Performance evaluation of stabilized clay using sodium lignosulphonate

Rapid urbanization often demands the development of infrastructure on challenging soils, necessitating strengthening and improvement. This study explores the application of Sodium Lignosulphonate (LS), a by-product of the paper and wood pulp industry, as an eco-friendly, non-toxic stabilizer for low-plasticity clay (CL, PI ≈ 24%). Through a series of laboratory tests, including Atterberg's limit, unconfined compression strength (UCS), swell pressure, and CBR, the engineering properties of the stabilized soil were assessed. The results show that as the LS content increases, the plasticity index (PI) of the soil decreases, and the UCS value increases, reaching a maximum UCS value at 0.75% LS content. Higher LS dosages (> 0.75%) resulted in gradual strength reduction due to excessive polymer chain formation and particle repulsion. Additionally, CBR tests on the soil treated with 0.75% LS after a 14-day curing period revealed significant improvements. Microstructural analysis demonstrated that LS created a bonding substance that coated soil particles, filling pores and binding them together, thereby enhancing soil stability and strength. Furthermore, increasing the curing time further enhanced strength and reduced swelling characteristics, as LS established a strong bonding between soil particles. This research underscores the potential of LS as a soil stabilizer, offering durability and sustainability to infrastructure in urban areas facing challenging soil conditions.