RMIT University researchers Rajeev Roychand, Mohammad Saberian and Dr Shannon Kilmartin-Lynch with Jordan Carter, Co-founder of the Indigenous-owned Talwali Coffee Roasters (pictured left to right). Credit: Carelle Mulawa-Richards, RMIT University
Key points:
- Researchers have found used coffee ground can make concrete stronger.
- When replacing the sand typically taken from river beds and banks, the biochar grounds make the concrete about 30% stronger.
- The innovation helps the construction industry be more sustainable while also keeping millions if not billions of kilograms of spent coffee out of landfills every year.
Engineers in Australia have found a way of making stronger concrete with roasted used-coffee grounds.
The new technique results in concrete that is 30% stronger by turning waste coffee grounds into biochar using a low-energy process without oxygen at 350◦C.
Australia generates 75 million kilograms of ground coffee waste every year—most of it goes to landfills. Globally, 10 billion kilograms of spent coffee is generated annually.
“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,” said Rajeev Roychand, a postdoctoral research fellow at RMIT.
Published in the Journal of Cleaner Production, the study is the first to prove that waste coffee grounds can be used to improve concrete.
According to the researchers, the coffee biochar can replace a portion of the sand that is used to make concrete. The ongoing extraction of natural sand around the world—typically taken from river beds and banks–to meet the rapidly growing demands of the construction industry has a big negative impact on the environment. Currently, about 50 billion ton of natural sand are used in construction projects globally every year.
“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,” said corresponding author and research team leader Jie Li. “With a circular-economy approach, we could keep organic waste out of landfill and also better preserve our natural resources like sand.”
Li and team say the construction industry needs to explore alternative raw materials to ensure its sustainability. Next, they plan to develop practical implementation strategies and work toward field trials.
“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,” said Roychand.