Quote Originally Posted by NortonDommi View Post
...Have you ever looked a foamed cement? snip... http://pelagic.wavyhill.xsmail.com/
I have looked at foamed cement for use in raised bed planters. It my research says it is not very durable. I also know that Portland cement is not very heat resistant at the temperatures you may want in a furnace. At 1500˚F portland begins dehydrate. Hydration is the process that causes the cement solidify and to bind to the materials in concrete. Any prolonged temperatures about 1500˚ will destroy the cement.

I have this link bookmarked for when I get around to building a foundry furnace.

I ask have an old ceramic kiln, that I recovered from the trash, stored alone with my other "will get to it someday" stuff. It has lots of that soft fire brick heating elements and a nice stainless steel exterior that will be easy to reconfigure to a crucible furnace.

John