Barrier coats & sealants for concrete & steel

andyroo

Jack Dempsey
Original poster
MFK Member
Apr 17, 2011
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MoBay, Jamaica
www.seascapecarib.com
Aquatistists,
7'x17"x34"tall in-wall build is underway. Reinforced concrete walls/base with angle-iron to hold & brace the glass, including tie-backs from the top brace to the back wall.

Q: Please suggest a material to seal the concrete & the steel, including a stuff that will adhere/set/seal the silicone around the glass interfaces.

a* I've got a gallon of WestMarine boat epoxy on-hand - good?
b* Benjamin Moore's pool-epoxy has been suggested (via Facebook) and there's a local dealer; however, i'm not seeing such a product on-line.
c* What else, preferably from a "common" company that might already be importing to Jamaica. Something for potable water tanks, for example.
d* Concrete/cement is to be steel-float, thus smooth. Do these products need a roughened surface?

Thanks in advance,
DrDroid.
 

Dloks

Potamotrygon
Feb 5, 2011
1,936
2,824
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in a car
Aquatistists,
7'x17"x34"tall in-wall build is underway. Reinforced concrete walls/base with angle-iron to hold & brace the glass, including tie-backs from the top brace to the back wall.

Q: Please suggest a material to seal the concrete & the steel, including a stuff that will adhere/set/seal the silicone around the glass interfaces.

a* I've got a gallon of WestMarine boat epoxy on-hand - good?
b* Benjamin Moore's pool-epoxy has been suggested (via Facebook) and there's a local dealer; however, i'm not seeing such a product on-line.
c* What else, preferably from a "common" company that might already be importing to Jamaica. Something for potable water tanks, for example.
d* Concrete/cement is to be steel-float, thus smooth. Do these products need a roughened surface?

Thanks in advance,
DrDroid.
We are contracted by Benjamin Moore to use their paint exclusively and I’ve never heard of they’re pool epoxy till now. Although BM is superior in paint, I’m sure there’s other brand that’s far superior in sealing a concrete tank/pond.
 

fishdance

Piranha
MFK Member
Jan 30, 2007
1,035
65
81
A lot of water proofing can be accomplished in the design.

Is it possible to cast as monolith (single pour for walls and base?). If you have to cast the base and walls separately, add keys in formwork so they interlock securely and a water plug between cold seams.

To waterproof my concrete tank I used dense concrete (42 Mpa) which is waterproof. Also added Xypex (crystalline additive) to the concrete mix as a back up waterproof. And then coated the cured concrete (28 days later) with Mapei membrane as this is flexible and can accommodate concrete movement which may not be a factor in smaller tanks like yours.
To protect steel, I used Dulux 2 part epoxy which I am extremely impressed by.
 

fishdance

Piranha
MFK Member
Jan 30, 2007
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I used Dow Corning 795 neutral cure silicon for the glass & steel interface. Mostly because of the 50% flexibility (modulus) but also because you can add more neutral cure silicon up to 2 or 3 days later with the slower cure times. It doesn't start skinning for 45 minutes which is beneficial on large glass panels, especially if only one person applying.
 

pacu mom

Goliath Tigerfish
MFK Member
Jun 8, 2006
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northern CA
Do a search on polyurea. The stuff is used to seal potable water tanks, etc. It is not a DIY product, so a company would have to be contracted to apply it. If I were building a tank, I would give polyurea great consideration.
 

fishdance

Piranha
MFK Member
Jan 30, 2007
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81
Polyurea is a solid product but needs a professional to apply and is not as easy to repair/patch if leaks do occur. The finished surface is surprisingly uneven and textured.

The good news is that water proofing products have come a long way and constantly expanding. I would narrow your requirements and use the best specspecification to choose.

Do you want a hard finish or flexible? Do you want something that can be re-coated easily (without having to drain or surface prep? Budget? Colour? availability? UV, warranty, etc.

In my case colour was a significant must have. This narrowed the range severely and I opted to use one liquid membrane product (Mapei) for the practical reality and top coated with a different liquid membrane for the colour. And a secondary water proofing barrier, Painted across the grain of first. My aquarium is 80,000L though so I over planned.

You could also look at fiberglass - just depends on your individual priorities so only you will know what suits you best.
 

fishdance

Piranha
MFK Member
Jan 30, 2007
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81
I've no experience with pool epoxies but I looked at pool PVC paints which were not fit for purpose. As you are unsure what to use, please choose something that can either be top coated over or easily removed if you decided later it was a mistake.

Getting back to the over planning /over thinking issue, most concrete tanks will self seal over time anyway. Algae and detritus clogs up micro cracks. Just make sure the foundations are solid. Having a concrete tank in your living room
 

andyroo

Jack Dempsey
Original poster
MFK Member
Apr 17, 2011
533
15
33
MoBay, Jamaica
www.seascapecarib.com
The mason doing the concrete does potable/rain tanks & swimming pools regularly and never with secondary seal unless it's DiamondBright for a pool - as such, I fully expect that his final white cement steel-float finish will be capable, I'm just a little leery of pH issues and any wee cracks in the longer-term.

The material I've got on-hand is WestMarine Epoxy that we've been using on an ancient BostonWhaler atop crazed gelcoat as well as poly resin/fibreglass I'm reasonably happy with the stuff and it'll take pigments, but haven't used on steel nor concrete (Q???) Repairs can be done underwater with a putty epoxy - I have that on-hand for work.

I'm also leery of raw steel long-term, thus barrier coats to the steel. Fishdance, you just set the silicone to the raw steel & the glass onto that? No oxidation/rust worries and it stuck alright?
Does raw steel rust particularly in a FW aquarium of rainwater over cement (<7pH), IE: do I need to screw about with sealing at all?
 

fishdance

Piranha
MFK Member
Jan 30, 2007
1,035
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81
Raw steel will rust even in air. I used Dulux 2 part epoxy paint on steel. They have several different variants depending on your specification /need. Very hard wearing.

I'm sure the dense concrete will be waterproof but adding admix to the recipe is very simple and prevents crack leaks as the crystals swell to fill voids even years later.

I would not worry about pH. 3 months of water will leach out the dissolvables. If you are familiar with west epoxy and satisfied, use that.

Yes I silicone the glass directly to steel with 60mm overlap but placed 15mm wide strip of 8mm thick neoprene so the glass couldn't touch the steel. This gave me an two concentric seals of silicon. My glass is 2m deep so I was worried about water pressure if the glass was touching steel. You could use a plastic spacer block on shallower tank. Be sure to use a spatula or putty knife to drive the Silicon in as this pushes out air bubbles.
 

fishdance

Piranha
MFK Member
Jan 30, 2007
1,035
65
81
Raw steel will rust even in air. I used Dulux 2 part epoxy paint on steel. They have several different variants depending on your specification /need. Very hard wearing.
I'm sure the dense concrete will be waterproof but adding admix to the recipe is very simple and prevents crack leaks as the crystals swell to fill voids even years later.

I would not worry about pH. 3 months of water will leach out the dissolvables. If you are familiar with west epoxy and satisfied, use that.

Yes I silicone the glass directly to steel with 60mm overlap but placed 15mm wide strip of 8mm thick neoprene so the glass couldn't touch the steel. This gave me an two concentric seals of silicon. My glass is 2m deep so I was worried about water pressure if the glass was touching steel. You could use a plastic spacer block on shallower tank. Be sure to use a spatula or putty knife to drive the Silicon in as this pushes out air bubbles.
 
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