TIL the difference between Roman concrete and modern stuff is they used volcanic ash and lime instead of Portland cement

I was watching a doc on the Pantheon last week and apparently their concrete gets stronger over time while ours degrades in like 50 years has anyone else geeked out on this comparison?

3 comments

3 Comments

finleyl399d ago

Man that's wild how something built almost 2000 years ago is outperforming our stuff. It's kind of humbling honestly, like we think we're so advanced but they were onto something we still can't fully recreate. Did you catch what it is about the volcanic ash that makes it last longer?

mark_ward9d ago

Wait, is it actually outperforming modern stuff or is that just a cool story people pass around? I looked into this a bit and there's a difference between "still standing after 2000 years" and "stronger than modern concrete." Roman concrete does have this thing where the volcanic ash reacts with seawater to grow crystals that actually heal cracks over time. But modern concrete is way stronger in compression and we can control exactly what it does. The Roman stuff just lasts longer in certain salty environments because of that self-healing trick. So it's not really about outperforming, it's about them solving a different problem entirely.

jessej239d ago

My buddy Dave (who's a materials engineer, not a trainer like me) actually broke this down for me once after I asked about the same thing. He said the volcanic ash from Pozzuoli has this specific mix of silica and alumina that reacts with seawater to form a mineral called Al-tobermorite think of it like tiny crystals weaving through the concrete, sealing up cracks before they get big. Mark_ward is right on that self-healing thing it's not stronger but it's way more forgiving in saltwater, which is why their harbors and piers are still holding up while our modern stuff crumbles after a few decades.