by
“Barsoum also found that portions of the pyramid samples appeared to be
amorphous; their structure is highly disorganized. It would be very unusual,
he points out, to find such disorganization in natural sedimentary stone
formed
on a geological timescale. Furthermore, the silica in one of the pyramid
samples was in the form of nanospheres—another structure that he says doesn't
form naturally in limestone”.
In
Search of Concrete Evidence
In Search of Concrete
Evidence
Materials scientist
suggests parts of the Egyptian pyramids were made from reconstituted limestone
February 11,
2008 ….
EVERY DAY on the
outskirts of Cairo, thousands of tourists brave the dust and heat of the
Egyptian desert to gaze upon the Great Pyramids of Giza. To say the pyramids
are colossal does not even begin to describe the sheer magnitude of these
man-made mountains. The largest—the Great Pyramid, built by the pharaoh
Khufu—is nearly 50 stories high and sits on a base the size of 10 U.S. football
fields. But the numbers simply don't do justice to these giants or to the
enormous feat of engineering it took to create them more than 4,500 [sic] years
ago.
Damien Mackey’s comment: But see e.g. my
article:
Giza Pyramids: The How, When and Why of Them
(5) Giza Pyramids:
The How, When and Why of Them
Michel
W. Barsoum, a materials science professor at Drexel University, grew up in the
shadow of the ancient pyramids. To Barsoum, the pyramids have always been a
symbol of his native Egypt, a wondrous example of his ancestors' engineering
acumen.
He never imagined
that one day he would be using high-tech instrumentation and his knowledge of
materials science and chemistry to challenge the theories that generations of
Egyptologists have held about how the pyramids were built.
"This is not my
day job," Barsoum says. It's the first thing he wants people to know
before they hear about his pyramid research. Passions run high when it comes to
the pyramids, and he is at pains to make it clear that the focus of his research—high-tech
carbides and nitrides—has absolutely nothing to do with them. "I have no
vested interest in this," he says. "I think it's a really neat
problem, and that's why I'm working on it."
Barsoum's saga began
six years ago, when he got a call from a retired engineer and pyramid
enthusiast named Mike Carrell who asked if he was familiar with the mystery of
the pyramids. Did Barsoum know that the Great Pyramid contains some 2.3 million
blocks, averaging 2.5 tons each? Did he know that Egyptologists estimate that
it took 23 years to construct that pyramid? Did he realize that, according to a
back-of-the-envelope calculation, one massive block would need to have been
laid into place every six minutes, assuming the builders worked around the
clock for more than two decades? Did he know that some blocks in the Giza
pyramids are so close together that it's impossible to slip even a piece of
paper between them?
Then Carrell told
Barsoum that the great mystery of how the pyramids had been constructed had
already been solved. He said the French geochemist Joseph Davidovits had
postulated decades ago that the pyramids had not, as Egyptologists thought,
been made of limestone carved by copper tools into great blocks that were then
hoisted into place by levers. Rather, Davidovits argued, they had been cast
from reconstituted limestone concrete.
The explanation,
Barsoum says, made him laugh out loud. If this theory held any weight, why had
no one gathered any scientific evidence to prove it? He said to Carrell,
"If I can't tell you the difference between natural limestone and
artificial limestone in about two hours on a scanning electron microscope, then
shame on me."
IN HINDSIGHT, Barsoum
recognizes his hubris in taking on the project. "What was supposed to take
me two hours on the scanning electron microscope turned into a five-year
odyssey," he says. To complete their analysis, Barsoum and his colleagues
had to take more than 1,000 micrographs, focusing their scanning electron and
transmission electron microscopes on samples taken from the Great Pyramid and
samples of natural rock from which the pyramids are thought to have been
constructed.
According to
Davidovits' theory, the ancient Egyptians used natural limestone rubble
combined with clay in a high-pH solution to create their concrete.
"Because all clays contain sodium and aluminum, we started looking for
sodium and aluminum in the cementing phase of the pyramid samples,"
Barsoum explains. "We didn't find any sodium, and we didn't find any
aluminum. The only thing we found was silica."
It's common to find
silica in limestone, so Barsoum's initial findings would seem to indicate that
Davidovits' theory, or at least his recipe, was incorrect. But Barsoum also
found chemical evidence that the natural stone differed significantly from stone
taken from the pyramids.
In all the samples
taken from the pyramids he found sulfur, but he found no trace of the element
in the natural stone samples. The stone taken from the pyramids appears to be
significantly more hydrated than natural limestone from the region.
Barsoum also found
that portions of the pyramid samples appeared to be amorphous; their structure
is highly disorganized. It would be very unusual, he points out, to find such
disorganization in natural sedimentary stone formed on a geological timescale.
