Secrets of Rome

I have to admit - I have something of a fascination with ancient Rome. At this point we've regained most of their technology and, of course, gone past it in many areas.

But there's one thing Rome was still better at: Sea walls.

And with climate change, we need good sea walls. The secret? The Romans worked out to make concrete that chemically reacts with seawater - in a way which makes the concrete stronger.

Of course, it'll probably take years to work out the full formula, but if we can - well, Roman concrete didn't need to be reinforced (and it's the metal reinforcements that fail, in most cases), didn't erode over time...

How?

It just so happened that the minerals they need were plentiful in volcanic soil...