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Researchers made used coffee grounds into concrete

additive

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Say makes concrete stronger and more sustainable

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Concrete production responsible for 7% of global emissions

-UN

By Peter Hobson and Stefica Nicol Bikes

MELBOURNE, May 23 (Reuters) - Your morning coffee could

help the planet.

That's the promise of an Australian university turning used

coffee grounds into a material that can be added to concrete to

make it stronger and more sustainable, potentially lowering

greenhouse gas emissions.

Concrete production, which involves mixing sand and gravel

with cement and water, is a major producer of greenhouse gases,

responsible for around 7% of the world's emissions, according to

the United Nations.

Researchers at Melbourne's RMIT University heated coffee

waste without oxygen, a process known as pyrolysis, to create a

substance called biochar that can replace up to 15% of the sand

used in concrete.

The inclusion of the biochar makes the concrete 30%

stronger and reduces the amount of cement needed by up to 10%,

said lead researcher Rajeev Roychand.

"This ticks all the boxes," he said. "You preserve carbon

and you are getting significantly higher strength."

Roughly 50 billion metric tons of sand is dug up each year,

mostly for use in concrete, a 2022 U.N. report said. Its

extraction is often environmentally destructive and it is in

increasingly short supply, the report said.

Cement production, which involves heating a mixture of

limestone and clay to around 1,500  degrees Celsius (2,732°F),

is responsible for most of concrete's emissions.

BIOCHAR COMPANY

The Macedon Ranges Shire Council near Melbourne used the

coffee concrete earlier this month to construct a footpath.

RMIT is talking with several construction firms and concrete

makers and with Starbucks ( SBUX ) to take its waste coffee

grounds, and could form a company to make biochar, Roychand

said. Starbucks ( SBUX ) did not respond to a request for comment.

Australian infrastructure company Bild Group said it planned

to trial the concrete and hoped to use it on major road

projects. Construction giant Arup supported the research.

Millions of tons of used coffee grounds are produced

globally and most are sent to landfills where they emit methane

as they break down.

Australia generates around 75,000 tons of waste coffee

grounds a year and biochar made from this could replace up to

655,000 tons of sand in concrete because it is a denser

material, Roychand said. Globally, coffee-waste biochar could

replace up to 90 million tons of sand in concrete, he said.

Food waste accounts for around 3% of Australia's emissions,

according to the government, and most could eventually be made

into biochar, Roychand said.

"We anticipate that about 60-70% (of organic waste) we can

divert from landfill into concrete applications," he said.

Other international universities are also researching the

potential of biochar and other bio-engineering in concrete. RMIT

was the first to use waste coffee grounds in this way, Roychand

said.