CO2 AS A PERFORMANCE-ENHANCING ADMIXTURE IN READYMIX CONCRETE PART 4

An online presentation by Sean Monkman on the American Concrete Institute (ACI) platform.

The ACI recently hosted a presentation on the innovative topic of utilising CO₂ as a performance-enhancing admixture in ready-mix concrete. This is the Part 4 of a four-part article.

…continued from Part 3.

Positioning CO₂ utilisation as a tool

Monkman reaffirmed the intended purpose of CO₂ utilisation technology: it is not presented as a sole solution to sustainability challenges but rather as a tool that concrete producers can leverage to reduce the CO₂ footprint of their products. The presentation emphasised the importance of evaluating the overall environmental impacts, considering emissions associated with CO₂ processing, transportation, and equipment operation. Monkman emphasised the need for a holistic approach to sustainability, where CO₂ utilisation technology is one component in a broader strategy to enhance the environmental performance of the concrete industry.

In the final segment of the presentation, Monkman delved into the environmental considerations and the carbon footprint associated with CO₂ utilisation technology. He acknowledged that the technology’s impact is influenced by the energy grid’s carbon intensity, with emissions associated with CO₂ processing, transportation, cryogenic tank creation, and injection system operation. Monkman highlighted that approximately 12% of the emissions are associated with dosing CO₂, while the vented and non-mineralised portion accounts for about 10% of the dose, resulting in a total emission of around 22%.

Comparing the carbon footprint of CO₂ as an admixture with other chemical admixtures, Monkman showcased the favourable environmental profile of CO₂. Even at different dosages, CO₂ demonstrated a lower carbon footprint compared to alternative admixtures, making it a more sustainable choice for concrete production.

Monkman emphasised that the technology contributes to a net removal of over 70% of the emitted CO₂, showcasing its potential as a tool for carbon reduction. He highlighted the ability to issue verified carbon units through methodologies like Verra (Verified Carbon Standard [VCS]), allowing companies to sell CO₂ reductions on the voluntary carbon market. This market-driven approach provides an incentive for adopting technologies that contribute to environmental sustainability.

Closing the presentation, Monkman shared the impressive track record of the technology, having been used in over 700 projects worldwide, with over 30 million cubic metres of concrete produced and 250 000 metric tons of CO₂ saved. He highlighted that the technology has resonated well in the industry, enabling users to enhance sustainability, reduce costs, and differentiate themselves in discussions with architects and stakeholders.

Monkman concluded by inviting the audience to further exploration through published materials for those interested in deeper reading. The presentation showcased not only the technical advancements of CO₂ utilisation in concrete but also its tangible impact on sustainability and industry practices.