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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?

#21

Post by tastyfreeze »

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.

Basalt rebar is chemically resistant and doesn't corrode. It does have a lower tensile strength than carbon fiber but is suitable for current designs.

Re: How are Rome's monuments still standing?

#22

Post by tastyfreeze »

hujni wrote: post #16
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.

You aren't the only one.

https://youtu.be/znQk_yBHre4

Re: How are Rome's monuments still standing?

#24

Post by mc32 »

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.

There are stainless steel rebar and epoxy coated rebar for structures exposed to the elements. Stainless steel rebar appears to be kind of expensive so its use is limited.

Re: How are Rome's monuments still standing?

#25

Post by dr_orpheus »

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.

I don't know how it compares to actual rebar reinforced concrete, but we do use fiberglass reinforced concrete.

Re: How are Rome's monuments still standing?

#26

Post by roca »

Did the Romans really know that using certain volcanic rocks would make their concrete structures last longer? Or did they mostly just use whatever aggregate was convenient and the structures that have survived are the ones that used the right rocks? The latter sounds more plausible to me.

Of course we can still learn valuable lessons from these surviving structures.

Re: How are Rome's monuments still standing?

#27

Post by WalterBright »

roca wrote: post #26

Did the Romans really know that using certain volcanic rocks would make their concrete structures last longer? Or did they mostly just use whatever aggregate was convenient and the structures that have survived are the ones that used the right rocks? The latter sounds more plausible to me. Of course we can still learn valuable lessons from these surviving structures.

Rome lasted for many centuries, so I imagine they were familiar with what worked and what didn't.

Re: How are Rome's monuments still standing?

#28

Post by microtherion »

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…

The explanation in the article is fascinating, but I wonder how much the Romans knew about the durability of their concrete at the time, and to what extent they just got lucky by the mix of material that happened to be available in their area.

Re: How are Rome's monuments still standing?

#29

Post by Pigalowda »

cblconfederate wrote: post #19
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

I recently found out about this sad column repurposed in 608 AD as an honor to the Eastern Roman Emperor, Phocas.

https://en.m.wikipedia.org/wiki/Column_of_Phocas

The city had been sacked multiple times at that point and I suppose it was the best they could do.

Re: How are Rome's monuments still standing?

#30

Post by SQueeeeeL »

WalterBright wrote: post #27
roca wrote: post #26

Did the Romans really know that using certain volcanic rocks would make their concrete structures last longer? Or did they mostly just use whatever aggregate was convenient and the structures that have survived are the ones that used the right rocks? The latter sounds more plausible to me. Of course we can still learn valuable lessons from these surviving structures.

Rome lasted for many centuries, so I imagine they were familiar with what worked and what didn't.

Jonathan Blow makes a bunch of great points about our simplified view of ancient people, versus the reality of their complex achievements which could only be brought about by lots of ingenuity and iterations.

https://youtu.be/pW-SOdj4Kkk

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