Furthermore, the
silica in one of the pyramid samples was in the form of nanospheres—another
structure that he says doesn't form naturally in limestone.
In the same pyramid
sample, Barsoum notes the presence of a layer of calcium phosphate, or bone.
The Egyptians had to mix calcium phosphate with some type of geological binder
to make it solidify and stick to a limestone block. He and his colleagues note
the presence of this binder not just in the calcium phosphate layer but also
deep within the limestone beneath the calcium phosphate. "I cannot come to
you with more convincing evidence of casting. After that, I'd need to get you a
videotape of them doing it," Barsoum says, referring to the ancient
pyramid makers.
That's not to say the
whole of the pyramids were cast, Barsoum emphasizes. He believes, on the basis
of his research, that only portions of the pyramids—their tops, backing blocks,
and outer and inner casings—were made from reconstituted limestone. The pyramids'
cores, he thinks, were most likely made from cut limestone.
Carved or Cast?
Barsoum believes the
pyramids' tops, backing blocks, and inner and outer casings were cast from
reconstituted limestone. Their cores, he says, are probably composed of carved
limestone blocks.
"I think Barsoum
has certainly made the case that there is something in some of the stones that
is not consistent with them being just straight limestone," remarks David Walker, a geology professor
at Columbia University. "I think it's also clear that geologists looking
at least at some of those rocks would have no question, no hesitation, not even
a glimpse of a doubt that they really are actually cut limestone. But that
doesn't mean they all are," he says.
It took Barsoum more
than two years to publish his results (J. Am. Ceram. Soc. 2006, 89,
3788). His report grabbed headlines and quickly prompted a backlash from both
the geology and Egyptology communities. Barsoum is still having trouble
publishing a follow-up paper. It has been, he says, a lesson in "political
science."
"THE IDEA of concrete
pyramids is preposterous," says Robert L. Folk, a professor of
geology at the University of Texas, Austin, who has studied the pyramid stones.
"It is well-known that the Egyptians applied some sort of coating to
surfaces they wanted to paint on. I suspect Barsoum has been looking at this
outer coating. He needs to get a few centimeters deep into the stone."
Folk also discounts
any conclusions drawn from the presence of silica nanospheres in the sample.
Silica nanospheres, he says, occur in opal, a geological constituent of the
pyramid stones.
Critics also point to
Barsoum's small sample size. He agrees that the small number of samples he
studied likely skews his results, but notes that he had difficulties procuring
official pyramid samples from Egypt's Supreme Council of Antiquities.
"There is a
natural mistrust of unusual theories in the Egyptology community," Barsoum
says.
There would have to
be, he adds, considering some of the strange ideas people have about the
pyramids—such as that they were nuclear power plants or giant batteries. Hear
enough of these oddball theories, Barsoum says, and you're bound to be
suspicious of anyone outside of the establishment.
Still, Barsoum
believes such suspicion is unfounded in the case of his findings. If parts of
the pyramids were made from an ancient concrete, he argues, it doesn't diminish
the achievement of their construction. Rather, he says, it means the ancient
Egyptians discovered concrete 2,000 years before the Romans. "That a
lime-based cement cast and cured at room temperature would survive for 4,500
years, whereas the best our civilization has to offer—Portland cement—under the
best of circumstances lasts 150 years or less, is both awe-inspiring and
humbling," Barsoum concludes.
The History of Concrete and the Nabataeans
The History of Concrete
and the Nabataeans
Professor Dr. Joseph
Davidovits is a recognized world expert on ancient cements and concretes. Much
of the following material is taken from his website: http://www.geopolymer.org. Dr. Davidovits is
involved in a great deal of cutting edge research into how the ancients made
and used cement. His research is focused on ancient ceramics, mortars, cements,
concretes, synthetic stone, and building arts representative of ancient civilizations
like: pharaonic Egypt, Mesopotamia, Rome empire, precolumbian America, as well
as stone age artefacts from Europe and Asia. We thank Dr. Davidovits and the
Geopolymer Institute for allowing us to use materials from his research in this
article.
Cement mortar and
plaster played an important role in Nabataean life.
They used this
essential technology from their very earliest years in the desert. Without
their special knowledge of cement, the Nabataeans would never have conquered
the desert, and would never have risen to the status of a civilization.
Other tribes in the
deserts of Arabia lived within the limits that nature put on them. They stayed
close to sources of water, and ranged their sheep and camels from there. The
Nabataeans on the other hand, built water channels and cisterns far out in the
desert to collect the scant rainfall and store it for their use.
