Aussie scientists find bizarre use for your morning cup of coffee

Friday, 28 November 2025 05:58

Heating up coffee grounds to about 350 degrees can help create more environmentally-friendly and stronger concrete.

Australian scientists have found a bizarre and unlikely use for coffee.

RMIT University researchers found that heating coffee grounds to about 350 degrees without oxygen creates biochar, which can be combined with sand to help produce concrete.

When the biochar replaced 15 per cent of sand in concrete, the strength of it increased by 30 per cent.

The findings suggested biochar could be a useful and practical way to produce concrete and reduce the pressure on sand supply.

Dr Jingxuan Zhang and Dr Mohammad Saberian have now led a cradle‑to‑grave analysis that measured carbon emissions, resource use and other environmental impacts from production through to the end of life.

They found that using biochar led to a reduced carbon footprint through lower levels of carbon dioxide, fossil fuels and better impacts on rivers and lakes.

Zhang said the findings strengthened the case for real‑world trials.

"We showed that coffee biochar can cut concrete's carbon footprint in the scenarios we assessed, while earlier trials demonstrated strength gains using the same approach," Zhang said.

The first coffee-biochar concrete has already been used on a section of the Victorian Big Build, and the concept has been showcased at the National Gallery of Victoria.

The team are now engaging with the construction industry, as well as local and state governments, on projects.

Saberian said the next steps are conducting larger pilots and aligning with industry standards so projects can confidently adopt coffee grounds as an alternative.

"We welcome collaboration on supply chains and field deployments," he said.

RMIT researchers have been investigating new ways to reduce the carbon footprint of construction by turning everyday organic waste into materials and reduce the reliance on natural sand.

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