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How Has Roman Concrete Lasted for Millennia? 1,900-Year-Old Latrine Offers Clues

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Re: How Has Roman Concrete Lasted for Millennia? 1,900-Year-Old Latrine Offers Clues

#121

Post by dnemmers »

iknownothow wrote: post #75
iknownothow wrote: post #74

For those not familiar, the secret ingredients are to do with the Lime Cycle [1]: 1) Quicklime/Slakedlime (Calcium Oxide, CaO) 2) Lime (Calcium Hydroxide, CaOH2) 3) Limestone (Calcium Carbonate, CaCO3) To keep it simple, typically you start with Quicklime (CaO) and after construction you end up with some mix of all three and after hundreds of years, the masonry transitions to mostly Limestone with microscopic traces…

I forgot another important reason why Portland cement is preferred over lime these days. Lime takes a while to set (a few days?), cement sets faster.

Cement will still take many days to reach full cure time (measured in increasing PSI ratings)

https://www.ce.memphis.edu/1101/notes/concrete/section_3_pro...

Re: How Has Roman Concrete Lasted for Millennia? 1,900-Year-Old Latrine Offers Clues

#122

Post by DannyBee »

meindnoch wrote: post #97
iknownothow wrote: post #74

For those not familiar, the secret ingredients are to do with the Lime Cycle [1]: 1) Quicklime/Slakedlime (Calcium Oxide, CaO) 2) Lime (Calcium Hydroxide, CaOH2) 3) Limestone (Calcium Carbonate, CaCO3) To keep it simple, typically you start with Quicklime (CaO) and after construction you end up with some mix of all three and after hundreds of years, the masonry transitions to mostly Limestone with microscopic traces…

>Cement/Concrete (based on Portland cement) is water proof That's patently untrue. Otherwise we wouldn't need concrete sealants.

You can also just see it with cement board - if you pour water on top of it, it will eventually migrate through and drip.

Re: How Has Roman Concrete Lasted for Millennia? 1,900-Year-Old Latrine Offers Clues

#123

Post by DannyBee »

kQq9oHeAz6wLLS wrote: post #19
defrost wrote: post #13

Earlier quoted context omitted.

but not ones willing to put the effort into properly fixing a pond.

If you're talking about the algae, it came back after Obama's $34m renovation, too. Turns out algae is hard to kill, especially when you feed the reflecting pool from a tidal basin.

I don't remember Obama pretending it was being caused by political agitators, etc.

Re: How Has Roman Concrete Lasted for Millennia? 1,900-Year-Old Latrine Offers Clues

#124

Post by DivingForGold »

iknownothow wrote: post #111
meindnoch wrote: post #97

Earlier quoted context omitted.

>Cement/Concrete (based on Portland cement) is water proof That's patently untrue. Otherwise we wouldn't need concrete sealants.

You are correct. I'm not sure why I remember cement to be water proof. Its possible I infered from how its been used around me. I have seen cement very often used where water contact is expected (bathrooms etc). I have also seen brick walls plastered with an extra layer of cement as putty considered to be rain proof and any leaks were thought of as poor workmanship rather than poor material choice. P.S. I'm not a bui…

[dead]

Re: How Has Roman Concrete Lasted for Millennia? 1,900-Year-Old Latrine Offers Clues

#125

Post by cm2187 »

GuB-42 wrote: post #107
cm2187 wrote: post #78

I am glad the pantheon still stands. But the real question is are there really any modern structure that will be worth preserving for 2000 years. Architects have long abandoned aiming for beauty to aim for originality. Originality doesn’t last. Humans in 2000 years will only wonder why on earth our society could manufacture atom level micro ships but couldn’t come with a single structure worth preserving.

