Behaviour of Lignosulphonate Amended Expansive Soil

Expansive soils are problematic soils which exhibit large volume change behaviour on exposure to moisture changes. These soils are often chemically treated to mitigate the volume change behaviour. The chemical treatment involves the addition of chemical additives and various other waste materials which can curtail the volume change behaviour. However, the usage of chemical additives leads to large environmental issues and affects the biodiversity of the surrounding environment. In an attempt to cater to these issues, a non-conventional additive, with a bio-polymer base namely Lignosulphonate is used for treating the expansive soil. The soil selected is of highly expansive in nature, and the additive is added in small percentages of 1, 1.5 and 3%, and its effects on various soil properties are evaluated. The bio-polymer based additive basically curtails swelling and has a good influence on strength and improvement of compaction characteristics. The microstructural aspects are also evaluated through XRD (X-Ray Diffraction) and SEM (Scanning Electron Microscope) techniques, in order to understand the changes at the microstructure level, particle orientation and probable formation of cementitious compounds, and the comprehensive behaviour of the additive amended expansive soil. The lignosulphonate-treated samples depicted a 5-fold increase in strength, due to the particle aggregation and floc formation.