Concrete revolution: Australian engineers boost strength with coffee waste

Engineers from Australia have found an innovative way to use coffee grounds in the construction sector. This often overlooked byproduct of brewing coffee can significantly, by almost 30%, increase the strength of concrete.

These findings, which The Guardian refers to, came to light in the "Journal of Cleaner Production." According to the data presented, a team of researchers from RMIT University in Melbourne developed a method of re-utilizing used coffee grounds to produce stronger concrete.

Adding processed coffee waste to the concrete mix can increase its strength by 29.3%. Scientists also emphasize that the pyrolysis process used in this method is energy efficient.

Dr Shannon Kilmartin-Lynch from RMIT, who contributed to the development of this technology, points out the issue of excessive waste of coffee grounds, including capsules. He highlights that such action is a response to inefficient coffee waste management, which, after being converted into biochar—a substance similar to charcoal, can replace a certain percentage of sand necessary in the concrete production process.

Dr Rajeev Roychand from RMIT explains that to produce biochar from coffee residues, it is crucial to roast the used grounds in anaerobic conditions to avoid carbon dioxide emissions.

Pyrolysis, a vital element of the method for producing stronger concrete, involves heating coffee waste to around 350 degrees Celsius and is an energy-efficient process, as noted by scientists. This is because pyrolysis occurs typically at much higher temperatures, reaching up to 900 degrees Celsius, while coffee grounds require little more than 350 degrees Celsius.

According to research, incorporating 15% biochar from coffee grounds into the concrete mix increases its strength by almost 30%. Moreover, because coffee waste is a porous material, cement quickly bonds with the biochar.

Although the RMIT team's research is still in its early stages, and additional tests regarding material durability are necessary, scientists are already collaborating with local authorities. They aim to use coffee ground-reinforced concrete in upcoming infrastructure projects, such as building pavements.

Another significant benefit is the reduction of coffee grounds ending up in landfills. If all Australian coffee grounds were processed, up to 25,000 tonnes of this eco-friendly concrete annually could be produced.