The present study primarily focuses on the mechanism of stabilization rendered by two different streams of additives, a biopolymer and an alkaline additive. Lime, an excellent alkaline additive and Ca-Lignosulphonate (Ca-LS), a biopolymer are adopted to curtail the swelling behavior of a potentially expansive soil. The effectiveness of any chemical additive in the stabilization mechanism depends on the unique interaction mechanism, the additive develops with the virgin soil. A chemical additive can bring out alteration in the physio-chemical properties, mechanical properties and micro structural modifications based on the type and nature of additive. The present experimental study brings out the comparative behavior of the lime and lignosulphonate treated expansive soil, in-terms of physio-chemical and mechanical improvement based on the index and engineering properties conducted at their respective optimum contents. The behavior is further analyzed using microstructural investigation through XRD (X-Ray Diffraction), FTIR (Fourier Transform Infrared spectroscopy) and PSA (Particle size analyzer) analysis. These analytical techniques can comprehensively reveal the micro-structural alteration which accounts for the significant changes in the macrostructural properties. The preliminary study carried out using the Ca-LS indicates formation of a close network of clay matrix in contrast to the formation of cementitious products with lime.