A pioneering research and development project in the field of 3D concrete printing exemplifies the growing integration of digital design, additive manufacturing, and sustainable building culture. The project focuses on the development and realization of a topology-optimized concrete slab with a span of 5 × 5 meters, designed as a free-spanning structure supported by a single mushroom-shaped central column. This slab serves both as a technical demonstrator and as a foundation for studying innovative construction methods and material-efficient structural systems. A key feature of the design is the fully 3D-printed concrete formwork, which enables complex geometric configurations and ensures the precise physical realization of the topology-optimized structure.

As the construction industry undergoes a profound transformation driven by resource efficiency, sustainability, digitalization, and automation, 3D concrete printing has emerged as a promising technology to reduce material consumption, shorten construction timelines, and maximize design freedom. However, implementing additive manufacturing in real-world construction practice faces major challenges due to a lack of standardized norms, testing procedures, and established legal frameworks. To bypass these regulatory barriers, the project utilizes an innovative hybrid execution method. The 3D-printed shell acts as an integral formwork system that is fitted with conventional steel reinforcement and subsequently filled with cast-in-place concrete. This approach yields a fully load-bearing structural component that complies with building regulations while advancing technological boundaries.

The permanently integrated 3D-printed formwork serves multiple functions simultaneously. It precisely reproduces the intricate rib geometry of the slab, visibly mapping the internal flow of static forces. Furthermore, the use of additive manufacturing unlocks geometrically demanding shapes that would be neither economically nor technically feasible through traditional timber or steel formwork methods. By strategically distributing material only where internal forces actually occur, the structure achieves an exceptionally high load-bearing capacity with minimal material volume and reduced self-weight. This optimization represents an essential step toward conserving natural resources and lowering the overall CO₂ footprint within the built environment.

This seamless integration of digital planning, automated manufacturing, and physical assembly highlights the true potential of an interconnected development workflow. The full-scale 1:1 demonstrator was successfully realized by prefabricating the individual printed components, assembling them with precise geometric tolerances, inserting the internal reinforcement cages, and monolithically casting them with in-situ concrete. Comprehensive material analyses and rigorous load tests were conducted to evaluate structural load capacity, deformation behavior, and long-term durability. The resulting empirical insights contribute directly to the ongoing global standardization of additive construction methods. Together, the structural documentation, technical drawings, and analytical steps show the emergence of a new generation of concrete structures that seamlessly unite spatial freedom, technical precision, and ecological responsibility.