In 2024, engineers turned 140,000 coffees’ worth of used grounds into concrete; the 30-cubic-metre footpath saved more than 3 tons of sand

Coffee concrete: What if your morning coffee could end up helping build a footpath? That is what happened in Pakenham, Victoria, where spent coffee grounds were turned into biochar and used in concrete as part of a major infrastructure project. In 2024, an innovation developed by researchers at RMIT University was used for the first time in a major infrastructure project. Major Road Projects Victoria and contractor BildGroup used concrete containing biochar made from spent coffee grounds in the Pakenham Roads Upgrade, part of Victoria’s Big Build.

The coffee grounds were not mixed directly into the concrete. Instead, they were converted into biochar, which replaced part of the river sand normally used in the concrete mix.

For the project, Earth Systems processed 5 tonnes of spent coffee grounds, about 140,000 coffees’ worth, into 2 tonnes of usable biochar. The material was then used in a 30-cubic-metre footpath along McGregor Road. BildGroup CEO Stephen Hill said the project diverted an estimated 140,000 coffees from landfill and saved more than 3 tonnes of sand, as per a RMIT University report.

How coffee grounds were turned into concrete biochar

Spent coffee grounds cannot simply be added to concrete. The organic material would decompose over time and weaken the building material.

RMIT researchers developed a way to turn the waste into biochar before it is added to concrete. Their technique uses a low-energy process without oxygen at 350 degrees Celsius.

The RMIT team found that concrete made using biochar produced through this technique could be 30% stronger.

That 30% figure comes from the team's research technique, rather than being a claim about the strength of the concrete used in the Pakenham footpath.

There was also a supply issue during the earlier Gisborne trial. RMIT said the team could not use its low-energy process to produce the biochar, and the coffee concrete used in that trial had a similar strength to standard concrete.

140,000 coffees’ worth of waste went into the Pakenham project

The numbers behind the Pakenham footpath give a sense of how much coffee waste was involved.

Earth Systems took 5 tonnes of spent coffee grounds, equivalent to about 140,000 coffees, and converted them into 2 tonnes of usable biochar.

That biochar was used in concrete for the 30-cubic-metre footpath along McGregor Road.

According to BildGroup, the project saved more than 3 tonnes of sand while diverting an estimated 140,000 coffees from landfill.

Australia produces 75 million kilograms of coffee waste every year

The Pakenham project also highlights the amount of coffee waste generated each year. Australia generates 75 million kilograms of ground coffee waste every year, most of which goes to landfill. RMIT said the waste could potentially replace up to 655 million kilograms of sand in concrete because the material is denser.

Around 10 billion kilograms of spent coffee is generated globally each year. According to RMIT, that amount could potentially replace up to 90 billion kilograms of sand in concrete.

The researchers also said organic waste going to landfill, including spent coffee grounds, contributes 3% of greenhouse gas emissions.

Coffee concrete makes its way into Victoria’s Big Build

The Pakenham Roads Upgrade was the first Victorian Big Build project to use the coffee concrete.

Major Road Projects Victoria and BildGroup used the biochar concrete as part of the upgrade. MRPV Program Director Brendan Pauwels said coffee concrete had the potential to cut costs and remove large amounts of waste from landfill.

The coffee concrete was one of several circular economy initiatives used on the project. Others included reusing in-fill soil and material for Princes Freeway embankments, as well as using foam bitumen and rubber tyre road barriers.

RMIT had already tested coffee concrete in Gisborne

The Pakenham project was not the first time RMIT had tested the idea. Earlier in 2024, RMIT worked with Macedon Ranges Shire Council on a world-first trial of coffee concrete in a footpath in Gisborne, Victoria.

That trial used biochar made from spent coffee grounds. The Pakenham project then became the first time the RMIT innovation was used in a major infrastructure project.

Dr Rajeev Roychand led the coffee concrete research

Dr Rajeev Roychand, an RMIT Postdoctoral Research Fellow, was the lead inventor of the coffee concrete. He partnered with BildGroup and Major Road Projects Victoria to help bring the RMIT team's research into Victorian government Big Build projects.

RMIT is also working with a commercialisation partner and companies in the construction and agriculture sectors that could potentially benefit from biochar products.

The research behind the innovation, titled “Transforming spent coffee grounds into a valuable resource for the enhancement of concrete strength,” was published in the Journal of Cleaner Production.

From coffee waste to a Pakenham footpath

The Pakenham project brought the RMIT coffee concrete research into a major infrastructure setting.

Five tonnes of spent coffee grounds, about 140,000 coffees’ worth, were converted into 2 tonnes of usable biochar.

The biochar was then used as a partial replacement for river sand in concrete for a 30-cubic-metre footpath along McGregor Road.

The project also saved more than 3 tonnes of sand and diverted an estimated 140,000 coffees from landfill.