Clay Breakdown

I'd like to work clay and/or cob work into my construction as I develop skills, but have been starting with the more familiar metal, brick and wood stuffs so far. I did take soil samples and put them in jars following one of Uncle Mud's PDF instructions, but the results seemed pretty ambiguous to me and my helper, and I've had plenty on my plate since then.

I was on the shore of Lake Superior this summer to find erosion had exposed a foot thick strata of some solid orange clay and I knocked off a chunk to fill a bread bag and took it home.

I've been working on a RMH and planned it out to use no cob/clay, mostly just foil tape on the seams. Looking closer at assembly videos, it looks like I'll need some sort of clay/mortar at least around the metal manifold and brick burn tunnel area where the foil won't stick and/nor handle the heat. Masonry stores around me only seem to carry refractory mortar which is $100+ bucks (and which I haven't been able to check on ingredients for), and I also see hardware stores with something less expensive but which carries a warning that it shouldn't undergo freeze/thaw cycles, so impractical to me even if that is only preapplication.

I think I will order some Lincoln fireclay from Dragontech to at least have some on hand, but not sure how long it will take to ship or how much that would hold up all of my construction that I'm working to complete as temperatures dip more and more below freezing around here.

Should I be able to tell more about the clay I picked up by colour, provenience, experimentation? I think it is plenty to cover the joints I need. I'm guessing some rehydration would be needed, would sand mixed in help for this application?

Coydon I have to say I am confused by your topic.
Where do you want to work with clay on a building or on the heater, its main use is in house building.

The reason fire clay is used in masonary and rocket mass heaters is because is doesn't expand or contract as much as other clays when cooled(humidity is added) or heated(dried out).

What are the properties of your clay, you would have to test them. Easiest way is to do a test build of your setup outside and see how the clay reacts when heated and after hard firings.