People Underestimate Human Ingenuity
I'm watching a show about how "Aliens must have built the pyramids because prehistoric humans weren't that smart."
But apparently they were.
A simple mix of lime stone diluted in water, with salt and ash added will form a concrete as the water evaporates. For years archaeologists stated simply that copper tools were used to cut stones, and they were hauled by thousands up to the pyramids from the quarries. One problem stood with that theory. Stone is stronger than copper, making it a *little* difficult to cut the stone.
A material scientist looked at the crystalline structure of the stones and realized that they were not in the formation htat comes from natural formed stones, but more like that of poured concrete.