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Sustainable 3D-Printed Glass Masonry

MIT engineers produce fully recyclable interlocking glass bricks

By Rain Noe - September 23

in Sustainability | Digital Fabrication

Circular manufacturing doesn't work with conventional masonry. Once you lay bricks or cinderblocks and mortar them into place, you can't practically smash them up to make new bricks or blocks. But a team of engineers at MIT has figured out that you can—if you use glass.

The team has successfully produced 3D-printed glass bricks, and their feedstock is molten recycled glass. "In mechanical testing, a single glass brick withstood pressures similar to that of a concrete block," they write. Moreover, the bricks can be melted down and re-printed.

"Glass is a highly recyclable material," says Kaitlyn Becker, assistant professor of mechanical engineering at MIT. "We're taking glass and turning it into masonry that, at the end of a structure's life, can be disassembled and reassembled into a new structure, or can be stuck back into the printer and turned into a completely different shape. All this builds into our idea of a sustainable, circular building material."

The bricks are printed in a figure-8 shape, and have two protruding pegs in the top, with corresponding holes in the bottom. This allows the bricks to lock together.

What they haven't addressed, or explained, are the details of any required mortar. They only say "Another material placed between the bricks prevent scratches or cracks between glass surfaces but can be removed if a brick structure were to be dismantled and recycled, also allowing bricks to be remelted in the printer and formed into new shapes." It's not clear what that material is.

The team has successfully built a curved wall with the bricks, and next aims to build larger self-supporting structures for evaluation. "We're thinking of stepping stones to buildings," says Kaitlyn Becker, MIT Assistant Professor of Mechanical Engineering, "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."

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The printing technology was developed by MIT spinoff Evenline, whose machines can do what you see above and below.

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Zach W

a month ago

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I hate to say it but the production of glass is anything but sustainable. The amount of energy required to melt the glass is astronomical. Yes, you can re-melt glass over and over but where is the heat energy coming from???? Certainly not wind power.....

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- m stauffer
  
  Zach W
  
  a month ago
  
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  Furnaces can be run on electric power. These could be powered by solar or wind energy. That capability has been available for years.
  
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Einar Blixhavn

a month ago

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There was an article on this site, about a machine that made bricks from rubble. This article effectively refutes the opening statement of this article. You can make new bricks from old bricks and mortar, and some people have already built a machine that can do that.
From a energy usage point of view, 100% of the mass in a glass brick will have to be heated, while for a brick made from rubble, only the binding agent (i.e. cement) will have to be heated, so much less. The other aspect is how dependent this glass is on correct cooling. If a cooling kiln is needed, it is more like a factory, and these bloks are just a version of the Heineken brick-bottle.

If however no post-printing cooling is needed, then one could take the machine to where the glass is, and in sunny climates one could probably use computer controlled mirrors to melt the glass, and make it the right temperature. If this could be achieved, then it could have some potential. Especially in countries that rely on local manufacture.

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