Engineers have created a new innovative type of masonry that is reconfigurable and constructed from 3D-printed, recycled glass. These bricks can be reused multiple times for facades and internal structures.
Imagine if building materials could be assembled and disassembled as easily as LEGO bricks? This reconfigurable masonry concept involves breaking down a building at the end of its life and reusing its components to construct new buildings, promoting a sustainable cycle that could serve generations with the same building blocks.
This concept is part of circular construction, which emphasizes reusing and repurposing materials from a building to limit the need for new materials and to decrease the “embodied carbon,” which encompasses all greenhouse gas emissions tied to the construction process, from creation to demolition.
Engineers at MIT, inspired by the potential of circular construction, are working on a new reconfigurable masonry made from 3D-printed recycled glass. With the help of Evenline, an MIT spinoff specializing in custom 3D glass printing technology, the team has produced robust, multilayered glass bricks shaped like figure eights, which are designed to interlock, similar to LEGO blocks.
In mechanical tests, a single glass brick was able to withstand pressures comparable to that of a concrete block. As a practical example, the team built a wall using these interlocking glass bricks. They believe this 3D-printable glass masonry could be repeatedly reused for both building facades and internal walls.
“Glass is highly recyclable,” explains Kaitlyn Becker, assistant professor of mechanical engineering at MIT. “We transform glass into masonry that can be taken apart and reassembled into a new structure at the end of its life, or it can be returned to the printer to be reshaped entirely. This aligns perfectly with our vision of a sustainable, circular building material.”
Michael Stern, a former graduate student at MIT and founder of Evenline, mentions, “Using glass as a structural element is truly mind-blowing for some people. We’re showcasing the potential to extend the boundaries of what architecture can achieve.”
Becker and Stern, along with their collaborators, present their glass brick design in a recent study published in the journal Glass Structures and Engineering. Their MIT teammates include lead author Daniel Massimino and Charlotte Folinus, along with Ethan Townsend from Evenline.
Lock step
The concept for this new circular masonry design originated partly from experiences at MIT’s Glass Lab, where Becker and Stern first engaged with glass blowing during their undergraduate studies.
“I found the material intriguing,” states Stern, who later designed a 3D printer capable of working with molten recycled glass while studying mechanical engineering. “This sparked my interest in how glass printing could have unique applications in various fields, including construction.”
In the meantime, Becker, after accepting a faculty position at MIT, began investigating the intersection of manufacturing and design to create innovative processes that facilitate new designs.
“I’m passionate about broadening the design and manufacturing landscape for challenging materials with unique features, like glass and its recyclability,” shares Becker. “As long as it remains uncontaminated, glass can be recycled virtually indefinitely.”
Becker and Stern collaborated to explore whether 3D-printable glass could be developed into a durable and stackable structural masonry unit similar to conventional bricks. For their study, the group utilized the Glass 3D Printer 3 (G3DP3), the latest version of Evenline’s printer, which works in tandem with a furnace to melt crushed glass bottles into a suitable molten form for printing in layered configurations.
The team produced prototype glass bricks using soda-lime glass, a common material in glassblowing studios. They added two circular pegs to each printed brick, akin to the studs on a LEGO block. These pegs allow the bricks to interlock and create larger constructions. Additionally, a material placed between the bricks helps prevent scratches or cracks on the glass surfaces but can be removed if a structure needs to be deconstructed and recycled, facilitating the remelting of bricks into new shapes. Ultimately, they opted for a figure-eight design for the bricks.
“The figure-eight shape lets us secure the bricks while assembling them into walls that can have gentle curves,” explains Massimino.
Stepping stones
The team printed and tested the mechanical integrity of the glass bricks using an industrial hydraulic press, which applied pressure until the bricks began to break. They discovered that the most resilient bricks could endure pressures similar to those tolerated by concrete blocks. These strongest bricks predominantly consisted of printed glass, with an interlocking component added separately to the base. The findings suggest that the majority of a masonry brick can be produced from printed glass, while its interlocking parts may be created through various methods—either printed, cast, or separately manufactured using different materials.
“Glass can be quite difficult to handle,” acknowledges Becker. “The interlocking components, which are made from another material, currently show the brightest prospects.”
The team is investigating the possibility of increasing the proportion of interlocking features made from printed glass, but they do not view this issue as a barrier to progress in scaling up their design. To showcase the viability of glass masonry, they fabricated a curved wall composed of interlocking glass bricks. Their next objective is to construct larger, freestanding glass structures.
“We now have a clearer understanding of the material’s limitations and the scaling process,” says Stern. “We’re envisioning intermediate steps towards building construction, starting with a temporary pavilion structure where people can engage and which could later be reconfigurable into a different design. These blocks have the potential for multiple uses throughout their lifecycle.”
This research received support from the Bose Research Grant Program and MIT’s Research Support Committee.
