🔥 Burnt Coffee Grounds Could Boost Concrete Strength by 30%, Say Researchers

Researchers are brewing up an innovative solution to two major environmental challenges at once: coffee waste and the strain on natural resources. Globally, around 10 billion kilograms (22 billion pounds) of coffee waste end up in landfills each year, releasing greenhouse gases like methane and carbon dioxide that accelerate climate change. At the same time, the booming construction industry is rapidly depleting natural sand, essential for concrete, causing long-term ecological damage.

A team at RMIT University has found a creative way to tackle both issues. By pyrolyzing coffee grounds—heating them above 350°C (660°F) without oxygen—they produce biochar, a carbon-rich charcoal that can bond with cement without weakening the concrete. Surprisingly, heating the grounds even hotter, to 500°C, produced weaker biochar, highlighting the importance of precise processing.

“Using a circular-economy approach, we can keep organic waste out of landfills while preserving natural resources like sand,” said engineer Jie Li. This method could reduce pressure on the planet while introducing a sustainable material into construction.

The researchers are testing the long-term durability of coffee-infused concrete, exposing it to stressors like freeze-thaw cycles, water absorption, and abrasion, to ensure it meets real-world standards. They’re also exploring biochar from other organic waste sources such as wood, food, and agricultural by-products.

Engineer Shannon Kilmartin-Lynch highlighted the broader vision: “From an Indigenous perspective, Caring for Country inspires us to ensure a sustainable lifecycle for materials and prevent waste from going to landfill, minimizing environmental impact.”

This breakthrough not only transforms everyday coffee grounds into a high-tech solution but also points toward a greener future for construction and waste management—one cup at a time.