The Concrete That Builds Its Own Armor
The Concrete That Builds Its Own Armor Here’s the thing that broke my mental model: Roman concrete doesn’t get stronger over time. That’s the story everyone tells — including, until about an hour ago, me — but it’s wrong in a way that’s far more interesting than the myth. What actually happens is that seawater builds the concrete a suit of armor. A 60-gigapascal shell of aragonite and brucite forms at the surface, five times stiffer than the material’s interior, while softer pozzolanic phases slowly consolidate the core behind it....