Scientists Have Discovered An Amazing Practical Use For The World’s Leftover Coffee Grounds

Researchers in Australia have uncovered an innovative method to enhance the strength of concrete by incorporating charred coffee grounds.

Every year, approximately 10 billion kilograms (22 billion pounds) of coffee waste are generated worldwide, with most of it ending up in landfills. The accumulation of organic waste contributes significantly to greenhouse gas emissions, including methane and carbon dioxide, both of which exacerbate climate change. “The disposal of organic waste poses an environmental challenge,” explained RMIT University engineer Rajeev Roychand when discussing their findings published in 2023.

At the same time, the booming construction industry continues to rely heavily on natural sand, a key ingredient in concrete production. “The ongoing extraction of natural sand around the world – typically taken from river beds and banks – to meet the rapidly growing demands of the construction industry has a big impact on the environment,” noted RMIT engineer Jie Li.

Simply adding coffee grounds to concrete isn’t an option, as the organic material releases chemicals that weaken the mixture. To counter this issue, the research team employed a process called pyrolysis, heating coffee waste to over 350°C (660°F) in an oxygen-deprived environment. This process transforms the waste into a porous, carbon-rich substance known as biochar, which integrates well with cement and enhances the material’s strength.

The researchers experimented with different temperatures and found that heating at 500°C resulted in weaker biochar, highlighting the importance of precise processing conditions. Although the initial results are promising, further testing is required to determine the long-term durability of coffee-infused concrete, including its resistance to freeze-thaw cycles, water absorption, and abrasion.

Additionally, the team is exploring the potential of converting other organic waste materials, such as wood, food waste, and agricultural byproducts, into biochar for concrete applications. “Our research is in the early stages, but these exciting findings offer an innovative way to greatly reduce the amount of organic waste that goes to landfill,” said RMIT engineer Shannon Kilmartin-Lynch.

He emphasized the importance of sustainability, stating, “Inspiration for my research, from an Indigenous perspective, involves Caring for Country, ensuring there’s a sustainable life cycle for all materials and avoiding things going into landfill to minimize the impact on the environment.”