OT: Sawdust waste turned into fire-resistant building panels, could reduce construction waste

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At the core of this new material is struvite, a mineral more commonly associated with wastewater treatment facilities.

Across the global timber industry, vast quantities of sawdust are generated as a byproduct of processing wood, often piling up with limited pathways for reuse. Most of this material is either burned for energy or discarded in landfills, where it gradually releases stored carbon back into the atmosphere without delivering further value.

By combining compressed sawdust with a mineral-based binder, the team has created a material suitable for interior walls and partitions, offering a more sustainable alternative for construction while reducing industrial waste.

Using sewage-derived mineral to create safer wall panels

At the core of this new material is struvite, a mineral more commonly associated with wastewater treatment facilities than construction sites. While it is typically known for clogging pipes, struvite also possesses inherent fire-resistant properties that make it an attractive candidate for building applications.

Its use, however, is far from straightforward: the mineral is highly brittle on its own, and achieving a uniform blend with wood particles presents a significant technical hurdle. Researchers at ETH Zurich addressed this by turning to biology, using an enzyme derived from watermelon seeds to control how struvite crystals form and bind within the composite, resulting in a more stable and cohesive material.

The material is stronger under compression perpendicular to the grain than the original spruce timber, explains Ronny KĂĽrsteiner, who developed the process as part of his doctoral thesis. Combined with its strong fire-resistant properties, these mechanical characteristics make the material particularly well-suited for interior applications such as wall systems, partitions, and other internal fittings, where both safety and durability are critical.

To test fire performance, researchers at ETH Zurich worked with the Polytechnic University of Turin using a cone calorimeter. The struvite-based panels took over three times longer to ignite than untreated spruce. Once exposed to flame, they quickly form a protective carbon and mineral layer that slows further burning, and as KĂĽrsteiner notes, the material effectively protects itself.

Recyclable alternative to cement-bonded boards

Beyond fire performance, the material also stands out for its recyclability. Unlike conventional cement-bonded particleboards that typically end up as demolition waste, this composite can be taken apart and reused.

Once removed, the panels can be mechanically ground and heated to just over 212°F, a process that releases ammonia and separates the sawdust from the mineral content. The recovered material can then be dissolved and reprocessed, allowing the precursor compound, newberyite, to be formed again as a solid. This circular approach offers a more sustainable lifecycle for building materials while reducing construction waste.

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For the chemists out there:

Struvite is a phosphate mineral, NH4MgPO4 * 6 H2O, composed of magnesium, ammonium, and phosphate, commonly known for forming “infection stones” in the human or animal urinary tract. They grow in alkaline urine caused by urea-splitting bacteria.

This use of a compound derived from waste water is brilliant…if the process for retrieving and using it turns out to be commercially feasible since it uses an unusual enzyme derived from watermelon seeds.

The controlled burn in the lab showed the composite to be fire-resistant. However, in a real house fire the composite would burn like fury and also release toxic ammonia fumes. That’s not a problem with common wallboard which has a mineral core.

Wendy

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Fire resistant is not “non-toxic”. Got it Wendy.

Fire resistant materials which slow or impair combustion gives time to react safely or eliminate the temperature threat. I believe that’s the best intention for a product like this. We have intumescent materials for structural components which has been industry practice for a VERY long time.

Here is a very public failure of this intumescent technology, largely due to very specific causes. Fireproofing key to Twin Towers’ collapse | New Scientist

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The recent bar fire in Switzerland again shows the conflict between tox issues and fire retardants. The fire began with the ignition of acoustic foam attached to the bar ceiling. The plastic used should have been treated w fire retardant to reduce flame spread. Videos suggest it was not treated.

Details are not yet published but the fire retardants used in plastics often contained bromine or phosphorus and have tox issues.

The Rhodes Island bar fire was similar. Acoustic foam was ignited by band fireworks. The foam producer was sued and reached a settlement.

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I hate crowds in enclosed spaces in general…but the moment fire was brought out I would be SO OUT OF THERE!

Wendy

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Crux problem: enforcing sanity (never mind morality) (as done reasonably well but not perfectly in hopefully modern building codes) on zillions of private businesses that are desperate to cut costs is best done by

bounty licensing private citizens to enforce code.

Why? Because private citizens self-finance, are cheaper, and if marginally literate way ahead of any possible governmental deliberative process.

I have no idea on exact implementation, but think could be done relatively quickly and usefully.

**In other words, in a major shift in their different incentive and research structures, Governing States can no longer reliably cope fast enough (as fast as tech advancement!!!) to watch, inspect, comprehend and then pass regulations fast enought to enforce the sanity necessary for our survival and economic prosperity.

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David,

This approach would be a panacea. Unfortunately, too many people know too little. I suspect this is a by product of our eternally good economic progress (yes, I know, ups and downs) which has not caused a reset of magnitude which forces the the lessons of learn all, know all, practice all which was a founding tenet of life only 100 years ago.

Even then (in the 1920s), innovation and change brought too much, too soon, to too many. Now, generations on, we are a country (world?) of people who expect everything, with no time to learn anything.

This group on fool.com is generally an extreme outlier. I expect you are fostering that locally as well, per your commentary.

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@flyerboys ideally that would work. However, real-world experience in the past (before building codes were implemented) shows that builders will minimize costs in any way possible, often building weak and/or dangerous flaws into structures that are only revealed much later.

There’s a reason for building codes. People have died in building collapses and fires. New materials that seem to be better need extensive testing (e.g. in actual fire conditions which require more than a small bench-top lab test). Leaving this up to individuals is a recipe for later disaster.

There are videos of test burns of small houses in a giant aircraft hanger conducted by professionals. Don’t try this at home.

Wendy

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Underwriters Labs runs the flamespread tests. Most building materials have flamespread ratings requirements. Yes, once ignited an overstuffed chair w “foam rubber” (urethane foam) cushions will burn like gasoline. The smoke is often toxic.

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I am an avid advocate of stricter building codes. However, I see the official inspection process as

  1. close to hopelessly corruptible
  2. often far behind ongoing changes in construction

and so would love to see a much stronger role for private citizens to be able to act as inspectorsl, and to receive a bounty from construction firms for revealing failures.

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After the Cocoanut Grove fire in Boston, flammable decorations were banned.

https://en.wikipedia.org/wiki/Cocoanut_Grove_fire

The Cocoanut Grove fire was a nightclub fire in Boston, Massachusetts, US on November 28, 1942, which resulted in the deaths of 492 people.

Interesting that acoustic foam is not regulated like crepe paper for flammability.

In most cases over crowding is a major factor making escape for a fire difficult as exits get jammed.

Rhode Island Nightclub fire is also reported. https://en.wikipedia.org/wiki/The_Station_nightclub_fire