by
Damien F. Mackey
“This approach can also be applied to the precision-fit Inca walls: [Apparently] … the ancients knew a technique to dissolve or soften the stone by use of acid plant extracts!”.
Colin Nickerson writes:
http://www.nytimes.com/2008/04/23/world/africa/23iht-pyramid.1.12259608.html
Did the Great Pyramids' builders use concrete?
CAMBRIDGE, Massachusetts — It is a theory that gives indigestion to mainstream archaeologists. Namely, that some of the immense blocks of the Great Pyramids of Egypt might have been cast from synthetic material - the world's first concrete - not just carved whole from quarries and lugged into place by armies of toilers.
Such an innovation would have saved millions of man-hours of grunting and heaving in construction of the enigmatic edifices on the Giza Plateau.
"It could be they used less sweat and more smarts," said Linn Hobbs, professor of materials science at the Massachusetts Institute of Technology.
"Maybe the ancient Egyptians didn't just leave us mysterious monuments and mummies. Maybe they invented concrete 2,000 years before the Romans started using it in their structures."
That is a notion that would dramatically change engineering history.
….
A handful of determined materials scientists are carrying out experiments with crushed limestone and natural binding chemicals - materials that would have been readily available to ancient Egyptians - designed to show that blocks on the upper reaches of the pyramids may have been cast in place from a slurry poured into wooden molds.
These researchers at labs in Cambridge, Philadelphia and St. Quentin, France, are trying to demonstrate that Egyptians of about 2,500 B.C. could have been the true inventors of the poured substance that is humanity's most common building material.
At MIT, Hobbs and two colleagues teach a course called Materials in Human Experience. Over the years, undergraduates in the program have recreated from scratch such artifacts as samurai swords, tinkling Meso-American bells and even a swaying 60-foot, or 20-meter, plant-fiber suspension bridge like those built by the Incas.
Now a scale-model pyramid is rising in Hobbs's sixth-floor lab, a construction made of quarried limestone as well as concrete-like blocks cast from crushed limestone sludge fortified with dollops of kaolinite clay, silica and natural desert salts - called natron - like those used by ancient Egyptians to mummify corpses. ….
And, according to this next article, what had happened in the Old World (e.g. ancient Egypt) was basically replicated in the New World (e.g. Meso-America):
http://primeross.blogspot.com.au/2011/11/ancient-stone-technology.html
Ancient stone technology
Everybody who has traveled to Egypt, Mesopotamia, South America and many more places has seen it: the astonishing craftsmanship of these ancient stoneworkers. The precision fit of large stoneblocks is eminent in both the Old and New World. It is hardly imaginable, that all of this should have been done by pure manual work alone.
The same applies to the smaller, but [surely] not less perfect artefacts, like stone bowls, vases etc.
The Mesoamerican cultures had a special affinity with obsidian, a very brittle volcanic glass. They used it for a variety of (mostly ritual) objects. An Aztec craftsman made these earplugs, which put our belief in manual work to a tough test...
They are polished to a thickness of less [than] a millimeter and completely symmetrical. The perfect geometrical shape and the somewhat small difference between the tube's diameter and the diameter of the flanges make them rather unusual. They're supposedly made with tools like bamboo drills, stone chisels and sand as an abrasive. I wonder … how often the poor man had to start over...
If one takes a closer look to things, unmistakable signs of machining emerge. Take all the time to visit this magnificant site: Ancient Egyptian Stone Technology (new window).
Experiments
Some years ago, a group of enthusiastic researchers ([led] by Roger Hopkins, a stonework professional who has done several of these experiments) carried out a small scale experiment in Egypt, regarding the building of a pyramid with a base of a few meters across, which is in itself a respectable project. But then they stated, rather boldly in my opinion, this could have been the way, the big ones had been build. Although they were cautious enough to use the word "could", translating the results of the experiment into a project a hundred times larger, seems careless and overconfident to me.
In Southamerica, the same mistake was made. In an attempt, to explain the [astonishing fit of the Inca stone walls,
like this one in the city of Cuzco, incorporating the famous "stone with 12 angles",
the [researchers] experimented with a technique to copy the shape of the top stone to the one beneath it. This involved some quite dangerous methods to hold the top stone in an elevated position, in midair, so to speak, which did well with stones of 30 cm across. What they couldn't provide, was an idea, how to bring it into practice with these stones, some of them more than 3 meters tall:
Sacsayhuaman is believed to have been a fortress. The interesting thing with these walls is that the builders took every measure to make the stones fit to an almost ridiculous degree of perfection in the most difficult shapes, while the front is rough and covered with deformations that make them look unfinished. That can bring up the idea, that these walls have been [built] in a much different way.
A bold theory
Professor Davidovits from the Geopolymer Institute in France has found a possible answer to these riddles. He asks if the Egyptian Pyramids at Gizeh have been build with a construction technique widely used in our time: Are Pyramids made out of concrete?
It seems ridiculous at first glance, but it solves a few nasty problems that couldn't be solved yet with the established theories. For instance: how did the pyramidbuilders in Egypt manage to haul the stones up to the summit, where the workspace is reduced to virtually nothing? All those man had to stand somewhere.
In short, his theory is that the 2 million blocks of limestone that make up the core of the pyramid of Chufu (Cheops), have not been cut into shape, but the limestone was solved in water, brought to the building place in small portions and then the blocks were cast in situ.
This approach can also be applied to the precision-fit Inca walls: [Apparently] … the ancients knew a technique to dissolve or soften the stone by use of acid plant extracts! Before you start laughing, take a closer look at these images (click the images to see larger, detailed versions in a new window):
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A detail from one of the walls of the Sacsayhuaman complex. Many stones show strange impressions or scrape marks, as if the surface has been soft during tooling. (Take also a closer look to the picture above). Just take a square piece of wood and push it in soft clay. You will make impressions just like these!
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The great wall at Ollantaytambo, Peru.
Observe the third large stone from the left with its long scrape marks and the large flat impression at the top edge of the second stone from the right.
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Detail from the great wall.
The middle stone. [Although] the surface is very rough and looks hewn or carved, I find it difficult to … explain the square marks and the slightly raised edge of the lower zigzag pattern. It is certainly possible to produce such marks with traditional methods, but then they would have to be made deliberately and [that’s] not what it looks like.
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Ollantaytambo, Peru
Soft stones could also explain the precision fit. The stones would settle by their own weight and the weight of the ones on top, thereby squeezing into any gaps. The protrusions could be formed by making marks in the support structure that would be necessary to prevent uncontrolled movement of the material at the outer face of the wall. It is sometimes mentioned, these protrusion were made to hold gold plating or to tie ropes to for handling. Unfortunately, they would work insufficiently for either use and are too randomly placed. Fact remains: we don't have a clue.
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Puma Punku complex at Tiahuanaco, Bolivia.
The approx. 1cm wide groove with inside a set of equidistant holes is one of many features there, who are so hard to explain, that the whole site is virtually hushed up by the archaeological community. [It’s] just a few hundred meters away from the famous site of Tiahuanaco, but almost never mentioned. If not advanced machining in ancient times is the key to the mystery, then the cast stone theory could provide some answers.
It would not be difficult to build a mold with a strip and pins in it, which had to be removed after hardening of the stone.
I think these theories are really interesting. There are several PDF-documents on the Geopolymer Library page that explain the theories and shows some results of tests conducted on similar types of stone.
To solve this mystery, it would be necessary to examine the actual stones for any signs of such a treatment. ….
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