Fiberglass impregnated concrete abd epoxy

[Shadowdog500]

I just read that fiberglass impregnated concrete can cause problems when epoxying a floor because the fibers stick out of the floor and have to be burned off or sanded after an initial epoxy cote. I'm getting a new floor installed next week that will have both steel and fiberglass( overkill). is a smooth finish sufficient to keep the fibers from sticking out like tiny wiskers? If not, what finish would you reccomend?
Thanks,

Chris

 

[Will S.]

I'll be watching this thread too, as I poured the same kind of concrete pad in my garage, just last week, and I want to apply a durable coating before using the building. Mine is trowel-finisher (smootha and almost glossy).

Hope you get some good answers.

 

[tncatadjuster]

About twenty years ago I did a job that had a high concentration of fiberglass. I coated the floor and right before my eyes the entire floor became a sea of bubbles.

Came back the next day and sanded the bubbles out, but the fibers just blew in the breeze. I had to flame them, and prime the floor a second time before installing a topcoat. Flame and epoxy don't mix well, so I would research or wait till one of the smart guys comes along and teaches us the proper method.

I think when I shotblast, it must melt the loose fiber. Only had that one problem.

 

[AlphaGarage]

This is stuff you need to speak with you concrete contractor about, but my non-expert take is this... I don't know if an attempt at a smooth finish would work, those fibers were still poking up on some pretty smooth finishes that I've seen. Something I'd be concerned about is that they work real hard to give you a 100% smooth finish, that means they have their floats and trowels out going over every inch again and again. Overworking the concrete like that has a tendency to bring "cream" to the surface, something you want to avoid. Cream is a whole bunch of the concrete components other than the aggregate sand, pebbles etc. It looks great, but is relatively weak and can spall, crack, flake off easier than concrete that is just poured and smoothed without all that extra attention.

We've had several clients just burn off the fiberglass hairs - before they apply any coating - without any problems. It's quick, easy, and apparently effective. What are you misgivings about a quick propane fired haircut?

BTW - For our coating system (3 coats; a 5mil prime, 12 mil top, and 4 mil clear) we spec a light broom finish with no sealers. Other products may require different concrete finishes, so check with the manufacturer.

 

[gabeancounter]

Not sure I agree with the light broom finish, but I am not a pro. I understand it should give a good bite. I was able to see even hairline cracks after applying the epoxy very thick ( almost double). Not sure I could get a light enough concrete brooming to keep from showing?

My vote goes for smooth, then etch, then a slight burn over the floor with a propane torch.

 

[AlphaGarage]

Not sure I agree with the light broom finish, but I am not a pro. I understand it should give a good bite. I was able to see even hairline cracks after applying the epoxy very thick ( almost double). Not sure I could get a light enough concrete brooming to keep from showing?

My vote goes for smooth, then etch, then a slight burn over the floor with a propane torch.

Good point - I'll modify the post to reflect that for our products we specify a "light broom finish." For other products, check with manufacturer.

 

[Hammerdown]

IMHO- After you acid wash the floor take a hand help propane torch and burn the fibers away. Clean away any soot or residue prior to coating application. The acid wash is typical for most epoxy finishes, and it will reveal more fibers. It is much easier to burn them away prior to application than afterward. ( I must not be computer savy because I can not upload the image I have of a coated floor with fibers in it- it looks like the non-skid aggregates you add)

 

[Hammerdown]

Just got the picture to upload. This was my first experience of coating a fiber reinforced floor without addressing the fibers PRIOR to coating. Needless to say I learned my lesson after spending way too much time and money correcting the issue. As always, it's in the prep! It looks like it is an anti-slip additive, but the bent over fibers look like hair close up.

 

[gabeancounter]

Hammerdown,
That really looks like a hard lesson to learn. Thanks for the pic of what could happen.

 

[PassnThru]

Hammerdown,
That really looks like a hard lesson to learn. Thanks for the pic of what could happen.

Agreed. Thanks for that real life example. Hard to argue with that picture.

 

[AlphaGarage]

BTW: Another problem you can run into is lint fibers from the roller brush shedding into the coating - and it looks very similar, although the spikes are a bit smaller and it's almost impossible to see the fibers unless you look closely.

Fortunately it's easy to avoid - buy high quality lint & shed free brushes and monitor the coating and brush, replacing the roller cover if the coating on it is setting up too firm.

 

[tncatadjuster]

BTW: Another problem you can run into is lint fibers from the roller brush shedding into the coating - and it looks very similar, although the spikes are a bit smaller and it's almost impossible to see the fibers unless you look closely.

Great advice, if you think it will take two roller covers, buy four. It's a cheap $20 insurance policy. I've had one or two defective roller covers over the years and it pays to be prepared.

 

[Hogan's Hero]

I have already purchased my epoxy, but have no floor to put it on. The concrete work will commence soon. I was planning on fibre but after reading this, I am not so sure. 40X64 building and the thought of bending over and burning those fibers with a tourch hurts my back. Should I just add rebar and mesh and forgo the fibre?

 

[AlphaGarage]

It's not that big a deal to burn it off. They have propane torches on handles that are made for de-icing sidewalks, clearing weeds, or flaming down roof shingles. They're about $40, or maybe you can rent them. No need to scuff the knees, just walk along and burn baby burn.