I have just discovered a 25lb bucket of this stuff in my grandfather's basement while on vacation. Having never seen it before, I am wondering if there is a consensus on its efficacy in j-tube and heat riser construction? Toxicity profiles and any previous experience utilizing this material before I commence an in depth internet research project would be greatly appreciated.
It seems as though it would make a very nice sealing material to prevent lateral drafts. I have an idea to possibly construct a rounded/smoothed edge j-tube for increased airflow. But I have not had a chance to actually build even one yet as I have no access to property/land yet. Maybe ernie and erica have attempted something of the sort?
A dry-mix that chemically sets and dries brick hard, this cement is perfect for casting into custom designs, as it will hold its shape while drying. It can even be used as the sole material when casting a solid stove bed or outdoor oven. Exceptionally strong and also works to fill large holes"
According to the product description, you can make some cool stuff with this as one single ingredient, however, you will want to mix it with 50-80% perlite (dry mix by volume) for rocket stuff insulation values.
People have made "shippable cores" and "j tubes" from casting their own molds. I have cast my own riser. Surround 2" thick, and it was strong, but I removed because I ran low on perlite and it wasn't insulative enough, that's how I know you will need at LEAST 50-80% perlite. My bottom cast "mass" is 50% and its good. but you should be able to cast stuff if you can make decent molds. Heavy cardboard tubes could make good molds because they can be burn out afterward, since you mentioned round smooth shapes.