Australian engineers have found a way to make concrete significantly stronger by replacing sand, a precious yet polluting natural resource, with coffee grounds, thus preventing this organic waste from ending up in landfills.
To make concrete 30% stronger, coffee grounds are turned into biochar, defined as “a stable solid rich in carbon that is made from organic waste material or biomass that is partially combusted in the presence of limited oxygen” by the U.S. Department of Agriculture.
According to Seven Mountains Coffee, in 2020-2021, 166.63 million 60-kilogram bags of coffee were consumed, leading to a significant waste problem as organic matters can’t break down in landfills – designed for storage, not decomposition – and are stuck in a limbo state releasing greenhouse gases like methane and carbon dioxide. Researchers at RMIT University are replacing sand, a precious natural resource, with coffee grounds, solving a waste problem and reducing the environmental burden of a polluting industry. Typical concrete is made of 10% cement, 20% air and water, 30% sand, and 40% gravel, per Concrete Supply Co. “With a circular-economy approach, we could keep organic waste out of landfill and also better preserve our natural resources like sand,” says study author Professor Jie Li.