Optimum Bacteria Suspension Volume for Stabilizing Silty Sand Soils by Sporosarcina pasteurii Bacteria

Recently, the bio-mediated soil improvement techniques have gained an increasing attention. In this method, bacteria was cultivated aerobically in laboratory and added to with reactant solutions such as urea calcium chloride. Most of existing studies are on sandy soils a few researches done silty soils. However, most nature compounds fine-grained coarse-grained soils, silt does not very good resistance due lack adhesion between its particles. Hence, study Sporosarcina pasteurii bacterium for stabilizing sand different percentages determine optimum suspension volume. After some bacterial tests measuring growth, standard plate count, gram staining, pH determination, growth without urea, urease test, geo-technical like sieve, compaction, Atterberg limits were also done. Standard count estimated 2.5*108 through serial dilution plating culture media determined 8.64 from samples. Moreover, achieve best results, sampling methods compared. As carbonate creates network calcified bridges calcite grains, electron microscope used scanning surface focused beam electrons. Results triaxial showed that by adding volume, maximum strength samples 0, 10, 20, 30 40% improved 700, 900, 750, 600 and550 1100, 1400, 1550, 1600, 1500 kPa, respectively.