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Working with waste: part 2

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World Cement,

World Cement profiles three semi-finalists in the NRG COSIA Carbon XPRIZE that offer solutions to reduce the carbon footprint of concrete. In this second article, Prof. Gaurav N. Sant, Carbon Upcycling Team, introduces CO2NCRETE, a functional equivalent to conventional concrete based on the idea of carbon upcycling.

Carbon Upcycling-UCLA, an interdisciplinary collaboration at the University of California, Los Angeles, addresses the challenge posed by manmade CO2 emissions by positively using these same emissions, referred to as upcycling, to help mitigate climate change.

To accomplish this, the team created CO2NCRETE™, a breakthrough material made by capturing and converting CO2 emissions that is functionally equivalent to conventional concrete (made using ordinary portland cement, OPC). Conventional concrete was targeted since it is the most widely-produced synthetic material in the world, and one whose primary binding agent, OPC, is responsible for nearly 9% of global carbon dioxide emissions. CO2NCRETE offers an economically feasible route for CO2 upcycling at the gigatonne scale, while simultaneously addressing the lack of scalable, cost-effective technologies for carbon capture and storage and the negative environmental footprint of the construction sector.

While the development of these materials and processes is motivated by the need to mitigate climate-altering emissions, Carbon Upcycling-UCLA adds value to the construction industry by transforming the materials and processes of concrete production. Therefore, the carbon upcycling process seeks to offer improved engineering performance relative to traditional concrete, and to reduce inefficiencies in concrete design, production, and installation by ensuring viability in future construction markets.

Led by Prof. Gaurav N. Sant, and with other team members including Prof. Richard Kaner, Prof. Laurent Pilon, Prof. Mathieu Bauchy, Prof. J.R. DeShazo, Dr Bu Wang, Gabriel Falzone, Dr Hyukmin Kweon, and Kelsey Jessup, CO2NCRETE’s production incorporates two breakthrough technologies:

  • An unconventional cement composition.
  • An approach to CO2 mineralisation that rapidly transforms the gas into stable mineral carbonates.

The unconventional cement composition features economical and abundant materials, and can be produced using typical processes. A range of performance criteria, such as strength, can also be tuned, while maximising CO2 upcycling. CO2NCRETE’s composition is designed to engender adaptability to a variety of processing and forming methods, ensuring that the material may replace conventional concrete in a variety of construction components and products.

CO2NCRETE gains strength by exploiting CO2 mineralisation through a proprietary multi-step reaction cycle. The process can capture CO2 from diverse industrial flue gas streams, such as chemical processing plants and coal and natural gas power plants. The entire sequence of material processing can be completed within a few days, or less, at atmospheric pressure, yielding CO2NCRETE that is as strong as traditional concrete after only seven days of maturation.

While CO2NCRETE is currently fabricated using conventional methods, the Carbon Upcycling-UCLA team is developing scalable digital 3D-printing technologies to integrate the benefits of automated mass production with the flexibility to produce geometrically complex, structurally optimised components that feature superior strength-to-weight ratios. This will result in the production of lightweight material that will be easier to install than traditional sections, accelerating construction workflows and improving job site safety.

Read the first and third parts of this series here and here.

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