In Australia, a team at RMIT University hopes mixing coffee grounds with concrete will reduce the amount of sand mined for concrete production while simultaneously divert coffee waste from landfills.
“Our research group was discussing shifting our focus to divert this waste from landfills and develop innovative solutions to transforming this waste into a valuable resource for different applications,” lead author Rajeev Roychand, a material scientist and structural design engineer at RMIT, tells Fast Company. “Incidentally, this discussion happened over a cup of coffee in our team meeting. That’s where we decided to start—with coffee grounds.”
According to the publication, 60 million tons of coffee grounds are landfilled annually.
The process involves swapping some of the sand used in concrete with pyrolysis-treated coffee grounds. The coffee-grounds biochar has the perfect combination of pore structure and carbon content to absorb water, Roychand says. “When the coffee biochar ismixed with concrete, its particles act like microscale water reservoirs distributed throughout the concrete,” he says. “As the concrete sets and starts to harden, the biochar slowly releases the water it stored, rehydrating it when needed, thereby reducing shrinkage micro-cracking. This results in the improvement in concrete strength.”
