Used Coffee Beans Could Make Concrete Stronger

Used Coffee Beans Could Make Concrete Stronger

Researchers at RMIT University have figured out a way to improve the strength of concrete by almost 30 per cent – by using coffee beans.

RMIT published a video of the research on its YouTube, featuring the team behind the study. Members of the team had already been working on concrete strength-improving additives, but a Nescafé machine and pod collection bin in the team’s meeting room inspired them to explore a more caffeinated solution. It’s not the only thing floated as a concrete strengthener – car tyres and recycled PPE could also be used to make concrete tougher, but we’re certainly not complaining about another option.

“The problem with the organic waste going to landfills is basically high methane emissions, which are probably 21 worse than carbon dioxide, and then we have to spend a lot of our natural resources to dispose of these waste materials,” RMIT research fellow Doctor Rajeev Roychand said.

“Coffee, in particular, we produce about 75,000 tonnes per year in Australia, and quite a large amount of it goes into landfills. And this waste [with this solution], is now converted into a resource which provides an improvement in the strength of concrete”.

The team developed a process where coffee beans are roasted without oxygen (at 350 degrees Celsius) to make it compatible with concrete, by turning the beans into biochar. Functionally, the coffee becomes a concrete additive.

Unroasted coffee beans (top), roasted coffee beans (left), spent and ground coffee (left), and coffee biochar. Image: Carelle Mulawa-Richards, RMIT University

It’s a two-pronged waste solution; not only does it lay the groundwork for coffee to be reused, where used coffee grounds could be re-roasted and added to concrete instead of being simply thrown away, but it potentially cuts down on the need to mine for other materials, such as sand, which the waste coffee could replace, according to Roychand.

“This inspiration for my research is sort of from an Indigenous perspective – it sort of involves going back to caring for Country, ensuring that there’s sort of the sustainable life cycle of all materials,” RMIT Indigenous Postdoctoral fellow and Taungurung man Doctor Shannon Kilmartin-Lynch added. Kilmartin-Lynch was the researcher behind the PPE-enhancing concrete study from last year.

The team is planning to implement the solution practically with field trials and to work with industry stakeholders to develop the research.

You can read the research in the Journal of Cleaner Production, or read about it on the RMIT website.

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