3-D printing enters the construction business

MIT researchers develop robot that can build a structure autonomously

The future of construction just got a little bit more present-day. Researchers at MIT have created a mobile robot that can 3-D print an entire building in a matter of hours — a technology that could be used in disaster zones, on other planets or even in our own backyards.

Though the platform described in the journal Science Robotics is still in early stages, it could offer a revolutionary tool for the construction industry and inspire more architects to rethink the relationship of buildings to people and the environment.

Current construction practices typically involve bricklaying, wood framing and concrete casting — technologies that have been around for decades, if not centuries. Homes and office buildings are often built from the same boxy, cookie-cutter-like templates, even though the environment from one area to another may change dramatically.

“The architecture, engineering, and construction (AEC) sector tends to be riskaverse: Most project fabrication data nowadays have been digitally produced, but the manufacturing and construction processes are mostly done with manual methods and conventional materials adopted a century ago,” Imperial College London researcher Guang-Zhong Yang, the journal’s editor, wrote in an editorial on the paper.

In recent years, scientists and engineers have begun exploring the idea that buildings could instead be built through additive manufacturing — that is, 3-D printing. A home could be customized to its local environment, it could use building resources more efficiently, and it could deploy materials in more sophisticated ways.

“Right now, the way we manufacture things is we go to the mine, we dig out minerals and materials, we ship them to a factory, the factory makes a bunch of mass-made parts, usually out of a single material, and then they’re assembled — screwed together, glued together and shipped back to consumers,” said lead author Steven Keating, a mechanical engineer who did the research as a graduate student under Neri Oxman’s group at the Massachusetts Institute of Technology.

But the group’s many projects, he added, revolved around this question: How do we actually fabricate in a way that is more consistent with how biology works?

Keating pointed to the tree as one example of a natural builder. Trees can self-repair, operate self-sufficiently, build on-site with locally sourced materials, and adapt to their environment.

“These are the kinds of principles that we’ve looked at for a lot of the projects in the group,” he said.

While several groups around the world have been working on large-scale 3-D printing techniques, there have been challenges in this process, Keating said.

“A lot of other research projects that are looking at digital construction often don’t create something of an architectural scale — and if they do, they’re not using a process that could be easily integrated into a construction site,” Keating said. “They’re not using materials or a process that can be easily code-certified. And what we wanted to make sure could happen is we could actually break into the construction industry, because it’s a very slow and conservative industry.”

Keating and his colleagues’ robot, called the Digital Construction Platform, seeks to address those issues. It features hydraulic and electric robotic arms and can be loaded with sensors, including lasers and Geiger counters, to measure the environment.

In about 13 hours, the robot was able to zip round and round, printing out of foam an open dome structure, 14.6 meters wide and 3.7 meters tall, that is ready to be filled with concrete. Since this is essentially what already happens in traditional construction, such a process could be integrated into current construction techniques. (In both traditional and 3-D printing scenarios, the formwork ends up as the building’s insulation.)

This process has a number of advantages that allow the robot to design and build more like living systems in nature do, Keating said. Three-dimensional printing uses fewer materials more efficiently. It can also create useful gradients, such as reducing wall thickness from the bottom of a wall toward the top. (Nature does this too: Think of a tree’s trunk at the base versus near the top.) This process can create and work with curves, which are usually more costly for traditional building methods.