Construction work as we well know is a team effort, requiring the synchronization of workers, equipment and materials.  And just as construction workers need to be trained to work among and around their fellow workers, getting robots to do the same, until now, has been a tougher nut to crack.

Scientists from Nanyang Technological University (NTU) in Singapore have unveiled a technology that allows two robots to work in tandem to 3D-print concrete structures and building components, which could be revolutionary for the industry.

Concrete has long been a prized material, for its relatively low cost, its strength and its durability.

Concrete has long been a prized material, for its relatively low cost, its strength and its durability. But it’s never really been a material synonymous with complex, intricate structures, as it’s typically formed into uniform shapes and surfaces after being poured into a cast to harden.

Concrete so far has had limited usefulness as a 3D printing medium, since current methods require printers that are the same size or larger as the object being printed, which isn’t always possible in cramped urban construction sites. The robots being developed by NTU are considerably smaller in size and better able to navigate close quarters, opening the door to broader 3D printing applications on the job site.

This new method of 3D printing concrete with simultaneously operating robots is known as “swarm printing,” and it’s exactly what it sounds like. NTU’s robots, which look like articulated robot arms on a fixed platform, are capable of creating large structures if given enough room to operate, but also performing fine detail work like ornate architectural features and custom-designed facades using a specially formulated cement mix designed to be 3D printed.

Watching them in action, you can almost hear the Nutcracker Suite in your head as the machines gracefully print a seamless 1.86 meter concrete structure in just eight minutes, all while carefully avoiding one another. After two days of curing and a week to reach full strength, the structure was ready to be installed.

NTU Assistant Professor Pham Quang Cuong heads up the NTU Singapore Centre for 3D Printing. Pham was the scientist behind the famous so-called Ikea Bot from earlier this year, which saw a pair of robots fully assemble an Ikea chair in under nine minutes.

“We envisioned a team of robots which can be transported to a work site, print large pieces of concrete structures."

“We envisioned a team of robots which can be transported to a work site, print large pieces of concrete structures and then move on to the next project once the parts have been printed,” Prof Pham from NTU’s School of Mechanical and Aerospace Engineering said in an NTU news release.

“This research builds on the knowledge we have acquired from developing a robot to autonomously assemble an Ikea chair. But this latest project is more complex in terms of planning, execution, and on a much larger scale.”

The robots operate using a computer-designed map as a guide, which assigns specific printing sections to each robot. Part of that design process is ensuring the arms will not collide during the running of the program, which is calculated using a special algorithm.

Concrete 3D printing is especially challenging because a structure cannot be simply printed in segments and fitted together, as the joints where the parts meet won’t properly bond if they don’t overlap during the printing process, NTU writes. The swarm printing robots use precise location positioning to ensure all joints between the parts overlap during printing.

Swarm printing brings together several construction technology trends, from advanced materials science to robotics to 3D printing to artificial intelligence. The minds behind the technology see it having great potential in the industry as it’s perfected and iterated on.

The minds behind the technology see it having great potential in the industry as it’s perfected and iterated on.

“This multiple robot printing project is highly interdisciplinary, requiring roboticists to work with materials scientists to make printable concrete. To achieve the end result of a strong concrete structure, we had to combine their expertise with mechanical engineers and civil engineering experts, says Professor Chua Chee Kai, Executive Director of the Singapore Centre for 3D Printing.

“Such an innovation demonstrates to the industry what is feasible now, and prove what is possible in the future if we are creative in developing new technologies to augment conventional building and construction methods.”

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