Do have a favorite recipe suggestion?
I use a calcined shale (5 parts) with a water glass mix of sodium silicate(4 parts) that is just on the irritant side of the scale and not corrosive. This mix equals one part that I mix for 5-6 minutes before I add 3 parts sand/gravel mix. It has the consistency of taffy and I need my forms to be sealed well. I use wax or vegetable oil. I cover them for 24hours to a week and then take them out. The stuff is really hard and difficult to pry from un-oiled wood. The problem with these though is the water glass(Potassium works better btw). It has to be small molecule water glass- meaning the silica should be in short chains of one to four silicon atoms per molecule; but if the company makes water glass that is all large molecules, it won't react.
So a water glass mixed with NaOH or KOH to a molar ratio that won't instantly burn you is a good starting point, but you will need to test it with some calcined stuff and see if it reacts. If after 24 hours it looks like stone you are probably good, the real test is to boil in water. The Pantheon was reported to be made with lime mixed with volcanic sands. Freshly dug Ignimbrite is the kind they used above water. I'm sure old volcanic ash like this could be calcined to make it reactive again. A rocket kiln on low would be the ticket there. And that was also 1:3 mix. Opus Signinum was also one part lime to three parts testa. The testa was clay tile that was under fired so calcined. It also has either analcime or phillipsite (zeolites) in the clay which helped react with the lime. This was used to waterproof the cisterns and aqueducts.
If you have access to slag from copper or iron smelters, as long as it is cooled relatively quickly, you can use that as an ingredient. The copper slag stuff makes a really nice black geopolymer.
I haven't tried this but it is supposed to be a good recipe.
20 parts calcined kaolin commonly called MK-750
20 parts blast furnace slag
24 parts potassium silicate water glass with a molar ratio of 1.25 at 50% concentration
then add 56 parts class F fly ash
supposed to reach over 9000 psi in strength
From the stuff I use to the lectures I've seen the basic premise is to take a weathered shale or a clay and heat it to 1200-1450 Fahrenheit for six hours and mix this with water glass and KOH/NaOH and maybe some alkaline minerals like slag ground fine and then mix this for a while before adding sand and gravel or other stones. You might have all the ingredients on your land.
One thing, this stuff will not stick to plastic, oils, etc; as well as cured epoxy, but if the epoxy is fresh it will bind with it. And PVA can be used as reinforcement in these concretes, because the alcohol molecule will react with the silica alumina reactions in these materials.
I hope this helps and is not to rambling and confusing. Sorry, it is late here and I am falling asleep as I type here. Oh and geopolymer.org is a great website with lots of papers and recipes.