Coffee-boosted concrete developed at RMIT University has been used for the first time in a major infrastructure project, being laid into a footpath along a busy Melbourne road in as part of Victoria’s Big Build.
Organic waste going to landfill, including spent coffee grounds, contributes to 3% of greenhouse gas emissions. This waste cannot be added directly to concrete because it would decompose over time and weaken the building material, which is why the used coffee is converted into biochar before being added to the concrete mix.
Related article: Coffee-boosted concrete is stronger, uses less energy
Australia generates 75 million kilograms of ground coffee waste every year—most of it goes to landfills, but it could replace up to 655 million kilograms of sand in concrete because it is a denser material.
For this project, Earth Systems converted 5 tonnes of spent coffee grounds—about 140,000 coffees worth of grounds—into 2 tonnes of useable biochar, which has been laid into the 30 metres cubed footpath along McGregor Road in Pakenham, which is being managed by Major Road Projects Victoria (MRPV) and project contractor BildGroup.
Lead inventor of the coffee concrete and RMIT Postdoctoral Research Fellow Dr Rajeev Roychand said, “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 3% of Australia’s greenhouse gas emissions.”
Earlier this year, RMIT teamed up with Macedon Ranges Shire Council to conduct a successful world-first trial of coffee concrete in a footpath in Gisborne, Victoria.
The RMIT team developed a technique to make concrete 30% stronger by turning waste coffee grounds into biochar, using a low-energy process without oxygen at 350 degrees Celsius.
Related article: Pep in your step: coffee-concrete footpaths cut emissions
Due to current supply chain limitations, the team could not use their low-energy process to produce biochar so the coffee concrete used in the Gisborne trial had a similar strength to standard concrete.
To translate the team’s innovation into a commercial reality, RMIT is engaging with a commercialisation partner and also with companies in the construction and agriculture sectors that would potentially benefit from using biochar products.
