Additive Manufacturing in Concrete Construction (2023-04)¶

In the course of the current transformation of the entire value chain of planning and construction, integrated production and construction processes with a high degree of automation play a central role. One example of this is the additive production of concrete, which has developed over the past ten years from an interesting idea of a few research institutes into a potential stimulus for the entire industry. The prospects of the process, also known as 3D concrete printing, range from lower costs and reduced use of personnel and materials to environmental benefits, reduced health and safety risks, greater geometric variability and increased productivity. It is therefore not surprising that numerous companies and research groups are currently promoting the innovative principle and that a wide range of pilot applications have been developed worldwide, including buildings and bridges. Recent studies show that a "Technology Readiness Level" (TRL) 6 or 7 has now been reached - a remarkably rapid development, particularly in view of the relatively small-scale and decentralized nature of the construction industry. Nevertheless, concrete printing has so far only been used in very few cases due to its advantages and cannot yet compete with conventional methods. Above all, there are still some technological challenges that need to be solved. For example, the very cement-rich printing mortars must be replaced by real concretes in order to reduce the CO2 footprint and these must be used where load-bearing concrete structures are actually needed - not just as a substitute for masonry, as has often been the case up to now. This requires, above all, reinforcement methods suitable for construction practice as well as digital quality controls and process adjustments in real time (this issue can provide suggestions for this with innovative imaging methods for fresh concrete testing). Finally, the concrete pressure must be implemented coherently in the overall process, which also includes joining and connection with other components as well as integration with the building equipment and technology. These issues are being addressed in national and international research projects and a wide range of solutions are already available. With a view to the necessary application-oriented further development towards an efficient technology, cooperation between science and construction practice must be further expanded. In addition, the right boundary conditions and generally recognized principles must be available. DAfStb, fib and RILEM are already working on concrete pressure guidelines, for which current cross-laboratory studies are to form an important basis. It must be ensured that the various guidelines are coordinated from the outset. In addition, specific training concepts must be developed, as otherwise the potential can only be exploited to a limited extent. At present, the few courses on offer tend to remain at a theoretical and scientific level with a small amount of teaching. Ultimately, the successful implementation of a new technology in engineering practice will only be possible if it becomes an integral part of a more comprehensive "Industry 4.0 package" in construction technology training at all levels, from skilled workers to universities. With its efficient construction industry and extensive development capacities, leading research institutions and extremely active and committed associations/committees, the DACH region is in an excellent starting position to lead the transformation process for promising technologies such as additively manufactured concrete towards large-scale application. There are still challenges along the way, but these can be overcome through the joint efforts of science, construction practice and construction supervision.