Their technique would make it possible to strengthen concrete by 30% by using waste coffee grounds transformed into biochar.

The method used to transform them is called pyrolysis and involves heating organic waste to 350 degrees in a low-energy, oxygen-free process. The result is biochar, a perfect substitute for sand.

Every year, over 10 billion kilograms of waste coffee grounds are generated worldwide, most of which ends up in landfill sites.

Disposing of organic waste poses an environmental problem, as it emits large quantities of greenhouse gases, notably methane and carbon dioxide, which contribute to climate change. Therefore, new ideas that allow such waste to be recycled are welcome across industries.

In their experiments, the researchers replaced sand with biochar in proportions of 5-20% for standard concrete mixes. They observed an almost 30% increase in concrete strength when using this mix.

In addition to coffee, the concrete industry can play a key role in supporting the recycling of other types of organic waste. Still in its early stages, the aim of this research is to find other solutions to reduce the amount of organic waste sent to landfill each year.

This work was published in the Journal of Cleaner Production.