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Homebuilder Hopes 3D Printing Will Remedy Labor Shortages, And Checks Expertise In 100 Houses

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Enlarge / Icon’s Vulcan building system prints walls layer by layer in 3D using specially formulated concrete.

ICON Technology, Inc.

Construction companies have been experimenting with 3D printing for years, but next year a major home builder in Austin, Texas will break the ground for the largest such development yet.

The new community will consist of 100 houses, the first floors of which will be made of 3D printed concrete and finished using traditional timber frame construction techniques. Construction technology startup Icon will take care of the 3D printing portion, and Lennar, a large home builder, will finish the houses. Bjarke Ingles Group, known for their creative and whimsical buildings, helps with the design.

Icon had previously built four houses in Austin using its 3D printing technology. “We’re graduating from singles and dozens of houses to hundreds of houses,” CEO Jason Ballard told the Wall Street Journal.

While the company hopes 3D printing will ultimately be cheaper and faster than traditional building methods, houses in the proposed Austin development will take about as long and cost about as much to build as wooden-framed houses . Right now, Icon can 3D print the first floor of a house in about a week.

Ultimately, the construction industry hopes that new technology will help alleviate the labor shortage that continues to plague the industry despite higher unemployment rates.

Squeeze houses

To build the first floor of a house, Icon sets up a gantry-style 3D printer that effectively wraps a huge frame around the base of the house and helps the print head walk around. Concrete is pressed out of a nozzle and looks like soft ice cream. The resulting walls have a layered appearance that resembles a crushed pile of pancakes. Other companies do without the portal and instead use a robotic arm that they move around the construction site. The end result looks pretty much the same.

Icon has built four houses in East Austin using its 3D printing technology.  The walls on the first floor were made of printed concrete, while the second floor and the surfaces were finished using traditional techniques.Enlarge / Icon has built four houses in East Austin using its 3D printing technology. The walls on the first floor were made of printed concrete, while the second floor and the surfaces were finished using traditional techniques.

ICON Technologies, Inc.

Earlier builds apparently relied on the material’s thermal mass to keep occupants comfortable. This works in regions with strong temperature fluctuations from day to night, but with relatively small differences between the seasons – the thermal mass buffers the daily highs and lows. But in places where there are major temperature fluctuations between the seasons – or consistently warm or cool conditions – houses with concrete walls without additional insulation would be too hot or too cold for comfort. Icon’s newer houses have spray foam insulation that is injected into the air space between the outer and inner concrete walls.

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Many 3D printing construction companies claim that their technologies can help alleviate the housing shortage by reducing construction times and labor costs. This is not currently the case, but Lennar hopes that as the technology matures, its pace will increase.

Counting carbon

Another common claim is that 3D printing can reduce the environmental impact of house building. This claim seems to be based on waste reduction. Since 3D printing is additive rather than subtractive – printing uses only the material it needs while carpenters have to cut wood to length – the claim is likely to stand up to scrutiny.

Several companies are experimenting with 3D printing in residential construction, and most have chosen concrete as their material of choice. Icon uses a proprietary blend called Lavacrete that combines typical Portland cement with “advanced additives” designed to help it survive extreme weather conditions.

However, using concrete could significantly increase the carbon footprint of these homes. Cement, the primary binder in concrete, is responsible for 8 percent of the world’s carbon pollution, much of it from heating limestone, a process that changes the rock’s molecular structure and releases carbon dioxide. On the other hand, wood naturally binds carbon. According to a study, one square meter of floor space supported by concrete has a carbon footprint almost seven times greater than that supported by wooden beams. (The most suitable insulation for this application – spray foam – often uses high GWP gases, but newer formulations attempt to address this problem.)

There are various attempts to decarbonize cement right now, and a 3D printing company, Mighty Buildings, is partnering with materials science startup Fortera to use cement made from carbon dioxide, which the companies say will reduce its carbon footprint by 60 percent.

Another alternative would be to do without traditional cement entirely. Materials scientist Sarbajit Banerjee and his colleagues at Texas A&M developed a cement-like material made of silicates in combination with nearby clay, alkaline water and a little cellulose. Once cured, the 3D printable material withstood a pressure of almost 430 psi (about 3 MPa). This is nowhere near specific – other non-3D printed formulations are coming closer – but it’s not bad for a first run.

Correction, 3 p.m.: Icon’s newer homes have insulation within the double-layer concrete walls. We have updated the article to reflect this.

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