No. 74: Mar-Apr 1991
"The Great Pyramid of Egypt, one of the seven wonders of the ancient world, may have been at least partially constructed with man-made concrete.
"Edward Zeller, cirector of the radiation physics laboratory at Univ. of Kansas Space Technology Center, Law rence, recently examined a stone sample, taken from a pyramid passageway, under a binocular microscope and discovered that it was filled with oval air bubbles, 'like you'd expect to see in plaster,' he says.
"The finding supports a theory proposed by French geochemist Joseph Davidovits, who says Egyptians built the pyramids by pouring concrete into forms. Such technology was not thought to have existed during the construction of the pyramids around 2690 BC.
"Zeller still has his doubts.
"'The sample is clearly made of manufactured stone and it's part of the pyramid,' he says. 'But a single speci-men does not a pyramid make.'"
("Did the Pharoahs Cheat with Concrete?" R&D Magazine, p. 5, December 1990. Cr. J. Wenskus.)
Reference. An earlier report on the theory proposed by Davidovits may be found in SF#54.