RMIT researchers are advancing new ways to reduce carbon concrete by turning everyday organic waste like coffee grounds into useful construction materials.
A life-cycle analysis has shown, for the first time, that biochar made from spent coffee grounds can help produce a lower-carbon concrete while supporting strength benefits seen in earlier lab trials.
Earlier experiments by the RMIT team heated used coffee grounds at about 350°C without oxygen to make a fine biochar. When this replaced 15 per cent of sand in concrete, 28-day strength increased by about 30 per cent, pointing to a practical way to reduce pressure on natural sand supplies.
Building on that work, a new study led by Dr Jingxuan Zhang and Dr Mohammad Saberian presents a life cycle assessment and analysis that measures carbon emissions, resource use and other environmental impacts from production through to end of life.
The results show life-cycle carbon dioxide reductions of 15 per cent, 23 per cent and 26 per cent at five, 10 and 15 per cent biochar replacing sand, along with up to 31 per cent lower use of fossil fuels and improvements in impacts on rivers and lakes.
This research supports Australia’s shift to a circular economy and net-zero goals by turning abundant waste into functional materials, reducing reliance on natural sand and building public engagement with resource recovery. 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,” said Zhang.
Professor Chun-Qing Li, who provided guidance to the team, said the innovation turned organic waste into a practical ingredient for lower-carbon infrastructure.
“Using moderate amounts of coffee biochar offers a clear, measurable pathway to lower-impact concrete,” he said.
The team is 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,” Saberian said.
“We welcome collaboration on supply chains and field deployments.”
RMIT and partners have already advanced public demonstrations, including a footpath pilot and the first coffee-biochar concrete section on the Victorian Big Build, and showcased the concept through the National Gallery of Victoria’s Making Good: Redesigning the Everyday exhibition.