Just as carbon ash from the fireplace has the same chemical makeup as a diamond, there's a bit more to it: namely the changing structure of the stuff itself. Th

Just as carbon ash from the fireplace has the same chemical makeup as a diamond, there's a bit more to it: namely the changing structure of the stuff itself. The CSH reaction (https://en.wikipedia.org/wiki/Calcium_silicate_hydrate https://en.wikipedia.org/wiki/Calcium_silicate_hydrate) is something that evolves over time, and even then the modern chemical reaction is not completely known in all its states (as far as I'm aware). > The [balanced chemical mass] of C-S-H in cement paste is variable and the state of chemically and physically bound water in its structure is not transparent, which is why "-" is used between C, S, and H The article actually misses how modern concrete (portland) get stronger over the first few years as the crystalline structures grow. So, I can well understand how it's a bit tricky to find out what the original roman mix was, just using observations 2000 years later: because a lot of things have happened from the original cake mix to what we see now.