3D concrete printing is becoming more and more popular, not only in research but also in practice of construction. One of the main challenges however remains the integration of reinforcement. This publication focuses on the use of continuous fibers for this purpose. The special feature of the new type of carbon yarns applied is the mineral impregnation used instead of the conventional polymer one. Such reinforcement not only yields excellent mechanical properties, but also offers many advantages, specifically with respect to processing flexibility and is therefore very well suited for additive manufacturing. The concrete for 3D printing to be reinforced with such yarns must meet particular requirements, especially when the finest concrete filaments are printed. This is also a subject of the article at hand.