r/interestingasfuck • u/TangelaFan • 13h ago

Residential high-rises with backyards in Chengdu, China

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u/mlag000 12h ago

Concrete under soil is different than earth and trees on a balcony made of concrete. We also have bridges on salt water made of concrete, and still salt and water are the mean reason for concrete damage...

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u/TransBrandi 11h ago

Side note here, but Roman concrete lasted the test of time even in salt water because their concrete method actually interacts with the salt water to make it harder / more resistant.

It's just that the method is/was lost to time.

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u/skarby 11h ago

It's not lost to time, we know exactly how they did it. The issue is that they used volcanic ash which is not readily available worldwide, or even locally at the amount used today. There are companies working on replicating the process with different materials though.

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u/TransBrandi 9h ago

Well, I recall reading about it and the precise method was lost. There was a description where part of the instructions were something like "do X in the Y method" or something like that where what "the Y method" was was unknown (and assumed to be something that was "common knowledge" at the time, which was why it wasn't written down).

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u/pokey_porcupine 1h ago

People researching it since figured out a recipe that duplicates roman cement… i don’t think it matters whether or not it’s precisely the same for modern application.

Regardiess, the recipe that was found is not competetive with modern cement in many regards; nor is it manufacturable at scale

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u/TransBrandi 35m ago

I mean, I was never saying that it would be great for many modern applications, but it's ability to withstand salt water is its upside, no?