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How are Rome's monuments still standing?

bbc.com

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Re: How are Rome's monuments still standing?

#11

Post by smegger001 »

FredPret wrote: post #9
simonebrunozzi wrote: post #2

TL;DR: their concrete was different. > Roman concrete, on the other hand, is a simpler mix of quicklime made from baking and crushing limestone rocks and, most importantly, volcanic rock aggregates of various types, which were abundant in the region surrounding Rome. In contrast to the aggregates used in modern concrete, these volcanic materials used by the Romans are highly reactive and the resulting concrete remain…

We use reinforced concrete, concrete with steel bars inside. This allows us to built really thin and strong concrete bridges, balconies, roofs, etc. But the steel rusts after a couple of decades. Rusted steel is marginally larger than new steel. So when the steel bars expand by rusting, it pushes against the concrete from the inside, causing cracks. Then lots of water can get in it rusts faster. Eventually chunks of…

I wonder how long carbon fiber rebar, or plastic coated steel rebar would last.

Re: How are Rome's monuments still standing?

#14

Post by FredPret »

smegger001 wrote: post #11
FredPret wrote: post #9

Earlier quoted context omitted.

We use reinforced concrete, concrete with steel bars inside. This allows us to built really thin and strong concrete bridges, balconies, roofs, etc. But the steel rusts after a couple of decades. Rusted steel is marginally larger than new steel. So when the steel bars expand by rusting, it pushes against the concrete from the inside, causing cracks. Then lots of water can get in it rusts faster. Eventually chunks of…

I wonder how long carbon fiber rebar, or plastic coated steel rebar would last.

Interesting idea, but carbon fiber would need to be really cheap. Would work well until a critter of some sort evolves that eats plastic

Re: How are Rome's monuments still standing?

#16

Post by hujni »

simonebrunozzi wrote: post #2

TL;DR: their concrete was different. > Roman concrete, on the other hand, is a simpler mix of quicklime made from baking and crushing limestone rocks and, most importantly, volcanic rock aggregates of various types, which were abundant in the region surrounding Rome. In contrast to the aggregates used in modern concrete, these volcanic materials used by the Romans are highly reactive and the resulting concrete remain…

I've wondered if maybe the "stones" of the Pyramids were poured. It wouldn't surprise me given the lack of gaps.

Re: How are Rome's monuments still standing?

#17

Post by 8ytecoder »

simonebrunozzi wrote: post #2

TL;DR: their concrete was different. > Roman concrete, on the other hand, is a simpler mix of quicklime made from baking and crushing limestone rocks and, most importantly, volcanic rock aggregates of various types, which were abundant in the region surrounding Rome. In contrast to the aggregates used in modern concrete, these volcanic materials used by the Romans are highly reactive and the resulting concrete remain…

I think we’re missing another key factor here. Most “well preserved” buildings are ones that are in continuous use. So they get maintained and repaired. A temple in south India is about a 1000 years old. It has seen repeated damages - some intentional during conquests - but survives to this day because the damages were patched up within a few decades. The “few decades” it can go - even with damages - is likely from the material and construction. But the centuries that add up comes from regular maintenance.

Re: How are Rome's monuments still standing?

#18

Post by Cerium »

smegger001 wrote: post #11
FredPret wrote: post #9

Earlier quoted context omitted.

We use reinforced concrete, concrete with steel bars inside. This allows us to built really thin and strong concrete bridges, balconies, roofs, etc. But the steel rusts after a couple of decades. Rusted steel is marginally larger than new steel. So when the steel bars expand by rusting, it pushes against the concrete from the inside, causing cracks. Then lots of water can get in it rusts faster. Eventually chunks of…

I wonder how long carbon fiber rebar, or plastic coated steel rebar would last.

Plastic coated rebar is a product. In theory it can solve the rusting problem, but in practice the coating will get some nicks during installation that can concentrate corrosion leading to point weaknesses. There are additional concerns with the bonding between the concrete and the coated bar.

Re: How are Rome's monuments still standing?

#19

Post by cblconfederate »

atdrummond wrote: post #10

They’re not. The Romans built a huge amount and much of their artistic architectural works remaining today were purposely preserved, even if reused for some alternative purpose. Yes, there are some construction techniques they used that contributed to better survival rates than some other structure types. But mostly we’ve ended up with what was lucky enough to survive. Replay the historical tape again and we might be…

> for the same reasons we preserve Victorian era buildings.

Not really, christians destroyed a huge amount and ruthlessly, and tons of marble was 'repurposed'. The best chance of a building to survive was being used as a church

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