Turning Carbon Dioxide into Concrete

J.R. DeShazo, left, director of the UCLA Luskin Center for Innovation, and Gaurav Sant, associate professor in civil and environmental engineering, hold a a sample of the new building materials they have created to replace concrete. (Image courtesy of UCLA.)

CO₂NCRETE represents a novel material with the potential to replace the ubiquitous concrete present in our buildings, roads and bridges.

What’s so special about this new material?

It turns one of the most harmful greenhouse gases into a sustainable resource, reducing the emissions from concrete production and putting the carbon dioxide we already have to good use. CO₂NCRETE is fabricated using 3D printers supplied with carbon captured from smokestack flue gas in a process known as “upcycling.”

Power plants are the largest source of carbon dioxide on the planet. The current approach to dealing with the CO₂ they produce is to simply capture and store it. Upcycling goes a step further by finding a use for that captured carbon.

“We can demonstrate a process where we take lime and combine it with carbon dioxide to produce a cement-like material,” said Gaurav Sant, associate professor of civil and environmental engineering at UCLA. “The big challenge we foresee with this is we’re not just trying to develop a building material. We’re trying to develop a process solution, an integrated technology which goes right from CO₂ to a finished product.

The process for carbonating portlandite using captured carbon dioxide. (Image courtesy of Industrial & Engineering Chemistry Research.)

The upcycling process for creating CO₂NCRETE is currently limited to laboratory-scale production in which 3D printers shape the material into tiny cones. Scaling it up to a size that’s practical for construction purposes will take time.

In addition, Sant and his colleagues believe that convincing stakeholders to welcome this product in an industry as old and established as construction will not be easy.

However, if these challenges can be met, this technology could have significant environmental impacts. For example, it could reduce greenhouse gas in the US, especially in regions with numerous coal-fired power plants.

Even more exciting is the potential to reduce emissions in China and India, the two largest greenhouse gas producers in the world. Considering the increasing threats from climate change, this technology truly has the potential to be a game-changer.

For more information, see the research paper published by Sant and his colleagues entitled, “Direct Carbonation of Ca(OH)2 Using Liquid and Supercritical CO2: Implications for Carbon-Neutral Cementation.”