Without this
knowledge of waterproof cement, the Nabataeans would not have become the far
ranging merchants of the Middle East, who easily traversed deserts and
inhospitable, barren mountains.
How was it that the
Nabataeans developed waterproof cement centuries before its use became common
in Europe? In this study, we will begin by examining cement in general, and
then looking at how cement was developed and used by other civilizations,
especially the Romans. The Romans were contemporary to the later part of the
Nabataean Empire, and whose historians recorded for us, how the Romans made and
used cement. Lastly, we will look at the special properties of Nabataean cement
and speculate about how they developed this amazing technology.
Cement in General
Cement and concrete
are often thought of as the same thing, however, they are by nature very
different. Cement is an ultra-fine gray powder that binds sand and rocks into a
mass which is called concrete. Cement is the key ingredient of concrete, but
concrete contains other substances like sand and rocks.
Cement has become one
of the world’s most widely used building materials.
Annual global
production of concrete hovers around 5 billion cubic yards, a volume
approximated by yearly cement production levels of about 1.25 billion tons.
Concrete’s global appeal is not accidental, for this stone-like material is
produced from some of the world’s most abundant resources.
It is important to
understand the development of cement on a more global basis, in order to see
how Nabataean cement relates to the worldwide development of cement technology.
Then we can ask the important question, did the Nabataeans learn their technology
from others, or did other civilizations learn their technology from the
Nabataeans?
Early History and
Development of Cement
The Romans are
generally credited as being the first concrete engineers, but archaeological
evidence says otherwise. Archaeologists have found a type of concrete dating to
6500 B.C. [sic], when stone-age Syrians used permanent fire pits for heating
and cooking. These fire pits, built from area limestone, showed a primitive
form of calcining on the exterior faces of the limestone rocks that lined the
fire pits and lead to the accidental discovery of lime as a fundamental
building material. The newly discovered technology was widely used in Syria, as
central lime-burning kilns were constructed to supply mortar for rubble-wall
house construction, concrete floors, and waterproofing cisterns.
Lime, quicklime, and
burnt lime are the common names for calcium oxide, CaO, a grayish-white powder.
Today over 150 important industrial chemicals requires the use of lime in order
to be manufacture. In fact, only five other raw materials (salt, coal, sulfur,
air, and water) are used in greater amounts.
Lime is used in
glass, cement, brick, and other building materials; as well as in the
manufacture of steel, aluminum, and magnesium, poultry feed; and in the
processing of cane and sugar beet juices. It is strongly caustic and can
severely irritate human skin and mucous membrane. Thus, the discovery of lime
as a building material opened the door for many other improvements as well.
….
The Egyptians used
cement as far back as 2500 B.C. Some scholars believe that a cementing material
produced from either a lime concrete or burnt gypsum was used in forming the
Great Pyramid at Giza.
The earliest known
illustration (dating to about 1950 B.C.) of concrete being used in Egypt is
shown in a mural on a wall in Thebes. Archeologists have long thought that the
Egyptians were masters of the stone as stone artifacts (hard stone vessels,
statues) made of metamorphic schist, diorite and basalt were produced. These
smooth and glossy stone artifacts (between 4.000 and 5.000 years old) bear no
trace of tool marks.
Some archeologists
believe that the ancient Egyptian artists knew how to convert ores and minerals
into a mineral binder for producing stone artifacts. They believe that many of
the Egyptian statues were not carved from rock, but rather were cast in molds,
and are synthetic stone statues.
The first evidence
for this comes from a new deciphering of the C-14 Irtysen Stele (dating 2.000
BC, Louvre Museum, Paris). The stele is the autobiography of the sculptor
Irtysen who lived under one of the Mentuhotep Pharaohs, 11th. Dynasty.
The stele C-14 of the
Louvre has been often studied. Yet many of its expressions pertain to the
domain of stone technology and have been tentatively translated in the past
with terms differing so widely that the translators were obviously not able to
understand the described technology.
According to sculptor
Irtysen, cast man-made stone was a secret knowledge. (Egyptian Made-Made
Stone Statues in 2000 B.C.: Deciphering the Irtysen Stele,(Louvre C14 6
pages) Was this material a type of cement?
Some
scientists are now proposing that the pyramids were made of poured stone,
rather than quarried stone. From a geological point of view, the Giza Plateau
is an outcrop of the Middle Eocene Mokkatam Formation. Yet, the outcrop that
dips into the wadi, where the quarries are located and also the trench around
the Sphinx and the Sphinx body, consist of softer thickly bedded marly
nummulite limestone layers with a relative high amount of clay. The amount of
water-sensitive parts, expressed as weight percent of stone, is strikingly very
high, ranging between 5.5% to 29%. It is obvious that the builders took
advantage of the thickly bedded softer limestones. The disaggregated muddy
material was ready for geopolymeric reagglomeration. Perhaps the biggest
surprise encountered in this study deals with the hieroglyphic verbs for to
build, namely khusi (Gardiner’s list A34).
