Geotechnical Behavior and Physico-Chemical Changes of Lime-Treated and Cement-Treated Silty Soil

An investigation performed on the interactions of silty soil treated with cement or lime demonstrates the strong relationship between microstructural phenomena and their engineering behavior. Cement hydration induces a rapid improvement in soil properties while the progressive pozzolanic reaction of lime leads to long-term improvement. Moreover, the cement-treated soil presents better mechanical properties (California bearing ratio and unconfined compressive strength). X-ray diffraction tests and thermo-gravimetric analyses show calcium aluminate hydrates in lime-treated soil and ettringite in cement-treated soil. Mineralogical changes and new hydrates formed in the treated soil demonstrate their positive effect on the engineering behavior of the soil. Swelling and indirect tensile strength indicate the soil suitability for treatment with specific amounts of binders. Cement-treated soil resists the immersion test, as ettringite and new calcium aluminate hydrate are detected by XRD after immersion, whereas dissolution of the unreacted lime and part of the calcium hydrates during the immersion test imply a low resistance to immersion of lime-treated soil.