The role of bacillus pasteurii on the change of parameters of sands according to temperature compresion and wind erosion resistance

Microorganisms have played a critical role in geological processes and in the formation of soils throughout geological time. It is hypothesized that biological activity can also affect soil properties in short engineering time-scales. Nowadays, Bio-grout is a new soil improvement method based on microbiologically induced precipitation of calcium carbonate. For this purpose, bacteria, which are able to convert urea into ammonium and carbonate, are injected into the soil, followed by a solution containing urea and calcium chloride and therefore it is produced carbonate precipitates with calcium. The calcium carbonate crystals form bridges between the sand grains, which increases the strength of the sand mass. In this study, focus is placed on bio-mediated calcite precipitation of sands and Sporosarcina pasteurii was chosen for the experimental part of the study. This study has examined the effect of temperatures and the soil compaction amount on optimising calcite precipitation induced by sporosarcina pasteurii. The result demonstrated that most bacterial activities were seen on 60◦C and according to the tests result, medium compaction (Dr 56%) is the best case for compatibility between the soil grain characteristics and bacteria size for transportation. It seems bio-mediated treatment techniques can result in the improvement of soil properties and increased the soil strength in wind erosion resistance test.