Chemical treatment is a widely accepted cost effective ground improvement technique for stabilising problematic soils. However, the traditional soil stabilisers (e.g. cement and lime) are not always readily acceptable in Australia due to stringent occupational health and safety issues. They have been identified to cause serious environmental problems by altering the pH of soil and groundwater upon treatment. Moreover, excessive use of traditional admixtures to stabilize soil would also affect the yielding capacity of soils. To overcome these consequences, an alternative soil stabiliser that improves the properties of soil without causing adverse effect on the environment must be found. In this context, lignosulfonate has proved its effectiveness in stabilising erodible and dispersive soils and thereby reducing soil erosion. However, currently there are no comprehensive studies carried out to understand the shear behaviour of lignosulfonate-treated soils. In this study, a series of direct shear tests was conducted on a highly erodible silty sand to understand the shear and volume change behaviour of lignosulfonate-treated soil. The laboratory shear tests indicated that the peak and ultimate shear strength, as well as the angle of internal friction increased with the increasing amount of lignosulfonate. The volume change behaviour showed a dilative response after the lignosulfonate treatment and the change in ductility due to lignosulfonate treatment was negligible. In this respect, the lignosulfonate-treated soils would have an advantage over conventional chemical treatment methods, especially for cyclic loading such as fast moving traffic and high-speed rail.