The ancient Romans were master cementers. They made all those miles of aquaducts and monuments and buildings out of cement. But their recipe for cement was lost when ancient Rome fell.
Our cement today is very weak by comparison. We add little rocks to it to make it stronger, and we call that mixture concrete. That's still not strong enough though, so they reinforce concrete with iron or steel rods or mesh to give it more strength. That introduces another problem. Since concrete is porous, moisture seeps in, the iron eventually rusts and expands, and that weakens and breaks the concrete. This is especially bad with salt water.
Roman cement gets stronger as it ages, our cement today becomes weaker and more brittle with time. The Pantheon in Rome (built 1900 years ago) is still the largest unsupported concrete dome in the world - modern concrete can't come close to doing that.
Modern concrete we put in the sea lasts no more than about 60 years, but there's a jetty on the Mediterranean in north Africa that I saw on NOVA that the Romans built in the second century AD that's been there for more than 1800 years through countless storms and it's still intact.
Researchers know the Roman builders used a form of volcanic ash found near
Naples in their mix and that they shipped tons of it all around the Mediteranean. But we can make cement out of the same ash deposits and it's no better than our other cement.
These people think they might have figured this mystery out:
Riddle solved: Why was Roman concrete so durable?
Our cement today is very weak by comparison. We add little rocks to it to make it stronger, and we call that mixture concrete. That's still not strong enough though, so they reinforce concrete with iron or steel rods or mesh to give it more strength. That introduces another problem. Since concrete is porous, moisture seeps in, the iron eventually rusts and expands, and that weakens and breaks the concrete. This is especially bad with salt water.
Roman cement gets stronger as it ages, our cement today becomes weaker and more brittle with time. The Pantheon in Rome (built 1900 years ago) is still the largest unsupported concrete dome in the world - modern concrete can't come close to doing that.
Modern concrete we put in the sea lasts no more than about 60 years, but there's a jetty on the Mediterranean in north Africa that I saw on NOVA that the Romans built in the second century AD that's been there for more than 1800 years through countless storms and it's still intact.
Researchers know the Roman builders used a form of volcanic ash found near
Naples in their mix and that they shipped tons of it all around the Mediteranean. But we can make cement out of the same ash deposits and it's no better than our other cement.
These people think they might have figured this mystery out:
Riddle solved: Why was Roman concrete so durable?
