Humans are predicted to go through nearly 175 million bags of coffee over the next year, totalling over 23 billion pounds of spent coffee grounds. For decades, most of that waste has been generally destined for landfills, the transport of which results in large amounts of greenhouse gas emissions. It stands to reason that these spent coffee grounds (after a cup of joe or two) offer a massive, untapped recyclable resource opportunity—and researchers at Australia’s RMIT University have potentially figured out just what to do with them.
According to findings recently published in the Journal of Cleaner Production, engineers have developed concrete that is almost 30 percent stronger than existing standards after mixing in coffee-derived biochar. To create the new, charcoal-like additive, the team employed a low-energy process known as pyrolysis, in which organic waste is heated to 350 degrees Celsius without oxygen to avoid generating carbon dioxide. Roughly 15 percent of sand used in traditional concrete was then swapped for the coffee biochar, offering not only a more resilient building material, but one that could take care of a massive food waste obstacle.
[Related: Dirty diapers could be recycled into cheap, sturdy concrete.]
“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,” Shannon Kilmartin-Lynch, a postdoctoral fellow and joint lead author, said in a statement.
Speaking with The Guardian on August 22, Kilmartin-Lynch explained although coffee biochar is structurally finer than sand, its porous qualities allows the cement to actually better bind to the organic material. While in its early testing stages, the coffee-concrete is showing immense engineering promise.
Replacing at least some of traditional concrete’s sand also offers a major additional bonus to the team’s innovation. According to the university, 50 billion metric tons of natural sand is annually used in construction projects across the globe—resulting in a huge stress on ecosystems such as riverbeds and banks. Minimizing sand mining in favor of recycled coffee grounds therefore offers an additional, positive environmental effect.
If further research and finetuning goes according to plan, essentially all spent coffee ground waste could be put towards new concrete projects.The research team now intends to explore practical implementation standards, as well as field trials in collaboration with outside industry leaders. Perhaps joining forces with both the diaper concrete engineers is in order.