Spent Coffee Grounds Could Make Concrete Stronger

A recent study at RMIT University in Melbourne, Australia, suggests that coffee grounds could be used as an ingredient in concrete, potentially making it stronger. Researchers roasted spent coffee grounds in the absence of oxygen, resulting in biochar, which was added to concrete as a replacement of sand, providing a 30% increase in the material’s compressive strength. Concrete is the world’s most widely used building material, and the researchers found that biochar from coffee waste can reduce the drying effect of desiccation, which causes shrinkage and cracking at a microscale. When mixed with concrete, the biochar acts as tiny water reservoirs, releasing water slowly as the concrete sets and begins to harden. This process reduces the impact of shrinkage and cracking, transforming waste into a valuable resource.

However, Kypros Pilakoutas, a professor of construction innovation at the University of Sheffield in the UK, finds it improbable that concrete produced in this way will ever find widespread use in large-scale applications. The main issue with waste is mainly collection and processing, and the cost of pyrolysis is not cost-free. The biochar’s potential to reduce cement content by up to 10%, contributing to climate change, has attracted interest from construction companies and organizations that recycle coffee grounds.

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