I am planning on making several irrigation pipe structures where I fill a 2 gallon bucket full of concrete and put a bunch of pipe in the concrete.

I want to be able to reuse the buckets.

What is the best way to keep the concrete from sticking?

I have heard pam will work but I am open to any suggestions.

They make release agents, but how about lining it with a small trash bag?

I think my concrete guy used mineral spirits for some imprint pads that I had.

Just a note, I tried this a few weekends ago. I used the regular bagged stuff mixed it in my wheel borrow and dumped it in with a couple bigger rocks. In the past when I have helped pour sidewalks or other things with from a concrete truck we took the forms off the next morning. Not so with this stuff in my case. It needed to sit at least a week. I had also poured a base for my aeration that was just formed. Anyway how long should the bagged stuff sit to cure? Mine stayed soft for over a week. I didnt know why it would be bad but a week or 2 later it sat up. During that time it was out of my bucket mold so it broke so I will start over again.
good luck
Dave

I like the bag idea a lot. I have seen petroleum oils used, but that as well as mineral spirits would make oily residue floaties in the pond(Assuming these irrigation pipe structures are going in the pond). Vegetable oil (spray Pam or regular vegi oil and a rag) would be a much better alternative to petroleum products, but trash bags have good promise. There would be some ripping of the plastic and some plastic pieces will be held by the concrete, but not too big of a deal, it could be burned off if need be. Vegi oil will still yield floaty films, but at least it is organic and will break down in weeks instead of years. Vegi oil will plasticize within a few days to weeks if left in the sun also reducing any oily film when submerged.

You might try one structure without anything as plastic buckets are pretty resistant to anything sticking to them. Let it set up for a few days so long as you don't end up with Customs scenario and try to pull it out, tapping on the bucket with a dead blow. You could even store it in a cool place then let the sun (or propane torch or hot water) heat the bucket up to get it to swell up a bit and it might release even better. Having a taper to the bucket will help a lot also. No taper will likely allow the concrete to swell and lock itself in the bucket.

CRISCO

Can you split the 5 gallon bucket and then hold the 2 halves together with bungee cords or ratchet straps and then release and split the halves?

PAM is soybean oil. Worth a try in concerned about the environment.

Otherwise anything that makes the inside plastic very slippery might work, consider sealing the pores with rainX (makes everything slippery!), quick coat of non-synthetic car wax, or silicone spray.

Cement can get old and lose its strength in making concrete. Sounds like you might have had some old cement. Cement has a shelf life. If I have an older bag of cement or quickcrete that I want to use up, I'll spike it with some fresh cement to make sure it sets up.

Concrete is not created equal. Concrete brought out on a truck for a sidewalk may well be 4000, or at least, 3500 psi test. Bagged concrete mix might be 3000 psi or less. Huge difference in set time depending upon cement content. (Note: cement is an ingredient in concrete, like flour is an ingredient in cake batter)

Also, the amount of added water, or slump, has a big effect on set times. And, concrete poured into a bucket has little exposure to air, AND it's thick, which will increase set time

I spray forms with wd40

I have purchased many plastic molds and make ornamental Items to sell. The man I buy my molds from recommended spraying with PAM non stick spray. Have been using it for years with GREAT SUCCESS!!! The generic brands work just as good and a lot cheaper.

PAM is just vegetable oil so if a person needed to do a lot a gallon of cooking oil in a hand sprayer should work.

When I ran out of old plastic tree containers I just screwed together some OSB and made a box and it worked well. Once set up just unscrew and tap the pieces off the concrete. The square shape was nice also for sitting sturdy on the bottom. Maybe check with a nursery and see if they have any used containers you can have.

Mold release agent is referred to as PVA (poly vinyl alcohol). It can be brushed on but spraying gives better results. One coat, let dry then second coat, let dry. Ready to go. This is what is used even for polyester resins (gelcoat/fiberglass).

If you are using a wax (auto or furniture), make sure to apply at least two coats. Two layers of wax will release better.

Forget buckets. Use 8x8 cinderblocks as molds (about $1 each) and use less cement.

I like the garbage bag idea, as well as the "split the bucket and hold together with bungees".

I'd pick the plastic bag method first, and even combine it with the split bucket method.

I don't think ANY of the release agents that you'd use would hurt the pond. Even motor oil. Coat inside of bucket. pour in cement, making sure it's not too wet. Let set up, knock the sides of the bucket with a dead blow hammer a few times, pull off.

They make a product called release. We used it when we did stamped concrete. It makes it so the concrete dosnt stick to the stamps and also puts a different color in the concrete. The harder you push it down in the darker it gets.

Cardboard worked for me, but you'll need to scrape it off afterward, and it might take a while. Plus, the Junk Bin Rental service staff that we had come over and dispose of all the garbage produced during the construction couldn't be more grateful as they needed cardboard for a recycling order they had at the moment. It was a win-win situation which also got us a decent discount on their services. We also felt better knowing that our garbage was going to be recycled instead of polluting the environment.