In the last years, the fight against climate change and the need for a reduction of greenhouse gas emissions has promoted the development of new, sustainable materials for the construction industry. This work focuses on the development of an eco-friendly one-part alkali activated binder, which is obtained starting from alkali activators in powder form, and blast furnace slag as aluminosilicate-precursor, in partial or total replacement of metakaolin. The first feasibility studies, with the analysis of different alternative formulations, are discussed first, and then the possible use of these binders to produce a sustainable mortar is investigated. Preliminary results in terms of microstructural characterization of the binders through SEM and XRD techniques, as well as the main mechanical properties in the hardened state, demonstrate the potential of these products as eco-friendly alternative to Ordinary Portland Cement (OPC). The use of alkali activators in powder form, together with the followed production process (with both activation and curing phases at ambient temperature) make the developed products similar to commercially available OPC bagged mortars, and therefore suitable for the use on construction sites.