. pasteurii will be increased using specific medium. Determination of the volume of bacteria needed is based on the soil porosity is studied and analysed. The preliminary result of B. pasteurii that use specific medium could increase the urease enzyme activity and already verified using urease measurement kit. The treatment period required for the initiation, of production of cementing material (calcite) has been reduced from one month to 3 days, while using this specific medium for enzyme urease production. This leads to the rapid filling of the soil pores that result in the hardening of soil. The bonding between the soil particles also increases that leads to increase in the density of soil. The final results of shear improvement are obtained by conducting Direct shear test and Unconfined compression test on sandy and silty soils respectively. Finally the cohesion between the soil particles was identified through the permeability test.