For To Make Hydraulic Mortar

So, having recently acquired the mountain. I have included a map that I made from overlaying Google Earth with a USGS subsurface geologic quadrangle.

I have been doing several (unsuccessful) experiments in producing a usable mortar/hydraulic cement from materials that I can obtain for free. I realize that if I had dirty limestone, this would be moot; I do not, as my mountain is made of Gneiss (Nice!)

Anywho, I pretty regularly look at the Primitive Tech guys on YT, including that Aussie named, appropriately enough, "Primitive Technology". He doesn't do as much as the Asian/Indian kids who've co-opted his genre (they make some REALLY cool stuff) but, he recently made what appears to be an hydraulic cement with wood ash. SEE VID:



I have been trying to use wood ash as well - first for the lye (trying to make a geopolymer - total failure, pH too low) but then I saw that he re-calcined the ash in a second burn.

Theoretically, all of this should be correct and straight forward - but my first attempt failed (maybe I didn't calcine it long enough?)

SO! I recall in some other thread, there was a link to the chemical analysis (average) of wood ash - and I cannot for the life of me find it again (245387145 posts, and Google is becoming useless) Anyone know the post of which I speak? Help me find?

On my mountain - named "Nebenhaus" - I have lots, and lots of super-brick-sized chunks of gneiss. Stone + mortar = Castle.

I'm not kidding.

Greenhouses, terraces, cistern, etc... all require copious amounts of a decent cement - I can get pallet-wood to make a mountain of ash should I so desire, but I gotta figure out the cement thing.

I am unable to replicate dude's result from the video.

Any suggestions?