Posted on 12/09/2006 4:41:35 PM PST by Maelstorm
Riddle Of The Great Pyramids Of Giza: Professor Finds Some Building Blocks Were Concrete
In partially solving a mystery that has baffled archeologists for centuries, a Drexel University professor has determined that the Great Pyramids of Giza were constructed with a combination of not only carved stones but the first blocks of limestone-based concrete cast by any civilization.
Picture of the Great Pyramid (Kheops pyramid). (Taken by Alex lbh in April 2005 / Courtesy of Wikipedia) Ads by Google
Michel Barsoum, professor of materials engineering, shows in a peer-reviewed paper to be published Dec. 1 in the Journal of the American Ceramic Society how the Egyptian builders of the nearly 5,000-year-old pyramids were exceptional civil and architectural engineers as well as superb chemists and material scientists. His conclusions could lead to a seismic shift in the kind of concrete used in construction and provide developing nations a way to build structures utilizing inexpensive and easily accessible materials.
Barsoum presented his findings at a news conference Nov. 30 at Le Palais de la decouverte, Avenue Franklin D. Roosevelt, in Paris, France.
The longstanding belief is that the pyramids were constructed with limestone blocks that were cut to shape in nearby quarries using copper tools, transported to the pyramid sites, hauled up ramps and hoisted in place with the help of wedges and levers. Barsoum argues that although indeed the majority of the stones were carved and hoisted into place, crucial parts were not. The ancient builders cast the blocks of the outer and inner casings and, most likely, the upper parts of the pyramids using a limestone concrete, called a geopolymer.
To arrive at his findings, Barsoum, an Egypt native, and co-workers analyzed more than 1,000 micrographs, chemical analyses and other materials over three years. Barsoum, whose interest in the pyramids and geopolymers was piqued five years ago when he heard theories about the construction of the pyramids, says that to construct them with only cast stone builders would have needed an unattainable amount of wood and fuel to heat lime to 900 degrees Celsius.
Barsoum's findings provide long-sought answers to some of the questions about how the pyramids were constructed and with such precision. It puts to rest the question of how steep ramps could have extended to the summit of the pyramids; builders could cast blocks on site, without having to transport stones great distances. By using cast blocks, builders were able to level the pyramids' bases to within an inch. Finally, builders were able to maintain precisely the angles of the pyramids so that the four planes of each arrived at a peak.
Although these findings answer some of the questions about the pyramids, Barsoum says the mystery of how they were built is far from solved. For example, he has been unable to determine how granite beams -- spanning kings' chambers and weighing as much as 70 tons each -- were cut with nothing harder than copper and hauled in place.
The type of concrete pyramid builders used could reduce pollution and outlast Portland cement, the most common type of modern cement. Portland cement injects a large amount of the world's carbon dioxide into the atmosphere and has a lifespan of about 150 years. If widely used, a geopolymer such as the one used in the construction of the pyramids can reduce that amount of pollution by 90 percent and last much longer. The raw materials used to produce the concrete used in the pyramids -- lime, limestone and diatomaceous earth -- can be found worldwide and is affordable enough to be an important construction material for developing countries, Barsoum said.
Background:
Barsoum graduated with a bachelor's degree in materials engineering from American University in Cairo in 1977, a master's degree in ceramics engineering from the University of Missouri at Rolla in 1980 and a doctoral degree in ceramics from the Massachusetts Institute of Technology in 1985. He joined Drexel's Department of Materials Engineering as an assistant professor in 1985 and has served as a distinguished professor of materials engineering at Drexel since 1999.
A fellow of the American Ceramic Society and academician of the World Congress of Ceramics, Barsoum has published more than 160 refereed publications, including ones in Nature, Nature Materials, Physical Review Letters and Science. He is also the author of the textbook Fundamentals of Ceramics, which is used worldwide.
At least one Pa. university seems to be producing something worthwhile.
ping
Portland cement injects a large amount of the world's carbon dioxide into the atmosphereIs this sentence supposed to make sense?
Wonder if it was a later repair job???
No! Volcanos spew alot of CO2 into the atmosphere but no one in academe seems to care!
This looks like an answer in search of a question.
whats the agenda here? and why so long to figure out the difference between concrete and stone?
I wonder about that, too.
