Kiev. Ukraine. Ukraine Gate – February 13, 2021 – Science / Article
Concrete is one of the most commonly used materials in the world, and unfortunately, its production is the main source of carbon dioxide in the atmosphere. Engineers from Purdue University have developed a new recipe for cement that can absorb CO2 twice as fast as usual.
Concrete production accounts for more than 8% of global carbon dioxide emissions. Every year the demand for it grows, and therefore researchers are studying ways to make concrete more environmentally friendly. Some steps include changing the recipe to reduce or replace the binder that causes the chemical reaction to release CO2. Some alternatives even include the capture of CO2 from other sources and its use in the mixture.
But there is another area of research that gives the material itself a more active role. After laying, concrete naturally absorbs CO2 from the atmosphere during its service life. This is not enough to fully combat the emissions that are released during its production, but it at least helps to reduce the environmental footprint. Some studies have found ways to increase this absorption to make concrete even more environmentally friendly – and a team of scientists from Purdue University has put the idea into practice.
“We can’t wait a decade for concrete to absorb the carbon dioxide it produces,” said Mirian Velay-Lizankos, lead author of the study. “My team is forcing the concrete itself to absorb carbon dioxide faster and in larger quantities. We are not trying to change the way concrete is used; he will just do useful work for us”.
The secret ingredient is titanium dioxide. Mixing small portions of this material with cement paste, the team found that it reduced the size of calcium hydroxide molecules, making the concrete more efficient at absorbing carbon dioxide.
The researchers tested the absorption of the concrete by placing the samples in a chamber filled with a high concentration of CO2 for 24 hours, then analyzed changes in their mass over time and performed a three-dimensional X-ray scan of the pore structure. They found that titanium dioxide could almost double the rate of CO2 absorption by concrete.
However, it was not just a matter of adding more titanium dioxide and further enhancing the effect. The team found that it worked to a certain percentage before efficiency began to decline. This percentage depends on the ratio of water and powder, as well as the age of the cement. The researchers plan to continue studying the new cement recipe in hopes of making it more durable and long-lasting.
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