N₂-BET surface area and FESEM studies of lime-stabilized montmorillonitic and kaolinitic soils

In this research, field emission scanning electron microscopy coupled with an energy-dispersive X-ray analyser was employed to study the micro-textural features and elemental composition of lime-stabilized soil. This technique was used to visualize the time-dependent morphological changes in different clay mineral structure and, moreover, to observe the formation of new cementing products that could not be detected by X-ray diffraction method. Due to the “surface associated” nature of soil–lime reactions, the N₂-BET surface area of treated soils was also monitored with curing time. Unconfined compressive strength test as an index of soil’s improvement was performed on cured samples. Based on the results it was found that the type of cementing compounds that were formed after 8 months of curing was dependent on the type of clay minerals present. Also the progression of pozzolanic reaction was highly sensitive to the impurities present on the surface of soil particles. From an engineering point of view, the lime stabilization technique was effective in increasing the strength properties of natural soils with sodium bentonite (comprised mainly of montmorillonite mineral) showing the highest degree of improvement.