By Isabelle Robinson, M.Sc.Apr 9 2018
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Since 2004, when Professor Behrokh Khoshnevis of the University of South Carolina first 3D printed a concrete wall, 3D printing in infrastructure has developed at an alarming rate. The FDM 3D printer has a robotic arm that extrudes concrete layers to create a 3D model.
The technology is called Contour Crafting and can reduce construction costs, reduce material waste, reduce the construction time as well as accidents on sites. The 3D concrete printing technology is evolving rapidly and the market is expected to hit highs of $56.4 million by 2021. However, the current technology is still bound by limitations.
The method of contour crafting is used to create large-scale 3D models with a smooth finish. To create this, rails are implemented around the site. These are installed in order to guide a robotic arm that moves backward and forward to print concrete over many layers that eventually create a 3D model or piece of infrastructure.
To ensure the strength of the infrastructure, trowels are used above and to the side of the nozzle. This is to ensure the extruded layers are flattened. It is important that quick setting concrete is used in the process. This is because conventional concrete would take a long time to harden and therefore increase construction time.
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The machines used can be up to 32 m long, 10 m wide and 6.6 m tall and can be used to print full structures. These structures can be made on-site with the use of concrete and glass fibers.
Construction Companies and 3D Printers
Construction companies have used a wide variety of technologies to develop 3D printing machines. Constructions-3D is a French company that uses a polar 3D printer; a machine that prints the structure in situ and then can leave through the front door. Similarly, Cazza Construction’s 3D printer is a mobile crane system that allows the company to create larger structures.
‘The man who 3D prints houses’, also known as Enrico Dini, is an Italian architect who uses a D-Shaped 3D printer to create interesting structures. This machine uses layers of sand mixed with binding powder to make it harden. This machine is 4 m wide by 4 m long and is able to create a smaller structure of around 6 m3 in size.
Furthermore, the Dutch company MX3D, in collaboration with Air Liquide and ArcelorMittal, has created an alternative and innovative construction method known as Wire Arc Additive Manufacturing (WAAM). This method allows consumers to create metal structures using a 6-axis machine. This method can print 2 kilograms of material per hour.
The 3D printer used by MX3D is made up of a welder and a nozzle. These are used to lay the metal rods layer by layer. This robot is compatible with stainless steel, bronze, aluminum, and Inconel, and works similarly to a soldering iron. MX3D has proclaimed that “we combined an industrial robot with a welding machine to turn it into a 3D printer that works with our own software.”
It is true that 3D printing is an ever-evolving field and has become a viable solution for many construction projects. Engineers will have to wait and see how far this new technology will push the boundaries of infrastructure.
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