Printing a solid, freestanding building in a day just got more feasible. Spanish architectural students created a portable, solar-powered robot that can construct 3-D shapes from sand or dirt and a nontoxic binding agent. The robot has already sprayed out small, incredibly strong structures.
The Stone Spray project is the brainchild of Anna Kulik, Inder Shergill and Petr Novikov from the Institute for Advanced Architecture of Catalonia in Barcelona. Their instructor, Marta Malé-Alemany, gave them a seemingly simple assignment: Create a robot that could work like a 3-D printer, only for manufacturing.
Existing robots can build on-site, but they have disadvantages. One requires prefabricated components, another only works with one material and several are just huge. The students wanted to make their prototype ecologically sound and small enough to be transported easily.
With help from Institute supervisors Jordi Portell and Miquel Lloveras, the group tackled technical challenges from nozzle design to the ideal additive. Using a prototype that only cost 150 euros, which is less than $200, they landed on a mixture of dry sand or soil and a small amount of binding agent from the LEED-compliant company PolyPavement. One liter of the agent can solidify 35 cubic feet of dirt. Although the exact recipe is proprietary, Novikov said it's essentially a combination of acrylic and ethylene acrylic rubber, often used on country roads.
When hooked up to a set of solar panels and controlled with CAD software, the multi-directional robot successfully deposited the mixture into Gaudí-like sculptures. Dry sand helped the structures cure quickly. Once completed, the sculptures were so strong that they didn't break when hit with a baseball bat, Novikov said. Next the team plans to make the nozzle more precise and incorporate solar power directly into the bot. They want to spray larger architectural structures, including bridges.
The students hope that one day their Stone Spray robot will be used as a humanitarian tool sent to disaster areas and difficult climates for constructing safe, sturdy shelters. "You just need to bring the robot, a bottle of PolyPavement, and you don't need any other building materials," Novikov said. "All the materials are under you."