Leftover Coffee Grounds Hold Exciting Practical Potential, Scientists Reveal

By incorporating charred coffee grounds into the mixture, as uncovered by Australian researchers, there’s a possibility of enhancing concrete strength by up to 30 percent. This innovative approach not only offers a solution to various challenges but also presents a new recipe with multiple benefits.

 

The world annually generates a massive 10 billion kilograms of coffee waste, much of which finds its way to landfills. This disposal of organic waste emits harmful greenhouse gases like methane and carbon dioxide, contributing to climate change, says Rajeev Roychand, engineer at RMIT University.

Simultaneously, the thriving global construction market drives up demand for resource-intensive concrete, posing additional environmental issues. Extracting natural sand from rivers disrupts the environment significantly, warns Jie Li, RMIT engineer. A circular-economy approach could tackle this issue by diverting organic waste from landfills and conserving precious resources like sand.

Coffee grounds can’t be directly added to concrete due to their chemical leakage weakening the material. To overcome this, the team used low-energy pyrolysis to heat coffee waste above 350°C without oxygen. This created porous biochar, carbon-rich charcoal, which binds with the cement matrix and enhances concrete.

Pyrolyzing coffee grounds at 500°C produced weaker biochar particles. However, the researchers must still assess the long-term durability of their cement product. They’re testing how the coffee-cement hybrid withstands various stressors like freeze/thaw cycles, water absorption, and abrasions.

The team aims to create biochar from other organic sources like wood, food waste, and agricultural waste. RMIT engineer Shannon Kilmartin-Lynch emphasizes that these initial findings offer an innovative way to significantly reduce organic waste ending up in landfills.

Guided by Indigenous principles of Caring for Country, the researchers aim to establish sustainable material life cycles and minimize environmental impact. Their research is published in the Journal of Cleaner Production.