November 30, 2006

Scientist Says Concrete Was Used in Pyramids
By JOHN NOBLE WILFORD

In new research on the Great Pyramids of Giza, a scientist says he  
has found more to their construction than cut natural limestone. Some  
original parts of the massive structures appear to be made of  
concrete blocks.

If true, historians say, this would be the earliest known application  
of concrete technology, some 2,500 years before the Romans started  
using it widely in harbors, amphitheaters and other architecture.

Reporting the results of his study, Michel W. Barsoum, a professor of  
materials engineering at Drexel University, in Philadelphia,  
concluded that the use of limestone concrete could explain in part  
how the Egyptians were able to complete such massive monuments,  
beginning around 2550 B. C. They used concrete blocks, he said, on  
the outer and inner casings and probably on the upper levels, where  
it would have been difficult to hoist carved stone.

“The sophistication and endurance of this ancient concrete technology  
is simply astounding,” Dr. Barsoum wrote in a report in the December  
issue of The Journal of the American Ceramic Society.

Dr. Barsoum and his co-workers analyzed the mineralogy of samples  
from several parts of the Khufu pyramid, and said they found mineral  
ratios that do not exist in any of the known limestone sources. From  
the geochemical mix of lime, sand and clay, they concluded, “the  
simplest explanation” is that it was cast concrete.

Dr. Barsoum, a native of Egypt, said in an interview that he expected  
his interpretation to be controversial — and it already is.

Zahi Hawass, secretary-general of antiquities in Egypt and director  
of the Giza Pyramids excavations, said in an e-mail message, “The  
idea that concrete was used is unlikely and completely unproven.”

Noting that the pyramids have been restored and reinforced many times  
with the extensive use of concrete, Dr. Hawass said, “I would ask Dr.  
Barsoum the question: where did he get the samples he is working  
with, and how can he show that the samples are not taken from areas  
that have been restored in modern times?”

Most Egyptologists think the pyramids were built with limestone  
blocks that were cut to shape in nearby quarries using copper tools.  
The blocks were then hauled to the pyramid sites, lifted up ramps and  
hoisted into place with the help of wedges and levers.

But a geologist and another materials scientist, who were familiar  
with the research, said that Dr. Barsoum was a careful and reputable  
scientist and that his work should be seriously considered.

“I don’t know whether he’s right or wrong,” said Sheldon Wiederhorn,  
an engineer at the National Institute of Standards and Technology, in  
Rockville, Md., and associate editor of the ceramic society’s  
journal. “He makes a case that’s convincing, and I think his view  
should be heard.”

David Walker, a Columbia geologist who has read the report, said that  
the microscopic examination of the blocks “certainly revealed things  
you wouldn’t expect to find in normal limestone.”

In the journal report, Dr. Barsoum and his co-authors, Adrish Ganguly  
of Drexel and Gilles Hug of the National Center for Scientific  
Research in France, wrote: “We hereby acknowledge that nature is  
quite resourceful and could have — however unlikely — produced all  
the microstructures examined herein. We believe, however, that our  
work presents enough evidence to entertain the possibility that  
crucial parts of the Great Pyramids are indeed made of reconstituted  
limestone; only more research will tell.”

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Copyright 2006 The New York Times Company











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s. e. anderson (author of "The Black Holocaust for Beginners" -  
Writers + Readers) + http://blackeducator.blogspot.com