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Roman concrete doesn’t have the same chemistry as modern concrete.

by willyt 7y ago

jabl 7y ago
And, Roman concrete doesn't have steel rebar which rusts and cracks the concrete.
- dsfyu404ed 7y ago
  Eh, properly done reinforced concrete should last hundreds of years. Of course it's possible to use the wrong concrete formula for the job (the concrete for your driveway is not the same as the concrete for a boat ramp) but if done right it should last.
marmaduke 7y ago
What’s different? I’m aware of the modern mix with cement sand stone, but I’m guessing romans didn’t have the cement?
- jbay808 7y ago
  As far as I know, the romans had better cement. We're still trying to reverse engineer it.
  - lsc 7y ago
    this is my understanding as well... but I wonder how much of that is that they just had more variable cement, and the stuff that wasn't incredibly great turned to dust long ago? Certainly, our modern processes are more repeatable and produce a narrower range of results. What if the existent buildings are outliers of the roman process?
    - jbay808 7y ago
      Attributing the accomplishments of the past to survivor bias is a popular line of thought these days, but... It's unlikely. They used a completely different chemical formula than we do. If you have two processes X and Y, and you observe consistently that Y >> X, and you know that Y and X are produced by different processes so you don't have a strong prior on the mean of Y being similar to the mean of X, then you should conclude it's very likely that the mean of Y is greater than the mean of X. Even if you know for certain that you only have the best samples of Y. But more importantly, we don't really care if the romans also built a bunch of bad buildings using counterfeit cement with a botched formula, that failed to last until today. What matters is that we don't have the technology today that can match their best work. That's what makes it worthy of study.

Roman concrete doesn’t have the same chemistry as modern concrete.

by willyt 7y ago

Roman concrete doesn’t have the same chemistry as modern concrete.

jabl 7y ago

And, Roman concrete doesn't have steel rebar which rusts and cracks the concrete.

dsfyu404ed 7y ago
Eh, properly done reinforced concrete should last hundreds of years. Of course it's possible to use the wrong concrete formula for the job (the concrete for your driveway is not the same as the concrete for a boat ramp) but if done right it should last.

marmaduke 7y ago

What’s different? I’m aware of the modern mix with cement sand stone, but I’m guessing romans didn’t have the cement?

jbay808 7y ago
As far as I know, the romans had better cement. We're still trying to reverse engineer it.
- lsc 7y ago
  this is my understanding as well... but I wonder how much of that is that they just had more variable cement, and the stuff that wasn't incredibly great turned to dust long ago? Certainly, our modern processes are more repeatable and produce a narrower range of results. What if the existent buildings are outliers of the roman process?
  - jbay808 7y ago
    Attributing the accomplishments of the past to survivor bias is a popular line of thought these days, but... It's unlikely. They used a completely different chemical formula than we do. If you have two processes X and Y, and you observe consistently that Y >> X, and you know that Y and X are produced by different processes so you don't have a strong prior on the mean of Y being similar to the mean of X, then you should conclude it's very likely that the mean of Y is greater than the mean of X. Even if you know for certain that you only have the best samples of Y. But more importantly, we don't really care if the romans also built a bunch of bad buildings using counterfeit cement with a botched formula, that failed to last until today. What matters is that we don't have the technology today that can match their best work. That's what makes it worthy of study.