Well, night before last I was pondering my stove, and the firebox in particular. I've built it all as you know from clay and perlite where I desire insulation, and it's working great. The downside is that where the wood bangs and rubs against it, the clay gets knocked and powders, so I'm slowly eating away the edges of the burn tunnel. I was thinking, "if only the straw would hold up in there, it needs the fiber reinforcement to be a complete system with high strength." So that got me thinking about fibers that hold up to heat, and I just went "DUH!!"
So, I grabbed a bunch of chopped fiberglass from my shop, mixed it into the thermal cob, and viola! Cobposite!! It works really well, and so far feels like concrete around the burn tunnel. It's holding up great. I'm really, really excited about this. I can see being able to build highly insulated burn units that have structural integrity far in excess of just the clay and perlite. I also have carbon fiber in my shop, which has an even higher melting point, but I do think that the regular glass can handle the temps it will see in there, especially encased in clay and perlite.
After I experimented, I went online, and found an excerpt from a ceramics book where they talk about reinforcing pottery and ceramics with fiberglass. It seems it's been done for a long time, and that it works very will to increase the strength of the piece. Even when firing temps exceed the melting point of the fibers, it apparently reforms after cooling and still adds significant strength.
I'm so stoked!!