Research: From coffee to concrete

Australian engineers have found a way of making 30% stronger concrete with roasted used coffee grounds. The technique involves turning waste coffee grounds into biochar using a low-energy process without oxygen at 350°C.

Lead author Dr Rajeev Roychand from RMIT University said the disposal of organic waste creates an environmental challenge as it emits large amounts of greenhouse gases such as methane and carbon dioxide.

Australia generates 75 million kilograms of ground coffee waste every year, most of which ends up in landfills. Globally, 10 billion kilograms of ground coffee waste is generated annually.

Several councils have engaged the researchers for upcoming infrastructure projects incorporating pyrolysed forms of different organic wastes.

Pyrolysis involves heating organic waste in the absence of oxygen.

Joint lead author Dr Shannon Kilmartin-Lynch said construction industries around the world can play a role in transforming the waste into a valuable resource.

The concrete industry has potential to contribute to increasing the recycling of organic waste, greatly reducing the amount of it that goes into landfill.

Coffee biochar can replace a portion of the sand that is used to make concrete, further impacting the environment by reducing the ongoing extraction of natural sand.

50 billion tonnes of natural sand are used in construction projects globally every year.

“There are critical and long-lasting challenges in maintaining a sustainable supply of sand due to the finite nature of resources and the environmental impacts of sand mining,” said corresponding author and research team leader Professor Jie Li.

Co-researcher Dr Mohammad Saberian said the construction industry needs to explore alternative raw materials to ensure its sustainability.

The research team has developed a range of biochars from different organic wastes, including wood, food, agriculture and municipal solid-waste.

The researchers plan to develop practical implementation strategies and work towards field trials.

Image credit: iStock.com/Nusara Angkuldee