The present study addresses the characterization of long-term and durability properties for employment in road subgrade construction of geopolymer-treated sediments. Four mixtures are presently selected based on a previous study: untreated sediment, sediment treated with 2% hydraulic lime (L) and 7% ordinary Portland cement OPC, and two geopolymer-treated mixtures using 5% and 10% of ground granulated blast furnace slag/sodium silicate-based geopolymers. Long-term properties are investigated through unconfined compressive strength and tensile strength tests. The resistance of designed materials to weathering conditions is tested through freeze-thaw cycles, humidification-drying cycles, and immersion in water. Sediments treated using 10% geopolymer binder are resistant to weathering conditions and showed long-term properties superior to those of sediments treated using an L/OPC mixture.