"Note the only andesite is in the renovated back fill. The structure is essentially reconstituted limestone, so no igneous component, derr…. despite dipstick comments in the thread."
I have had a hard time keeping straight which rock is which in the various sites around the world. I had thought for the longest time that Sacsayhuaman was igneous. And it was a nice convenient way to perceive the work simplistically segmented into pillow stones = igneous. Then you can oversimplify the 'magic' to being a material manipulation of the crystal structure totally uniformly, where as in limestone, if you only manipulate the crystalline content of that rock, then it will look different, like the core blocks of GP.
But its not that simple clearly.
Limestone is formed by pressure. And you can't melt it and reform it to appear the same like igneous might be able to. But to reconstitute it back into typical limestone hardness, you need to simulate that pressure somehow. Or, as the geopolymer theory suggests, that hardness is entirely based on the properties of the binder. A 'magic' binder of sorts, that survives thousands of years, so we're all vulnerable to the WOO moniker, to be fair.
So I guess my next big question to the geopolymer camp is this: Are you proposing that the ancients invented a compound from available sources that cures so hard as to simulate the hardness of natural rock, which by far outperforms most typical modern day concrete, even with the advantage of steel bar reinforcement inside?
If I consider the possibility that we can, at present, duplicate that binder performance, then I have to assume the reason why it hasn't taken over the global industry is because its so cost preventative a process to make. And that potential high cost is either because of extremely expensive and complex advanced processing plants to produce it, OR, that its constituent material components are rare enough to make it very costly to find and extract in large enough volumes.
And that cost calculation is also presumably taking into account the significantly reduced amount of material necessary, (as it so thoroughly outperforms regular concrete 1:1), while used in conjunction with rebar to give it every advantage, to duplicate the present day concrete performance industry standards. So even having to use far less of this material, its still financially infeasible.
If the answer to the above question is yes, then I have to assume you are open to the existence of a highly advanced ancient global civilization. Because building materials should be the spear tip of our best applications of the highest level of material science, and if we haven't even worked through the economies of scale to implement today, what they used all over the world in ancient times, then our present level of advancement pales in comparison.