How Fireproof Is Cement? I Tryed To Make A Mold For Metal Casting Out Of It, But It Fell To Pieces. Did I Make It Wrong, Or Is Cement No Good For 1100?C+ ??
It depends on how long it has been there, and if removing the section would make the driveway unusable. If it has been there a long time, you are not likely to be able to do anything about it. There are several doctrines that would make this so. If you want to get a portion removed, i would talk to them first. If they get a lawyer, you will be fighting this for a long time, so it is best to just try diplomacy first. Whatever you do, don't go out there with a jackhammer and start breaking concrete. This is a great way to end up in bigger trouble. Before you start, you will need an accurate survey as well.
The only thing I know about this is that for metal casting you are supposed to cover a concrete floor with sand, so if molten metal spills onto the floor possibly remaining water in the floor won't make it break up/explode. So I guess concrete is no good or you have at least to heat it up so all water will have evaporated. For bronze casting one generally uses a plaster-silica sand mix (between 1:1 to 1:2). Other options are sand molds. You could google green sand mold and look what info you find on that. Green sand mold means that the sand is just held together by using water. Another option is a resin bonded sand mold. Yet another are ceramic shell molds, but they are much more bother to make, so I'd not recommend trying to set this up just for yourself. It depends what level of detail you need and what you want to cast. For jewelry style casting bought investment material are generally better, but uneconomical for anything larger.
It is possible to mix silica flour and plaster of paris 50-50 and make a mold that can be heated to the right temps. I haven't done it. Silica flour can be bought at ceramics (pottery) supply places as can plaster. Handle silica flour with care to avoid breathing the dust, it can cause silicosis because it is not washed out of the lungs by the body.
