Processed spent coffee grounds can enhance concrete strength

Researchers at the Royal Melbourne Institute of Technology (RMIT) have recently published a paper which shows that the addition of processed spent coffee grounds to a concrete mix can significantly increase its strength and make it more environmentally friendly.

Furthermore, the majority of spent coffee grounds currently end up in landfills, where the material decomposes and produces methane, a greenhouse gas, while a small portion of it ends up being recycled as fertilizer.

The idea to introduce it into concrete arose in the lab, as the researchers were frequently enjoying their cups of coffee and realized how more than 60 million tons of spent coffee grounds produced each year could be reused.

As for the method followed, the team used pyrolysis at 350 and 500 degrees Celsius to create biochar from the grounds and replaced a portion of the concrete mixture’s sand with it.

More specifically, replacing 15% of sand with biochar resulted in a 30% stronger product, compared to traditional concrete.

The process of cement production uses large amounts of energy, namely accounting for 8% of worldwide CO2 emissions, while concrete demand is steadily increasing and has reached a consumption of 30 billion tons a year, which is triple what it was forty years ago.

Hence, using spent coffee grounds biochar can help reduce cement used in concrete by 10%, in addition to using less sand in the mixture.

However, concerns exist about the material’s capability of being used on the largescale. For example, professor Kypros Pilakoutas, from the University of Sheffield said, “Whilst it would be great to collect all coffee grounds from around a country, the associated costs would be considerable and prohibitive.”

Joining the discussion, Ali Abbas, director of the University of Sydney Waste Transformation Research Hub, said that he saw it as part of a wave of promising research into concrete and sustainability, according to the Washington Post.

Finally, RMIT is expected to put the new material into real-world use during the following six months.