Australian scientists discovered that charred coffee grounds can enhance concrete strength by up to 30%.
This innovative approach could tackle several issues simultaneously.
Each year, people around the world generate about 10 billion kilograms (22 billion pounds) of coffee waste, most of which ends up in landfills.
Addressing Waste and Concrete Demand
“Disposing of organic waste harms the environment by releasing large amounts of greenhouse gases like methane and carbon dioxide, which fuel climate change,” said RMIT University engineer Rajeev Roychand when the study came out in 2023.
At the same time, the growing global construction industry is fueling a rising demand for concrete — a resource-heavy material — creating additional environmental pressures.
“The continuous extraction of natural sand—usually sourced from riverbeds and banks—to meet the fast-growing needs of the construction sector is causing serious environmental harm,” said RMIT engineer Jie Li.
Sustainable Concrete from Organic Waste
“Maintaining a sustainable sand supply is increasingly difficult due to limited resources and the environmental damage caused by sand mining. By adopting a circular economy approach, we can reduce landfill waste and conserve natural materials like sand.”
However, organic materials such as coffee grounds can’t be directly mixed into concrete, as they release chemicals that compromise its strength.
To address this, the team applied a low-energy process to heat the coffee waste to over 350 °C (about 660 °F) in an oxygen-free environment.
This method, known as pyrolysis, breaks down organic molecules and produces a porous, carbon-rich material called biochar. This biochar can bond with the cement matrix, allowing it to integrate effectively into the concrete.
Roychand and his team also experimented with pyrolyzing the coffee grounds at 500 °C, but the resulting biochar was less strong and effective.
Testing Durability and Expanding to Other Waste Sources
The researchers noted that more testing is needed to evaluate the long-term durability of their coffee-based cement.
They are currently examining how the material holds up against freeze-thaw cycles, water absorption, abrasion, and other stress factors.
In addition, the team is exploring the production of biochar from other organic waste sources, such as wood, food scraps, and agricultural residues.
Read the original article on: Sciencealert
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