There's work underway to make concrete carbon negative "greener" by mixing it in a sealed container and adding other chemicals to it to bind the CO2 and added c

There's work underway to make concrete carbon negative "greener" by mixing it in a sealed container and adding other chemicals to it to bind the CO2 and added carbon as a solid component of the finished concrete. I can't recall if it's the lime or Portland cement step of the process.