Study of the Unconfined Compressive Strength Characteristics of Organic Soil Stabilized with Bacillus Subtilis Bacterial

Abstract

This research aims to evaluate the effect of adding bacteria to improve the mechanical properties of high organic content soil by bio cementation using the microbially induced calcite precipitation (MICP) process. In general, this study consists of three stages, the first stage involves preparing the bacterial culture and soil samples. The samples tested consist of a combination of silt soil, organic soil, and bacterial solution with several variations of treatment, including curing time, bacterial culture time of 2,4,6 days, bacterial solution concentration of 4%, 6%, 8%, and organic soil material addition of 10 to 60% of the total weight of dry soil. The third stage involves testing the physical and mechanical properties of silt and organic soil including compaction test and unconfined compression strength test, Based on the physical characteristic test results, the organic soil used had an organic content of 58.15% and was classified as having high organic material. From the mechanical characteristic test results, it was found that the addition of Bacillus subtilis bacterial solution resulted in a 649.95% increase in compressive strength. The optimum value was obtained under the condition of a sample combination between silt soil material and a 6% bacterial solution with a 4-day culture period, curing for 28 days. The factors that influence compressive strength are curing time, bacterial culture time, bacterial solution concentration, and the addition of organic content. These results prove that the addition of Bacillus subtilis bacteria as a stabilization material is highly effective in improving and enhancing the physical and mechanical properties of organic soil.