Coffee grounds for a concrete circular economy

Australia drinks 1.3 million cups of coffee daily and a new project from RMIT University could see the coffee waste turned into concrete used for homes or driveways.

An engineering lecturer and his students have looked to the construction industry for a novel solution to reduce the amount of coffee grinds going to landfill, by using them in concrete.

With concrete mixes containing up to 80 per cent sand, the group found coffee grinds could replace up to 10 percent of sand in concrete mixes.

Sand is the third most used resource on the planet, but it is struggling to keep up with demand. Extracting sand from places with fragile ecosystems can also have a significant environmental impact.

‘Coffee bricks’ created by the team will be on display at RMIT’s EnGenius event on Wednesday 23rd of October.

Bachelor of Engineering (Civil and Infrastructure) (Honours) students Senura Kohombange and Anthony Abiad worked with Senior Lecturer in the School of Engineering Dr Srikanth Venkatesan to test and develop the ‘coffee bricks’.

Mr. Kohombange said its seems fitting to be working on the project in Melbourne, a city known for its great coffee culture.

“We are very excited to present the project, share the idea with others and showcase how some innovative thinking can turn a waste product into an everyday construction material,” he said.

In 2017 the City of Melbourne was home to an estimated 2,600 cafes alone, producing around 156,000 kilograms of coffee-ground waste every month.

Dr. Venkatesan said as a regular cappuccino drinker he was inspired to find a solution to the waste he was making each day.

“The biggest challenge is ensuring the addition of spent coffee grinds does not lead to a reduction in strength of concrete, and this is the focus of further testing and development to make this product viable for use in real-world applications,” he said.

Swinburne University did similar tests in 2016 to determine if coffee grounds could be used in subgrades.

Lab testing indicated the mixture was strong enough to compare to other road binder materials however it had yet to be tested in practical applications to determine performance over time.