For a long time scientists have been stumped over how ancient engineers constructed the pyramids in Egypt but now scientists believe the answer may lie in something we step on everyday with little more than a passing thought, concrete.
NY Times: “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.”