Are the Egyptian pyramids made out of concrete ?
Were the great pyramids of Egypt built with re-agglomerated stone blocks, that is, concrete, a mixture of natural limestone fragments with a binding substance? Such is the theory of French professor Joseph Davidovits, a super-expert in the field of geo-polymers and a member of the International Association of Egyptologists.
Engineer Davidovits, author of important research on the chemistry of materials and polymer reactions (cements, binders), began in 1975 a long study of the technologies, mining and alchemical researches of the ancient Egyptians, in an effort to solve some of the so-called "mysteries of the Pyramids." In 1988 he collected his considerations in the volume "They have built the Pyramids" second edition in 1990, and in 2002 he published his book in French with the publisher Godefroy, under the title Ils ont bâti les Pyramides: a ponderous volume, in which he condenses his research and also responds to the controversy that has accompanied it over time.
Davidovits' theory rests on a series of archaeological evidences, and on the interpretation of some hieroglyphic texts referring to the construction of the gigantic monuments. No one has so far been able to say a definitive word about how a civilization, which did not yet know the use of metals, managed to work the hardest stones with the utmost precision and lift huge blocks of limestone up to the tip of the pyramids, more than 140 meters high.
The observation that caused the most stir a decade ago was the discovery of organic fibers (hair or hair?), along with air bubbles and bits of red-colored plaster, inside a limestone block of the Great Pyramid.
Ancient Egypt worshipped two distinct deities in charge of the creation of the world, two gods opposed to each other, each of whom experienced their own age of splendor.
The first creator god was Khnum, worshipped by Cheops (so much so that the god's name appears in the scroll along with that of Pharaoh, who called himself "Khnumu-Khufu"). He was the god of petrifaction, of the potters who accomplished their work by agglomerating clay, as well as of the agglomeration of artificial stone, used for the pyramids. Khnum was considered the creator god from 3000 to 1800 B.C.E.: he was believed to have kneaded humanity from the silt of the Nile, using natron and mafkàt. With such manipulations, not clay bricks were produced, but a real "artificial stone."
Natron is a salt - sodium carbonate - found in Egypt in its natural state, particularly at the bottom and shores of some lakes. What about mafkat? It is a group of copper minerals (hydrated silicates, such as chrysocolla), light blue-green in color, similar to turquoise, that the Egyptians extracted from the Sinai mines and that could be used as catalysts for the chemical reactions of "re-aggregation" of hard stones. In copper ore deposits, one finds a large quantity of minerals derived from the alteration of the metal: sulfates, arsenates, phosphates and copper silicates. All are bluish or greenish in color.
The second demiurge was Amun, who imposed himself on the great cult 1500 years later (around 1600 B.C., at the time of the New Empire), worshipped by Rameses II.
He was the god of Upper Egypt, who created the world by carving it out of living stone, the raw material for making temples and obelisks. For those two major and competing religious currents, the handling of stone (whether it was re-agglomerated or carved material) was a sacred act, repeating the act of man's creation. The material of the gods, for the Egyptians, was stone, while for the Greeks it was gold (Krysós). This fact, according to Davidovits, also generated a misunderstanding, perpetuated over the centuries in the traditions of the Alchemists: they sought to regenerate the divine body, and regularly obtained stone, while they were convinced that they had to obtain gold, because the Alexandrian culture, of a now Greekified late Egypt, had shifted the interpretive terms of their knowledge and secrets.
From remote antiquity, searches for minerals and their treatment with heat generated the processes of Alchemy. Such researches had naturally to lead to the discovery of conglomerated, or regenerated, stone sooner than to the melting of metals (since the former procedure requires a lower temperature than the latter: enamels can be obtained at temperatures of 600°-700° C, while copper melts at 1083° C, or possibly a little lower, thanks to the use of "melting" substances such as natron).
Therefore, Davidovits's hypotheses are far from ahistorical or unbelievable.
A large number of "stone" vessels found in ancient Egyptian tombs appear to be made of very hard and extremely difficult stones: microgres or metamorphic schist, anorthositic gneiss, andesite, basalt, breccia. Indestructible and mysterious objects, found in enormous quantities (tens of thousands). In the same materials, the ancient Egyptians shaped statues, smoothed with a perfection that seems unattainable even with the use of modern techniques. Some objects worked in very hard stone even predate the extraction of metals suitable for their workmanship. Indeed, paradoxically, the working of hard stone vessels disappears at the time when bronze and iron tools become widespread. The use of metal tools is matched by the working of softer materials, such as alabaster, steatite, and talc.
Davidovits believes that the "hard stone" works are actually objects shaped or worked on a lathe, with a recomposed lithic material, made of an inert and a binder, that was shaped like clay or clay. The final effect is that of a very hard stone, but the working of those vessels--according to Davidovits' elegant demonstration--was not done with drills and other sculpting implements, but with the tools and techniques typical of those who shape and mold a plastic material, and then harden it.
Davidovits also reports the case of the sculptures of Akhenaten and Nefertiti, which belonged to the so-called "Mansùr collection." A series of subsequent expert reports have declared the historical and archaeological authenticity of these sculptures, while others, apparently contradictory to the former, claim that they are not carved in stone, but made from an artificial lithic surrogate, and perhaps even modeled on the mask of the faces of the subjects depicted. which corresponds exactly to the theses held by our author!
Davidovits identifies the following five stages in the progress of alchemical research:
- the discovery of enamel (related to the discovery of copper in its ores), ca. 4000 BC.
