Our Concrete Lasts 100 Years. Roman Concrete Lasts 2,000. And It's Still Getting Stronger.

Added: 2026-05-17

[00:00:00]The Pantheon has been standing since 128 AD. Its dome is still the largest unreinforced concrete dome ever built.

[00:00:08]That is not the strange part. The strange part is this, it is getting stronger. Every decade, Roman concrete in sea walls grows new mineral crystals inside its cracks. The crystals seal the damage before it spreads. Modern concrete does the opposite. It weakens, it crumbles. We design our bridges to last 100 years. In 2017 scientists at UC Berkeley analyzed Roman sea walls and found the mechanism. Volcanic ash, lime, and sea water react over decades to grow a mineral called tobermorite inside the concrete. It fills every crack as it forms. We have tried to reproduce it.

[00:00:46]Portland cement is cheaper and faster, but it does not do this. The Pantheon dome has no rebar, no steel, no modern additives, and no building since has matched it in 1900 years.