What if construction materials could be put together, taken apart, and reused as easily as Lego bricks? That’s the vision a team of MIT engineers hopes to realize with a new kind of masonry it’s developing from recycled glass. Using a custom 3D-printing technology provided by the MIT spinoff Evenline, the team has made strong, multilayered glass bricks, each in the shape of a figure eight, that are designed to interlock and stack. The bricks can easily be taken apart for reuse in new structures.
“Glass as a structural material kind of breaks people’s brains a little bit,” says Evenline founder Michael Stern ’09, SM ’15, coauthor of a paper on the work. “We’re showing this is an opportunity to push the limits of what’s been done in architecture.”
Stern and Kaitlyn Becker ’09, an assistant professor of mechanical engineering and another coauthor, got the inspiration for the bricks partly from their experience as undergraduates in MIT’s Glass Lab.
“I found the material fascinating,” says Stern, who went on to design a 3D printer capable of depositing molten recycled glass. “I started thinking of how glass printing can find its place.”
“I get excited about expanding design and manufacturing spaces for challenging materials with interesting characteristics, like glass and its optical properties and recyclability,” says Becker, who began exploring those ideas as a faculty member. “As long as it’s not contaminated, you can recycle glass almost infinitely.”
For their new study, Becker, Stern, and coauthors Daniel Massimino, SM ’24, and Charlotte Folinus ’20, SM ’22, of MIT and Ethan Townsend at Evenline used a glass printer that pairs with a furnace to melt crushed glass bottles into a material that can be deposited in layered patterns. They printed prototype bricks using soda-lime glass that is typically used in a glassblowing studio. Two round pegs made of a different material, similar to the studs on a Lego brick, are incorporated into each one so they can interlock. Another material placed between the bricks prevents scratches or cracks but can be removed if a structure is to be dismantled and recycled. The prototypes’ figure-eight shape allows assembly into curved walls, though recycled bricks could also be remelted in the printer and formed into new shapes. The group is looking into whether more of the interlocking feature could be made from printed glass too.
The bricks’ mechanical strength was tested in a hydraulic press that squeezed them until they began to fracture. The strongest held up to pressures comparable to what concrete blocks can withstand. The researchers have used the bricks to construct a curved wall and aim to build progressively bigger, self-supporting structures.
“We’re thinking of stepping stones to buildings,” Stern says, “and want to start with something like a pavilion—a temporary structure that humans can interact with, and that you could then reconfigure into a second design. And you could imagine that these blocks could go through a lot of lives.”
