Researchers create fireproof building material from sawdust
Experts at technology university ETH Zurich and research institute Empa have developed a process that uses the mineral struvite to convert sawdust into a recyclable, non-combustible composite material.
According to the research, which was led by Ronny Kürsteiner, the material could be used for internal walls and offer a lightweight alternative to cement-bonded particleboards.
To make the composite material, the researchers used an enzyme extracted from watermelon seeds to control the crystallisation of struvite – a colourless ammonium magnesium phosphate with fire protection properties.
Large crystals were formed in the process, which filled the cavities between sawdust particles and bound them together. The material was pressed in a mould for two days and later taken out to dry.
The researchers claim the material could gain the same fire protection class as cement-bonded particleboards, which are often used for interior fittings.
Cement-bonded particleboards are typically heavy and have a high carbon footprint, but the struvite sawdust composite offers a lightweight, environmentally friendly alternative.
The research found the struvite sawdust composite to have both non-combustible and fire-resistant properties.
When heated, the mineral breaks down and releases water vapour and ammonia, absorbing heat from the surroundings and creating a cooling effect. The released gases also displace air, helping to smother fire.
As part of the research, a heat test found that the struvite sawdust composite formed a layer of inorganic material and carbon when ignited, which also prevented further fire spread.
"The struvite sawdust panels essentially protect themselves," says Kürsteiner.
The struvite sawdust board is also recyclable – it breaks down into its individual components when broken up by a grinder and heated, releasing the ammonia and allowing the sawdust to be sifted out.
Researchers hope to continue optimising the material and find cost-effective ways to scale up the production process. Struvite is expensive compared to polymer binders or cement, but it is thought that it could be sourced from sewage treatment plants, where it often clogs sewage pipes.
"We could use these deposits as a raw material for our building material," says Kürsteiner.
Other material innovations that have recently featured on Dezeen include research from MIT that transformed recycled plastic into floor trusses for housing, and research from the University of Edinburgh that used bacteria to turn plastic waste into a Parkinson's drug.
The photography is by Ronny Kürsteiner unless stated.
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