Why Roman Concrete Is So Strong 🏛️

Morning Engineers!

Ancient Roman concrete was actually WAY better than modern concrete…

Huh?

I mean, look at all the things they built:

Still standing after thousands of years!!

Whereas, with modern concrete, we’d be lucky if it lasted 50 years…

So, what's the secret?

Well, we make concrete by mixing cement, sand, gravel, and water in a big tub…

Then we just pour… 

And wait for it to harden.

But Romans made concrete a little differently…

They would mix together volcanic ash, something called quicklime, and sea water in a big tub…

Pour it into place… 

And wait for it to harden.

Now, that doesn't sound like much of a difference… but it is!

See, when the salt water is mixed with the quicklime stuff, it produces a hot chemical reaction which leaves chunks of undissolved lime throughout the mixture.

This creates concrete that can literally REPAIR ITSELF!!

How?

Look, if you crack it, it exposes the little lime chunks inside the concrete.

So, when it rains, rainwater can leak in and react with the lime, reactivating the cement and filling in the crack!

However… if you try this with our concrete.

It would just break.

Yeah, the Romans win this one lol.

Stay Cute,
Reece, Henry & Dylan 🌈

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