Researchers have found a way to turn sawdust into a durable and sustainable interior wall panel, but whether it gets commercialized as a product depends on how cost-effectively manufacturers can access a mineral that’s key to the production process.
The key ingredient is struvite, a crystalline ammonium magnesium phosphate that builds up in water treatment plant pipes.
In pipes, the mineral is a problem. It creates clogs that can lead to backups. But because it has fire-resistant properties, it can have utility in building applications, including panel boards, researchers at the Swiss university ETH Zurich say in an article they published on the institution’s website.
“The struvite sawdust panels essentially protect themselves,” says Ronny Kürsteiner, a doctoral candidate and research assistant at the university, who developed the process as part of his doctoral thesis.
“Struvite is not only non-combustible, it also helps to actively increase fire resistance,” the article says. “When heated, the mineral breaks down, releasing water vapor and ammonia. This process absorbs heat from the surrounding environment, producing a cooling effect. The non-combustible gases that are released also displace the air, hindering the fire from spreading further.”
By itself, struvite is brittle, so researchers mixed it with an enzyme extracted from watermelon seeds. That strengthened the mineral to the point where it could be used as a filler for the sawdust.
The enzyme works by enlarging the struvite crystals so they fill the cavities between the sawdust particles, binding them together. When the compound is poured into a mold, heated and then cooled, it creates a panel that can be used as building material.
“The material is stronger … than the original spruce timber” from which the sawdust is derived,” Kürsteiner said.
The panel boards are also sustainable, the article says. When they’re ground up and heated, the components separate and can be reconstituted into new panels.
“This new material could therefore be an important contributor to the circular economy,” it says.
Using struvite as a building material wouldn’t be cheap. Compared with polymer binders or cement, the mineral is relatively expensive, the article says. But if manufacturers can find a way to access it cost-effectively from sewage treatment plants, they would gain a source for the mineral while also helping to keep pipes from clogging.
“We could use these deposits as a raw material for our building material,” says Kürsteiner.
