There are many sectors of industry being shaken up by the transformative technology of 3D printing but it is nothing compared to the disruption that is coming to construction.
Construction remains a largely manual work, which makes it very expensive. It also makes the global need for housing and infrastructure very hard to meet.
Construction is open to being disrupted by automation, and 3D printing is one technology that can help.
Although 3D printers are commercially available for manufacturing, there are significant differences between printing aeroplane parts and printing a house.
It needs to be printed out in the weather instead of printing in factory conditions,
Tonnes of materials need to be handled rather than just a few kilos. And although there is no need for the same accuracy as the aerospace industry, that has to be traded for low cost.
Two approaches were explored to address the challenges. The interim option is to ‘powder bed’ 3D printing.
This means that the printer spreads a thin layer of concrete powder, then prints a water-based ‘ink’ that sets the concrete where the ink is applied.
The process is repeated layer by layer. The challenge here was to automate the collection and reuse of the vast quantities of unreacted powder that each print run generated.
Powder bed was a good option for forming precast sections of a building in a factory. Intricate structures can be made but it was not a process that can be done out in the wind and rain.
For onsite concrete printing, a machine is needed that extrudes liquid concrete. And the main issue here is the concrete itself.
The concrete must remain liquid inside the printer, but set as soon as it is printed to retain its shape in order for the next layer to be applied.
Traditional concrete does not behave this way. Currently, the most common approach is to heavily dose the concrete with chemical retardants that keep it liquid and then heavily dose it with accelerators as it is extruded.
But this approach compromises the mechanical properties of the finished product.
New types of cement are being made that have these properties intrinsically/
Although the details cannot be disclosed yet, one option is to use geopolymer cement, which is a material made from an industrial waste called fly ash.
Architects already design everything by computer so instead of printing their plans out on paper, the ultimate dream may be achieved with 3D printing.
Just press the button and the machine will start building the design.