The sign khusi
represents a man pounding or packing material in a mold. This is one of the
oldest Egyptian hieroglyphs. (Construction of the Egyptian Great Pyramids,
2500 B.C., with Agglomerated Stone. Update of the latest Research,: 42
pages)
The Egyptians also
used a more common form of concrete. The durability of their concrete is
evidenced by the fact that concrete columns built by the Egyptians more than
3600 years ago are still standing.
The Greeks on the
other hand were using cement by 600 B.C., when Greek builders discovered a
natural pozzolan that developed hydraulic properties when mixed with lime.
It was the Romans,
however, who used cement in large amounts, for huge building projects. Early
Roman use of cement dates back to around 300 B.C. Since that period, the Romans
steadily improved their concrete technology, they also gave it its name. The word
“concrete” comes from the Latin ‘concretus’, meaning “grown together” or
“compounded”.
Roman concrete
structures still stand today. Both the Colosseum (complete in 82 A.D.) and the
Pantheon (completed in 128 A.D.) contain large amounts of concrete.
The Basilica of
Constantine and the foundations of the Forum buildings also were constructed of
concrete. Since Roman cement has been so well studied, it will give us a basis
for understanding the issues that are important in investigating Nabataean cement.
Roman Cement
Augustus (33 BC - 14
AD) [sic] is reputed to have stated, “I found Rome a city of mud bricks, and
left her clothed in marble.”
Augustus’ reign is
called “the principiate” and it marks the juncture of the Roman Republic and
the Empire. Marcus Vitruvius Pollio, who served as an engineer with Augustus´
uncle Julius Caesar, wrote a treatise on architecture during the principiate.
Mackey’s comment: But, regarding Jullius
Caesar, see e,g. my article:
Mark Antony and death of J.C.
(10) Mark Antony
and the death of J.C.
Vitruvius quoted
earlier authors and defined his ideal in architecture and building, though most
buildings of the time fail to meet his standards. Vitruvius´ work and modern
archaeological discoveries give us a starting place for our search.
From the digging of
ancient Roman ruins, one knows that approximately 95% of the concretes and
mortars constituting the Roman buildings consist of a very simple lime cement,
which hardened slowly through the precipitating action of carbon dioxide CO2,
from the atmosphere. This is a very weak material that was used essentially in
the making of foundations and in buildings for the populace. Cato was the first
Roman to write about making lime and early Roman construction methods about 200
years before Christ. This book is important to define the practice of making
lime under quality control measures. Quality lime was important as it was an
ingredient of Roman concrete, and without consistent quality lime the
structures of Rome would not survive. (E. B. Rehaut, Cato the Censor on
Farming. Octagon Books, Inc., New York, 1966, p. 64).
For the building of
their “ouvrages d’art”, the Roman architects did not hesitate to use more
sophisticated and expensive ingredients. Roman cement has been studied in
detail. Initially, conventional mineralogical analysis did not provide
satisfactory explanation of the hardening mechanism.
Dusty ancient history
books taught us that Roman concrete consisted of just three parts: a pasty,
hydrate lime; pozzolan ash from a nearby volcano; and a few pieces of
fist-sized rock. If these parts were mixed together in the manner of modern
concrete and placed in a structure, the result certainly would not pass the
test of the ages.
A most unusual Roman
structure depicting their technical advancement is the Pantheon, a brick faced
building that has withstood the ravages of weathering in near perfect
condition, sitting magnificently in the business district of Rome. This
building humbles modern engineers not only in its artistic splendor, but also
because there are no steel rods to counter the high tensile forces such as we
need to hold modern concrete together.
Solving the riddle of
ancient concrete requires understanding the chemistry of the cement, and
secondly, understanding how the cement was used.
To understand its
chemical composition, we must go back in time much before Moses. People of the
Middle East made walls for their fortifications and homes by pounding moist
clay between forms, often called pise work. To protect the surfaces of the clay
from erosion, the ancients discovered that a moist coating of thin, white,
burnt limestone would chemically combine with the gases in the air to give a
hard protecting shied.
Sometime around 200
BC the Romans started using volcanic, pozzolanic ash in their concrete.
This was an immediate
improvement as a chemical reaction took place between the chemicals in the wall
of volcanic ash (silica and small amounts of alumina and iron oxide) and the
layer of lime (calcium hydroxide) applied to the wall. ….
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