- Brilliant enamels made around 3800 BC are found.
- the use for self-glazing of statuettes of caustic soda, obtained from the natron-lime mixture, ca. 3600 BCE.
- the discovery of sodium silicate, ca. 3600 B.C.
- the agglomeration of stone thanks to turquoise, used as a catalyst, ca. 3600 B.C.
- the agglomeration of aluminous limestone, for the construction of large blocks, with caustic soda (Arch. Imhotep, "inventor" of the great pyramids), ca. 2700 BCE.
What is the evidence adduced by Eng. Davidovits for his theory on the construction of the Pyramids?
The nummulitic limestone of the Gizah plain, used to make the Great Pyramids, is a fossiliferous rock. In deposits of such rock, the tiny shells all rest "oriented," in the position they assumed when they were deposited at the bottom of the sea. In the pyramid blocks, on the other hand, their orientation is haphazard, random, and denotes the use of chunks of limestone as "inert," in a reaggregated mixture. Gizah limestone, according to Davidovits, is the most suitable stone for its "artificial recomposition." In fact, it is soft and, macerated in water, easily disaggregates (the mass becomes a kind of slurry, while the shells it contains remain intact, like pebbles). Notably, it contains a small amount of "natural and reactive geo-polymeric ingredients," such as clay with kaolin, which is essential for the setting reaction with caustic soda. This can be obtained, simply by mixing to the limestone slurry a little (1%) natron (salt found in Egypt in its natural state) and a little (2%) lime.
In the wake of the alchemical procedures used to make hard stone vessels, it seems that Pharaoh Zoser's architect, the famous Imhotep, who was later deified, discovered a way to "build" artificial stone blocks by exploiting the special properties of Gizah limestone, mixed in the right proportions with natron and lime. The official titles held by Imhotep were Chancellor of Lower Egypt, Prime Minister of the King in Upper Egypt, Administrator of the grand palace, Physician, Hereditary Nobleman, High Priest of Anu (Heliopolis, for the Greeks), Chief Architect of Pharaoh Zoser, Sculptor and "maker of stone vessels." The author surmises that, in an effort to strengthen and "stabilize" the unfired clay bricks that were in general use for construction, Imhotep discovered the special properties of the mixture limestone+cholinitic clay+natron+lime, and exploited them for the construction of Pharaoh Zoser's Step Pyramid, and then for the even more extraordinary ones on the Plain of Gizah.
Thus, in about twenty years the Pharaohs could well have made the two and a half million limestone blocks, weighing between 2 and 30 tons each, needed for the construction enterprise of the great pyramids. The blocks are well connected, so that their surfaces match perfectly (which seems obvious, when one begins to think of "cast-in-place" blocks, for which the already-made blocks served as formwork). The volume of stones "made" in just forty years (forty million cubic meters of limestone) would have equaled that of stones "quarried" and placed in place for monuments over the next 1500 years.
Many other considerations of Davidovits collaborate to support his theses: from the microclimate found inside the pyramids, to the distribution of the sizes and dimensions of the blocks on the different layers of the buildings.
Certainly, the most surprising elements are: the size of the "sarcophagus" of Cheops, inside the King's Chamber of the Great Pyramid, the presence in the Valley of the Kings of a large red syenite sarcophagus (now in the Louvre Museum), larger than the narrow entrance gorge to the Valley, and the presence in the plain of the Pyramids, in the funerary temples of Khefren and Menkaure (Mycerinus), of limestone blocks of truly disproportionate size, 2-3 maters high and weighing up to 500 tons.
Davidovits dismantles, one by one, the "evidence" of the proponents of the traditional theses, who would have the pyramids built by a myriad of men, scrambling to drag blocks with wooden rollers up very long inclined ramps.
Instead, the blocks of the pyramids would be composed of 90-95% natural limestone with fossil shells, and 5-10% natural geological binders ("geo-polymeric" cements). A manufacturing technique very similar to that of our concrete, in which caustic soda, obtained from the special compositions of the minerals used (mafkat and natron), took the place of our blast furnace cement.
Instead of 100,000 men, busy all day long over a span of forty years, according to Davidovits' theories, 1,400 workers and twenty years of labor would have sufficed to build the Great Pyramid; and the problem of "lifting the blocks" would no longer arise, since these would have been thrown in place, and the transportation of the inconsistent material can be done with sacks, baskets or other containers of all sorts.
That would leave the problem of lime manufacture, which the author elegantly solves with the observation that the ashes of reeds and papyrus are rich in Calcium Oxide (quicklime). He therefore surmises that, during the period of pyramid construction, the generalized collection of ashes was practiced, from all the bread ovens throughout Egypt. Thus 7,200 to 36,000 tons of lime per year could have been supplied.
On the other hand, it is well known that the great vaults and domes of Antiquity were built with the concrete technique: we cite the examples of the Pantheon, the Basilica of Maxentius, and the Hagia Sophia in Constantinople. The Romans, in particular, used mortars and concretes made from pozzolan, a rock of volcanic origin, which enabled them to build piers and port works capable of withstanding the chemical and physical aggression of sea water over the centuries.
Davidovits also lays out his study of these cases, along with his own hypotheses about the Pyramids of Egypt, on his rich website http://www.geopolymer.org/archaeo.
A film, made in France during 2002, showing the experimental fabrication of some "pyramid limestone" blocks can also be downloaded from the site.
