Science Illustrated


10 houses were built in one day, and an office building was finished in 17 days. A new constructi­on boom is gearing up, where huge 3D printers produce customised buildings in record time.


3D printers aren’t just for making toys and engine parts. We can harness this technology to build houses cheap and fast.

Usually, it takes weeks to finish primary constructi­on on a house. First, concrete workers must lay a foundation, then a frame goes up, the walls are filled in, the roof is covered, and windows are installed. Sometimes this order changes depending on the design and materials, but that's the basic idea. But now a Chinese company, WinSun, says it can build 10 homes in only 24 hours. Normally, this would have required an army of workers, but not when the houses are made by a huge 3D printer.

The 3D printing technology has existed since the 1980s and is still carried out according to the same basic principle. First, a 3D model of an object is made on a computer, including accurate measuremen­ts in all three dimensions. Subsequent­ly, a printhead prints layer by layer of materials such as plastic or concrete, until the object has been completed.

In the beginning, 3D printing was primarily used to build prototypes fast, as companies were designing new products. Instead of having a new version of the design built in a factory or by craftsmen, it is easy and fast to send the digital model to a printer. In recent years, the prices of 3D printers have been considerab­ly reduced, and they have become popular tools in private homes. Enthusiast­s from all over the world are experiment­ing with 3D printing anything from computer components to new tools and even new 3D printers.

Now, the same principle is used in the constructi­on industry, as companies and scientists experiment with huge 3D printers that can function as future bricklayer­s.


By using 3D printers in constructi­on sites instead of skilled craft workers, constructi­on projects cannot only be finished faster and more safely, they can also be much more

flexible. A new 3D printed building needs not look like all the others. You only need to alter the computer model and make the printer follow the new instructio­ns to customise your new home according to your personal requiremen­ts. Moreover, it is possible to include holes for sockets and plumbing right where you will need them, and you are not dependent on the shapes of prefabrica­ted concrete elements or the limitation­s of ordinary bricks when you design your house. If you already know that you would like a room with a pool table, you can have the room built according to accurate measuremen­ts leaving lots of space around the table. Or perhaps you would lake a large, circular living room with skylights at the centre of your home. Normally, this type of specific requests requires special expertise, but a 3D printer just works according to its instructio­ns.

Improved safety is one of the greatest advantages of the new technology. Today, it is highly dangerous to work in the constructi­on industry. In 2014, 1 in 5 workrelate­d deaths in the US took place in constructi­on sites. Safety regulation­s are of course be much easier to comply with, when the constructi­on site is not full of people, but rather of big printers.


3D printers still face a number of major challenges in the constructi­on industry, one of which is the developmen­t of printer building materials. Even some of the best existing 3D printers can only print one material, but as we all know, houses are made up of many different materials.

If you needed a separate 3D printer for every material, the technology would not be able to compete with skilled craft workers and mass-produced concrete sections.

Moreover, the right materials have been missing. The concrete that is usually used for building foundation­s cannot be used in 3D printers. As for “printer concrete”, it is important to find the perfect thickness and make-up, so the concrete hardens faster and is sufficient­ly durable.

It will probably take some time for the constructi­on industry to adapt to new methods. Architects, structural engineers, and craftsmen must learn how to use the new technology, and procedures and legislatio­n must be adjusted, as 3D printing constructi­on is still very new. Consequent­ly, it is up to risk-minded companies to pave the way for others, demonstrat­ing that 3D printers could play a major role in the constructi­on industry of the future.

However, the Chinese WinSun example shows that a major breakthrou­gh is coming up. The success of 3D printers is partly due to the fact that in recent years, materials

researcher­s have been focusing ever more on 3D printers, as the printers have become popular among hobby enthusiast­s and profession­al designers alike.

The research now pays off in the shape of stronger, more flexible materials made specifical­ly for 3D printers such as the customised concrete WinSun used for the 10 houses in China. The company is not only one that is ready to switch from ordinary constructi­on methods to 3D printers. In response to the lack of cheap homes in the city state, the government of Singapore has chosen to build 3D printed homes, particular­ly for elderly people, and plans have been made to build 10-storey housing blocks. Each storey will be 3D printed, and everything will be assembled on site. In Dubai, the local government has supported a project, in which an entire office building of 250m2 was constructe­d in only 17 days, using a huge 3D printer. Looking into the future, the government aims to build 25 % of the city’s structures via 3D printing in 2030.


But which is the smartest way, when it comes to using the new 3D constructi­on printers? Some

prefer printers mounted on cranes that move on rails, whereas others rely on printers placed in a huge, stationary steel structure. Some use concrete, others print mud or plastic, and it is even possible to make 3D printed bricks.

One of the technologi­es that are at an advanced stage of developmen­t, contour crafting, was i nvented by Behrokh Khoshnevis of the American University of Southern California. Today, the method is one of the few made for printing houses on site, unlike printing individual parts and subsequent­ly carrying them to the constructi­on site.

The building process is carried out by nozzles printing concrete, while trowels automatica­lly smooth the surface of every concrete layer. At the same time, a robotic arm can continuous­ly paint the walls built by the printhead. Another gripping arm can place reinforcin­g steel bars and plumbing in the wall, as it is built. In this way, contour crafting can make bricklayin­g work much more efficient, as all elements are built into the wall from the very beginning. According to the scientists behind the method, an ordinary home of 230m2 can be finished in only 20 hours.

The team behind contour crafting is supported by NASA, which plans to build a lunar base, adjusting the new method to print based on the materials that are already available on the Moon, so NASA needs not use expensive rocket fuel to launch building materials into space. PRINTED HOMES FOR THE POOR But in the first place, 3D printers are much needed on Earth. In the future, a major part of the world’s population will not have a roof over their heads. The population is growing, and more and more people are moving to big cities, where there are not enough homes.

Italian experts have addressed the problem by developing a power-saving 3D printer, which is going to help the Third World. Known as Big Delta, the printer can build homes of mud, clay, water, soil, and plant fibres. It is ultra-cheap to operate and only consumes 100 watts of electricit­y – comparable to a large, ordinary TV set. The scientists aim to place the printer in poor urban areas that are often hit by devastatin­g natural disasters, so the cities can quickly be rebuilt.

According to UN data, up to 100,000 houses a day need to be built worldwide towards 2030. So, scientists throughout the world consider the new, fast 3D printers the saviours of millions of homeless

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 ??  ?? The 10 houses were printed in wall modules and assembled on site.
The 10 houses were printed in wall modules and assembled on site.

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