Polymer bricks made of industrial waste bond together without mortar


Construction is one of the largest sources of greenhouse gas emissions, so finding new materials and methods is a crucial goal. Researchers at Flinders University have now developed a new type of polymer, made out of industrial waste, that can be formed into building bricks that bond together without needing any mortar.

Concrete is an extremely versatile material, but the production of cement is alone responsible for as much as 8% of all carbon dioxide emissions caused by humans. That huge footprint could be reduced by finding ways to incorporate waste materials like wood or old tires into the mix, using different binders, or developing alternative materials entirely.

The new study explores one such alternative. The team had previously developed polymers made mostly of sulfur left over from industrial processes, which could be used to capture heavy metal pollution or for more sustainable fertilizers. Now, these polymers have been put to work as more environmentally friendly building blocks.

The polymer is made by mixing sulfur with varying ratios of canola oil and dicyclopentadiene (DCPD). The sulfur and DCPD are both byproducts of petroleum refining that currently go to waste, while the canola oil can be sourced from kitchen waste. The polymer is heated, molded and cured into bricks, with the whole process consuming far less energy than cement production.

But the really impressive thing is how these bricks stick together, essentially acting as their own mortar without the need for any other adhesive. In tests, the bonded bricks resisted shear forces better than superglue.

“An amine catalyst is sprayed onto the surface,” Professor Justin Chalker, corresponding author of the study, told New Atlas. “The catalyst causes the S-S (sulfur-sulfur) bonds in the brick to rearrange and bind the two bricks together. The catalyst only needs to initiate the reaction, and it evaporates from the bricks after bonding.”

The team says that the bricks are also lightweight, and resistant against water, acid and other weather conditions, even more so than conventional bricks and concrete. In other tests, the researchers added carbon fiber to the polymer, and found that the resulting bricks were almost 16 times stronger.

While further development is required, the Flinders team is collaborating with Clean Earth Technologies to work towards scaling the polymer bricks up for possible commercialization.

The research was published in the journal Macromolecular Chemistry and Physics.

New Atlas, 1 August 2022
; https://newatlas.com