Biosolutions beneath our feet: How fungi are rewriting roads and pavements

At the microscopic level, mycelium is largely made of two natural carbohydrates: chitin and beta-glucans. These two materials play very different roles, but together they give mycelium its distinctive physical abilities that we can leverage in developing binders for construction out of them.

Chitin is the source of strength. It is a rigid and durable natural material that can hold its shape under pressure, best known for forming the exoskeleton (shells) of crabs, shrimps, and insects like locusts. In mycelium, chitin reinforces the thread-like fibers, giving them the ability to bear loads and resist deformation.

But strength alone is not enough. A material that is only strong, but not flexible, tends to be brittle. It can hold weight, but once pushed beyond its limit, it cracks or breaks suddenly. This is where beta-glucans come in.

Beta-glucans act as a binding and toughening agent, commonly found in plants, especially in cereals and grains such as oats, barley, wheat, and rice. In those grains, beta-glucans help tissues stay intact during milling, soaking, cooking, and drying by allowing them to flex and redistribute stress instead of breaking apart. In simple terms, beta-glucans help materials bend slightly, absorb shocks, and recover, rather than fail abruptly.

A useful analogy is to imagine bones that could bend slightly under pressure instead of snapping. They would still support weight, but they would absorb shocks and recover. That, in essence, is how mycelium behaves.

This ability to combine strength with toughness — rigidity with flexibility — is the unique ability of mycelium, which makes it a great natural product to be leveraged as a construction binder, holding materials together while enduring stress.

^{The ability to combine strength with toughness makes mycelium a great natural construction binder.} 
 

So how does mycelium turn into pavements and roads?

Imagine this. You tie a thin metal wire around the trunk of a young tree and leave it there. When you return a decade later, you find that the wire did not stop the tree from growing. Instead, the tree has grown all around it. The trunk has slowly wrapped itself around the metal, absorbing it into its body.

That is the simplest way to understand what a mycelium-based binder does — just much faster.

Earlier, you learned how fungi feed. They do not sit in one place and “eat” the way we do. They grow around their food, the substrate, and form mycelium.

In construction, the same idea is used, but in a controlled environment.

Instead of letting mycelium grow through forest soil or fallen wood, it is encouraged to grow through the same loose materials we use to build roads and pavements — aggregates such as crushed stone and sand.

And how does the mycelium find its way around these hard, mineral particles? By following food. Organic material — the substrate the fungi feed on — is spread throughout the mix. As the mycelium grows in search of this food, its thread-like strands expand in every direction, wrapping around whatever lies in their path.
 

So what does that look like in practice?

Picture a large tank or controlled growing environment. Into it go two broad ingredients:

• Food for the fungi (like agricultural waste or wood shavings)
• Aggregates such as sand, gravel, or crushed stone

Then selected fungal strains are introduced, and the fungi are simply allowed to do what they do best — grow.

As the fungi feed on the organic material, the hyphae spread in every direction. They creep through tiny gaps, cross over and under particles, and gradually wrap around the mineral pieces. Over time, the loose mix begins to behave less like a pile of stones and more like a single, interlocked structure, because a living network is forming inside it.

At the end of this growth phase, the fungi have consumed much of the food. What remains is something remarkable: a block of aggregates tightly held together by mycelium, with the binding coming not from heat or chemistry, but from growth.

Cement and bitumen come from nature too — cement from limestone, bitumen from crude oil. But they are not living. To turn them into binders, raw materials must be extracted and pushed through extreme industrial steps: very high heat, combustion, and chemical changes. Only then do they become materials that can glue sand and stone together.

Mycelium flips that logic. Cement and bitumen bind because we force them to. Mycelium binds because it grows. Once the desired amount of growth is reached, it is deliberately stopped, so it can no longer spread or form mushrooms (see fun facts below). What remains is no longer active, but it retains the structure created during the growth phase.

From growing binders to building roads and pavements

This is exactly the approach taken by Visibuilt, a startup based in Copenhagen. Visibuilt has developed a construction binder based on mycelium, known as visiBINDER. It can be adapted to different construction needs but the basic idea stays the same: use mycelium’s natural growth as the binding force.

Let us first look at the visiBINDER based pavement blocks, visiPAVER. In a conventional paver (blocks used in pavements), stones and sand are held together by cement and water. In the mycelium-based version, aggregates, filler, water, and the binder are shaped together. The mycelium grows through the block, locking everything together from within. Once strength is achieved, growth is halted, leaving a stable, usable pavement block.

The same principle applies to road construction. Instead of heating bitumen, aggregates are mixed with living fungal material, which gradually grows around the stones, weaving them into a solid network. Once this growth is complete, it is stopped, leaving behind a stable road surface so that it ends up looking like a road. But the binder is not oil-based bitumen and heat-driven. It is biological, grown into place, and then stabilized.

And now the bigger question becomes hard to ignore: if we can grow a binder instead of burning fuel to manufacture one, what does that change for the future of roads, pavements, and the carbon emissions tied to building them?
 

Why biological binders matter

When biological binders are placed next to cement and bitumen, the differences are hard to ignore.

• Producing cement requires heating limestone to around 1,450°C (2,642° F). Bitumen, too, must be heated to 160–200°C (320–392° F) before it can be used for road construction. Mycelium-based binders operate on a very different scale — typically between 25 and 120°C (77–248° F) — because their strength comes from biological growth rather than extreme heat. Less heat means less energy, and that matters in an industry still heavily dependent on fossil fuels.
   
• Where these materials come from also matters. Cement production relies largely on coal-fired kilns. Bitumen is derived directly from oil, tying roads to global oil markets and a small number of exporting regions, making it sensitive to price volatility, and geopolitical vulnerability.
   
• There are benefits on the ground as well. Traditional cement and asphalt work involves high temperatures, heavy machinery, and exposure to toxic fumes. Biological binders avoid many of these hazards simply because they do not require extreme heat or harmful chemicals to function.
   

Taken together, these differences point to more than a new material. They raise a deeper question: why are cement and bitumen so central to modern construction in the first place—and what challenges are now forcing that reliance to be reconsidered?

If you’re curious, our article “Rethinking the materials that hold the modern world together" steps back to examine how today’s construction industry came to depend so heavily on these binders, and why their fossil-fuel foundations are increasingly under scrutiny.

At the same time, these differences point to a different way of thinking about infrastructure itself. Biosolutions like mycelium-based binders show that performance does not have to come from extraction, combustion, and force. It can come from biology—grown rather than manufactured, local rather than imported, and shaped by biological processes rather than extreme heat. Beneath our feet, roads and pavements may still look the same. But the way they are made—and the systems they depend on—can be fundamentally different.