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Joseph Davidovits (born 23 March 1935) is a French materials scientist. He posited that the blocks of the
Great Pyramid The Great Pyramid of Giza is the largest Egyptian pyramid. It served as the tomb of pharaoh Khufu, who ruled during the Fourth Dynasty of the Old Kingdom. Built , over a period of about 26 years, the pyramid is the oldest of the Seven Wond ...
are not carved stone but mostly a form of limestone
concrete Concrete is a composite material composed of aggregate bound together with a fluid cement that cures to a solid over time. It is the second-most-used substance (after water), the most–widely used building material, and the most-manufactur ...
or man-made stone.


Limestone concrete hypothesis

Davidovits believes that the blocks of the pyramid are not carved stone, but mostly a form of
limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...
concrete Concrete is a composite material composed of aggregate bound together with a fluid cement that cures to a solid over time. It is the second-most-used substance (after water), the most–widely used building material, and the most-manufactur ...
and that they were "cast" as with modern concrete. According to this hypothesis, soft limestone with a high
kaolinite Kaolinite ( ; also called kaolin) is a clay mineral, with the chemical composition Al2 Si2 O5( OH)4. It is a layered silicate mineral, with one tetrahedral sheet of silica () linked through oxygen atoms to one octahedral sheet of alumina () ...
content was quarried in the
wadi Wadi ( ; ) is a river valley or a wet (ephemerality, ephemeral) Stream bed, riverbed that contains water only when heavy rain occurs. Wadis are located on gently sloping, nearly flat parts of deserts; commonly they begin on the distal portion ...
on the south of the Giza Plateau. The limestone was then dissolved in large, Nile-fed pools until it became a watery slurry. Lime (found in the ash of cooking fires) and
natron Natron is a naturally occurring mixture of sodium carbonate decahydrate ( Na2CO3·10H2O, a kind of soda ash) and around 17% sodium bicarbonate (also called baking soda, NaHCO3) along with small quantities of sodium chloride and sodium sulfate. ...
(also used by the Egyptians in
mummification A mummy is a dead human or an animal whose soft tissues and organs have been preserved by either intentional or accidental exposure to chemicals, extreme cold, very low humidity, or lack of air, so that the recovered body does not decay furt ...
) were mixed in. The pools were then left to evaporate, leaving behind a moist, clay-like mixture. This wet "concrete" would be carried to the construction site where it would be packed into reusable wooden moulds and in a few days would undergo a chemical reaction similar to the curing of concrete. New blocks, he suggests, could be cast in place, on top of and pressed against the old blocks. Proof-of-concept tests using similar compounds were carried out at a geopolymer institute in northern France and it was found that a crew of five to ten, working with simple hand tools, could agglomerate a structure of five, 1.3 to 4.5 ton blocks in a couple of weeks. He also claims that the Famine Stele, along with other
hieroglyphic Ancient Egyptian hieroglyphs ( ) were the formal writing system used in Ancient Egypt for writing the Egyptian language. Hieroglyphs combined ideographic, logographic, syllabic and alphabetic elements, with more than 1,000 distinct characters. ...
texts, describe the technology of stone agglomeration. Davidovits's method is not accepted by the academic mainstream. His method does not explain the granite stones, weighing well over 10 tons, above the King's Chamber, which he agrees were carved. Geologists have carefully scrutinized Davidovits's suggested technique and concluded his concrete came from natural limestone quarried in the
Mokattam Formation The Mokattam Formation is a Eocene, Middle Eocene-aged geological formation in northern Egypt. Consisting of Nummulite, nummulitic marine limestone outcropping across the Mokattam, Mokattam Hills, it has been extensively quarried from Ancient Egyp ...
.Harrell, James A. and Bret E. Penrod. 1993. "The Great Pyramid Debate -- Evidence from the Lauer Sample." Journal of Geological Education, vol. 41:358-363. However, Davidovits alleges that the bulk of the soft limestone came from the same natural Mokkatam Formation quarries found by geologists, and insists that ancient Egyptians used the soft marly layer instead of the hard layer to re-agglomerate stones. Davidovits's hypothesis gained support from Michel Barsoum, a materials science researcher. Michel Barsoum and his colleagues at
Drexel University Drexel University is a private university, private research university with its main campus in Philadelphia, Pennsylvania, United States. Drexel's undergraduate school was founded in 1891 by Anthony Joseph Drexel, Anthony J. Drexel, a financier ...
published their findings supporting Davidovits's hypothesis in the ''Journal of the American Ceramic Society'' in 2006. Using
scanning electron microscopy A scanning electron microscope (SEM) is a type of electron microscope that produces images of a sample by scanning the surface with a focused beam of electrons. The electrons interact with atoms in the sample, producing various signals that ...
, they discovered in samples of the limestone pyramid blocks mineral compounds and air bubbles that do not occur in natural limestone. Dipayan Jana, a petrographer, made a presentation to the ICMA (International Cement Microscopy Association) in 2007 and gave a paper in which he discusses Davidovits's and Barsoum's work and concludes "we are far from accepting even as a remote possibility a 'man-made' origin of pyramid stones."


See also

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Great Pyramids of Giza The Giza pyramid complex (also called the Giza necropolis) in Egypt is home to the Great Pyramid, the pyramid of Khafre, and the pyramid of Menkaure, along with their associated pyramid complexes and the Great Sphinx. All were built during the ...
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Pyramids A pyramid () is a Nonbuilding structure, structure whose visible surfaces are triangular in broad outline and converge toward the top, making the appearance roughly a Pyramid (geometry), pyramid in the geometric sense. The base of a pyramid ca ...
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Egyptian pyramid construction techniques The construction of the Egyptian pyramids can be explained with well-established scientific facts; however, there are some aspects that even today are considered controversial hypotheses. The construction techniques used seem to have developed o ...


Bibliography

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References

{{DEFAULTSORT:Davidovits, Joseph 1935 births Living people French Egyptologists Johannes Gutenberg University Mainz alumni French materials scientists