LAUSR

Lime stabilization is a well-established technique to improve the subgrade properties of different soil for pavement construction, despite construction difficulties and its ineffectiveness in certain conditions. However, a greater level of understanding is needed to know the mechanism of alteration in the properties of soils, particularly to longevity potential of ionic interaction. In the present study, mechanism of long-term strength behaviour of lime-treated soil has been brought clearly through alteration in ionic exchange (Ca 2+ , Mg 2+ , Na + and K + ), mineralogy and microstructure by performing series of physico-chemical and micro-analyses (XRD, SEM and EDAX). The results revealed that addition of lime to soil influences greatly the concentration of sodium (Na + ) and calcium (Ca 2+ ) ions with marginal alteration in potassium (K + ) and magnesium (Mg 2+ ) with curing periods. The variation in concentration of Ca 2+ with curing periods has attributed to the strong cation exchange reactions at early stage and consumption of calcium in the formation of cementitious compounds with an increase in curing periods. However, concentration of Ca 2+ increases after curing for longer periods, indicating the increase in solubility of cementitious compounds. Alterations in mineralogy and microstructure with an increase in curing periods of lime-treated soil substantiate the effect of changes in ionic concentration. Further, a significant increase in the strength up to 28 days and marginal up to 1 year substantiates that variation in Ca 2+ and thereby, formation of cementitious compounds control the strength behaviour of lime-treated soil.