a concrete issue

[lorddread]

One of the most amazing things the Romans did was to build everything out of concrete. Every Roman structure that is still intact today (aquaducts, the Colosseum, the pantheon (which had a massive 1 piece concrete dome roof, the largest of its kind even today at 142 ft across) the baths, etc are all made out of concrete and then had marble or travertine blocks

They also made the first real bricks (that is made from clay and baked in a kiln. Aurelian's wall around Rome was made this way.

So much was lost during the dark ages.

[Coracle]

It was a great invention. I suppose the Construction tech applies to this.


A structural masonry material made by mixing broken stone or gravel with sand, cement, and water and allowing the mixture to harden into a solid mass. The cement is the chemically active element, or matrix; the sand and stone are the inert elements, or aggregate. Concrete is adaptable to widely varied structural needs, is available practically anywhere, is fire resistant, and can be used by semiskilled workers. 1
The use of artificial masonry similar to modern concrete dates from a remote period but did not become a standard technique of construction until the Romans adopted it (after the 2d cent. B.C.) for roads, immense buildings, and engineering works. The concrete of the Romans, formed by combining pozzuolana (a volcanic earth) with lime, broken stones, bricks, and tuff, was easily produced and had great durability (the Pantheon of Rome and the Baths of Caracalla were built with it). Enormous spaces could be roofed without lateral thrusts by vaults cast in the rigid homogeneous material. 2
Scientifically proportioned concrete formed with cement is an invention of modern times; the name did not appear until c.1830. Modern portland cement has revolutionized the production and potentialities of concrete and has superseded the natural cements, to which it is vastly superior. The component materials of concrete are mixed in varying proportions, according to the strength required and the function to be fulfilled; the proportions were first worked out by Duff Abrams in 1918. The ideal mixture is that which solidifies with the minimum of voids, the mortar and small particles of aggregate filling all interstices. A typical proportioning is 1:2:5, i.e., one part of cement, two parts of sand, and five parts of broken stone or gravel, with the proper amount of water for a pouring consistency. A simple test called a “slump test” is used to confirm the proportions and consistency of the mixture, and it is then poured into wood or steel molds, called forms. Concrete usually takes about five days to cure, or reach acceptable hardness, but a technique called steam saturation can shorten that curing time to less than 18 hours. A wide variety of additives allow the concrete to harden faster or slower, resist scaling, or adopt the final shape more easily. 3
Concrete used without strengthening is termed mass, or plain, concrete and has the structural properties of stone—great strength under compressive forces and almost none under tensile ones. F. Joseph Monier, a French inventor, found that the tensile weakness could be overcome if steel rods were embedded in a concrete member. The new composite material was called reinforced concrete, or ferroconcrete. It was patented in 1857, and a private house in Port Chester, N.Y., first demonstrated (1857) its use in the United States. It is now rivaled in popularity as a structural material only by steel. Concrete reinforced with polypropylene fibers instead of steel yields equivalent strength with a fraction of the thickness. Reinforced concrete was improved by the development of prestressed concrete—that is, concrete containing cables that are placed under tension opposite to the expected compression load before or after the concrete hardens. Another improvement, thin-shell construction, takes advantage of the inherent structural strength of certain geometric shapes, such as hemispherical and elliptical domes; in thin-shell construction great distances are spanned with very little material. The perfecting of reinforced concrete has profoundly influenced structural building techniques and architectural forms.

[Dauphin]

I can just imagine some Roman "Brickies" wolf-whistling the passing Patrician women.

[lorddread]

whistling

Originally posted by Sagacious Dolphin
I can just imagine some Roman "Brickies" wolf-whistling the passing Patrician women.

They would only get to do it once. Then they get to meet the lions.

[aaglo]

Re: a concrete issue

Originally posted by lorddread
So much was lost during the dark ages.

Lost? The techiques the domes were made is not lost. Today it is not used, because it is not efficient use of building materials (or so the designers think).
The romans didn't use any reinforcing steels in their structures, and that is the main reason they still exist. The steel has a tendency to rust. The volume of rust is greater than the volume of steel. Thus the rust makes the concrete crack.

The domes are based on archs. When an arch is loaded, all the bending forces (which cause tension) are turned to compression (concrete has a good capacity against compression, but poor capacity against tension).

Nowadays the tension in concrete structures are taken care of with reinforcing steels. That is the reason why nobody (practically) never builds archs...

[lorddread]

Dark Ages

Originally posted by aaglo


Lost? The techiques the domes were made is not lost. Today it is not used, because it is not efficient use of building materials (or so the designers think).
The romans didn't use any reinforcing steels in their structures, and that is the main reason they still exist. The steel has a tendency to rust. The volume of rust is greater than the volume of steel. Thus the rust makes the concrete crack.

Actually I wasn't refering to the dome or concrete even. ABout 80% of everything that had been learned in the previous centuries was lost starting in about 520 AD. This is the reason this period is called the dark ages.

PBS had a scholar on once. He was talkting about the dark ages. If we hadn't had the dark ages, we would probably be living on the moon and exploring Mars. That's how much science we lost.

