citation: Nick Beckelman, Scientific American, February 2023
A number of articles are emphasizing that "recycled carbon content" cement has the potential to reduce greenhouse gases even more than electric vehicles does.
Solving Cement’s Massive Carbon Problem
New techniques and novel ingredients can greatly reduce the immense carbon emissions from cement and concrete production
In this blog I explore how Recycling Policy Organizations like MassRecycle.org, NERC.org, ReMA.org, EarthwormRecycling.org, NRRArecycles.org have the experience to look at "recycled content" rules of procurement to become important to putting "hardened cement" (the value-added by captured carbon ash in the cement) into the quiver of EPR and procurement law.
How do we get our memberships to think about cement manufacturing as an important "recycled content" story, as we did with recycled content paper procurement in the 1990s? I guess we need to write complicated blogs hoping to get the interests of academics who we can then get to make the "recycled content cement" case, invite them as conference speakers. Part of this "fishing for swordfish" strategy will involve incorporating keywords that keep the Tilapia and Perch of the press interested in our press releases.
If recycling advocates currently consider glass aggregate / daily cover in our recycling rates (never an obvious call to raw material originalists, but that referee's call has sailed), I was wondering about some forms of carbon sequestration, especially cement and concrete. See article in Nature below.
Green concrete recycling twice the coal ash is built to last
- May 15, 2024 Scienc Daily
- RMIT University
Hardened carbonation approaches involve concrete preparation and mixing, concrete casting, concrete exposure to CO2 gas, and concrete hydration23,24,25. The pressure, temperature, duration, and general environmental conditions at which CO2 is placed in contact with hardened concrete distinguish the different types of hardened concrete carbonation approaches. Besides these differences, all hardened concrete carbonation approaches involve chemical reactions that engage the active cementitious constituents of hardened concrete with the conversion of CO2 gas into solid CaCO3 crystal forms. Nevertheless, as these approaches are driven by diffusion-controlled kinetics, they are limited by the minimal extent of CO2 diffusion in hardened concrete, which enables carbonation reactions from the surface of hardened concrete to a depth of a few millimeters26. Pressurized vessels, usually between 1 and 5 atm27, can improve the carbonation degree and penetration depth24,28,29. However, the resulting cost-effectiveness diminishes as the applied pressure increases30, with CO2 uptake rates that remain within 5–20%24 at the expense of significant energy and infrastructure needs. Furthermore, the nature of these approaches limits their applicability to precast concrete, as they require CO2-rich or high-pressure environments31.
Fresh concrete carbonation approaches involve concrete preparation and mixing with the simultaneous injection of CO2 gas, concrete casting, and concrete hydration20,32,33. With these approaches, chemical reactions engage fresh concrete with the conversion of CO2 gas into solid CaCO3 crystal forms. Therefore, two main advantages characterize fresh compared to hardened carbonation approaches: (1) the possibility to carbonate a greater volume of concrete via CO2 injections during mixing; (2) the possibility to incorporate relatively easily CO2 injection nozzles in industrial processes.
- Article
- Open access
- Published:
Storing CO2 while strengthening concrete by carbonating its cement in suspension
Communications Materials volume 5, Article number: 109 (2024)
Another paper on the same method, published in 2020, uses "Recycled" and might be easier to sell than the June 2024 article - if you need to emphasize the keywords to keep the Siloed Interests.
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