A new type of concrete that uses biochar made from spent coffee grounds, developed by RMIT University in Melbourne, is being rolled out in the Pakenham Roads Upgrade project in Victoria.
The inclusion of spent coffee grounds, which often go into landfill, replace river sand. The waste coffee grounds are heated to high temperatures to form biochar and then added to the concrete mix. In tests, the resulting building material was 30 per cent stronger than standard concrete mixes.
Major Road Projects Victoria (MRPV) and project contractor BildGroup have utilised this new concrete to lay a footpath next to a busy road in Pakenham. RMIT Postdoctoral Research Fellow Dr Rajeev Roychand is excited to partner with BildGroup and MRPV for the translation of the RMIT team’s research into the Victorian government’s Big Build projects.
“This proactive support plays a significant role in creating a potential for diverting all forms of biodegradable organic waste which is currently ending up in landfills and contributing to three per cent of Australia’s greenhouse gas emissions,” he says.
The use of coffee biochar is one of several circular economy initiatives delivered for the Pakenham Roads Upgrade, which also include reusing the in-fill soil and material for the Princes Freeway embankments and installing foam bitumen and rubber tyre road barriers.
According to the team at RMIT, organic waste sent to landfill, including spent coffee grounds, contributes to three per cent of greenhouse gas emissions. This waste cannot be added directly to concrete because of its decomposition over time, which would weaken the building material, yet the grounds can retain their structural integrity.
Australia generates 75 million kilograms of ground coffee waste every year. While most of it goes to landfill, it could replace up to 655 million kilograms of sand in concrete because of its density.
MRPV Program Director Brendan Pauwels says coffee concrete has the potential to cut costs and remove vast amounts of waste material from landfill.
“These numbers are remarkable in terms of ecological benefit, and we’re excited to see the Pakenham Roads Upgrade be the first Victorian Big Build project to use the coffee concrete,” he says.
Globally, 10 billion kilograms of spent coffee is generated annually, which could replace up to 90 billion kilograms of sand in concrete.
For this project, Earth Systems converted 5 tonnes of spent coffee grounds – roughly 140,000 coffees worth of grounds – into 2 tonnes of useable biochar, which has been laid into the 30 cubed-metre footpath along McGregor Road in Pakenham.
