In a potential revolution for sustainable building materials, researchers at the Royal Melbourne Institute of Technology (RMIT) are tapping into the surprising fire-resistant properties of mycelium—a network of fungal strands usually found thriving on organic waste in the absence of light.

According to Tien Huynh, an associate professor specializing in biotechnology and mycology, this innovative approach involves growing mycelium from renewable organic waste sources. The result is a layerable, engineered material offering multiple applications, from construction panels to sustainable fashion.

"Fungi are usually found in a composite form mixed with residual feed material, but we found a way to grow pure mycelium sheets that can be layered and engineered into different uses—from flat panels for the building industry to a leather-like material for the fashion industry,” Huynh, from the School of Science, commented on the groundbreaking development.

The production process for this material preserves the inherent filament network of mycelium, eschewing pulverization. The researchers instead manipulate the growth conditions and use specific chemicals to create thin, uniform sheets with significant fire resistance.

RMIT scientists are targeting the creation of bio-derived, fire-retardant cladding for buildings, inspired by the need to prevent calamities akin to the Grenfell Tower fire—a disaster exacerbated by a highly combustible cladding component. The findings from the new study were published recently in the journal Polymer Degradation and Stability.

“This paper presents research findings on the influence of alkaline deacetylation on the thermal stability and fire reaction properties of non-pathogenic Basidiomycota fungi (mycelium) grown in molasses, the authors wrote. “The relationship between deacetylation conditions, such as incubation time and NaOH concentration, and the thermal and fire reaction properties of mycelium was investigated.” 

The study authors continued, stating that “the degree of deacetylation was also examined for its influence on the high-temperature thermal stability of mycelium, such as char formation. The findings indicated that the high-temperature thermal stability increased as the degree of deacetylation increased due to the conversion of chitin into chitosan as well as the presence of char-promoting hydroxyl‑terminated polysaccharide moieties. The study further investigated the influence of hollow glass microspheres on the thermal properties and microscale combustion behavior of unmodified and deacetylated mycelium.”

Everson Kandare, an associate professor with expertise in the flammability and thermal properties of biomaterials, noted the significant potential of mycelium as a fireproofing material.

“The great thing about mycelium is that it forms a thermal protective char layer when exposed to fire or radiant heat. The longer and the higher temperature at which mycelium char survives, the better its use as a fireproof material,” Kandare remarked.

In addition to its effectiveness, mycelium-based cladding is eco-friendly, deriving from renewable organic waste, and does not pose environmental threats when burned, unlike conventional composite cladding panels containing plastics.

“Bromide, iodide, phosphorus, and nitrogen-containing fire retardants are effective but have adverse health and environmental effects. They pose health and environmental concerns, as carcinogens and neurotoxins that can escape and persist in the environment cause harm to plant and animal life,” Kandare added. In contrast, "bioderived mycelium produces naturally occurring water and carbon dioxide."

This pioneering research could transform the way buildings are clad, leading to a more sustainable future. While fungi production may be slower and more challenging than producing plastics, Huynh indicated that a potential collaboration with the mushroom industry could leverage their waste products for mycelium growth, fulfilling fire safety requirements sustainably.

The RMIT team is now eyeing the production of reinforced fungal mats designed to delay ignition, reduce flaming intensity, and enhance fire safety. This development is chronicled in their paper, “Fireproofing flammable composites using mycelium: Investigating the effect of deacetylation on the thermal stability and fire reaction properties of mycelium.”