All structures are worth preserving. The article is about a latrine. Do you think ancient Romans thought a literal shithole was worth preserving? And yet, it is now an important piece of history. As for beauty, you never know, take the Eiffel tower for instance, when it was built, people found it ugly, and it was to be a temporary structure. Now it is the symbol of Paris, more popular than the Paris Pantheon, which m…

The Eiffel Tower dates from the XIX century. Pre the shift to originality. Which XX century building in Paris is objectively beautiful? The tour Montparnasse? The Centre Pompidou? Or Jussieu’s campus? Even the Opera Bastille is pretty lame, not outright ugly but lame.

Re: How Has Roman Concrete Lasted for Millennia? 1,900-Year-Old Latrine Offers Clues

#126

Post by cm2187 »

fhub wrote: post #85
cm2187 wrote: post #78

I am glad the pantheon still stands. But the real question is are there really any modern structure that will be worth preserving for 2000 years. Architects have long abandoned aiming for beauty to aim for originality. Originality doesn’t last. Humans in 2000 years will only wonder why on earth our society could manufacture atom level micro ships but couldn’t come with a single structure worth preserving.

Sydney Opera house comes to mind as something that might still be curious to people in 1000 years.

A curiosity is one thing. But where is the wow factor you get when you enter Rome’s pantheon?

Re: How Has Roman Concrete Lasted for Millennia? 1,900-Year-Old Latrine Offers Clues

#127

Post by jaapz »

Barbing wrote: post #23
eru wrote: post #8

Earlier quoted context omitted.

Yes, but you have to replace the sacrificial anode every so often. https://en.wikipedia.org/wiki/Galvanic_anode

Like the plate of food on the grass for the bees at the barbecue

Wait, does this actually work?

Re: How Has Roman Concrete Lasted for Millennia? 1,900-Year-Old Latrine Offers Clues

#128

Post by tpm »

gravypod wrote: post #116
tpm wrote: post #113

Earlier quoted context omitted.

it's not waterproof

Neither is grout. Grout is water permiable. You shower is water proof from the water proof backing we install the tile on top of. Cement board + roll on or something like kerdi system. https://youtu.be/B5DVpruLygw?si=jD8eMHHGQoWG4hI2

right, but lime will be washed away by the water if no waterproof layer is added

Re: How Has Roman Concrete Lasted for Millennia? 1,900-Year-Old Latrine Offers Clues

#129

Post by Maken »

aiauthoritydev wrote: post #24

The whole promise of engineering is not to build a bridge that stands but to build a bridge that barely stands. It is not a good idea to build a bridge that last 500 years. You likely destroyed valuable resources to build one. Build a bridge that lasts 100 years and save those resources. In 100 years the technology to build bridges improves so much that it is lot easier to build a new one. At least in most countries…

>It is not a good idea to build a bridge that last 500 years.

Why not? A well-build bridge from 500 years ago is perfectly functional today [1]

[1] https://en.wikipedia.org/wiki/Puente_de_Segovia,_Madrid

Re: How Has Roman Concrete Lasted for Millennia? 1,900-Year-Old Latrine Offers Clues

#130

Post by throw4847285 »

Aurornis wrote: post #25
userbinator wrote: post #14

Earlier quoted context omitted.

Most infrastructure is paid for by taxes, and the cost of building to Roman standards is rarely impossible, but often beyond what the public would consider reasonable. Would you pay 10x more to have something that lasts 100x or even 1000x longer? The upfront cost is higher, but the TCO is ultimately lower. IMHO it's ultimately a form of planned obsolescence. This becomes even more obvious when plenty of expense is sp…

No, for two reasons. First, we can’t summon infinite money to pay for things. Paying 10X more per bridge means we can build 1/10th as many bridges or we have to start stealing from other budgets. Second, we don’t know what the needs will be for the bridge in that location 100 or 1000 years from now. It could need to be torn down to be widened. Maybe we’re all riding around in electric vehicles that coordinate perfect…

You don't have to wait 100 years. You can build a bridge to alleviate traffic without any understanding that the bridge will in fact generate more traffic, and then you have to widen it a few years later (which also doesn't help). I know this has happened several times in NYC and I'm sure it has happened many other places where engineering know-how far outstrips knowledge of urban planning.
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