Shah also said that “cement carbonation requires very specific conditions” including humidity of between 40 and 80 per cent and open-air conditions.
“Submerged or buried concrete or concrete will not undergo carbonation,” he said, adding that “concrete carbonation happens at an extremely slow rate: an average of one to two millimetres per year.”
Shah added that he was “a bit frustrated with the IPCC using the word ‘sink’ because that gives the impression that it is beneficial.”
“Cement and concrete are not carbon sinks,” Shah said. “They are net sources [of CO2].”
Also: “Carbonation in concrete refers to the chemical reaction between carbon dioxide (CO₂) from the atmosphere and calcium hydroxide in the concrete. This reaction forms calcium carbonate and gradually reduces the pH of the concrete, which can lead to the corrosion of embedded steel reinforcement.”
So, not exactly a process you want to occur in your buildings or bridges. So if you’re hoping waiting around until it turns into limestone (if it’s not buried, submerged or sealed) it will probably mostly be demolished and long buried in a landfill somewhere potentially leaking toxins where it will never undergo the natural processes to absorb carbon anyway.
Beautiful in theory but impractical in mass scale execution. But certainly a good way to justify the continuation of a multibillion dollar industry. (This is not to say that there aren’t serious material scientists working on this problem, but a lot of it unfortunately is straight up greenwashing rather than advocating for reduction in initial footprint and investment in long-term sustainable alternatives.)
Doesn’t concrete also absorb CO2?
Or was that cement
Article: Cement and Concrete “are not carbon sinks” says Cambridge material scientist
Also: “Carbonation in concrete refers to the chemical reaction between carbon dioxide (CO₂) from the atmosphere and calcium hydroxide in the concrete. This reaction forms calcium carbonate and gradually reduces the pH of the concrete, which can lead to the corrosion of embedded steel reinforcement.”
So, not exactly a process you want to occur in your buildings or bridges. So if you’re hoping waiting around until it turns into limestone (if it’s not buried, submerged or sealed) it will probably mostly be demolished and long buried in a landfill somewhere potentially leaking toxins where it will never undergo the natural processes to absorb carbon anyway.
Beautiful in theory but impractical in mass scale execution. But certainly a good way to justify the continuation of a multibillion dollar industry. (This is not to say that there aren’t serious material scientists working on this problem, but a lot of it unfortunately is straight up greenwashing rather than advocating for reduction in initial footprint and investment in long-term sustainable alternatives.)
Thanks for the fact check!
Cement is an ingredient in concrete