A Modern Experiment Rich in Potential
3D Printing in Construction
3D (three-dimensional) printing has been maturing rapidly since the beginning of the decade, although the process can be traced back to a 1984 patent filing by a group of French inventors – Alain Le Mehaute, Oliver de Witte, and Jean Claude Andre. As Alain Le Mehaute recounts in an interview with the French website, Primante3D, their patent application was abandoned by the French General Electric Company where they worked. Just a few weeks after this initial patent application, Charles Hull filed a patent for a similar process that he called Stereolithography and was granted the patent.
The main limitation of this early form of 3D printing, compared to what is available today, was in the range of materials that could be used. Stereolithography was typically limited to polymers and resins, while today a much broader variety of materials are available.
The principle at the core of 3D printing, however, involves translating a computerized design schematic, which typically begins as a computer-aided design (CAD) diagram, into a physical object. The 3D image is ‘sliced’ into a multitude of two-dimensional layers, which are then fed to the 3D printer and turned into a physical object layer-by-layer. This technique is called additive manufacturing because an object is built up from nothing, through the process of adding layers.
One of the key reasons that 3D printing has been taking off in recent years is due to the expiration of many of the early patents that are responsible for its invention, as John F. Hornick explained in a 2016 article in the Robotics Business Review. “From 2002 to 2014, about 225 early 3D printing patents expired. About sixteen key patents relating to 3D printing processes called material extrusion, powder bed fusion, and vat polymerization expired in 2013-2014. This means that 3D printing technology that is at least twenty years old is now available for anyone to use,” he said.
Hornick also pointed out, however, that, although patent expiration means that these technologies are now in the public domain, it can be complicated to figure out “when a patent actually expires.” Also, the scope of what becomes public domain after a patent expires is limited to the exact technology covered by the expired patent. In this sense, the cost reductions that result from patent expiration may be more limited to consumer 3D printing devices, rather than industrial ones. However, it does seem to allow for a greater range of innovation in this space, starting from a now public domain technological foundation.
Adapting 3D printing to the construction industry comes with a unique set of challenges, primary among them being the size and scale of the objects with which the industry typically deals. It is one thing to use the technology to manufacture a consumer object such as a shoe or even parts of an airplane, but how do you print a skyscraper or even a house? 3D printing at the scale of construction involves large-scale additive manufacturing (LSAM) and methods such as extrusion, powder bonding, and additive welding. However, the vast majority of current 3D printing work in construction uses extrusion to distribute concrete or a concrete-like paste from a nozzle to form the outer walls of the structures.
Familiar methods of 3D printing, which typically involve producing an object inside a printing machine are not always feasible for the construction industry. To this end, Behrokh Khoshnevis is credited with inventing contour crafting, one of the stand-out technologies now in development to adapt 3D printing to the construction industry.
Contour crafting is a bit like a gigantic 3D printer without an enclosure, making use of extrusion nozzles that disperse fast-drying concrete to build the structure from the ground up. In a 2015 interview with Khoshnevis for 3DPrint.com, he envisioned the technology maturing to the point that building infrastructures such as plumbing and electrical wiring can also be installed at the same time that the structure is being ‘printed.’ While this process certainly has a lot of promise, it is still in the early stages of development.
Toward the end of 2017, Shanghai-based company, WinSun 3D used similar technology to produce a 3D printed bus stop. According to a report by industry magazine 3D Printing Industry, the company plans to create other 3D structures in and around the Zhangjiang Yangtze River Delta science and technology city, a planned settlement along the border between the Shanghai and Zhejiang regions.
Cazza Construction showcases another way of tackling the use of 3D printing in the construction industry. Instead of printing materials off-site or within a large enclosure like the contour crafting method, Cazza puts the 3D printing nozzle on a long, crane-like apparatus that is attached to a robot, allowing for greater adaptability. The technique of ‘printing’ the building materials is not that different from the one used by contour crafting, but the apparatus is more flexible. The technology, however, has not yet been proven and is, as yet, only a concept the company plans on developing.
In large part, these are the areas in which 3D printing is being actively adapted to the construction industry, and given the scale and the logistics involved in such projects, there is still a way to go before the technology has matured to the extent that it can be put into widespread use. The advantages, however, are fairly clear. WinSun 3D, for example, built its bus shelter from raw, recycled materials, according to industry magazine 3DPrint.com. Coupled with the reduced waste that comes naturally to additive manufacturing methods, this could, no doubt, prove to reduce construction costs significantly and in an environmentally friendly way.
3D printing in the construction industry also has the potential to reduce the time required to build structures. It took, for example, one day to make WinSun 3D’s bus shelter. However, WinSun also claimed, in a 2014 press release, to have built ten single-story houses in twenty-four hours.
There are still considerable challenges to adapting 3D printing technology to the construction industry, particularly compared to how the technology is being used in manufacturing. “Currently none of these systems can handle major elements of the construction process of a regular building, such as electrical services, plumbing, doors, windows, joinery, and finishes,” Antu Nelson reported in Scultpteo back in 2014. The application of 3D printing to construction, then, requires considerable human labour to make up for its technological limitations. As of 2018, this remains true, but the technology nevertheless continues to advance.
Regulation, too, continues to be an issue that 3D printing in construction has yet to surmount, as Oliver Balch pointed out in a Guardian article from January 2017: “Building by Numbers: How 3D Printing is Shaking Up the Construction Industry.” Regulation is one area where 3D printing meets a unique challenge, compared to its counterpart in manufacturing. There is yet “no track record,” of safety standards for 3D printed buildings, which is a problem given that standards “for conventional building materials have been honed over the decades to ensure our built environment is safe and dependable.”
Given the complexity involved in construction, it is difficult to say whether the advances will truly take root in the next ten to twenty years, and it is important to note that much of the focus on 3D printing in construction involves creating the walls that form the skeleton of the structure. There is less focus, at the moment, on other key aspects of constructing a building or structure, such as plumbing, electrical, insulation, windows, and doors. Although, as 3DPrint.com reported in January 2018, Swedish company NorDan has taken an interest in using 3D printing to create doors and windows. This, however, remains at the moment an experimental method of making these specific elements and is separate from attempts to construct larger structures such as skyscrapers and houses using 3D printing technologies.
Nevertheless, as a method for constructing pre-fabricated parts of a larger structure off-site or even as a method for making basic parts of a larger structure, 3D printing in construction has much potential. Not only can it save the raw materials used in construction, but it also allows for other kinds of recycled materials to be used. In this sense, 3D printing may – for now – be best thought of as a supplement to traditional construction processes, rather than a replacement of them, much less an area in which there is an imminent possibility of automating the construction industry.
It is worth watching the technology advance, as the strides made, however small they may sometimes seem, have the potential to bring important changes to the way we think about and build the structures around us.