Mushrooms: A Natural Alternative to Cement?
Chloe Badger in conversation with Nikki Stefanoff
Photos by Tom Ross
This conversation was originally published in Issue 2
Monash University’s Chloe Badger is working on a solution to combat seven percent of the world’s human-made carbon dioxide.
Nikki Stefanoff: Tell us a little bit about what you’re getting up to at Monash Uni.
Chloe Badger: I’m studying biomedical science and materials engineering as a double degree – I’m in my final year. Because my engineering degree has built in honors, we spend the last year working on a final individual project and mine is on mycelium ‘concrete’.
For the layperson (me!) what exactly is mycelium?
Think about it as if the mushroom is like the apple and the mycelium is like the tree. The mycelium usually grows underground, like tree roots, then the mushrooms come out of the ground as the fruiting bodies, which then produce spores for reproductive purposes. So, the mycelium itself is sort of like a branching network with very fine branches called ‘hyphae’. They form a really big web underground or wherever they are growing. It’s thought that the biggest living organism in the world is a mass of mycelium growing in a jungle!
While it grows quite quickly (like all fungi), it’s also reasonably strong and the structure and the strength of it can be altered by what it’s digesting. It functions in the same way as a plant does but it’s closer to a living animal as it needs to take in oxygen, puts out carbon dioxide and needs to consume food. What it can digest tells us a lot about the building blocks it needs to grow.
And is that what you’re looking at?
What I’m looking at is the different rations of cellulose and starch mycelium needs in order to grow. Cellulose is wood and so I’m working with sawdust and potatoes and looking at starch versus cellulose, because some research has shown that if you feed mycelium starch-based food it can grow a stronger structure, which is ideal if we’re going to use it as a building material.
Is using mycelium as a building material the desired outcome? Are you trying to decipher whether it could be used as a sustainable building material?
Yes, that’s the goal. At the moment, it looks like the structural properties we’ll get won’t be as strong as concrete but concrete is used in a lot of applications where it's not actually the structural component it's just used because it's convenient, like internal walls for example, which aren’t actually loadbearing. So, we’re looking at creating alternatives for that kind of thing. It’s very much a starting point for what might be a larger area for future research.
Is anybody else looking into this at the moment?
Yes, there’s a pretty big area of research around ways to make cement production more sustainable and alternatives to cement. Some people are looking at bacteria based processes and others are looking at taking the same ingredients as traditional cement but findings ways to make that process more environmentally friendly. There’s also a guy in America called Philip Ross who makes art pieces out of mycelium. He grows it and then moulds it into objects like chairs, it’s quite interesting and proves that mycelium is a strong structure, which is really cool.
I’m guessing that the carbon dioxide production from cement is a well-known problem within the building industry?
Yeah, it contributes seven percent of all human-made carbon dioxide, which is huge for a singular industry and makes it a big issue. Some companies are doing things to try and reduce it. Some use a material called ‘fly ash’ as a filler so they can use less cement. I don’t think any will be investing in alternatives to cement as they’re more focused on making cement less harmful.
Tell me more about your role in the project.
I’ve done a fair bit of research into the different species of mushroom and the different things they’re able to digest. We’re also looking to see if there is potential to feed them food waste, because we do waste a lot of food. But the food they eat affects their structure and there’s only certain things that the species can digest. I’ve picked a few species that I know can digest starch and cellulose and I’m feeding them different ratios of sawdust and potato to see whether they preferentially digest one over the other. I also want to know how the different rations affect the structure. There’s sort of a ‘proof of concept’ to how quickly it can be grown and how strong the resulting bricks are. I’m basically growing it in little glass bricks that I got from Kmart! I’m slowly building off the preliminary research of ‘Let’s get a home mushroom kit!’.
I got over the first big hurdle, which was when they became contaminated. That’s a big problem when you’re hoping to produce something that can be applied to industry.
How do they become contaminated?
It’s mould. When you feed them food there are other things in the air that love the same food. It’s all about being able to introduce mycelium to a sterile enough environment so it won’t get mouldy. The mould can sometimes outcompete the mycelium but it doesn’t have the structural advantage of mycelium.
Are you doing it in the lab or just at home?
Oh no, I’m doing it in the lab! It’s very smelly. I just bought a pressure cooker, which seems to be helping a lot. Just by cooking the substrate before I add the mycelium helps with sterilisation. So, that’s relatively industrially applicable because preparing everything in the mould and then just putting them through an autoclave is easy enough to do.
Mostly what I’m doing is proof of concept – proving that we can turn mycelium into bricks. Once we have the bricks we can test them, see what they like eating and how it affects the final structure so we can hone in on a final species and substrate and decide how to work with it for future development.
So, say it works and you successfully turn mycelium into bricks how do you then stop them from continuing to develop and grow?
We already use living building materials so the idea is not uncommon. We just have to kill it before it goes into, say, a house. You can kill the mycelium by cooking it in an oven. When it’s finished growing you will be able to take it out of the mould, heat it up and stop the mycelium’s growth. And, if done properly, that should have the same effect as chopping down a tree. The only concern is that it will dry out and because there is a fairly high amount of water in mycelium we’re looking at ways to made sure the brick doesn’t shrink.
Did you ever think you’d be doing something like this?
When I read about it I thought using mycelium as a building material sounded so interesting. I think because I have a biomed background I had a bit of knowledge about cellular processes and how cells grow, which helped me a little bit because I haven’t had to go on a really steep learning curve. I don’t think I could have chosen something like this myself as I don’t think I would have had the imagination!
It has the potential to not only disrupt an entire industry but to really change the world from an environmental perspective. That's pretty incredible.
It definitely does. I think if it gets to the point where it can be used as a building material there will be a bit of a cultural barrier to get over. People aren't necessarily 100 percent comfortable with living in a house built by fungi! But hopefully as time goes on then perceptions will be able to be changed.
It’s going to be a case of who will go first! Someone will do it.