In which I answer your questions about cement

Oct 31, 2019

I recently turned an old post on cement into a surprisingly popular Twitter thread:

Many people replied with questions that I couldn’t answer to my satisfaction, such as:

What was it about the volcanic ash the Romans added to their cement that made it set underwater? How does that work?
Why was Portland cement stronger than previous cements?
If cement re-absorbs CO2 from the air, the lime cycle would seem to be carbon-neutral; why is cement cited as a major CO2 contributor?
Did the Romans have a lost formula for cement that we’ve been unable to surpass?

So I went back for another round of research. Here’s what I found…

The Roots of Progress