Stabilization of Black cotton soil using plastic bottle granules

Abstract

In design and construction of any structure, the role of soil is very crucial. Since the soil is in direct contact with the structure, it acts as a medium of load transfer and hence for any analysis of forces acting on structure, one has to consider the aspect of stress distribution through soil, as stability of structure itself depends on soil properties. Geotechnical study of site is crucial at feasibility stage, taking place before the design begins (a critical design input) in order to understand the characteristics of subsoil upon which the structure will stand. In this study we carried out with an intention to evaluate the effects of granules on the geotechnical properties of the available expensive soil of Nargund taluk Karnataka state. In this study the effect of granules on the index properties of black cotton soil stabilized with 2%, 4%, 6% & 8% granules by weight of the soil. In this study the Atterberg’s limits, differential free swelling, compaction characteristics,CBR tests, were conducted as per relevant IS codes practice. The test study shows the behavior of the Black cotton soil. The Atterberg limits i)Liquid limit (WL) is 51.9% ii) Plastic limit (WP) is 42.5% iii) Plasticity index (IP ) is 9.65%. Swelling index of the soil is 50% and specific gravity is 2.45.

Shrinkage limit (WS) is 7.46%. The optimum moisture content is 22% and maximum dry density is 1.501g/cm3. Compaction and CBR tests were conducted as relevant IS code practice. The CBR test results show that unsoaked CBR value increases from 6.69% to 9.2% that is 2.51% increase in CBR value with addition of the granules. Conclusion drawn from conducting the above experiments is that the black cotton soil is very weak and hence stabilization of soil is done by using plastic granules as stabilizer to control its stability, swelling and to increase its safe bearing capacity.