Robot Builds Stable Architectural Support Columns with Just Gravel and String

Modern buildings are only viable because of materials used to support them. The tallest wood building in the world is 13 stories tall, which is still an amazing accomplishment in its own right. To build the towering skyscapers of today, steel beams and reinforced concrete are necessary. Even concrete itself is a fairly modern engineering feat. But, a new robot is now eschewing those materials to build structural columns from just loose pebbles and string.

This robot builder was created by the Gramazio Kohler Research Lab at the Swiss Federal Institute of Technology in Zurich with the express purpose of stacking pebbles. Each column that it constructs is made up solely of small rocks held together by string. This unusual construction method is currently being demonstrated on the Rock Print Pavilion in Winterthur, Switzerland, where eight columns are being used to hold up an eight ton steel roof.

The robot resembles a small backhoe, and stacks the tiny stones like a three-dimensional puzzle using computer vision. As it assembles each layer, it keeps the thousands of pebbles in place with just a thin piece of string. The structures remain stable thanks to jamming, which is the same effect that keeps the salt from falling out of an upturned shaker until you shake it. The string is really only there to keep the outer rocks from falling off the stack, and jamming provides the real strength. All told, the Rock Print Pavilion is made of 30 tons of gravel and 74 miles of string. It’s set to be destroyed and recycled next month, but proves the viability of this sustainable building method.