Researchers are advancing methods to turn everyday organic waste like coffee grounds into useful construction materials in order to reduce the carbon footprint of infrastructure.
RMIT researchers have found that biochar made from spent coffee grounds can help produce a lower-carbon concrete while supporting strength benefits seen in lab trials.
The new study builds on previous experiments, which heated used coffee beans at about 350 degrees Celsius to make a fine biochar. When this biochar replaced 15 per cent of sand in concrete, results showed a 28-day strength increase by about 30 per cent.
The study, led by Dr Jingxuan Zhang and Dr Mohammad Saberian, presents a comprehensive life cycle assessment that measures carbon emissions, resource use and other environmental impacts from production through to the end of life.
The results show reductions of up to 26 per cent of carbon dioxide when biochar replaces sand in concrete. Carbon dioxide falls by 26 per cent if 15 per cent of biochar is used in concrete. Results also show up 31 per cent lower use of fossil fuels and improvements in 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.”
The study supports Australia’s shift to a circular economy and the nation’s net-zero goals by turning waste into functional materials.
Saberian said the team was already engaging with industry as well as state and local governments on construction projects.
“Next steps include larger pilots, mix optimisation and alignment with standards so projects can adopt this confidently,” he said.
