Massachusetts Institute of Technology researchers have made recycled plastic into floor trusses for housing, arguing the waste stream could provide an abundant and sustainable structural building material. The US-based researchers 3D printed a functional, construction-grade element using a composite material they developed from recycled polyethylene terephthalate (rPET) plastic – mostly derived from discarded drinks bottles – mixed with glass fibres.
In the future, they say the system could be used in place of wood for house frames, making residential building cheaper while avoiding the overexploitation of forests. “We’ve estimated that the world needs about 1 billion new homes by 2050,” said engineer and inventor AJ Perez, who led the project. “If we try to make that many homes using wood, we would need to clear-cut the equivalent of the Amazon rainforest three times over.”
To make the floor trusses, Perez and his collaborators 3D printed their polymer composite into a long rectangular element reinforced by an internal zigzag shape, similar to the structure of traditional wood and metal floor trusses. Four of these trusses were configured into a plywood-topped floor frame and bend-tested by placing concrete blocks on top.