Author : L.S Subramanyam, Y.S G Govind Babu and G V R Prasada Raju

Expansive soils are mostly found in the arid and semi-arid regions and occupy major area of the world. About 22% of the land mass in India mostly entire Deccan plateau. These kinds of highly swelling soil are usually termed as Black Cotton Soils. The delta region in Andhra Pradesh formed between 60 and 68 million years ago at the end of the Cretaceous period. In this region the main classes of soil are black, brown soil. The volcanic, clay-like soil of the region owes its black colour to the high iron content of the basalt from which it formed. As the Delta region is mainly dominated by Black Cotton Soil, it is one of the types of expansive soil, which has a high prospective for shrinkage and swelling under varying moisture environment. These deposits, due to their dominating physical and chemical constituents, are subject to change in volume with seasonal variations. Because of the inherent property of swelling, these soils are a latent peril to the natural balance and it results in incomparable disfigurement world-wide every year. Usage of expansive soils in sub grades in its natural form is not viable and chemical stabilization is one of the many alternative tried. One of the many a established methods is stabilizing with chemicals like KCl, CaCl2, FeCl3. Expansive soils untreated and treated with chemicals have been tested for various Engineering properties and also analyzed in Scanning Electron Microscope to understand the mineralogical changes manifested at different resolutions.

Keywords: Expansive Soils, mineralogical changes, chemical stabilization, Crystalline and Amorphous structures.

Article published in International Journal of Current Engineering and Technology, Vol.5, No.6 (Dec-2015)