Transforming Coffee Waste into Sustainable Concrete: A Breakthrough by RMIT Researchers

Researchers from the Royal Melbourne Institute of Technology (RMIT) have developed a method to incorporate spent coffee grounds into concrete, significantly reducing its carbon footprint. This innovative approach utilizes biochar, created by heating used coffee grounds at approximately 350°C in a low-oxygen environment, to replace a portion of sand in concrete mixes. Previous laboratory trials indicated that replacing 15% of sand with coffee biochar could enhance concrete strength by about 30%. The recent life-cycle analysis conducted by the RMIT team, led by Dr. Jingxuan Zhang and Dr. Mohammad Saberian, confirms that this method can reduce carbon dioxide emissions by 15%, 23%, and 26% when 5%, 10%, and 15% of sand is replaced, respectively.

Interesting EngineeringResearchers use coffee waste to lower carbon concreteCoffee waste cuts concrete emissions

The life-cycle assessment evaluated the environmental impacts of using coffee biochar in concrete from production through to end-of-life. The findings revealed a potential reduction in fossil fuel use by up to 31% and improvements in the ecological impacts on rivers and lakes. This research aligns with Australia’s goals for a circular economy and net-zero emissions by transforming organic waste into functional materials, thereby decreasing reliance on natural sand resources.

Researchers use coffee waste to lower carbon concrete

Dr. Jingxuan Zhang emphasized the significance of their findings, stating, “We showed that coffee biochar can cut concrete’s carbon footprint in the scenarios we assessed, while earlier trials demonstrated strength gains using the same approach.” Professor Chun-Qing Li, who guided the project, noted that this innovation provides a "clear, measurable pathway to lower-impact concrete." Dr. Mohammad Saberian highlighted the importance of collaboration with industry and government entities for future construction projects, stating, “Next steps include larger pilots, mix optimization, and alignment with standards so projects can adopt this confidently.”

Coffee waste cuts concrete emissions

While the research presents promising results, some critics may question the scalability of using coffee biochar in concrete production. Concerns about the availability of sufficient coffee waste to meet large-scale construction demands could pose challenges. Additionally, the long-term durability and performance of concrete made with biochar compared to traditional mixes remain to be fully assessed.

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The RMIT team is actively engaging with industry partners and local governments to implement pilot projects that utilize coffee biochar in construction. They have already conducted public demonstrations, including a footpath pilot and a section of coffee-biochar concrete in the Victorian Big Build. Future initiatives will focus on optimizing the concrete mix and ensuring compliance with construction standards.

Coffee waste cuts concrete emissions

• “Using moderate amounts of coffee biochar offers a clear, measurable pathway to lower-impact concrete,” — Chun-Qing Li, PhD, Civil Engineering Professor, RMIT

Researchers use coffee waste to lower carbon concrete

• “We showed that coffee biochar can cut concrete’s carbon footprint in the scenarios we assessed, while earlier trials demonstrated strength gains using the same approach,” — Jingxuan Zhang, PhD, RMIT

Researchers use coffee waste to lower carbon concrete

• “Next steps include larger pilots, mix optimization and alignment with standards so projects can adopt this confidently,” — Mohammad Saberian, PhD, RMIT

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This research, published in the *International Journal of Construction Management*, underscores the potential of repurposing organic waste to create sustainable construction materials, paving the way for greener infrastructure solutions.

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