This paper presents the variation of modulus, in terms of E/qu, with strain for clay soils stabilised by a non-traditional admixture, lignosulfonate. The E/qu has been computed from the stress-strain curves obtained from unconfined compressive strength tests. Lignosulfonate (LS) treated soil shows an increase in the value of E/qu with the addition of LS, especially for soil containing the reactive clay mineral, montmorillonite. The observed variation of E/qu with strain was compared with cement treated soils, and it was found that soils treated with more than 1.0% cement exhibited a decreasing E/qu. Moreover, micro-chemical changes in the soils due to the addition of admixture (e.g. LS & Cement) were captured using electrical conductivity tests. Electrical Conductivity (EC) is found to be increased with LS and decreased over time. This may be due to the formation of clay mineral-lignosulfonate amorphous compounds, which are stable when comes in contact with water. However, cement treated soils showed an increase in EC with curing time, unlike LS that confirmed the existence of unstable compounds (i.e. dissolvable CSH and CASH) resulting in a decrease of E/qu.