A recent study published in the Journal of Cleaner Production demonstrated that spent coffee grounds, when treated properly, can improve the properties of concrete. Researchers from RMIT University in Melbourne, Australia, discovered a method to transform leftover coffee grounds into a component that makes concrete up to 30% stronger, offering a new perspective on how everyday waste could contribute to building the cities of the future.
The key to the innovation lies in a process called pyrolysis, which involves heating coffee waste to over 350 degrees Celsius in the absence of oxygen to produce biochar. This carbon-rich material can integrate into the cement matrix, enhancing the strength of the concrete. The RMIT team, led by engineer Rajeev Roychand, demonstrated that pyrolyzing coffee grounds turns them into a porous, carbon-rich biochar, effectively replacing a portion of the sand used in concrete mixtures.
"When the coffee grounds were heated to 500 degrees Celsius, the biochar produced was weaker and less effective," the researchers found, emphasizing the importance of precise temperature control in the pyrolysis process. This finding underscores the necessity of maintaining optimal conditions to achieve the desired improvements in concrete strength.
Every year, the world discards 10 billion kilograms of coffee waste, most of which ends up in landfills. This not only contributes to greenhouse gas emissions, especially methane, but also represents a missed opportunity for resource recovery. "The disposal of organic waste poses an environmental challenge as it emits large amounts of greenhouse gases," explained Roychand, underlining the broader environmental benefits of this approach, according to Science Alert.
Organic products like coffee grounds cannot be added directly to concrete because they could weaken its strength due to the chemicals released. However, by transforming coffee grounds into biochar through pyrolysis, the researchers were able to overcome this issue. The study revealed that concrete blocks incorporating biochar derived from coffee grounds achieved a 29.3% increase in compressive strength compared to conventional concrete.
The construction industry faces two challenges: managing organic waste and reducing dependence on sand mining, which has an environmental impact. There is a booming construction market globally, leading to an ever-increasing demand for resource-intensive concrete, which causes environmental challenges. "There are critical and long-lasting challenges in maintaining a sustainable supply of sand due to the finite nature of resources and the environmental impacts of sand mining," said Jie Li, an engineer at RMIT University, according to Science Alert.
By partially replacing sand with biochar made from coffee grounds, the environmental benefits include reducing landfill waste and greenhouse gas emissions while conserving natural sand resources. This innovation aligns with global efforts to transition to a circular economy, where waste materials are repurposed instead of discarded.
The research team is also exploring the potential of creating biochar from other organic wastes, including wood, food scraps, and agricultural byproducts. "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 Dr. Shannon Kilmartin-Lynch, an engineer at RMIT University, according to INQUIRER.net.
The researchers cautioned that they still need to assess the long-term durability of their cement product. The team is currently testing the long-term durability of coffee-infused concrete under conditions such as freeze-thaw cycles, water absorption, and abrasion resistance. This ongoing work aims to ensure that the coffee-based concrete performs reliably over time in environmental conditions.
The article was written with the assistance of a news analysis system.