RMIT researchers are advancing new ways to cut the carbon footprint of infrastructure by turning everyday organic waste 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.
The study, “Carbon footprint reduction in concrete using spent coffee grounds biochar: a life cycle perspective,” is published in the International Journal of Construction Management.
Earlier experiments by the RMIT team used heated coffee grounds at about 350 degrees Celsius without oxygen to make a fine biochar.
When this replaced 15% of sand in concrete, its 28 day strength increased by about 30%, pointing to a practical way to reduce pressure on natural sand supplies.
Building on that foundation, a new study led by Dr. Jingxuan Zhang and Dr. Mohammad Saberian presents a comprehensive life cycle assessment—a cradle to grave 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%, 23% and 26% at 5, 10 and 15% biochar replacing sand, along with up to 31% 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 from the School of Engineering.
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.
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 optimization and alignment with standards so projects can adopt this confidently,” he 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.
