Australian scientists have discovered a surprising new use for discarded coffee grounds.
Researchers at RMIT University found that when coffee grounds are heated to around 350°C in the absence of oxygen, they turn into biochar, a material that can be mixed with sand to produce stronger concrete.
Their experiments showed that replacing 15% of sand in concrete with coffee biochar increased the concrete’s strength by 30%. The findings suggest that biochar could be a practical and sustainable alternative in construction, helping reduce reliance on natural sand supplies.
Dr. Jingxuan Zhang and Dr. Mohammad Saberian conducted a full cradle-to-grave analysis, assessing carbon emissions, resource usage, and environmental impacts throughout the production cycle. They found that using biochar significantly reduced the carbon footprint, lowering carbon dioxide emissions, fossil fuel use, and improving impacts on rivers and lakes.
Zhang said the results further support the need for real-world applications:
“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.”
The first batch of coffee-biochar concrete has already been used in a section of the Victorian Big Build, and the concept has been showcased at the National Gallery of Victoria. RMIT researchers are now collaborating with the construction industry and government bodies to expand the project.
Saberian said the next steps include larger-scale trials and aligning with industry standards to encourage broader adoption.
“We welcome collaboration on supply chains and field deployments,” he added.
This research is part of RMIT’s ongoing efforts to reduce the environmental impact of construction by transforming everyday organic waste into sustainable building materials.
