Coffee biochar: the key to stronger, cleaner concrete

How is this biochar-based material reducing both waste and emissions?

Spotted: The World Economic Forum has flagged sand mining as being “close to being an environmental crisis”. And, as the world’s cities and towns expand, demand only increases for construction materials like concrete and glass that use this unsustainably mined sand. Now, researchers, led by Dr Rajeev Roychand, at Australia’s RMIT university, have developed a creative solution.

Using some of the 75 million kilogrammes of ground coffee waste produced in the country every year, the team replaces sand in concrete with a new, stronger material. The scientists used a 350-degree Celsius high-heat, low-energy process that doesn’t use oxygen to transform spent coffee grounds and wood chips into biochar, which is added to concrete to make it 30 per cent stronger.

The new material reduces methane emissions from landfill, which is where most coffee ground waste currently goes, while also minimising the construction industry’s reliance on an increasingly limited supply of sand. And because biochar is a denser material than sand, less of it is needed, making it quick to replace large volumes of sand with less biochar.

Working with the Macedon Ranges Shire Council in Victoria, the RMIT team is testing the new concrete in several sections of a footpath. And in a partnership with infrastructure company BildGroup, the scientists will provide material for a range of additional projects. The research team plans to continue exploring organic waste materials for additional sources of biochar and seeks to expand its network of contacts in the concrete supply chain, with a goal of making the new material commercially available.

Written By: Keely Khoury