From coffee to concrete

As Melbourne workers return to the city, so do the legions of coffee drinkers, and although most of us cart around a keep-a-cup, millions of coffee cups end up in the bin every day.

Last week, ABC reporter Kate Ashton came to Victoria University's Footscray Park to interview Dr Yanni Bouras about his new research using recycled coffee cups in concrete.

If you've ever felt a pang of guilt as you sipped hot coffee from a takeaway cup, you're not alone. While reusable cups have been around for a while, data suggests plenty of Australians are still reaching for the disposable option.

Australians consume an estimated 2.7 million coffee cups a day, the vast majority of which end up in landfill, according to Sustainability Victoria. That's why engineer Yanni Bouras has been trialling ways to turn old coffee cups into something useful.

"As a structural engineer, there's two things I love, coffee and concrete," he said. Yanni Bouras hopes his innovation can be used for things like construction or footpaths. "We were having coffee one day in the cafe here at VU and we sort of looked at the coffee cups and thought, 'why not give this a go?'" he said.

The cups are ground up and mixed in as a substitute for a proportion of the sand that goes into a typical concrete mix. So far, testing has found the material is weaker than standard concrete but has a higher thermal performance.

That means it could be useful for non-structural purposes, like footpaths or even insulation. If 10 per cent of sand was replaced by takeaway coffee cups, there could be up to 700 coffee cups used per cubic metre of concrete. "We do need to find ways to build greener and more sustainably, so solutions like this are quite important," Dr Bouras said.

While people like Dr Bouras investigate novel ways to repurpose coffee cup waste, many individual businesses are working on reducing their consumption. Christian Sullivan McNeill co-owns a café in Brunswick in Melbourne's inner north, that has made some recent tweaks to try and minimise plastic waste. "The changes weren't big themselves, but we just needed a little bit of advice in what changes to make," he said.

Mr Sullivan McNeill's cafe is now using coffee cup lids made from corn starch, which are fully home compostable. They have also moved away from plastic straws and cutlery. "It wasn't until we were able to get advice, that we realised that there are more sustainable products out there, especially with our lids," he said.

Cafe owners say the past two years of the pandemic interrupted the shift towards reusable cups. In her role as Plastic Free Places co-ordinator for Victoria, Birte Moliere meets with businesses, like Mr Sullivan McNeill's cafe, to examine what plastic products they use and give advice on what they can eliminate or replace.

"We do have a lot of businesses who are very confused at the moment around what they are allowed to use, what they're not allowed to use, and what is the more sustainable option for them," she said. "It is incredibly confusing in Australia because at the moment, we don't have mandatory labeling around our packaging, which makes it hard for our businesses to find what is right."

She said it was encouraging how many businesses were willing to adopt more sustainable packaging options, and they often found there was little to no price difference. From February 2023, Victoria will introduce a single-use plastics ban. The ban will include polystyrene packaging, plastic straws, cutlery, plates and drink stirrers, but the proposed rules won't wipe out takeaway coffee cups or lids just yet.

The message Ms Moliere wants to get across is that reusable options are always the most sustainable. She said while finding new second uses, like coffee cups in concrete, was a start, it was not a perfect solution.

"We are heavily reliant at the moment on single use, and that really needs a big rethink," she said. Ms Moliere said a greater focus was needed on the "circular economy", where materials were reused for quite some time.

Environmental advocates say choosing a keep cup over a disposable cup is the best way to tackle the issue.

This story first appeared in ABC online, Saturday 13 June 2022.