Experimental evaluation of clayey soil stabilisation using wood ash and lime additives

The structures constructed on expansive soils pose a severe challenge to their stability, especially when these soils come in contact with water. Montmorillonite minerals, in general, are mainly responsible for this instability caused by excessive swelling and shrinkage associated with variations in moisture. Such volumetric changes generally cause failures of foundations, significant structural and safety damage. Thus, it is indispensable to increase the mechanical properties of expansive soils to guarantee the durability and safety of this structure in the ground. The mechanical behaviour of problematic soils can be improved by means of soil stabilisation. Since it increases shear strength, it controls shrink-swell characteristics, and it increases the load bearing capacity of the subgrade, it is suited to support pavements and foundations. The goal of this study was to stabilise expansive soil using cost effective and environmentally friendly materials: wood ash and lime. Proportions of 6%, 8%, and 10% of wood ash and 4%, 6%, and 8% of lime, by weight, within the soil. These stabilising agents were evaluated through a series of laboratory tests, Standard Proctor Compaction Test, California Bearing Ratio (CBR) Test, and Unconfined Compressive Strength (UCS) Test. The objective of these tests was to obtain the value of maximum dry density (MDD), optimum moisture content (OMC), bearing ratio, unconfined compressive strength (UCS), and shear strength of the treated soil. The results of the experiment showed that wood ash and lime can effectively stabilise expansive soils, which can significantly improve all measured parameters. The study supports the sustainable use of industrial by-products in geotechnical engineering applications.