ETH Zurich and Empa Develop Fireproof Composite Made From Sawdust and Struvite

Published date:15/04/2026 | Last updated date:15/04/2026

Researchers at ETH Zurich and Empa have developed a new composite material that turns ordinary sawdust into a recyclable, non-combustible panel, offering a lighter alternative to traditional cement-bonded particleboards for interior construction.

The material, led by researcher Ronny Kürsteiner, uses the mineral struvite together with an enzyme extracted from watermelon seeds to bind sawdust into a fire-resistant board. The result is a building material that not only resists combustion but also points toward a lower-carbon route for internal wall systems.

A mineral-based route to fire-safe wood composites

The core of the innovation lies in how the material is formed.

Instead of relying on conventional polymer binders or cement, the research team used an enzyme from watermelon seeds to control the crystallization of struvite, a colorless ammonium magnesium phosphate known for its fire-protection behavior.

During processing, large struvite crystals formed between the sawdust particles, filling internal cavities and binding the wood material together. The composite was then pressed in a mould for two days before drying.

That approach matters because it replaces more common combustible or carbon-intensive binder systems with a mineral-based structure that contributes directly to fire resistance.

Designed as a lighter alternative to cement-bonded boards

According to the researchers, the new composite could potentially achieve the same fire-protection class as cement-bonded particleboards, which are widely used in interior fittings and partition systems.

But unlike cement-bonded boards, the struvite-sawdust composite is expected to offer two major advantages:

• lower weight
• reduced environmental burden

Cement-bonded particleboards are effective in fire performance, but they are also heavy and carry a relatively high carbon footprint. That makes the new composite especially relevant for applications where builders want both fire safety and lower material mass.

How the material protects itself in fire

The fire-resistant behavior comes from the chemistry of struvite itself.

When exposed to heat, the mineral breaks down and releases:

• water vapor
• ammonia

This reaction absorbs heat from the surroundings, creating a cooling effect. At the same time, the released gases help displace air around the material, which can suppress combustion.

The researchers also found that when ignited, the panel forms a protective layer of inorganic material and carbon on its surface. This barrier helps stop the fire from spreading further.

As Kürsteiner put it, the panels essentially protect themselves.

Recyclability adds another layer of value

One of the more interesting aspects of the material is that it is also recyclable.

When the panel is broken up mechanically and heated, it separates back into its main components. The ammonia is released, and the sawdust can then be sifted out.

That gives the composite an advantage over many bonded wood-based materials, which are often difficult to recycle cleanly once they have been manufactured into boards.

Scaling remains the next challenge

The research team is continuing to optimize the material and explore ways to scale production more cost-effectively.

At present, struvite is more expensive than common cement or polymer binder systems. However, the researchers believe that supply economics could improve because struvite can potentially be recovered from sewage treatment plants, where it often accumulates as a problematic deposit in pipes.

If that recovery pathway becomes commercially viable, it could turn a waste stream into a raw material for safer building panels.

Editor’s Note

This development is notable because it combines several priorities that rarely come together in one board material: fire resistance, recyclability, lighter weight, and bio-based content.

The real test will be whether the material can move beyond the lab and into cost-effective production. But the concept is strong. Instead of treating sawdust as a low-value byproduct and fire resistance as something that must be added through heavy or synthetic systems, the researchers have shown a different route—one built around mineral chemistry and circular material thinking.

For interior wall applications, that could become a meaningful alternative if scale and cost can be brought into line.