Concrete is the most widely used material in the world. And as you might know already, it’s also one with a gargantuan environmental footprint, producing over eight percent of the world’s CO2 emissions. What’s less known about this binding material, however, is that it can also capture CO2 from the air and store it.
A new concrete recipe developed by engineers at Purdue University seeks to shrink concrete’s carbon footprint by enabling the material to absorb CO2 twice as fast, as usual, hopefully turning it into a useful carbon capture technology.
Although concrete naturally absorbs CO2 from the air over its lifetime, it’s not enough to fully counter the emissions associated with its production. That’s exactly what the Purdue team wanted to address with its study.
“We can’t wait decades for concrete to absorb the carbon dioxide produced in its manufacturing process,” says Mirian Velay-Lizancos, study lead author. “My team is making the concrete itself absorb carbon dioxide faster and in greater volumes. We’re not trying to change the way we use concrete; we’re making the concrete work for us.”
The new recipe’s secret ingredient is titanium dioxide. By adding a small portion of this compound to the cement paste, the team discovered that it reduced the size of calcium hydroxide molecules, and thus made the concrete much more efficient at absorbing CO2.
After testing the new concrete’s CO2 absorption potential, the researchers found that titanium dioxide almost doubled the speed at which the material captured the greenhouse gas. Now the engineers are working to further improve the new concrete recipe by making it more sustainable and durable.