Evaluation of Amended Black Cotton Soil Using Bagasse Ash with Liquid Alkaline Activator for Sustainable Pavement Subgrade Performance

This study delves into the sustainable use of bagasse ash (BA) in conjunction with a liquid alkaline activator (LAA) for pavement subgrade construction. The selection of BA is based on its robust chemical composition, including SiO₂, Al₂O₃, Fe₂O₃, and CaO. These chemical compounds and the LAA enhance the properties of black cotton soil (BCS), specifically its California bearing ratio (CBR) and swelling characteristics, such as expansion ratio (ER). The strength and swelling attributes of the BCS were assessed at 7, 14, and 28 days of curing time. BA and LAA were applied to treat the BCS for use as a pavement subgrade construction material. The effectiveness of BA was gauged by examining the soaked CBR and ER of the modified BCS. The CBR value of the specimen exhibits an increase with up to 20% BA content and prolonged curing time. The microstructural analysis of both natural BCS and BCS treated with BA and LAA was conducted using field emission scanning electron microscopy. The CBR values of the natural BCS and treated BCS are used to determine the thickness of the pavement. The designed pavement thickness also prompted calculations for the initial construction cost and carbon dioxide equivalent (CO_2e).