Scientists replaced 40 percent of cement with rice husk cinder, limestone crushing waste, and silica sand, giving concrete a rubber-like quality, six to nine times more crack-resistant than regular concrete. It self-seals, replaces cement with plentiful waste products, and should be cheaper to use.

[u/mvea]

https://newatlas.com/materials/rubbery-crack-resistant-cement/

[u/ImFamousOnImgur]

I did a paper in undergrad about Roman concrete. Their recipe was no joke. It’s a big reason why their stuff is still standing to this day.

Coliseum? Yup. Roman concrete. Oh and you know how some of the walls collapsed after an earthquake in 1500 something? Yeah those were the sections that were built by a different architect and he didn’t use the same materials.

[u/noelcowardspeaksout → u/ImFamousOnImgur]

For the Pantheon they used different grades of concrete made with different additives depending on the qualities they required. The dome has pumice included to make it light for example. It has stood for around 2000 years without being rebuilt.

Edit: Pantheon

[u/ImFamousOnImgur → u/noelcowardspeaksout]

Yup. It’s quite amazing the amount of knowledge they had. A lot of that knowledge was lost when the empire fell.

They think the secret to the quality was the volcanic rock used, and if I recall, it was especially good at setting underwater even.

[u/Opeewan → u/ImFamousOnImgur]

There's a bit more to it than that, salt plays a big part in it:

https://www.nature.com/news/seawater-is-the-secret-to-long-lasting-roman-concrete-1.22231

[u/Opeewan → u/[deleted]]

Obviously they didn't and either came up with their recipe through trial and error or it was a lucky coincidence.

[u/BarkingWilder → u/[deleted]]

This probably isn't a million miles from the truth to be honest.

[u/greenwrayth → u/BarkingWilder]

We often fail to remember that the human brain hasn’t changed at all in the last, say, 5,000 years. They were just as smart as we are, we just have more available knowledge, easy calories, technology, and leisure time to use ours.

[u/BarkingWilder → u/greenwrayth]

Always thought Tim Minchin put it best. We're just monkeys with shoes.

[u/James_n_mcgraw → u/greenwrayth]

I always think its dumb when people are like people couldnt have built the pyramids or insert great work here. People werent dumb, they had more free time than us and labor was cheap. The pyramids were built by skilled architects and hired farmers in the off season. we may not know exactly how they did it but just because the method was lost to history doesnt mean it wasnt possible. Construction equipment doesnt last 6000 years, stone blocks do. Hell a good example is mount rushmore, a giant statue carved out of a mountainside without making any mistakes all before computers or advanced surveying equipment, or the sphynx is another good example. Very big things that are difficult to imagine how they even accomplished it, but they still did even if you domt understand how.

[u/[deleted] → u/James_n_mcgraw]

And.... Lots and lots and lots and LOTS of slaves. Same with Roman roads. Technology met raw human labor on a massive scale.

[u/supbrother → u/BarkingWilder]

I do work as a construction materials tech and I can assure you that its basically the same sort of methods we use today for some tests (just with fancier tools).

[u/sambar101 → u/BarkingWilder]

Hey Hoplite come stab this rock right quick

[u/ChzGoddess → u/sambar101]

And I probably should have put the drink down before reading this...

[u/currytacos → u/sambar101]

Not to rain on your parade but Rome didn't have hoplites.

[u/[deleted] → u/BarkingWilder]

It also isn't very different from how we would measure it today.

[u/Nollhypotes → u/BarkingWilder]

Still, we'll need some concrete evidence.

[u/mia_elora → u/Nollhypotes]

Of coarse you do! I think it's a good enough article that you can take it for granite, this time. :)

[u/CptOblivion → u/BarkingWilder]

Well sure, you'd have to leave the planet and go well past the moon to be that far from the truth.