Progress Group has developed a new form of concrete 3D printing.
Their process, called “selective paste intrusion”, or “SPI”, is somewhat reminiscent of other 3D print processes, but utterly unlike any of the common 3DCP processes that normally extrude concrete.
The standard 3DCP setup today involves mixing cement and aggregate externally, and then using a concrete pump to push it to a toolhead. The toolhead then moves around to selectively deposit the concrete, layer by layer.
SPI is also layer by layer, but quite different. It is similar to a powder-based binder jet system, but different.
Here’s how it works. A layer of pure aggregate (sand in this case) is laid down. A toolhead then moves over the aggregate base and selectively deposits cement paste. This mixes with the aggregate, forming concrete. Then, just like SLS, SLM or similar processes, another layer of aggregate is spread over the print bed and the process repeats.
After a number of layers are deposited, the concrete object is inside the build chamber, buried in loose aggregate. It needs only to cure and then be removed from the aggregate.
This is a very interesting process because, like most powder processes, overhangs are automatically supported by the loose powder, or in this case the loose aggregate. That means that SPI could be used to print quite complex geometries. This is very different than 3DCP, which can handle only the smallest of overhangs.
Because of the nature of SPI, they don’t intend on using it to print entire buildings or even walls. Instead, their goal is to print concrete components for buildings, such as facade elements, formwork or artistic components.
The build volume is large, but smaller than some of the enormous 3DCP systems. Progress Group said the build volume of their SPI10 system is 4000 x 2500 x 1000 mm. That’s large enough to print big concrete components, but not large enough to print a building or much of a wall.
They say, however, that they can customize the size of the machine for buyers requiring somewhat different dimensions. They also provide a print service for customers, using their own in-house equipment.
Progress Group said that SPI provides the “highest print resolution on the market”, for concrete devices, presumably. The process also uses standard cement and aggregate mixes, unlike some of the 3DCP solutions that require tweaked mixes to ensure proper flow to the toolhead.
The SPI process isn’t the entire answer for concrete 3D printing, but certainly should be a large part of the solution. Many projects require smaller, high-resolution concrete elements, and it looks like Progress Group can make them with SPI equipment.
Via Progress Group
