Sawdust May Be Put to Use in Flame-Stopping Building Panels

Why It Matters

The innovation offers a sustainable, lightweight alternative to heavy cement boards, reducing landfill waste and enabling circular‑economy practices in construction. Its comparable fire safety and recyclability could reshape building‑material standards worldwide.

Key Takeaways

• Enzyme from watermelon seeds controls struvite crystal growth
• Panels outperform spruce timber in compression strength
• Fire resistance matches cement boards but lighter weight
• Panels recyclable via low‑temperature heating and grinding
• Utilizes waste sawdust, reducing landfill and energy use

Pulse Analysis

The construction sector has long searched for lightweight, fire‑resistant panels that can replace heavy cement‑bonded boards while addressing waste streams. Sawdust, a by‑product of the lumber industry, is typically incinerated or landfilled, contributing to carbon emissions and resource loss. Struvite, an ammonium‑magnesium phosphate mineral, possesses inherent flame‑retardant properties but is brittle and difficult to integrate with organic fibers. Combining these two materials promises a circular‑economy solution, yet previous attempts failed because struvite crystals did not bond effectively with the porous sawdust matrix.

Researchers at ETH Zurich, Empa and the Polytechnic University of Turin solved the bonding issue by introducing an enzyme extracted from watermelon seeds. The enzyme directs the crystallisation of struvite from a newberyite precursor, producing large, interlocking crystals that fill the voids between spruce sawdust particles. After two days of mould pressing and ambient drying, the resulting panels exhibited compression strength exceeding that of native spruce timber. In fire tests, the struvite decomposes, releasing water vapour and ammonia, absorbing heat and displacing oxygen, which dramatically slows flame spread.

The new panels deliver fire protection comparable to conventional cement‑bonded particleboards but at a fraction of the weight, opening opportunities for high‑rise construction where load reduction is critical. Moreover, the material is designed for closed‑loop recycling: heating to 100 °C separates sawdust and precipitates newberyite for reuse, eliminating the waste associated with demolition. By turning an abundant forestry waste into a high‑performance, recyclable building component, the technology aligns with stricter building codes and sustainability targets, positioning it for rapid commercial uptake.