‘Double Shot at Life’
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Scientists discovered that replacing sand with spent coffee grounds (SCG) can make concrete up to 30 percent stronger.
Globally, about 60 million tons of coffee grounds are generated each year, making it the largest waste product from coffee making – with the majority ending up in landfills.
SCG can serve as good fertilizer and the organic material has been proposed as a useful component for construction applications because of its fine particle size.
In their experiments, a research team collected coffee grounds from cafés in Melbourne, Australia, dried them, and heated them at two different temperatures – 662 and 932 degrees Fahrenheit – using a low-energy, oxygen-free process called pyrolysis.
Through this process, the researchers produced different types of biochar which they combined with concrete, with the SCG acting as a replacement for fine aggregate – in this case, natural sand – at different percentages.
Their findings showed the concrete’s strength increased by 29.3 percent when the team replaced 15 percent of sand with biochar pyrolyzed at 662 degrees Fahrenheit.
Lead author Rajeev Roychand explained that the study aims to give SCG a “‘double shot’ at life,” noting that the results are promising and could be used in construction globally.
Specifically, the authors hope that the study can provide a solution to the overuse of sand in concrete production, which damages the environment.
“With a circular-economy approach, we could keep organic waste out of landfills and also better preserve our natural resources like sand,” according to co-author Jie Lie.