Prof.dr.ir. Theo Salet, Eindhoven University of Technology and Witteveen+Bos, The Netherlands
Theo Salet is professor Concrete Structures at Eindhoven University of Technology (TU/e) where he started an important research project on 3D printing of concrete structures. He is also connected the large Dutch Consulting office Witteveen+Bos as partner and senior advisor.
Around the globe, ground breaking projects and case studies are being presented to showcase the potential of Digital Fabrication with Concrete, better known as 3D printing of concrete. On a trial-and-error basis, the frontiers of the new technology are rapidly being explored, primarily focusing on geometries. However, the progress of fundamental understanding of the structural properties of such structures is not keeping the same pace. To bridge this gap, the TU/e is directing research efforts for 3D concrete printing to become a viable solution for building structures.
Initial experiments have provided strength, stiffness and fracture data on printed concrete. Directional dependency of these properties caused by the typical layered structure of objects, is one of the relatively obvious and expectable outcomes. More important than the characterization of a specific printed material, however, is the development of both suitable and generally accepted test methods and of an understanding of the relationships between the print process parameters and the structural properties of the printed product.
With these explorations underway, the key quest in 3D concrete printing is for ductility. This need could be avoided by designing compression loaded structures. Despite promising results, this would limit the applicability all too seriously. Hence, proof-of-concepts are being developed for both printable FRC and concrete with in-process ‘printed’ reinforcement. Experimental research on the failure behavior has been promising.
In the end, the properties and dependencies of a printable, ductile concrete composite, and the appropriate test methods, are indispensable to the structural engineer to ensure safe 3D printed concrete structures. This is mostly unchartered territory, but one in which major progress may be expected in the coming years.