Benvenuti in queste pagine dedicate a scienza ed arte. Amelia Carolina Sparavigna

Wednesday, December 29, 2010

Revisiting the construction of pyramids

"The Kufu pyramid, with a volume of 2,7 millions of meter cubes, was completed over a period of 20 to 30 years. From this one can estimate a daily rhythm of 300 to 400 blocks, each having an average volume of 1 meter cube. This means one block put at the right place every 2 minutes.  To achieve this goal,  1 meter square of block face would have to be hewn every 20 seconds! What a performance, with tools made of stone or with soft copper ..."  As we can read in the Europhysics News Vol. 40, No. 1, 2009, pp. 27-31, Revisiting the construction of the Egyptian pyramids, Guy Demortier,  www.europhysicsnews.org/epn20091p27.pdf ...
"In 1978,  the French chemist Joseph Davidovits rejected the generally accepted technique of carving and hoisting stones. He proposed that the building method involved the moulding on site: blocks were made of a kind of concrete whose basic binding compound was natron: a sodium carbonate extracted very close to the site of Giza.  The binder was obtained by some chemical reaction leading to a geopolymer (a name given by Davidovits). It is a poly-sialate containing an alkaline nucleus: sodium from natron.  Natron, lime and water form caustic soda,  which reacts with aluminous limestone to yield the basic geopolymer.  X-ray fluorescence and X-ray diffraction have shown that the blocks consist of limestone (85 to 92%) associated with a binder.  Additional analyses were performed by PIXE (Particle-Induced X-ray Emission), PIGE (Particle-Induced gamma-ray Emission) and by NMR-Spectroscopy for structural characterization in laboratories of Namur and Lecce. One of the pyramid’s samples appeared  to be made of  a central compact structure embedded in a material of different composition. The central part is identified as natural limestone but the outer part contains a large amount of F,  Na,  Mg,  Al,  Si."