Directly trapping carbon for over 50 years is pretty good, and the main CO2 release in concrete is the cement - both in heating it and the actual reaction neces

Directly trapping carbon for over 50 years is pretty good, and the main CO2 release in concrete is the cement - both in heating it and the actual reaction necessary to create it. Aggregate availability isn't the issue there. On top of that, large scale structural concrete is a fairly new technology, and while improvements to longevity have been made, many buildings will be lucky to make it to 100 years.