Scientists Strengthen Concrete By 30 Percent With Used Coffee Grounds

According to a team of researchers from RMIT University in Australia, coffee grounds can be used as a silica substitute in the concrete production process to yield a significantly stronger chemical bond than sand alone. Engadget reports: "The disposal of organic waste poses an environmental challenge as it emits large amounts of greenhouse gases including methane and carbon dioxide, which contribute to climate change," lead author of the study, Dr Rajeev Roychand of RMIT's School of Engineering, said in a recent release. He notes that Australia alone produces 75 million kilograms of used coffee grounds each year, most of which ends up in landfills. Coffee grounds can't simply be mixed in raw with standard concrete as they won't bind with the other materials due to their organic content, Dr. Roychand explained. In order to make the grounds more compatible, the team experimented with pyrolyzing the materials at 350 and 500 degrees C, then substituting them in for sand in 5, 10, 15 and 20 percentages (by volume) for standard concrete mixtures. The team found that at 350 degrees is perfect temperature, producing a "29.3 percent enhancement in the compressive strength of the composite concrete blended with coffee biochar," per the team's study, published in the September issue of Journal of Cleaner Production. "In addition to reducing emissions and making a stronger concrete, we're reducing the impact of continuous mining of natural resources like sand," Dr. Roychand said.

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