The production of concrete consumes a significant amount of sand each year, leading to shortages of this valuable resource. However, researchers from RMIT University in Australia have discovered that used coffee grounds can be used as a substitute for sand in concrete production. The team found that coffee grounds, when pyrolyzed at the right temperatures and mixed in the proper proportions, can provide a stronger chemical bond than sand alone. This innovation not only reduces the reliance on sand mining but also offers a solution for the disposal of organic waste, such as coffee grounds, which emit greenhouse gases when left in landfills.
Lead author Dr. Rajeev Roychand emphasizes that the disposal of organic waste, including coffee grounds, contributes to climate change by emitting greenhouse gases. Australia alone produces 75 million kilograms of used coffee grounds annually, most of which ends up in landfills. By using coffee grounds as a silica substitute in concrete production, not only can the emissions from organic waste be reduced, but the concrete also becomes stronger. This innovative approach shows promise in significantly reducing the amount of organic waste that goes to landfills, where it would decompose and generate methane, a potent greenhouse gas.
To make coffee grounds compatible with concrete, the research team pyrolyzed them at different temperatures and substituted them for sand in varying percentages. They found that a pyrolyzing temperature of 350 degrees Celsius produced the best results, with a 29.3 percent enhancement in the compressive strength of the concrete. In addition to strengthening the concrete, this method also reduces the environmental impact of sand mining. Dr. Shannon Kilmartin-Lynch, co-author of the study, highlights the potential of the concrete industry to increase the recycling of organic waste like used coffee, offering an innovative way to minimize the amount of organic waste ending up in landfills and mitigating its contribution to greenhouse gas emissions.