Engineers in Australia have found a way of making stronger concrete with roasted used-coffee grounds to reduce waste going to landfills.
Lead author of the research paper entitled, ‘Transforming spent coffee grounds into a valuable resource for the enhancement of concrete strength’, Dr Rajeev Roychand, from RMIT University, says the team developed a technique to make concrete 30 per cent stronger by turning waste coffee grounds into biochar, using a low-energy process without oxygen at 350°C.
“The disposal of organic waste poses an environmental challenge as it emits large amounts of greenhouse gases including methane and carbon dioxide, which contribute to climate change,” says Rajeev, Postdoctoral Research Fellow from the School of Engineering at RMIT.
According to RMIT, Australia generates 75 million kilograms of ground coffee waste every year, most of which going to landfills. Globally, 10 billion kilograms of spent coffee is generated annually.
Published in the Journal of Cleaner Production, the study by RMIT engineers is one of the first to prove that waste coffee grounds can be used to improve concrete.
“The inspiration for our work was to find an innovative way of using the large amounts of coffee waste in construction projects rather than going to landfills – to give coffee a ‘double shot’ at life,” says Rajeev.
“Several councils that are battling with the disposal of organic waste have shown interest in our work. They have already engaged us for their upcoming infrastructure projects incorporating pyrolysed forms of different organic wastes.”
The Indigenous-owned coffee supplier Talwali Coffee Roasters provided used ground coffee for the research.
Joint lead author, Dr Shannon Kilmartin-Lynch, a Vice-Chancellor’s Indigenous Postdoctoral Research Fellow at RMIT, says construction industries around the world could play a role in transforming this waste into a valuable resource.
“The concrete industry has the potential to contribute significantly to increasing the recycling of organic waste such as used coffee,” says Shannon.
“Our research is in the early stages, but these exciting findings offer an innovative way to greatly reduce the amount of organic waste that goes to landfill.”
Corresponding author and research team leader Professor Jie Li says the coffee biochar can replace a portion of the sand that was used to make concrete.
“There are critical and long-lasting challenges in maintaining a sustainable supply of sand due to the finite nature of resources and the environmental impacts of sand mining,” Jie says.
“With a circular-economy approach, we could keep organic waste out of landfill and also better preserve our natural resources like sand.”
The researchers plan to develop practical implementation strategies and work towards field trials, collaborating with various industries to develop their research.