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In a Melbourne laboratory, concrete cylinders are subjected to extreme pressure.
The cylinders look like ordinary concrete, but they are far from it.
They are created from polyester fibers extracted from high visibility clothing used by workers in factories and construction sites.
Many high-visibility vests end up in landfills – around 11,000 tonnes each year – according to Associate Professor Malindu Sandanayake of Victoria University who is leading the project.
“High visibility vests don’t last long, they only last about 25 washes. So that means we tend to find a lot of these high visibility vests ending up in landfills. So we wanted to find an effective solution to be used, probably as a replacement material for cement in concrete.
Social enterprise Assembled Threads helped source the uniforms for this research, supported by Sustainability Victoria.
The vests were chosen for the project because their yarns are very durable, says Professor Sandanayake.
“Due to the synthetic fibers present in high visibility vests, they can act as a reinforcing agent within the concrete. And also because they bind all the materials together, they improve the fire properties of the concrete and retard the deterioration process.”
Concrete is the second most used substance in the world after water. It is therefore crucial to find sustainable alternatives.
Cement is a key ingredient in concrete – so this new approach is a win-win.
In addition to diverting waste from landfills, Professor Sandanayake says it replaces cement with waste, saving natural resources and helping to reduce greenhouse gas emissions.
“So if you take it as a whole, the automobile production industry across the world is similar to cement production. So it’s a huge amount of carbon emissions that are generated, which accounts for almost 8% of total global carbon production.”
So far, the new concrete has been used to carve a 20-metre-long path through the grounds of the Mahamevnawa Buddhist monastery, where Professor Sandanayake is a disciple.
Monk Sasana Bodhi Thero said they were happy to participate in the trial.
“The environment contributes directly to our happiness and above all to our health, I mean, so if we are truly trying to protect our environment, that means we are truly trying to help every being that lives in the world. »
And they couldn’t be happier with the result.
“Actually, we’re so happy because even when we walk, it’s the same. I mean, it’s pretty much like normal concrete.”
Amila Goonaratne, a volunteer at the monastery, explains that the monks share the path with the local community.
“In Buddhist teachings, we learned that you should treat all living things with kindness. And so if you care about all living things and if you show kindness, you care about the environment. So be sustainable is certainly one of them.”
The concrete was also tested in a storage complex on a major construction site in Melbourne.
Professor Sandanayake says both trials were a success.
“The results showed that the target strength we wanted was achieved earlier than expected, which was really good. And it is almost as comparable to the traditional concrete mix design we designed for, and it achieved superior results in durability and in terms of ”
And it’s not the only new sustainable concrete project: RMIT researchers are working with used coffee grounds and dumping them into a busy footpath in Australia’s coffee capital, Melbourne.
Researcher Rajeev Roychand says the soils are being 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 collecting your spent coffee grounds and then roasting them in the pyrolysis unit. Roasting is basically the absence of oxygen. You roast it at a temperature of 350 degrees Celsius, and here is the black colored coffee biochar… The natural resource, sand, which we use for concrete, becomes rarer over time and this waste can take its place.
Results from a previous sidewalk test showed a 30 percent increase in concrete strength.
The researchers now want to develop a consumer product intended for commercial application.
Clean Up Australia president Pip Kiernan says reusing products reduces the need for raw materials.
“We need to view our resources as such – resources, not waste and not things we use for a short period of time and then send to landfill. (…) Australia as a nation “It’s not as circular as others around the world.”
Professor Sandayanake says his team is now working to increase the amount of waste in their concrete.
But the supply of fibers extracted from high visibility vests can prove problematic.
“Sourcing carbon fiber was really difficult. … So there needs to be more and more support in the upper chain of the supply chain to convert these high-visibility fibers into fiber materials so that we can start to use them.
A challenge to overcome for this innovative approach to creating sustainable concrete.
