In Germany, researchers from the Technical University of Braunschweig are working on the development of a new concrete 3D printing process. Instead of currently available technologies, they are relying instead on injection to design more complex shapes. To accomplish this, the reasearchers are injecting a fine-grained concrete into a non-hardening carrier liquid (a suspension of crushed limestone to be exact). The latter acts as a matrix that supports the structure; injection 3D concrete printing could thus make it possible to imagine intricate designs which would be impossible to produce otherwise.
When it comes to 3D concrete printing, we often think of extrusion: a robotic arm deposits successive layers of material until the final structure is obtained. This is the most widespread process to date. However, some players are interested in using injection 3D concrete printing, which consists of depositing a fluid material in another material with specific properties. The first material is maintained in a stable way in the second one, which allows users to create more complex structures. For example, French start-up Soliquid, which has developed a process for printing concrete parts in a gel matrix. One of the co-founders, Amaury Thomas, is a co-author of this study.
Injection concrete 3D printing would allow for more complex designs (photo credit: TU Braunschweig)
In their work, they explain that Injection 3D Concrete Printing (I3DCP) could be classified into three categories: injection of a fine-grained concrete into a non-hardening carrier liquid; injection of a non-hardening suspension into a fine-grained concrete; injection of a fine-grained concrete with specific properties into concrete with different properties. The team chose the first category and therefore injected their material into a liquid, in this case into ground limestone.
In the paper the researchers expanded, “For a deeper understanding of the underlying physical mechanisms, we carry out experiments that vary the rheological properties of the carrier liquid, the concrete flow rate, and the nozzle displacement velocity. We use a ground limestone suspension as carrier liquids in this study. We investigate the effect of the rheological properties of the carrier liquid on the positional stability of the injected concrete in small-scale print experiments. Based on this, we develop an analytical model that describes the positional stability as a function of the rheological properties.”
Photo Credits: TU Braunschweig
As the pictures show, it seems that the structures printed in 3D via this process are more complex in terms of shape: instead of a block of material, there are concrete strands that interlock with each other. This method could be used in the aerospace sector, in particular to imagine innovative light structures capable of going into space. Or at least this is the goal of the researchers – you can find their entire study HERE.
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