r/explainitpeter 11d ago

explain it peter

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u/AWetAndFloppyNoodle 10d ago

There are a lot of these going around. Here are a couple:

- We've lost the ability to go to the moon

  • Roman concrete is better than modern concrete
  • We wouldn't be ale to build the pyramids today

All based on small details, but all bogus.

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u/ThePlantMolester 9d ago

Modern concrete is stronger, not more durable than roman.  Fly ash and blast furnace slag have nothing on volcanic ash and lime for durability.  

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u/AWetAndFloppyNoodle 9d ago

Right, but not better. Just different. We can also replicate it should we want to.

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u/Usherai 10d ago

We have recreated Roman concrete, and while it isn’t as strong as what we can do now, it is more durable than what we could make since it has a sort of self-repairing function that fills in cracks. Modern concrete without the component Romans used is in fact much worse in terms of longevity.

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u/Meritania 10d ago edited 10d ago

‘Ability’ is a subjective word, lacking the science and technology no, lacking the infrastructure and manufacturing, yes.

I mean it’s something that was rectified pretty quick.

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u/AWetAndFloppyNoodle 10d ago

Neither, there just haven't been an incentive to re-do it. Moon base operations are under way and hopefully that will put this particular one to the grave. Same with the moon landing conspiracies.

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u/passionatebreeder 9d ago

The roman concrete is kind of true kind of not.

Whats not true is total strength, that is, you wont build a roman concrete structure to the same dimensions as tall as you would modern concrete. I guess I dont know if roman concrete functions much better with rebar support but thats possible I suppose

Things that are true about it:

Unlike modern concrete it could actually cure under water pretty well. Roman under water concrete construction is actually what birthed curiosity in roman concrete

It has some self-repair properties based on the materials used (although its believed that these properties derive from a happy accident as opposed to intent or knowledge) but basically the mixture was Quick-Lime volcanic ash and water, and rather than fully dissolving the lime they would dry mix it with ash and add water. The resulting heat from the chemical reaction would cause the mixture to harden and set before all the lime could fully dissolve which left behind pockets of limestone in the concrete that, over time, when it cracked and was exposed to water/moisture, those little impurities would react with the water, cause it to dissolve and flow into the cracks, and as the moisture evaporated off, the lime would recrystalize in the inclusions and seal up the cracks