Found out Roman concrete was stronger than modern stuff

I was reading through a journal article last night about how Roman concrete actually gets stronger over time instead of cracking like ours does. They figured out it's from a specific kind of volcanic ash mixed with lime that causes a chemical reaction as seawater seeps in. I always thought old stuff was just weaker but this blew my mind. Has anyone else looked into how they built those harbor structures?

2 comments

2 Comments

victor2203d ago

Heard a podcast mention the mineral growth is basically self-healing concrete. Wild.

gavin_hill274d ago

A couple things there. It's not really that seawater seeping in makes it stronger exactly. What happens is the volcanic ash and lime mix creates a mineral called stratlingite that crystallizes in the tiny cracks over time, which seals them up before they can turn into big cracks. The seawater part matters because it provides the right conditions for that reaction, but it's more about the specific mix used in the concrete itself. Roman harbor structures held up so well partly because the recipe was that good, but also because they poured it underwater, which forced the lime to react differently than if it set in air. Modern concrete actually does get stronger over time too, just not in the same way, and it doesn't heal cracks on its own.