چكيده به لاتين
In many parts of the world, soil does not satisfy the minimum requirements for construction which may lead to disaster if not consider. So there is a need to improve soil mechanical properties such as shear strength and hardness of the soil. To improve these properties some processes are utilized named as soil improvement methods. Large portions of soil improvement methods utilize Portland cement and its derivatives as a major component, but production and use of Portland cement consumes a lot of energy and contribute to the production of the CO2. These raise environmental concerns about the production and use of the Portland cement. To compensate these problems recently a new sustainable method was devised named as microbially induced calcite precipitation (MICP). In this method, soil particles are bind together by calcite precipitated in the presence of produced carbonate and calcium using a urease positive bacterium. Many parameters contribute to this method owing to its complex biochemical and geotechnical nature and there is a progressive demand to study these parameters. In the present study different parameters such as particle size, the amount of calcium carbonate introduced to the soil, entrance rate of the solution and parameters that affect precipitants by three different entrance methods of the solution to the soil are studied. After cementation, the bio-cemented samples were tested by unconfined compressive, microscopic and X-ray diffraction tests analyzed with and without statistical methods. Finally, owing to the dust problem around the world, feasibility study of this method in dust suppression were performed and the derived samples were tested in wind tunnel. Results of soil cementation are revealed that the coarser soil particles had a higher unconfined compressive strength (UCS) which was 2.5 MPa. Moreover, increasing the amount of entered calcium carbonate, decreasing the entrance rate of solution to the soil and increasing the rest time of solution are resulted in increasing of UCS of the cemented soil. Finally, the results of wind tunnel tests revealed that this method is appropriate for dust suppression.
