Ash-Stabilized Clay?

[rural]

I'm working on a DIY emergency heating and/or tent rocket stove project. The build is based around two metal 5-gallon buckets, but exists only on paper and as a small pile of scavenged bits at the moment. I'm hoping to play with a number of design parameters over the winter and some different building materials.

My question is about ash stabilized clay as a possible firebox liner and as a riser material. I'm sure I've read about folk using it, but I can't find or remember the details. I'm willing to experiment as I have lots of ash and gobs of clay, but I'd rather stand on the shoulders of giants than the ground.

My hope is that ash-stabilized clay doesn't shrink and crack as it dries and stands up to heating cooling cycles as well as impact (ie. in the firebox). Does anybody have any experience with this material or can point me in the right direction? Maybe I just don't have the right search term.

[martyn]

I found this…. donkey32.proboards.com/thread/233

[rural]

Oct 12, 2021 11:48:33 GMT -8 martyn said:

I found this…. donkey32.proboards.com/thread/233

Nice! Thanks for that. I think that's exactly the discussion I was foggily remembering.

Just to summarize the discussion linked by martyn: Donkey was playing with wood-ash clay mixtures at around a 1:1 ratio. He also tried mixing in rice-hulls to make the mixture more insulative. He liked the stuff. Hopefully, I can secure the rest of the materials on my list and get my idea off paper this winter.

Just to share a bit of my motivation: I hot-tent camp in the winter. I've got a little and very lightweight wood stove which works fine, but one has to tend it at least every half-hour in cold temperatures (-20C/-4F) to keep the tent comfortable. Without a really good sleeping bag, getting a good night's sleep is basically impossible. Forgiving that, as the stove is just a small cylinder with a chimney, and no baffle, it isn't very efficient. I want to make something a bit bigger, with more complete combustion and more surface area to extract more heat from the exhaust. This version of the stove would be all metal, and fairly light gauge metal at that.

At the same time, we are about a month from moving into a new off-grid house. We have propane for heating and domestic hot water, but also wanted the option to heat with wood. So the house was designed with a masonry heater in mind. I really, really, wanted to build our masonry heater, but code won't allow it. So we have ordered the Cadillac of masonry heaters (because that's how my wife rolls). Unfortunately, it has a long way to travel and may not make it to us until spring because of the shipping crisis. In case propane prices go insane, and I'm no longer sure of price stability of anything, I'd like a backup plan for the winter, even if it is just a design and a partial collection of scavenged parts in the garage. I'd whip up a small masonry stove, but we still have several inspections ahead of us. The emergency version stove is what I have the ash-stabilized clay in mind for. The riser and firebox lining would be ash-clay.