Secret of how Roman concrete survived tidal battering
for 2,000 years revealed
http://www.telegraph.co.uk/science/2017 ... -revealed/
Chris.
Secret of Roman concrete surviving 2,000 years
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Moose On The Loose
- Posts: 965
- Joined: Thu 24 Feb 2011, 14:54
Lets not leave out their roads that are still in use in many places.nic007 wrote:It's actually incredible what the Romans achieved. Their water and sewerage systems were top notch.
They also invented a robust form of government that would be best described as something close to a democratic republic. The citizens were selecting the senators. Later when it turned into a one man rule situation it was on the way down. When Rome fell it was a long time before anything near that was created again.
Not to mention their excellent legal system. Up and till this day we are using Roman-Dutch Law as cornerstone of South African Law. Just think of all those lovely Latin terms. In fact I reckon most common law practised anywhere in the world comes from the Romans.Moose On The Loose wrote:Lets not leave out their roads that are still in use in many places.nic007 wrote:It's actually incredible what the Romans achieved. Their water and sewerage systems were top notch.
They also invented a robust form of government that would be best described as something close to a democratic republic. The citizens were selecting the senators. Later when it turned into a one man rule situation it was on the way down. When Rome fell it was a long time before anything near that was created again.
One Roman law I don't like is the one where...
If someone makes an accusation against you...
And you don't refute it [for whatever reason]...
Then the accusation is held to be true.
[You might waste your life refuting innumerable spurious accusations]
EXAMPLE:
Jesus of Nazareth was accused by the Romans of claiming to be the King of the Jews.
And he made no reply [hence he didn't refute it]...
Therefore methinks the accusation was held to be true, and he was sentenced.
Nowadays we have a similar situation in law, where...
At the time when someone is charged...
If they choose to remain silent, and later use a defence in court that they didn't mention at the time the charges were made...
Then that will be held against them.
If someone makes an accusation against you...
And you don't refute it [for whatever reason]...
Then the accusation is held to be true.
[You might waste your life refuting innumerable spurious accusations]
EXAMPLE:
Jesus of Nazareth was accused by the Romans of claiming to be the King of the Jews.
And he made no reply [hence he didn't refute it]...
Therefore methinks the accusation was held to be true, and he was sentenced.
Nowadays we have a similar situation in law, where...
At the time when someone is charged...
If they choose to remain silent, and later use a defence in court that they didn't mention at the time the charges were made...
Then that will be held against them.
I think the main reason modern concrete doesn't last is that most of it contains rebar, which rusts inside the concrete. The rust expands the original volume of the steel, breaking the concrete the same way water breaks pipes when it freezes. Concrete poured without rebar will probably last as long as the Roman concrete would in the same circumstances.
Dear puppians,
I was shown a bridge in Merv (Turkmenistan) https://en.wikipedia.org/wiki/Merv some 15 years ago that dated from the time of Alexander the Great. The director of the museum there explained that the builders mixed eggs in with the mortar, and that explained why it was still standing. Very impressive.
I believe they did not have GMO chickens back then.
With kind regards,
vovchik
PS. Merv was the largest city in the world from 1145 to 1153.
@ Flash: My father was an architect and engineer. He explained to me that the eventual disintegration comes not so much from rust as from the difference in the thermal expansion coefficients of sand and iron, although rust may play a part. And the ratios of air, water, sand and lime are important. As he was responsible for designing and calculating these things, often for large and critical structures, I think he knew what he was talking about.
I was shown a bridge in Merv (Turkmenistan) https://en.wikipedia.org/wiki/Merv some 15 years ago that dated from the time of Alexander the Great. The director of the museum there explained that the builders mixed eggs in with the mortar, and that explained why it was still standing. Very impressive.
I believe they did not have GMO chickens back then.
With kind regards,
vovchik
PS. Merv was the largest city in the world from 1145 to 1153.
@ Flash: My father was an architect and engineer. He explained to me that the eventual disintegration comes not so much from rust as from the difference in the thermal expansion coefficients of sand and iron, although rust may play a part. And the ratios of air, water, sand and lime are important. As he was responsible for designing and calculating these things, often for large and critical structures, I think he knew what he was talking about.
Okay, thanks. In any case it seems that one way or another, rebar causes concrete to crack and fail.
Another thing that causes concrete to fail is lack of water. Concrete can dry out in the desert and crumble. That happened to the concrete liner for a huge canal that was built in Arizona from the '60s through the '80s. It took 20 years to complete and they didn't put water in the canal until it was about done. When they did let water in, the first sections of the canal cracked and had to be redone because they'd sat in the sun for so long that they dried out. Anyway that's what the contractor blamed it on, not substandard concrete or sloppy workmanship.
