Durability of lime-treated soil structures, such as earth dams, dikes or river levees, is related to stability, or long term physicochemical evolution of soils in their service environment. The present work aims at (i) providing information on the long term physicochemical behaviour of lime-treated soils subjected to leaching, and (ii) assessing if leaching could be detrimental to the durability of lime-treated soils. Lime addition improves the unconfined compressive strength (UCS) of silt by formation of secondary cementitious phases (C-A-S-H, C-A-H,…) and carbonation of lime. The UCS increases with the lime added. Leaching induces a leaching of these secondary phases, as recorded by the evolution of the chemistry of the leachates. The results obtained indicate that addition of lime up to soil lime modification optimum (LMO at 1% lime) is not sufficient to maintain long term durability of lime-treated soils. Addition of important lime contents extends the resistance of materials, but the UCS decreases. However, leaching of cementitious phases has no effect on the hydraulic conductivity of materials.