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Australian engineers to make stronger concrete with old coffee grounds

Australian engineers to make stronger concrete with old coffee grounds. Researchers have given tons of waste coffee grounds a “double shot” at life, by infusing it into concrete—where it not only increases material strength by 30%, but also could be a significantly more sustainable alternative to the mined sand on which the concrete industry depends. In Australia alone, where the study was based, shops and households produce around 75,000 tons of coffee grounds every year. This study’s secret was that it pyrolyzed the coffee grounds to make a carbon-rich biochar, heating them experimentally at different temperatures, before placing the grounds into the concrete mix. This enabled the researchers to pinpoint the precise temperature that gave the coffee the right material properties to reinforce the concrete without weakening it.

A close analysis of the concrete followed, using x-rays, scanning microscopy, and an assessment of its carbon, hydrogen, nitrogen, and sulfur content, to draw up a profile of the interior. This helped reveal that at this temperature and ratio, the grounds create a helpful porous structure in the concrete.

Increased strength is obviously a boon for the construction industry. But there are other reasons to bring this waste material into buildings. The researchers calculated that replacing 15% of Australia’s concrete mix with coffee grounds would generate enough demand to use up all the available coffee waste in the country and divert it from the landfill. This would be a rare double-win for the environment, meanwhile for industry there is a dangling carrot in the form of reduced production costs from the cheap, available waste.

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