Engineering Properties of Expansive Clay Soils with Sustainable Stabilization Methods

Abstract The production of Industrial waste is increasing day by day in many countries around the world. One of the industrial wastes is Coal Bottom Ash (CBA) which is a coal combustion by-product of thermal power plants, which is categorized as creating environmental pollution if it is not disposed of properly. The objective of the present study is to evaluate the compressive strength and bearing capacity of Black Cotton (BC) soil/Subgrade soil by conducting the Unconfined Compressive Strength (UCS) test and California Bearing Ratio (CBR) test. In the present study, a total of 20 combinations of mix proportions were prepared using the following materials: BC soil, Coal Bottom Ash (CBA), and Wollastonite Microfiber (WMF). The mix proportions involved replacing BC soil with (10%, 20%, 30%, and 40%) CBA and (5%, 10%, and 15%) WMF. Samples were prepared by following the curing process for up to 28 days for UCS testing. The results of standard Proctor tests reveal that the addition of CBA and WMF leads to a decrease in the Optimum Moisture Content (OMC) and an increase in the Maximum Dry Density (MDD). It is also observed that the swelling of the soil reduces drastically with the addition of CBA and WMF mixture. Engineering behaviour delineates the corresponding increase in UCS and CBR values with the increase in mix proportions of CBA-WMF mixes. Assessment of the UCS and CBR values confirms that the utilisation of the CBA and the WMF in Subgrade soil stabilisation provides improved engineering behaviour to deploy in several construction applications.