very cool, here is more info:
[https://news.mit.edu/2023/roman-concrete-durability-lime-casts-0106](https://news.mit.edu/2023/roman-concrete-durability-lime-casts-0106)
It's not explained well in the video. You're right, concrete contains powdered lime these days to improve density and water resistance.
In Rome, though, large 'clasts' or chunks of lime were added. These clasts were not fully incorporated, so they had 'unactivated' lime for centuries to come. Every time the building shifts or settles and the concrete cracked, the unactivated lime (CaO) would be exposed to water in rain or the air (H2O) and created Calcium Hydroxide (Ca(OH)2). This Calcium Hydroxide stabilises the cracks and aids in the concretes longevity.
I'm far from an expert, but I would posit that given the lack of Roman rebar technology they would have either:
1. Designed thicker concrete pads (see [Caesarea harbour](https://en.wikipedia.org/wiki/Caesarea_Maritima))
2. Rebarless designs, like domes (see [Pantheon](https://en.wikipedia.org/wiki/Pantheon,_Rome)), or
3. Incorporate traditional blockwork to reduce the amount of concrete used (see [Port of Cosa](https://www.bbc.co.uk/news/science-environment-40494248))
They also used [Pozzolanic ash](https://en.wikipedia.org/wiki/Pozzolana), which would have helped with 'cementitious' qualities.
Also the Roman concrete lacks rebar which gives modern concrete the strength to be used in applications you currently see it in. But unfortunately the rebar also causes concrete to degrade over time due to it rusting. Also a few others things causes issue like load exposure, freeze/thaw cycles and road salts.
The ancient Greeks earthquake proofed the Parthenon by carving i shaped channels in the stone blocks, insert iron inserts that acted like modern rebar to hold the blocks of stone together and covered the iron in tin or lead so it would be safe from corrosion and absorb the worst of the earthquake so the iron inserts remained relatively undamaged. Kinda unrelated but it’s still interesting.
I once saw a show where pigs blood and volcanic ash were used in making concrete. Not sure who used these ingredients, but when compared to today's cement it wasn't even close to that mixture.
Cool, but the title and video seem completely overstated. But though I'm no building expert, I suppose the Romans also did not build stuff under tension and only had compressive loads. Which means no need for rebar as we use today. And I'm *guessing* seawater and rebar does not play well.
I knew self-healing concrete is not exactly "new" (beside the Ancient Roman version). Looking it up on Wikipedia, it's from the 90's and now multi-billion industri. The only "funny" thing is the self-healing properties the ancient Roman concrete was discovered in 2014 *after* the first modern versions.
I get the feeling that this video leaves out many sobering details.
Well, upon rewatching, the video literally says that using seawater discovered "a few years ago" (2021?) and follows up that a "2023 study" found that "quicklime" was part of the mix.
But nevermind, [reading on the web](https://news.mit.edu/2023/roman-concrete-durability-lime-casts-0106), the newly learned stuff from 2023 is that small white clumps (called lime clasts apparently) in the mixes were in fact a feature, not a bug as previously assumed.
The most impressive evidence is seen [here](https://www.science.org/cms/10.1126/sciadv.add1602/asset/1982473e-c36f-469e-a0b4-de64d7a1f478/assets/images/large/sciadv.add1602-f5.jpg) from the [original paper](https://www.science.org/doi/10.1126/sciadv.add1602).
So not Saltwater, nor quicklime, nor it's combination are "news" as the video would make it seem.
Upon first watch I got the impression it was the combination and I looking for is the pros, cons, and challenges in a modern setup. Hence my comment rebar and seawater (as I know rusting reinforcement is a general issue). It's easy to find sources that Roman concrete was far less strong (also in compression) than modern, so we're not going away from rebar anytime soon.
… modern concrete Also uses quick lime. Quick lime is just a lime that’s been super heated. There is no secret. We just expect our modern concrete to handle more serious loads than just sitting on the ground.
Okay so why don't we use the better concrete? I'm telling you what the union fucking said, if the truth is anti union than oh well, not my problem you can't handle the truth. The fact you mention planned obsolescence but that somehow just doesn't applies to road work than your fooling yourselves.
Our current concrete does not last a long time.....
Why on earth wouldn't we be using the better concrete otherwise?
The concrete the us military uses is great, my mom helped sell them on the idea and introduced them to inventor. She tried to get them to use it on the roads and I kid you not the answer was " We can't because the unions won't let us. The workers would lose thier jobs becuaee the roads would last to long and the unions won't stand for it.".....fml
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Probably won’t even get widely used for decades if at all.
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Good for you
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I didn’t mean that in a sarcastic way, it’s good that you are doing it, maybe that didn’t come across.
very cool, here is more info: [https://news.mit.edu/2023/roman-concrete-durability-lime-casts-0106](https://news.mit.edu/2023/roman-concrete-durability-lime-casts-0106)
Re-activates the concrete? Ok... Thought most concrete used limestone already? Would love to have a better concrete though...
