To lower CO2 emissions, there is a growing use of concretes incorporating low-clinker cements. Since 2023, concrete fines have also been approved as an inert main constituent under DIN EN 197-6, enabling further reductions in clinker content. Alkali-activated materials offer a completely cement-free and potentially more sustainable alternative, in which concrete fines are not merely treated as inert fillers but actively contribute to the reactive system. This study presents the results of an investigation into the partial replacement of ground granulated blast furnace slag with recycled and carbonated concrete fines in an alkali-activated concrete system. The aim was to develop a concrete of strength class C20/25 and to assess the effects of these recycled materials on fresh and hardened properties, as well as on reaction kinetics. The findings indicate that, with appropriate substitution levels, comparable final strengths can be achieved relative to a reference mix without recycled concrete fines. In particular, carbonated concrete fine show considerable promise for practical application.