Polyurethane foam as cement / binder

[jaredef]

I’m thinking of using Great Stuff Pond and Stone polyurethane spray foam as a cement mixed in with aragonite gravel in order to make an aqua scape. I can’t find anything comparable in search.
Great Stuff notes on the bottle that their foam isn’t designed for structural purposes, but I know polyurethane is sometimes used in light weight concrete applications. Anyone ever try this?

 

[Pistondog]

I’m thinking of using Great Stuff Pond and Stone polyurethane spray foam as a cement mixed in with aragonite gravel in order to make an aqua scape. I can’t find anything comparable in search.
Great Stuff notes on the bottle that their foam isn’t designed for structural purposes, but I know polyurethane is sometimes used in light weight concrete applications. Anyone ever try this?

I'd be concerned about any chemicals getting into the water. Perhaps if you cure the aquascape you might be good?
Have not heard of this.

 

[jaredef]

I'd be concerned about any chemicals getting into the water. Perhaps if you cure the aquascape you might be good?
Have not heard of this.

That is a concern. Thankfully, it seems Great Stuff Pond and Stone has a pretty good track record in aquaria.

 

[TDEcoral]

I think you should give it try. I'd be curious to find out if it works. In theory, it sounds promising.

 

[jaredef]

I think you should give it try. I'd be curious to find out if it works. In theory, it sounds promising.

I’ll post pics, failure or otherwise!

 

[jaredef]

Well, I tried it out. First, I’m amazed that it appears to have worked. I mixed the arag gravel at about 1 can of Great Stuff to 15 a 20 lbs of aragonite. I’ve heard of sealed membrane curing for polyurethane foam so I attempted something similar with Saran wrap. Great stuff doesn’t “cling” to the wrap after curing, which is a plus. You’ve got about 1 minute or so of workability before the foam becomes difficult to manage and sticks to your gloves as well as it sticks to itself. After 30 minutes the foam is cured hard to the touch. After a few hours it’s handleable. This stuff is VERY porous and noticeably heavier after removing from submersion. You could probably think up a lot better way to use it in aquascaping than what I’ve done here. My plan is to foam it again on the exterior and use silicon to adhere aragonite sand for aesthetics and to promote coralline growth.

 

[TDEcoral]

Cool! From seeing how it's used in creating backgrounds in terrariums and the like, I was pretty confident it would work for this. I think a good application in reef tanks would be for cementing an aquascape together. Not sure if it would be easier to work with than mortar though. One benefit to the foam is that it can kind of be molded while curing and cut to shape after it cures.

Instead of using silicone to adhere aragonite to the foam, I would suggest using super glue gel. From what I've seen/read, super glue holds up better for this long term.

 

[jaredef]

Instead of using silicone to adhere aragonite to the foam, I would suggest using super glue gel. From what I've seen/read, super glue holds up better for this long term.

Cool! Thanks for the heads up!

 

[BackToTheReef]

I’m thinking of using Great Stuff Pond and Stone polyurethane spray foam as a cement mixed in with aragonite gravel in order to make an aqua scape. I can’t find anything comparable in search.
Great Stuff notes on the bottle that their foam isn’t designed for structural purposes, but I know polyurethane is sometimes used in light weight concrete applications. Anyone ever try this?

There is only certain kinds you can use. One type of Great Stuff will 100% nuke your tank. I want to say original you are ok and the window/door you are not. Not sure about the pond stuff, we sold a brand of pond foam but I can't remember if it was ok to use in saltwater.

I used Great Stuff in my tank and used sand and rubble to "hide" it a little, then hoped for coralline to cover the rest.

 

[Fam5dad]

This is a topic of interest to me because we are going to have our floors refinished and I am worried about the fumes. I am just finishing my cycle and to be safe I won't want to add much more than fish till the floors are done, but that is months from now when we are gone on vacation. The wait will kill me! LOL. The contractor says he will use an oil based polyurethane which is not water soluble. Ill put a big bag of carbon in that week too. Anyone have their floors finished with a reef tank in the house?

 

[garbled]

One word of warning about these foams, they dry at varying rates. Lets say you make a football out of some of this stuff. Well in a few hours, it's dry. And you can squeeze it, and it looks happy. Cut it in half, it's still completely wet in there. Even more so.. in a few weeks, it will dry, but it also keeps expanding slightly, so measure that football again, and yup, it's ever so slightly larger.

I'm not commenting on if it will nuke your tank or not.. it will probably be fine. But be aware, it doesn't always dry all the way through right away. I one time used some to fill a cavity between some MDF and steel, and then used an angle bracket to hold the MDF to the steel. It was dry.. it was perfect. 3 weeks later, I heard the loudest bang ever. It ripped the steel angle bracket in half, and had popped the MDF up 2" above where it was.. it was slowly expanding/drying the whole time...

Use it, sure, but maybe blow a few test pieces, same size as whatever you are making, and then give it all like 2-3 weeks to dry, and then start cutting the test pieces in half to make sure they are fully cured on the inside before you stick it in the tank.

 

[Not_Eeyore]

... I one time used some to fill a cavity between some MDF and steel, and then used an angle bracket to hold the MDF to the steel. It was dry.. it was perfect. 3 weeks later, I heard the loudest bang ever. It ripped the steel angle bracket in half, and had popped the MDF up 2" above where it was.. it was slowly expanding/drying the whole time...

Agree! If making a large/thick item, then best to do it in layers. Let each layer cure before adding the next.