Scientists are turning leftover coffee grounds into powerful concrete
Scientists are turning leftover coffee grounds into powerful concrete
Engineers in Australia have discovered that processing and adding charred coffee grounds to cement mix makes it up to 30% stronger.
The ingenious approach also addresses multiple environmental issues simultaneously.
Each year, a mindblowing 10 billion kilograms of coffee waste is generated globally, with most of it ending up in landfills.
“The disposal of organic waste poses an environmental challenge as it emits large amounts of greenhouse gases including methane and carbon dioxide, which contribute to climate change,” says RMIT University engineer Rajeev Roychand.
The global construction boom has led to an increasing demand for resource-intensive concrete, resulting in another set of environmental challenges.
“The ongoing extraction of natural sand around the world – typically taken from river beds and banks – to meet the rapidly growing demands of the construction industry has a big impact on the environment,” said RMIT engineer Jie Li.
“There are critical and long-lasting challenges in maintaining a sustainable supply of sand due to the finite nature of resources and the environmental impacts of sand mining.”
“With a circular-economy approach, we could keep organic waste out of landfill and also better preserve our natural resources like sand.”
How this new power concrete is made
Since coffee grounds are an organic product, they can’t be added directly to concrete. This is because they release chemicals that weaken the material.
To overcome this, the team used a process called pyrolysis, which involves heating the coffee waste to over 350°C without oxygen.
This process transforms the coffee grounds into a porous, carbon-rich charcoal known as biochar, which can bond with the cement matrix.
Roychand and his colleagues also tried this process at 500 °C, but found the resulting biochar particles were not as strong.
The recipe could work with other organic waste
While this has been a breakthrough for cement, the researchers are still assessing the long-term durability of their product.
The hybrid coffee-cement is also being tested under freeze/thaw cycles, against water absorption, abrasions and other stressors.
The team is working on creating biochars from other organic waste sources too. This includes wood, food waste and agricultural waste.
“Our research is in the early stages, but these exciting findings offer an innovative way to greatly reduce the amount of organic waste that goes to landfill,” added RMIT engineer Shannon Kilmartin-Lynch.
“Inspiration for my research, from an Indigenous perspective, involves Caring for Country, ensuring there’s a sustainable life cycle for all materials and avoiding things going into landfill to minimise the impact on the environment.”