"Carbon dioxide emissions from a cement plant are divided into two source categories: combustion and calcination. Each accounts for about one-half the total CO2 emissions from a cement manufacturing facility. The combustion-generated CO2 emissions are related to fuel use. The calcination CO2 emissions are formed when the raw material is heated and CO2 is liberated from the limestone. Calcination is a necessary key to cement production. Therefore, the focus of reductions in CO2 emissions during cement manufacturing is on energy use, and since 1975, the cement industry has reduced GHG emissions from fuel use by 33 percent. Today, the cement industry accounts for less than 1.5 percent of U.S. CO2 emissions, well below other sources such as electric generation plants for heating and cooling (33 percent), transportation (27 percent), and industrial operations (19 percent)."
http://www.bipac.net/page.asp?g=PCA&content=issue_greenhouse&parent=PCA
Had to go look.
GGG ping
Cement manufacturing is the third largest cause of man-made carbon dioxide emissions. While fossil fuel combustion and deforestation each produce significantly more carbon dioxide (CO2), cement-making is responsible for approximately 2.5% of total worldwide emissions from industrial sources (energy plus manufacturing sectors).
Cement is a major industrial commodity. Manufactured commercially in at least 120 countries, it is mixed with sand and gravel to make concrete. Concrete is used in the construction of buildings, roads, and other structures, as well as in other products and applications. Its use as a residential building material is particularly important in countries where wood is not traditionally used for building or is in short supply. Annual CO2 emissions from cement production in nine major regions of the world are shown in Figure A below.
Large quantities of CO2 are emitted during the production of lime, the key ingredient in cement. Lime, or calcium oxide (CaO), is created by heating calcium carbonate (CaCO3) in large furnaces called kilns. Calcium carbonate is derived from limestone, chalk, and other calcium-rich materials. The process of heating calcium carbonate to yield lime is called calcination or calcining and is written chemically as:
CaCO3 + Heat -> CaO + CO2
http://www.cs.ntu.edu.au/homepages/jmitroy/sid101/uncc/fs030.html
Explains the form lines plainly visible in the cantilevered passageways. Forty years ago before polymers were kewl, my brother, a retired stonemason, said the walls were probably poured in some sections. Why not? Plenty of sand around. Add a little water and stuff, mix well, and viola! A pyramid.
Paint it white for the albedo effect. Global warming fixed!
This is nothing new. I read several articles with microphotography back in 1989 by a Professor Davidowits published in Concrete International.
I was persuaded by these articles that this was worth investigating. The type of cement used has different common names but the technical one is alkalai-activated alumino-silicate cement. This cement is quite distint and different from ordinary portland cement and has several advantages over portland cement such as durability, strength, dimensional stability (non-shrink) and rapid cure.
What doesn't make sense is this guys apparent assertion that block were cast and then dragged into place. It makes for more sense, if you are using concrete in the first place, to cast the blocks in situ.
This is not a new theory.
It appeared many years ago and was discredited.
Is this sentence supposed to make sense?
Isn't it obvious? Ancient Egyptians caused global warming!
That explains why the pyramids are in a desert!!!!!!! <;^(
Years ago, the Smithsonian proved that, with the use of only eight pieces of wood, large stone blocks could be easily moved with just a fraction of the manpower. They do this by forming two wooden "wheels", held together with pins, which turn the rectangular blocks into cylinders.
To build a pyramid, you first lay the bottom layer of stones, and then you pile dirt around them to form a dirt ramp that you can then roll the next layer up. Eventually, all but the top of the pyramid is covered with dirt. And when it is done, take away the dirt and there is your pyramid.
Dirt ramps were long since used in the region. Perhaps the most famous example was the giant dirt ramp used to attack Masada, in AD 70, by the Romans--far larger and more complex than anything the Egyptians would have needed.
Now if things were so relatively easy, compared to the traditional model, at the pyramid site, it would also explain why the quarry and stone carving cities have been found, but no equivalent giant slave city to actually build these same pyramids.
As far as the concrete blocks, I would think that when making the majority of the pyramid, the blocks could be somewhat irregularly sized. However, for the final outside layer, you would want them as regularly sized as possible--hence molded concrete blocks, for aesthetic reasons.
The reason that such blocks only seem to exist at the top of the pyramid can be explained by the fact that many of the lower blocks were long ago looted for other buildings.
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