Physicists propose ancient Egyptians used cast concrete for the Great Pyramid

Nuclear physics professor Guy Demortier and materials scientist Michel Barsoum suggest that the Great Pyramid of Khufu in Egypt might have been constructed using a form of ancient concrete rather than solid stone blocks.

Demortier conducted new research on pyramid samples using magnetic spectroscopy and X-ray methods. He found that the samples consist of 85 to 92 percent limestone.

He argues that certain characteristics of these samples differ from limestone found in nearby natural deposits, which suggests the Egyptians might have manufactured the building blocks on site. This theory originally appeared in the 1970s when French chemist Joseph Davidovits proposed that workers poured a mixture of crushed limestone, diatomite, clay, sodium carbonate, and lime into wooden molds at the construction site. Demortier supports this idea by pointing to the logistical difficulty of the traditional construction method.

He estimates that if the pyramid took 30 years to build, workers would have had to place one cubic meter block every minute. He believes manufacturing the blocks on site offers a more plausible explanation for such high construction speeds. Archaeologists and historians generally reject this theory in favor of the traditional view. They maintain that the Egyptians quarried massive stone blocks and transported them to the site using ramps and wooden devices.

While some researchers previously failed to find evidence of artificial stone in similar samples, the new analysis from physics and materials science has brought the debate back into the scientific community.