Are the pyramids made out of concrete, an artificial reagglomerated limestone

It is a theory that gives indigestion to mainstream archaeologists. Namely, that some of the immense blocks of the Great Pyramids of Egypt might have been cast from synthetic material - the world's first concrete - not just carved whole from quarries and lugged into place by armies of toilers.

Such an innovation would have saved millions of man-hours of grunting and heaving in construction of the enigmatic edifices on the Giza Plateau