The low-density polyethylene that forms part of a typical disposable coffee cup makes the cups difficult to recycle, but may one day be a suitable substitute for sand in making concrete. Researchers at Australia’s Victoria University have found that concrete made with 10% to 20% coffee cup granulates instead of sand showed higher thermal resistance, though less strength than traditional concrete.



A research team at Victoria University is exploring using granules made of disposable coffee cups as a substitute for sand in concrete.A coffee catch-up was all it took for Victoria University researchers to realise the waste material they needed to produce sustainable building products was already in their hands.

“I’m a structural engineer and lecturer in built environment, so coffee and concrete are two things I really love,” says Dr Yanni Bouras, Lecturer at the College of Engineering and Science, Victoria University.“A few of us met up at a cafe to explore options for waste materials. We ended up looking down at our cups and thinking, ‘Why not?’”

The team had been searching for a suitable high-volume, readily-available waste material that had not been researched as much as glass, rubber or recycled concrete aggregates. After initial tests on a range of other waste materials including used mattresses and cardboard, disposable coffee cups had all the properties they were looking for.

According to Sustainability Victoria, on an average day in Australia more than 2.7 million disposable coffee cups are thrown out. While the plastic lids are recyclable, the cups themselves are typically made from a paperboard product that includes a low-density polyethylene layer.

That layer prevents the cups from being compostable or easily recycled without significant effort or additional processing.In 2020, the coffee cup recycling project as well as 24 other projects received part of $1 million in funding from Victoria University as part of its whole-of-university commitment to protecting country.