Researchers find a way to cut CO2 emissions from concrete


Did you know that cement, a component of concrete, produces 8% of the world’s carbon footprint?

With that much at stake and with 30 billion tons of concrete produced a year, Purdue University research engineers figured out a way to cut carbon emissions from concrete dramatically.

They found that adding small portions of nanoscale titanium dioxide to the cement paste that makes up concrete can nearly double the concrete’s natural ability to sequester CO2. The concrete’s carbon dioxide absorption varies by the mix of water, cement paste and sand and gravel used.

Titanium dioxide is found in sunscreen, paints, plastics and preservatives.

A team at Purdue led by Miran Velay-Lizancos, an assistant professor of civil engineering, made the discovery. Her research focuses on making concrete a more sustainable building material.

Concrete was invented thousands of years ago and used in the Pyramids and Roman aqueducts. Modern concrete needs to be strong, durable and economical, but the manufacturing process is energy-intensive. Concrete naturally absorbs CO2, but not very quickly and not in great amounts.

“We can’t wait decades for concrete to absorb the carbon dioxide produced in its manufacturing process,” Velay-Lizancos said in a statement. “My team is making the concrete itself absorb carbon dioxide faster and in greater volumes.”

She said the research is not intended to change the way concrete is used.  “We’re making the concrete work for us,” she added. Even a small improvement in the carbon footprint of concrete could have a big impact globally.

“Our research may lead to lower net carbon dioxide emissions,” she said.

Velay-Lizancos and two doctoral students, Carlos Moro and Vito Francioso made the discovery after initially studying how titanium dioxide interacts with cement to make concrete stronger. They noticed their concrete samples with nano-titanium dioxide absorbed CO2 from the surrounding air faster than other samples.

 On further examination, they found the nano-titanium dioxide in the concrete mix decreased the size of calcium hydroxide molecules to make them more efficient at absorbing CO2.

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