Mortars used in 3D-printing typically contain large amounts of cementand other high-value powders to ensure printability. Consequently, 3D-printedconcrete structures have a high carbon footprint. In the Baltic states, power plantsutilize oil shale, producing significant amounts of non-biodegradable oil shale ash(OSA). To address these environmental problems, we are aiming to formulate apreblended dry product for extrusion 3D printing which contains oil-shale ash. Toassess suitability for the use in cement-based composites, the properties of rawOSA are studied, including particle size distribution, chemical composition,specific surface, reactivity, and shape with SEM. Additionally, the influence onmechanical properties has been studied when substituting reactive powders in apre-blended mix with oil shale ash in varying quantities. Additionally, workabilityand buildability of mixtures in fresh state is investigated to determine suitabilityfor 3D printing. The preliminary results have revealed that replacing up to 20%of reactive powders with oil shale ash does not lead to a significant decrease inmechanical strength in the hardened state. Moreover, in the fresh state,substituting up to 20% of reactive powders with OSA enhances workability.Based on findings thus far, OSA is a viable substitute for cement in printableconcrete, with the potential to reduce the carbon footprint of printed structures.