In any case it seems that one way or another, rebar causes concrete to crack and fail.Another thing that causes concrete to fail is lack of water. Concrete can dry out in the desert and crumble. That happened to the concrete liner for a huge canal that was built in Arizona from the '60s through the '80s. It took 20 years to complete and they didn't put water in the canal until it was about done. When they did let water in, the first sections of the canal cracked and had to be redone because they'd sat in the sun for so long that they dried out. Anyway that's what the contractor blamed it on, not substandard concrete or sloppy workmanship.
I saw a TV program about the building of the Hoover Dam, which at the time was the largest concrete build in the world. Concrete generates heat during the hardening process, and it may cause an expansion inside a concrete construction, and make it crack. In the Hoover Dam, they had to build cooling pipes into the construction, because they were pouring cocrete continuously, and had no time to stop the build to prevent cracks
I guess the generated heat inside the concrete also contributed to the crumbling concrete liner that Flash describe, the newly cast concrete would have to be sprayed with water for a long time in such a dry slimate.
BTW, the info on waterproof concrete is not new, I learnt about the volcanic ash mix some 15-20 years ago. The old harbors around the Mediterranian are full on underwater concrete constructions. And don't forget that the romans picked up the making of concrete from ancient Greece sources, and where they got it is a mystery.
tallboy
I guess the generated heat inside the concrete also contributed to the crumbling concrete liner that Flash describe, the newly cast concrete would have to be sprayed with water for a long time in such a dry slimate.
BTW, the info on waterproof concrete is not new, I learnt about the volcanic ash mix some 15-20 years ago. The old harbors around the Mediterranian are full on underwater concrete constructions. And don't forget that the romans picked up the making of concrete from ancient Greece sources, and where they got it is a mystery.
tallboy
True freedom is a live Puppy on a multisession CD/DVD.
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bark_bark_bark
- Posts: 1885
- Joined: Tue 05 Jun 2012, 12:17
- Location: Wisconsin USA
Now...now >> BBB.
Those were the days my Friend.
https://www.quora.com/Were-the-Romans-evil-people
http://www.raceandhistory.com/historicalviews/rome.htm
""""""""
10 Innovations That Built Ancient Rome
http://www.history.com/news/history-lis ... cient-rome
Chris.
Those were the days my Friend.
https://www.quora.com/Were-the-Romans-evil-people
http://www.raceandhistory.com/historicalviews/rome.htm
""""""""
10 Innovations That Built Ancient Rome
http://www.history.com/news/history-lis ... cient-rome
Chris.
volcanic ash in roman concrete crystalizing, and other forms of weaker crystalization blocked because of it.
Darn good stuff. Strong as snot, and as the crystalization of the ash keeps occurring, it keeps getting stronger.
But, alas, getting the ash is the problem.
The Romans sort of had a right-next door "real" volcanic ash factory courtesy of Mother Nature.
Not so easy to reproduce given where major concrete manufacturers/exporters are located.
Darn good stuff. Strong as snot, and as the crystalization of the ash keeps occurring, it keeps getting stronger.
But, alas, getting the ash is the problem.
The Romans sort of had a right-next door "real" volcanic ash factory courtesy of Mother Nature.
Not so easy to reproduce given where major concrete manufacturers/exporters are located.
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Moose On The Loose
- Posts: 965
- Joined: Thu 24 Feb 2011, 14:54
I think that once it is hardened, it takes a quite high temperature to drive the water back out of concrete. The most likely thing is that they let it dry out in the first few weeks after it was poured. It takes at least 10 days of being wet for concrete to reach the design strength. It continues to get harder for at least a month.Flash wrote:Okay, thanks.
Another thing that causes concrete to fail is lack of water. Concrete can dry out in the desert and crumble. That happened to the concrete liner for a huge canal that was built in Arizona from the '60s through the '80s. It took 20 years to complete and they didn't put water in the canal until it was about done. When they did let water in, the first sections of the canal cracked and had to be redone because they'd sat in the sun for so long that they dried out. Anyway that's what the contractor blamed it on, not substandard concrete or sloppy workmanship.
I was having a talk with a mate about that Sylvander, I never really understood that quote that the coppers make when they arrest someone.Sylvander wrote: Nowadays we have a similar situation in law, where...
At the time when someone is charged...
If they choose to remain silent, and later use a defence in court that they didn't mention at the time the charges were made...
Then that will be held against them.
Basically, my mate was saying that it is a warning by the cops to keep your mouth shut, they have arrested you on suspicion of doing something and are letting you know what may happen.
Don't know if his interpretation is right. Don't know if the law is still an ass as George Chapman/ Charles Dickens/ or William Shakespeare said!
But I do think some legislators are rubbish and probably self interested...
And also a so called "Fascist" can only exist in a "Socialist State" to facilitate the control of the people and assets.
What this has to do with Roman concrete is tentative, but we're in off topic and I have a sieve brain at the moment!