RMIT Discovers Leftover Coffee Grounds Can Make Stronger Concrete

Scientists in Australia have found a clever new use for leftover coffee grounds: making concrete stronger. Every year, the world produces around 22 billion pounds (10 billion kilograms) of #coffee waste, most of which ends up in landfills, where it releases harmful greenhouse gases like #methane and #carbon dioxide. This adds to the growing environmental challenges we face, including #climate change.

At the same time, the global construction industry uses massive amounts of natural sand, often taken from riverbeds. This practice harms #ecosystems and is unsustainable because sand is a finite resource.

Researchers from RMIT University discovered that by heating coffee grounds to over 350°C (660°F) without oxygen—a process called pyrolyzing—they can turn the waste into a type of charcoal known as biochar. This biochar can be mixed with concrete to make it up to 30% stronger. If used widely, this method could reduce the demand for natural sand and keep coffee waste out of landfills.

However, the team found that heating the coffee waste to 500°C produced weaker biochar, so they are focused on the lower temperature method. They are now testing how this coffee-concrete mix holds up over time, including how it performs in extreme weather conditions and under pressure from water and wear.

The researchers are also looking into making biochar from other types of waste, such as wood and food scraps. While the research is still in its early stages, the team is optimistic that this approach could lead to a more sustainable way of managing waste and building materials.

The study was inspired by the idea of "Caring for Country" from Indigenous cultures, aiming for a sustainable life cycle for all materials to reduce environmental impact.

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