Concrete/Cement and CO2

This question came up sometime between 2010 and 2012, during the great Evergreen sidewalk debate. I did not have the answer then, and this article crossed my newsfeed this morning, so I am placing it here.

https://www.bloomberg.com/news/articles/2019-06-23/green-cement-struggles-to-expand-market-as-pollution-focus-grows

Army Corps of Engineers Turns to Nature

https://dirt.asla.org/2019/02/05/the-u-s-army-corps-of-engineers-turns-to-nature/

This article may not seem to be related to Evergreen, but if you have been paying attention, you will understand how and why it is.