In an innovative breakthrough, Australian researchers have uncovered an unexpected application for coffee grounds. Scientists at RMIT University have discovered that by heating coffee grounds to approximately 350 degrees Celsius in the absence of oxygen, they can be transformed into biochar. This biochar can then be mixed with sand to create a more robust form of concrete.

The research revealed that substituting 15 percent of the sand in concrete with this biochar results in a 30 percent increase in the material’s strength. This finding not only highlights biochar’s potential as a viable component in concrete production but also suggests it could alleviate the demand on the world’s sand resources.

Dr. Jingxuan Zhang and Dr. Mohammad Saberian spearheaded a comprehensive analysis assessing the environmental impact of this innovative process. Their research evaluated carbon emissions, resource utilization, and other environmental factors from the initial production stage to the material’s end-of-life phase.

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.