The reason Roman structures survive so long is because they used volcanic ash in their concrete, which slowly transforms to aluminum tobermorite when exposed to sea water. Something modern scientists have been trying to do for decades.

Why modern mortar crumbles, but Roman concrete lasts millennia

Modern concrete—used in everything from roads to buildings to bridges—can break down in as few as 50 years. But more than a thousand years after the western Roman Empire crumbled to dust, its concrete structures are still standing. Now, scientists have finally figured out why: a special ingredient that makes the cement grow stronger—not weaker—over time. Scientists began their search with an ancient recipe for mortar, laid down by Roman engineer Marcus Vitruvius in 30 B.C.E. It called for a concoction of volcanic ash, lime, and seawater, mixed together with volcanic rocks and spread into wooden molds that were then immersed in more sea water. History contains many references to the durability of Roman concrete, including this cryptic note w… Continue Reading (2 minute read)

12 thoughts on “The reason Roman structures survive so long is because they used volcanic ash in their concrete, which slowly transforms to aluminum tobermorite when exposed to sea water. Something modern scientists have been trying to do for decades.”

  1. slugbabyrat

    This reads as if scientists have been trying to transform into aluminium tobermorite for decades, and I love that.

  2. MrMathemagician

    Do we have any indication if they knew this was better or if they just were like, “We need ash for our cement; hey, the volcano makes a ton.”

  3. Riptide360

    The wisdom of our elders is rediscovered. I wonder if anyone is backing up the internet or if humanity will go through another period of losing what we know?

  4. sethmod

    That’s tobermorite, baby!

  5. mercuchio23

    All that’s left is Greek fire!

  6. grizzlysquare

    Modern scientists can’t figure out how to incorporate ash into concrete mixtures?

  7. Veritas3333

    They also massively overbuilt things with concrete. They didn’t have rebar, so everything was just solid concrete with no internal reinforcement. Since there wasn’t internal reinforcement, they had to make things much thicker.

  8. museo_del_prado

    That’s part of the reason

  9. fiddlenutz

    Wasn’t this the recipe that was lost when religious folks just started burning everything?

  10. FeculentUtopia

    The main problem with this method is that to takes hundreds of years to fully cure. Long lasting concrete structures would be great, but we don’t have that kind of patience.

  11. ImClaytor

    I’m 30% Aluminum Tobermorite

  12. liberalzrcancr

    I wonder if a catalyst will be found to speed up the process, looks like its too slow for any sort of widespread use. That would be cool

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