> Geopolymer Institute is an amazing resource on the subject.
https://geopolymer.orgI find it odd that so much of their front page and entire site is dedicated to defending the theory that the pyramids were made of man-made or re-agglometared stone. The hypothesis is mentioned in the Wikipedia article "Egyptian pyramid construction techniques"[0] under the hypothesis subsection but mostly dismissed:
Dipayan Jana, a petrographer, made a presentation to the ICMA (International Cement Microscopy Association) in 2007[46] and gave a paper[47] in which he discusses Davidovits's and Barsoum's work and concludes "we are far from accepting even as a remote possibility a 'man-made' origin of pyramid stones."
Apart from that, the only other references to the theory or institute are in the Pyramidology article subsection Ancient astronauts [1] which references an article by Joseph Davidovits of the Geopolymer Institute:
Several proponents of ancient astronauts claim that the Great Pyramid of Giza was constructed by extraterrestrials, or influenced by them.
Reading through all of this it comes off as fanciful and reminds me of reading those books about Ghosts, Bigfoot or Monsters in elementary school.
[0] https://en.wikipedia.org/wiki/Egyptian_pyramid_construction_...
[1] https://en.wikipedia.org/wiki/Pyramidology#Ancient_astronaut...