In the summer semester of 2025, a groundbreaking research and development project in the field of 3D concrete printing (3DCP) was launched at the Institute of Structural Design and Building Construction (KGBauko) at TU Darmstadt. The project was carried out in close cooperation with Sika Germany, the Riedel Bau Group, and Staikos 3D and is a prime example of the increasing integration of digital planning, additive manufacturing, and sustainable building culture.

The aim of the project is to develop and implement a topology-optimized concrete ceiling with a span of 5 x 5 meters, which was designed as a self-supporting ceiling with a mushroom-shaped, central single support. This ceiling is intended not only to serve as a technical demonstrator, but also as a basis for investigating innovative construction methods and material-efficient design approaches. A special feature is the fully 3D-printed concrete formwork, which enables the complex geometry of the ceiling and ensures precise implementation of the topology-optimized structure.

The construction industry is currently undergoing profound change. Issues such as resource efficiency, sustainability, digitalization, and automation are becoming increasingly important. In this context, 3D concrete printing is considered one of the most promising technologies for reducing material consumption, shortening construction times, and increasing design freedom.

However, one of the biggest challenges for the use of additive manufacturing in construction practice is the lack of standardized norms, testing procedures, and legal frameworks. To meet these challenges, the project is pursuing an innovative hybrid approach. The 3D-printed formwork is used as integral formwork, reinforced with conventional reinforcing steel and then poured with in-situ concrete. This creates a load-bearing component that is both legally compliant and technologically advanced.

The printed formwork fulfills several functions at once. On the one hand, it precisely replicates the complex rib geometry of the ceiling and visually reveals the internal force flow of the structure. On the other hand, additive manufacturing enables the realization of geometrically complex shapes that would be neither economically nor technically feasible with conventional formwork methods.

Through the targeted use of material along the actual forces that occur, a high load-bearing capacity is achieved with minimal material consumption and the lowest possible dead weight – a basic principle of topology-optimized construction. The project thus makes an important contribution to conserving resources and reducing the carbon footprint in the construction industry.

The implementation of the project follows a digitally integrated process chain:

• Topology optimization and shape finding based on static simulations

• Digital planning and parameterization of the formwork geometry

• 3D printing of the formwork with specially developed materials

• Reinforcement and concreting in collaboration with industry partners

This close integration of digital design, manufacturing technology, and practical construction implementation illustrates the potential of an integrated planning process in which design, statics, and production are closely linked.

The 1:1 scale demonstrator was manufactured at the Riedel Bau Talentfabrik in Schweinfurt. After intensive planning and testing, the reinforcement work was successfully carried out. The 3D-printed formwork elements were assembled with a precise fit and the system was then monolithically connected with in-situ concrete.

During the planning of the project, load tests and material analyses were carried out to evaluate the load-bearing capacity, deformation behavior, and durability of the component. The findings obtained in this process will be incorporated into future research projects and possible standardization processes for additive construction methods.

The accompanying illustrations and drawings document the individual steps of the project – from 3D printing the formwork to integrating the reinforcement to concreting and completion. They offer a fascinating insight into the emergence of a new generation of concrete structures that combine design freedom, technical precision, and ecological responsibility. This project exemplifies KGBauko's commitment to combining research, teaching, and practice in the construction industry and actively shaping the construction world of tomorrow.

KGBauko Institute, TU Darmstadt: Prof. Dipl.-Ing. Architect Stefan Schäfer, Nikola Bisevac

SIKA Germany: Dr.-Ing. Slava Markin, Dr.-Ing. Shifan Zhang

Riedel Bau Group: Dr.-Ing. Rebecca Wolff, Thomas Bauer, Christian Seuling, Timo Helemann

Staikos 3D: Georgios Staikos, Yannik Berkensträter

Participating students: Alessandro Garruto, Ahmet-Münir Telci, Max Rösner, Summer Wazy