TRANSCRIPT
In a laboratory in Melbourne, concrete cylinders are being subjected to extreme pressure.
The cylinders look like ordinary concrete, but they're far from it.
They're created with polyester fibres extracted from high visibility clothing used by workers in factories and construction sites.
Many hi-viz vests end up in landfill – around 11,000 tonnes of it every year - according to Associate Professor Malindu Sandanayake from Victoria University who leads the project.
"High-vis vests don't last for long, it just only lasts around 25 washes. So that means we tend to find these high-vis vests quite a lot going to landfills. So we wanted to find an effective solution to be used, probably as a cement replacement material in concrete."
Social enterprise Assembled Threads helped source the uniforms for this research, which is backed by Sustainability Victoria.
Vests were chosen for the project because the threads are very durable, says Professor Sandanayake.
"Because of the synthetic fibres that are present in high-vis vests, it can act as a reinforcing agent within the concrete. And also because it bonds all the materials together, it improves the fire properties in concrete and delays the spoiling process."
Concrete is the second most used substance in the world after water – so finding sustainable alternatives is crucial.
Cement is a key ingredient in concrete – so this new approach is a win win.
As well as diverting waste from landfill, Professor Sandanayake says it replaces cement with waste products saving natural resources and helping to cut greenhouse gas emissions.
"So if you take as a whole, the car production industry across the world is similar to the cement production. So it's a huge amount of carbon emissions that is generated, which is almost 8% of the total global carbon production."
So far, the new concrete was used to make a 20 metre-long path through the grounds of the Mahamevnawa Buddhist Monastery, where Professor Sandanayake is a disciple.
Monk Sasana Bodhi Thero says they were happy to be part of the trial.
"The environment is directly helping to our happiness and especially our health beings for our health, I mean, so if we are really trying to protect our environments, that means we are really trying to help for every single being who are living in the world."
And, they couldn't be more pleased with the result.
"Actually we are so happy because it, even when we are walking , it is very same. I mean it is pretty like a normal concrete."
Monastery volunteer Amila Goonaratne says the monks share the path with the local community.
"In Buddhist teachings we learned that you have to treat all living beings with loving kindness. And so if you care about all living beings and if you have loving kindness, you care about the environment. So being sustainable is definitely a part of that. "
The concrete was also tested in a storage compound at a major construction site in Melbourne.
Professor Sandanayake says both trials have been a success.
"The results showed that the target strength that we intended was achieved earlier than what we expected, which was really good. And it is almost as comparable with traditional concrete mix design that we designed for, and it had superior durability results plus in terms of fire testing, it performed really well. So we believe that the presence of these textile fibers enhance the fire properties within the concrete panel. So this could be a good fireproof concrete material for future use".
And its not the only new sustainable concrete project - researchers at RMIT are working with spent coffee grounds, pouring it into a busy footpath in Australia's coffee capital, Melbourne.
Research Fellow Rajeev Roychand says the grounds are used to make biochar to replace sand - another key ingredient in concrete - which is becoming increasingly scarce.
"So the process of creating biochar is basically you grab your spent coffee grounds, so you roast it in the pyrolysis unit. Roasting is basically the absence of oxygen. You roast it at 350 degrees celcius temperature, and there comes the black coloured coffee biochar. ... The resource natural sand that we use for concrete, it's getting scarce over time and this waste can take its place."
Results from a previous footpath trial saw a 30 per cent increase in the concrete's strength.
The researchers now want to develop a mainstream product for commercial application.
Clean Up Australia Chair Pip Kiernan says re-using products reduces the need for raw materials.
"We need to think about our resources as just that - resources, not waste and not things that we use for a small period of time, and then send to landfill. ... Australia as a nation is not as circular as others throughout the world, we're at about 4%, whereas the rest of the world that's doing it well is around 8%. So there's lots of room for improvement, for less to go to landfill and more to be recovered and reused."
Professor Sandayanake says his team is now working on increasing the amount of waste in their concrete.
But sourcing the fibres extracted from high vis vests can be a problem.
"Sourcing these carbon fibres was really difficult. ... So more and more support is needed in the higher chain of the supply chain to convert these high-vis into fibrous materials so that we can start using them.
A challenge worth tackling for this innovate approach to creating sustainable concrete.
