3D concrete injection printing: are we moving towards the manufacture of more complex structures?
In Germany, researchers from the Technical University of Brunswick are working on the development of a new 3D concrete printing process. Instead of currently available technologies, they instead rely on injection to design more complex shapes. To do this, the researchers inject a fine-grained concrete into a non-hardening carrier liquid (a suspension of crushed limestone to be exact). The latter acts as a matrix which supports the structure; 3D concrete injection printing could thus make it possible to imagine complex designs that would be impossible to achieve 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. It is the most widespread process to date. However, some players are interested in the use of 3D concrete injection printing, which consists of depositing a fluid material in another material with specific properties. The first material is stably held in the second, which allows users to create more complex structures. For example, the 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 co-author of this study.
In their work, they explain that Injection 3D Concrete Printing (I3DCP) could be classified into three categories: injection of fine-grained concrete into a non-hardening carrier liquid; injection of a non-hardening suspension into fine-grained concrete; injection of fine-grained concrete with specific properties into concrete with different properties. The team chose the first category and therefore injected its material into a liquid, in this case in crushed limestone.
In the article, the researchers developed, “For a better understanding of the underlying physical mechanisms, we perform experiments that vary the rheological properties of the carrier liquid, the concrete flow rate and the nozzle movement speed. We use a suspension of crushed limestone as carrier liquids in this study. We study the effect of the rheological properties of the carrier liquid on the positional stability of injected concrete in small-scale printing experiments. On this basis, we develop an analytical model that describes positional stability as a function of rheological properties.
As the pictures show, it seems that structures 3D printed via this process are more complex in terms of shape: instead of a block of material, it’s concrete strands that fit together. This method could be used in the aerospace sector, in particular to imagine innovative lightweight structures capable of going into space. Or at least that’s the researchers’ goal – you can find their entire study HERE.
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