I would sure give it a try. Make sure the surface is nice and wet, use a bonding admix (or just old fashion ElmerÂs wood glue) Use slurry to do the bonding. Then maybe put a coat of some kind of concrete or tufa to cover the cracks. The only thing I not real sure how it would hold up to a fire inside. There has been a lot of discussion here on building ovens or fire pits. Check out this discussion on Tufa under fire.

Here is a link that might be useful: Tufa under fire

IF anything would work, I don't think a cement-based mix would be the solution.

The only thing that comes to mind is to go to a shop that caters to potters and sells terra-cotta clay. Ask if they know of a way to repair it, with or without all the pieces. I wonder if you could get some terra-cotta clay, add a bit of water to it to make a "slip", paint it on the broken edges, then gradually "glue" the thing back together. (Would the pieces and the main part have to be wet?) If there are any pieces missing, work the clay really well to get all the air bubbles out of it, then press it into the gaps. I THINK terra cotta clay has to dry for a while before you fire it. Do what has to be done, then build a fire in it and keep it going for whatever period of time that that type of clay requires.

To make it look decent, you may have to put a layer of clay over the whole outside before you fire it. And THAT could give you some grief, too.

But you really need to talk to clay people. And if you do get it repaired, you'd also better move it out of reach of cars!

Sue