Will concrete stick to PVC?

I'm thinking about making a concrete tube, and I was wondering if I used two different diameter pvc pipes as the mold if I could remove the concrete without damaging it too badly.

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Jsulser2 months ago

I want to make a fire pit out of concrete. Can I use paper towel rolls for air vents

Slice a poster tube down the center so you can peel it apart later. Wax the inside of the Tube or put some cooking spray in there (like PAM) tape it up and pour your concrete. Peel the Tape when it cures and split the cardboard.

Ronyon4 years ago
I have been thinking about this as well, and I think I will try an outer tube split length wise with newspaper pasted on the inside. After pasting, the tube would be duct taped back together.
The inner would also be wrapped in paper, and after casting the whole thing would be soaked, and hopefully the concrete would release.
NachoMahma7 years ago
.  I don't know, but concrete will stick to most things, so a release agent is brushed or sprayed on the molds before pouring. Polyvinyl alcohol (PVA) is a popular release agent that may work with PVC.
.  If no one has an answer, that should point you in the right direction on your favorite search engine.
I think PVA is polyvinyl acetate. There are a number of products available such as Bondcrete which are basically PVA, and are used to help bond cementitious products such as render and concrete/masonry, together. It is also good for woodworking. If I'm not mistaken and we are talking about the same thing, I wonder how good a release agent it would make?

Although having had some experience with this type of product, it seems to emulsify when exposed to moisture and then the render eventually falls off. Not a great product.
. Same abbreviation, different compounds.
OK.
Re-design7 years ago
Use different sized carboard or paper tubes. If you use the pvc tubes you'll NEVER get them apart. Concrete shrinks slightly while it's drying so the inside will be "welded" by friction to the concrete.

You could make your own tubes to get the correct size using several or many layers of heavy brown paper and varnishing it for rigidity.  Then collapse it when the conc. cures.
I'm fairly sure I have seen those cardboard concrete tubes used for footings before and then they were peeled away. Also as a side note, the concrete forms that builders use when pouring a concrete foundation are usually sprayed down with diesel, so that may help you separate some things. So I would say go on with some mini experiments and see what happens
aeray7 years ago
It doesn't actually stick, but the friction will be so great that you won't be able to get the pipe out. A cheap solution might be to use a closed-cell foam tube (a.k.a. pipe insulation, which would stretch in length and contract in cross section when one end was pulled) for the inside form, and a "fabric" outside form like, or similar in concept to this. A quicker, easier to come by, one-off solution would be to use cardboard tubes. The outside one would be fairly easy to peel off, and the inner one might be able to be "unwound" internally like pulling ribbon from the center of a roll. If not, it could be soaked or burnt out once the concrete was cured.