Lime stabilization of sulfate-rich soil using quarry fines as a sustainable co-admixture

Abstract

The engineering properties of the underlying soil govern the durability and performance of civil engineering infrastructures. Chemical stabilization using lime is adopted widely to treat problematic clayey soils that do not possess acceptable engineering properties. However, the presence of sulfate salts is often counterproductive due to ettringite formation. Precompaction mellowing or the addition of amorphous silica-rich co-admixtures like fly ash or ground granulated blast furnace slag are widely used to mitigate ettringite-induced heaving. This research study investigates the potential of utilizing a crystalline silica-rich sustainable co-admixture derived from quarry dust to improve the engineering properties of sulfate-rich soil with kaolinite as the predominant clay mineral. Unconfined compressive strength tests, with and without capillary soaking, and one-dimensional (1D) free swell tests were performed on specimens treated with lime alone and lime along with quarry fines after different curing periods to assess the extent of strength reduction and swelling characteristics after moisture exposure. Mineralogical and microstructural analyses using X-ray diffraction and scanning electron microscope imaging with energy-dispersive X-ray spectroscopy were used to investigate the potential causes of the observed changes in strength and volume change characteristics. Results indicate that lime, along with quarry fines, effectively stabilized the problematic sulfate-rich soil. The improvement in engineering properties was prominent at higher dosages of quarry fines and after prolonged curing time.