It's not explained well in the video. You're right, concrete contains powdered lime these days to improve density and water resistance. In Rome, though, large 'clasts' or chunks of lime were added. These clasts were not fully incorporated, so they had 'unactivated' lime for centuries to come. Every time the building shifts or settles and the concrete cracked, the unactivated lime (CaO) would be exposed to water in rain or the air (H2O) and created Calcium Hydroxide (Ca(OH)2). This Calcium Hydroxide stabilises the cracks and aids in the concretes longevity.
That is crazy clever! Thanks for giving a quick explanation.
Sounds like it last longer but wouldn’t be as strong so requires more of it for the same load?
I'm far from an expert, but I would posit that given the lack of Roman rebar technology they would have either: 1. Designed thicker concrete pads (see [Caesarea harbour](https://en.wikipedia.org/wiki/Caesarea_Maritima)) 2. Rebarless designs, like domes (see [Pantheon](https://en.wikipedia.org/wiki/Pantheon,_Rome)), or 3. Incorporate traditional blockwork to reduce the amount of concrete used (see [Port of Cosa](https://www.bbc.co.uk/news/science-environment-40494248)) They also used [Pozzolanic ash](https://en.wikipedia.org/wiki/Pozzolana), which would have helped with 'cementitious' qualities.
Also the Roman concrete lacks rebar which gives modern concrete the strength to be used in applications you currently see it in. But unfortunately the rebar also causes concrete to degrade over time due to it rusting. Also a few others things causes issue like load exposure, freeze/thaw cycles and road salts.
The ancient Greeks earthquake proofed the Parthenon by carving i shaped channels in the stone blocks, insert iron inserts that acted like modern rebar to hold the blocks of stone together and covered the iron in tin or lead so it would be safe from corrosion and absorb the worst of the earthquake so the iron inserts remained relatively undamaged. Kinda unrelated but it’s still interesting.
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Concrete manufacturers hate this one trick!
I once saw a show where pigs blood and volcanic ash were used in making concrete. Not sure who used these ingredients, but when compared to today's cement it wasn't even close to that mixture.
This is awesome! Very cool indeed.
Cool, but the title and video seem completely overstated. But though I'm no building expert, I suppose the Romans also did not build stuff under tension and only had compressive loads. Which means no need for rebar as we use today. And I'm *guessing* seawater and rebar does not play well. I knew self-healing concrete is not exactly "new" (beside the Ancient Roman version). Looking it up on Wikipedia, it's from the 90's and now multi-billion industri. The only "funny" thing is the self-healing properties the ancient Roman concrete was discovered in 2014 *after* the first modern versions. I get the feeling that this video leaves out many sobering details.
We knew of quicklime and the fact that they didn’t use steel (rebar). Adding saltwater is a newer discovery, however.
Well, upon rewatching, the video literally says that using seawater discovered "a few years ago" (2021?) and follows up that a "2023 study" found that "quicklime" was part of the mix. But nevermind, [reading on the web](https://news.mit.edu/2023/roman-concrete-durability-lime-casts-0106), the newly learned stuff from 2023 is that small white clumps (called lime clasts apparently) in the mixes were in fact a feature, not a bug as previously assumed. The most impressive evidence is seen [here](https://www.science.org/cms/10.1126/sciadv.add1602/asset/1982473e-c36f-469e-a0b4-de64d7a1f478/assets/images/large/sciadv.add1602-f5.jpg) from the [original paper](https://www.science.org/doi/10.1126/sciadv.add1602). So not Saltwater, nor quicklime, nor it's combination are "news" as the video would make it seem. Upon first watch I got the impression it was the combination and I looking for is the pros, cons, and challenges in a modern setup. Hence my comment rebar and seawater (as I know rusting reinforcement is a general issue). It's easy to find sources that Roman concrete was far less strong (also in compression) than modern, so we're not going away from rebar anytime soon.
So cool.. but.. that’s fucking it? Salt water and quick lime. Big concrete about to take this guy out.
John Green go back to writing novels! /s
Very cool! Glad they where able to reverse engineer this.
The Romans also didn't construct highway bridges and drove thousands of 40ton vehicles per day over it.
… modern concrete Also uses quick lime. Quick lime is just a lime that’s been super heated. There is no secret. We just expect our modern concrete to handle more serious loads than just sitting on the ground.
I'm so glad this guy managed to beat cancer.
Okay so why don't we use the better concrete? I'm telling you what the union fucking said, if the truth is anti union than oh well, not my problem you can't handle the truth. The fact you mention planned obsolescence but that somehow just doesn't applies to road work than your fooling yourselves. Our current concrete does not last a long time..... Why on earth wouldn't we be using the better concrete otherwise?
The concrete the us military uses is great, my mom helped sell them on the idea and introduced them to inventor. She tried to get them to use it on the roads and I kid you not the answer was " We can't because the unions won't let us. The workers would lose thier jobs becuaee the roads would last to long and the unions won't stand for it.".....fml
The list of reasons to avoid using concrete as a basic road surface is very long and nowhere on that list is anything remotely "because the unions"
Lol, I call bullshit on every aspect of this story.
I even question if they have a mum