Engineers from the Royal Melbourne Institute of Technology (RMIT University) in Australia are exploring a process that would divert spent coffee grounds from landfills and simultaneously fortify concrete.

By turning roasted coffee ground waste into biochar — a carbon-enriched biomaterial produced in the combustion of biomass via a low-energy process called pyrolysis, which occurs in the complete or near absence of oxygen at 350° C — and adding it to concrete, the team reportedly strengthened concrete by 30%.

Graphical abstract. Source: Journal of Cleaner Production (2023). DOI: 10.1016/j.jclepro.2023.138205

According to the researchers, coffee biochar can be used to replace a portion of the sand that goes into the manufacture of concrete — the extraction of which for the construction industry alone has had a significant impact on the environment.

"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…With a circular-economy approach, we could keep organic waste out of landfill and also better preserve our natural resources like sand," the researchers explained.

An article detailing the process "Transforming spent coffee grounds into a valuable resource for the enhancement of concrete strength," appears in the Journal of Cleaner Production.

For more on the process for strengthening concrete with coffee grounds, watch the accompanying video that appears courtesy of RMIT University.