This guy, professor at the French Polymer Physics institute cracked the Egyptian proto-concrete recipe. Unfortunately his excellent book "Ils Ont Bati les Pyramides" (How they Built the Pyramids) is not available in English (to the best of my knowledge).
Which is the conundrum, as long as there is a market for what the trade term "Pyramidiot" books, there is no incentive to publicise the excellent scientific research done in this area (ancient mysteries). So the public never learns the truth.
The Luke