Australia faces a dual environmental challenge: managing organic waste and reducing environmental impacts in the construction sector. One of the most common types of organic waste is the coffee grounds used, which often end up in dumps, releasing methane, a gas that captures heat and makes a significant contribution to climate change. To address waste and pollution, the researchers looked at whether this waste could be reused to make specific concrete stronger and more environmentally friendly.
Dr. Rajeev Roychand and Professor Shannon Kilmartin from RMIT University conducted a detailed study, which was recently published in the Journal of Cleaner Production in the Journal of Science. The team explores whether coffee spots (porous materials made of burning organic matter without oxygen) can replace some of the sand that is usually mixed into concrete after being heated in science and turned into a charcoal-like substance.
In their experiments, the researchers found that using untreated coffee grounds directly in concrete did not work well. Natural compounds on the ground can interfere with the way cementation changes, making the concrete weaker. However, when the coffee is heated in an oxygen-free environment (a process called pyrolysis) breaks down the organic material into stable carbon forms, the results are very different. Add this treated coffee material to the concrete to make it significantly stronger.
The increase in strength comes from some key reasons. First, the treated coffee material has tiny holes that can be fixed in water. This helps cement harden more efficiently from the inside, even after the outer surface is dry. Additionally, the cement mixture can enter the pores of treated coffee particles, creating a better connection between the materials and helping the concrete stay together more firmly. Due to these effects, coffee materials not only fill the space, but can actually help the concrete become stronger.
“As we add more coffee materials, the coffee materials treated at lower temperatures get stronger – to a certain point,” Dr. Roychand explained. “Other than that, the benefits start to upgrade, but the overall performance of the concrete is still good.” This means how much coffee materials should be used for the best results.
Environmentally and economically, the results are encouraging. Australia throws away a lot of second-hand coffee fields every year. According to the study, if these wastes are turned into treated coffee materials, enough useful materials can be generated to replace most of the sand used in the concrete structure. This will help reduce waste in landfills and reduce the need to dig sand, which often harms the natural environment.
The team notes that the strategy fits well with the idea of using waste to create new products – a concept commonly known as the circular economy, which refers to the continuous reuse and recycling of materials rather than discarding them. It can benefit the environment, enhance the economy, and even create jobs. By turning waste into something valuable, the demand for fresh raw materials is reduced, and recycling and green building may create new business opportunities.
“The addition of coffee-based materials not only makes concrete better; it also provides us with a practical way to manage waste,” said Professor Kilmartin. They believe that more research should be done to understand how this material continues over time, especially in different weather conditions and building types.
Journal Reference
Roychand R., Kilmartin-Lynch S., Saberian M., Li J., Zhang G., Li CQ, “Convert spent coffee grounds into a valuable resource to enhance concrete strength.” Journal of Cleaner Production, 2023. doi:
About the Author
Dr. Rajeev Roychand He is a researcher at the School of Engineering at RMIT University, Melbourne, Australia, specializing in sustainable building materials. His work has a background in civil engineering and a strong interest in environmental innovation, and his work focuses on recycling industrial and organic waste into high-performance building materials. Dr. Roychand led several projects exploring the use of alternative materials such as fly ash, waste plastics and biochar to improve specific sustainability and performance. He is passionate about reducing the carbon footprint of the construction industry by developing practical, scalable solutions. Dr. Roychand is known for his hands-on approach and industry collaborations to bridge the gap between academic research and real-world applications in infrastructure.
Shannon Kilmartin-Professor Lynch He is a former Indigenous Research Fellow at RMIT University and a rising leader in sustainable materials research. Her work combines environmental science with community-focused engineering solutions. To advance indigenous representation in STEM, she explores how waste, such as spent coffee sites and personal protection equipment, can transform it into valuable building resources. Professor Kilmartin-Lynch focuses on research on circular economy practices and environmental equity, aiming to reduce landfill waste and promote green innovation. Her work not only enhances sustainable technology, but also supports scientific participation in inclusion and cultural awareness.
