ETH Zurich Researchers Transform Waste Sawdust Into Sustainable Fire-Resistant Building Material Using Mineral Struvite

ETH Zurich researchers develop a recyclable, fire-resistant composite using sawdust and struvite, offering a green alternative for interior construction.

By: AXL Media

Published: Mar 19, 2026, 5:55 AM EDT

Source: Information for this report was sourced from ETH Zurich

Innovating Carbon Sequestration Through Timber Waste

In an effort to improve the environmental footprint of the global timber industry, researchers at ETH Zurich have unveiled a method to repurpose millions of tonnes of waste sawdust into high-performance construction materials. Traditionally, sawdust is incinerated for energy, a process that prematurely releases stored carbon dioxide back into the atmosphere. The new composite, developed by the Chair of Wood Materials Science, utilizes the mineral struvite to bind wood particles together, extending the carbon storage life of the material while providing a sustainable alternative to carbon-intensive building components.

Biochemical Engineering of Mineral Crystallization

The primary challenge in developing the composite was the difficult crystallization behavior of struvite, a colorless ammonium magnesium phosphate. To overcome this, the ETH team employed a unique biochemical catalyst: an enzyme extracted from watermelon seeds. This enzyme allows for the controlled crystallization of struvite from an aqueous suspension, producing large crystals that effectively fill the voids between sawdust particles. The resulting mixture is pressed and dried at room temperature, creating a solid architectural panel without the need for high-heat manufacturing processes.

Active Fire Protection and Thermal Cooling Mechanisms

The structural integrity of the new material is complemented by its extraordinary reaction to fire, which goes beyond simple non-combustibility. When exposed to extreme heat, the struvite binder undergoes a chemical breakdown that releases water vapor and ammonia. This reaction absorbs heat from the immediate environment, creating a potent cooling effect that delays ignition. Testing conducted alongside the Polytechnic University of Turin demonstrated that while untreated spruce ignites in approximately 15 seconds, the struvite-sawdust composite withstands the heat for more than three times as long before catching fire.