An Investigation on the Effect of Calcite Bacteria Seeding on Shear Strength of Peat Soil via an Unconfined Compression Test

Peat soils have been known for their problematic characteristics which include high water content, high compressibility and low shear strength. In this study, an attempt was made to investigate the effect of 1 week addition of modified Urea-CaCl2 liquid medium with and without Sporosarcina pasteurii on the shear strength of unsterilized dried peat soil using the Unconfined Compression Test. After the treatment period, significant increase in the shear strength of the soil was found to be highest for peat + medium at 42 kN/m2, moderate for peat + medium + Sporosarcina pasteurii at 27 kN/m2 and unchanged for peat + water control at 24 kN/m2. Although the growth dynamics of all the microbes involved in the calcite formation in the treated peat soil were not known, the addition of the modified Urea-CaCl2 liquid medium into the soil clearly had contributed to the marked increased in the shear strength of the soil. It is probable that the medium had promoted a better growth of indigenous calcite bacteria population in the soil which may have been suppressed by the slow growing S. pasteurii population being added daily to the soil