Utilizing Coffee Waste for Sustainable Pavements
Researchers from RMIT University and Macedon Ranges Shire Council have forged a path towards eco-friendly construction with the world's first coffee concrete pathway in Gisborne, Australia.
Harnessing the Potential of Coffee Grounds
Australia produces a staggering 75 million kilograms of coffee grounds annually, largely destined for landfills. Untreated organic materials in landfills contribute significantly to global greenhouse gas emissions. Recognizing the value of this waste stream, Dr. Rajeev Roychand of RMIT University and colleagues sought to redirect it from landfills.
Biochar: A Key Ingredient
Directly incorporating organic waste into concrete was not feasible due to its tendency to decompose over time, weakening the structure. Enter biochar, a solid carbon substance obtained by heating organic waste in an oxygen-limited environment. By heating coffee grounds to 350 degrees Celsius under these conditions, the researchers produced a coffee biochar that increased the waste's durability and suitability for concrete applications.
Replacing River Sand with Biochar
The biochar serves as a sustainable substitute for river sand in the concrete mix. "Sand is becoming scarce over time, and this waste source can replace up to 15% of the sand in concrete," explains Dr. Roychand. With 75 million kilograms of coffee waste, which is denser than sand, this innovation could replace over 655 million kilograms of river sand in concrete production. Globally, an estimated 10 billion kilograms of coffee grounds are generated annually, potentially replacing a staggering 90 billion kilograms of river sand.
Testing the Durability
"We're going to let people walk all over it, and RMIT will come back and see how it's standing up," said Shane Walden, Macedon Ranges Shire Council's Director of Infrastructure.
Reducing Cement Content
"Our research has even hinted at the potential to reduce the amount of cement. Because we get a 30% increase in strength with the coffee concrete, we can potentially reduce the amount of cement required by about 10%," said Dr. Roychand. While the Gisborne pathway does not yet incorporate reduced cement levels, the RMIT team is actively pursuing this avenue.
Summary
The coffee concrete pathway in Gisborne represents a significant step forward in sustainable construction. By harnessing the potential of coffee waste and utilizing biochar, researchers are unlocking new possibilities for eco-friendly infrastructure. This innovative approach not only diverts waste from landfills but also reduces the environmental impact of concrete production. As the research continues, the team aims to optimize the use of coffee biochar and further reduce cement requirements, paving the way for a greener and more sustainable future in construction.