Researchers at ETH Zurich have created a machine that controls the setting rate of concrete to offer a "seamless transition between casting and 3D printing" so that structures can be made that use less material.

The system called Fast Complexity combines two existing technologies for creating concrete forms – 3D printing concrete and casting into formwork.

It was developed by Ana Anton, Andrei Jipa, Benjamin Dillenburger from ETH Zurich's Digital Building Technologies group and Lex Reiter from its Physical Chemistry of Building Materials group.

By controlling the setting rate of concrete, the system can either 3D print the fast-hardening concrete for more structural elements without formwork or extrude a more fluid concrete that can flow into castings.

"The major innovation is the concrete 3D printing process developed by ETH Zurich," Anton told Dezeen.

"Our material can be digitally controlled from a fluid concrete mix to a fast hardening concrete. In this way, we can have a seamless transition between casting and 3D printing."

The system could lead to a reduction in the amount of concrete used to create buildings as only the material that is needed would be poured or printed.

"Both the geometry of the slab and the deposition path are optimised to only add material where needed," said Anton. "Such geometries would be otherwise too expensive to fabricate."

"That reduction is project-specific and depends on structural evaluation, but compared to a massive slab, there is a lot of space for material saving," she continued.

To demonstrate the system, the researchers 3D printed a prototype of a highly optimised post-tensioned structural slab using a 3D printed casting.

"Our prototype uses binder jetting and concrete 3D printing selectively: the optimal technique is used for the optimal project feature," said Anton.

"Binder jetting is excellent for producing precise high-resolution apparent surfaces. Concrete 3D printing can deliver rougher but fast deposition for the underlying structural elements."

Anton hopes that the Fast Complexity system created at ETH Zurich will form part of the advancement of 3D-printed technologies that will enable more complex structures to be printed with concrete.

"Our vision is that in the near future large-scale building components for both structural and non-structural applications will be directly 3D-printable in concrete," she said. "This opens up new material saving and design potential."

3D printing in a variety of materials is increasingly being integrated into architecture projects. Recently Chris Precht and Arthur Mamou-Mani use sand to 3D print a pavilion in Saudi Arabia, while AIRLAB used 3D-printed stainless steel nodes to build a pavilion in Singapore.

At the end of 2019 robotic construction company Apis Cor built the world's largest 3D-printed building in Dubai.