We all know there is no shortage of coffee in Melbourne, but with an abundance of anything there is always some kind of waste product that has to be dealt with.
Coffee grounds are great to be used for home composting and are perfect for food waste recycling programs (which are ultimately made into a high grade compost product), but what else could coffee grounds be useful for?
A recent study at Swinburne University has seen civil engineers experimenting with used coffee grounds and turning them into road materials, claiming that the end product could be as strong as cement!
The research was led by Professor Arul Arulrajah who heads up the university’s Geotechnical Engineering group. His studies have focussed on how various recycled materials (such as crushed brick, glass and concrete) could be used for construction of roads. From here his thoughts moved on to other materials:
“I see the baristas throwing away the used coffee grounds and I think, why not look at this as an engineering material,” Arulrajah said.
Used coffee grounds were collected from the cafes surrounding the Hawthorn campus and dried out for several days. They were then sieved to filter any lumps and mixed with slag and an alkaline solution to bind them together. The mixture then compressed into cylindrical that was proven to be strong enough to potentially use as the subgrade material that sits under a road surface.
“On average the cafes we collect from dispose of about 150 kg of coffee grounds per week,” says Professor Arulrajah. “We estimate that the coffee grounds from Melbourne’s cafes could be used to build five kilometres of road per year. This would reduce landfill and the demand for virgin quarry materials.”
The next stage of the project is another testing phase to simulate how the coffee-based material will react under real traffic conditions.
Further details of the study can be found here.