[Dauphin]

If we hadn't had the dark ages, we would probably be living on the moon and exploring Mars. That's how much science we lost

So was Europe the only centre of technology. I don't doubt the statement has truth, but I thought the knowledge was only lost in Europe and survived elsewhere to be rediscovered (as opposed to re-invented) during the renaissance.

I also heard stories about an old advanced civilization (on a par with Rome) from around 10,000 years ago that was destroyed and all trace of it lost, and is buried or know under the ocean. (I'm not talking about Atlantis)

The evidence for advanced but lost technologies from this period are compelling.

[lorddread]

The Dark Ages

[QUOTE] Originally posted by Sagacious Dolphin

If we hadn't had the dark ages, we would probably be living on the moon and exploring Mars. That's how much science we lost

So was Europe the only centre of technology. I don't doubt the statement has truth, but I thought the knowledge was only lost in Europe and survived elsewhere to be rediscovered (as opposed to re-invented) during the renaissance.
QUOTE]

Actually, the dark ages hit almost everywhere in the world with 200 years. China, Central America, Japan, Egypt, and even part of South America experienced their own Dark Ages. In China, it came and went quick, Japan's is believed to have last several hundred (300+/-) years. South America and Central America's cultures never recovered.

[Kramerman]

That is very correct. I saw that same program you were referring to, or at least a similar one. It said how we could be hundreds of years technologically advanced to how we are if it weren't for the fall of the increasingly decadent Roman empire and dark age that ensued(which did, as mentioned earlier, hit the whole world, and not just Europe). All lost Technology had to be relearned and it was durring the high middle ages and renassaince that most of this was done. Luckly the Arabs were able to perserve some of Greece's and Rome's works, both scientific and artistic. Humanity didn't finally start to gain ground and learn new techs until the Enlightenment .

One thought to chew on is that some Greek guy, not sure what his name was or if he was even Greek, but this Mediterrainian guy had developed a steam engnige and it was used to open the doors of a temple. It was a novolty that made people awe-struck at the time. Unfortunately slaves were so prevelant at the time and for many other reasons, this steam sngine was never developed and the tech was eventually lost after the dude's death. But, just think, it could of been possible to have the Industrial Reveloution right then and there. In thte pursuit to make businesses more profitable, as we do today, science would of boomed and we could very well be 1500-2000 years ahead technologically compared to how we are now.
Kman

P.S. I read somewhere that the Romans mixed some kind of volcanic ash found in northern italy into their concrete which increased its strength very much. In fact, until recently scientists could not explain why Roman concrete seemed to be stronger than modern non-reinforced concrete up until the 1920s. Then the ash technique was discovered and gave valuable insight into the stregnth properties of concrete. So the Romans (and all Ancients, for that matter) were still teaching us new things even into modern times. And the Greek analog computer they discovered, that just amazes me that they had such advancements more than 2000 years ago.

[jdd2007]

hasnt anyone seen one of those volkswagon commercials?

[notyoueither]

Unfortunately, what the guides fail to point out is that science and technology are more dependant on attitude than anything else. Europeans were straining at the leash that the church(es) imposed on them for a long while before more liberal clergy and then the Reformation snapped constraints (largely).

I'm not saying that the fall of Rome was not a set back for the progress of knowledge. However, I am not willing to accept arguments that were it not for the fall we would be significantly ahead of where we are today.

Europe of the 14th and 15th centuries was a unique mix of classical bases with invader cultures. The pressures and influences of the 1000 years (or so) from the decline of Rome in the West have as much to do with the progress of the renaissance and later ages as classical knowledge did. Where would the world be without the rather Germanic notions of individualism and it's importance?

Interesting thoughts.

[Dauphin]

Originally posted by Kramerman But, just think, it could of been possible to have the Industrial Reveloution right then and there. In thte pursuit to make businesses more profitable, as we do today, science would of boomed and we could very well be 1500-2000 years ahead technologically compared to how we are now.

Major socio-economic transformations need several elements. One of the main elements in the industrial revolution was indeed technology such as the steam engine.

However the large population to both produce and purchase the good was not present. Nor was the agricultural set-up ready to support a large industrial population.

[Kramerman]

But if the potential of the steam engine would of been realized, there would of been a pursuit for such needed elements such as agricultural techniques to help increase crop yields to help sustain a larger population. I didn'y mean to convey that it would of happened over night, but the dude who had this steam engine lived like 500 B.C. and most of the needed advances could've under the progressive societies of most of the ancients have been discovered by 0 A.D, about 2000 years ago. And i disagree with your statement of a large population as needed to purchase and produce the goods, this ancient industrialization would still be just as revolutionary with a small 30 -50 million population, it would just produce on a much smaller scale than our industrialization, but it wouldn't be significantly smaller in proportion to their population.
Kman

[lorddread]

Ancient Advancements

There is a new twist to the story about concrete. PBS had a special about a problem plaguing European museums. Seems that most curators believed that a lot of the artifacs from Egypt and Babylon were solid gold. Come to find out that the ancients had discovered how to electroplate silver and brass using a archaic form of electricity. They would mix some type of acid, lead and fruit juices in a clay pot. One of these "Bagdad Batteries" was found in the mid 80's along with partially plated figurines.

Cool huh?

[Kramerman]

Yeah, I had heard about that. That is very intersting. only if they could of realized the potential of electricity on top of steam....

Kman