I believe I may have not been fully clear about GeoPolymers, many of the recipes do require a higher temperature while curing . The temperature are never above 100C and I think I recall seeing 60C as the average temperature needed in many of those recipes. Some are done at room temperature (like concrete substitutes). I just thought I'd add that for clarity. Building the equivalent of a pottery kiln that would go to those lower temperatures would be fairly cheap and easy. It could even be used in conjunction to a wood gasifier for heat generation.
I also attached 3 PDF referring to studies made on using it as a coating on metals in case it helps someone. I haven't read them all, so not sure what they say, but may save the time for someone to have to find them. I can see GeoPolymers as a really nice way to make a burn chamber that can last an eternity and only need regular cleaning of ashes... The downside is that it's not a simple product that you can buy off the shelves and you're done. It will require some small or larger level of dedication to make it work, but the reward, in my opinion is in what it gives people like us that are into prepping and would like to have control of our technologies and do everything on the cheap. What I want to do with that new science on my ranch are water tanks, roads, pond sealant, CNC machine frames (dampens vibration), coating on metal to preserve and limit rust, insulation (sprayed or pre-cast like concrete), Construction replacement (foundation, walls, and name it), and the last is material science (they made high amp fuses out of that stuff. There's got to be more uses). That's just what comes to mind very quickly.