How to deal with this crack?

[lyonkster]

I had an epoxy coating applied to my garage floor 6 months ago, which is now lifting off and will be redone by the installer next week.

In the meantime, I noticed that a hairline crack in the concrete is causing some weird behavior in the epoxy - it looks like the epoxy has formed some sort of a bump over the crack, as seen in photos below. The epoxy is also chipping off in one area, as you can see, but that should be fixed when they come to reapply the epoxy coat. It's the bump that I am worried about.

I am not sure how to deal with this hairline crack - looks that whatever they did the first time did not work well. So I am thinking of doing something myself before they come back to recoat the floor. Should I grind the crack to 1/8" width and fill it with a gel epoxy? Or is there a better or simpler approach?

 

[Edger]

Two things. First you are probably right about grinding out and filling the crack, but the crack is moving so it will continue to move in and out a fraction even with the new epoxy over the top.

Second is that the peeling back indicates very poor adhesion, seen it many times on cracks but it will not happen when the epoxy is ground off and reapplied because it will be adhered properly.

A good test for a floor to check adhesion is either to score it with something or to look for where a heavy object has scored it. Poorly adhered coatings will always split off flakes like your crack along each side of the score while coatings that are adhered properly will only score a scratch line down into the concrete with no splitting along the line.

Good luck with that recoat job, hope it works out.

 

[lyonkster]

Edger,

Thanks for your continued advice, much appreciated. I agree, the biggest issue seems to be the lack of adhesion, which will hopefully be resolved when they grind the concrete and reapply the epoxy.

Sounds to me like you are saying what I am also beginning to think, that the problem is not as much the crack as the poor surface preparation, and that after they grind the surface and recoat it, I will not have the same problem with this crack. In other words, I should probably leave the crack alone rather than grind and patch it. Would you agree?

 

[Edger]

Sort of agree. It should be filled with something because the diamond grind will open the crack a bit more, I was never confident with cracks and there have been more advances so Legacy's epoxy gel seems an obvious choice if you get the chance - just thoroughly vacuum it first. Solid epoxy in the crack when hardened will tend to crush the concrete (not the epoxy) when the crack closes on a hot day.

Others might have different opinions, but I regard cracks as permanently moveable so they are impossible to fix invisibly.

 

[thegarageguy]

sorry to disagree but it looks like poor patch work with inferior material. The reason it would peel is because as soon as it hairlines, any moisture intrusion will slowly delaminate the area. It'll only get worse if you leave it be.

Get a v-groove crack chaser, pull off any peeled parts, square off the area, sand and solvent wipe, patch crack with a flexible paste or joint sealer, then recoat the squared off area with epoxy. It'll look like a patch but won't peel or crust up on you again.

 

[lyonkster]

They'll be redoing the whole garage floor since the epoxy is peeling off, so that's a given. I'm just wondering about the crack shown here. If I chase it with a v-groove grinder and fill it with a gel epoxy, where should I stop the v-groove - right where the painted and unpainted areas meet? You can see in the photo that the crack goes from the painted area in the garage to the unpainted driveway, and I am not sure where to make the transition.

 

[Cabby89]

Do the entire length of the crack. It will just be visible on the apron and if you want you could get an overlay material for the entire apron and hide the repair.

 

[lyonkster]

Turns out that Legacy Industrial cannot ship the crack filler to my clean air district in LA county, time for a Plan B.

 

[D.J.]

Got any freinds that don't live in the clean air district?

 

[LegacyIndustrial]

We can ship this outside the South Coast Air Quality Management District.

 

[Big-Foot]

Once you got the old epoxy off, I would grind out the crack a bit and use a thinset mortar like you would use for ceramic tile. That stuff is tenacious as all heck and will immediately start bonding to that concrete.

 

[ConCretin]

Others might have different opinions, but I regard cracks as permanently moveable so they are impossible to fix invisibly.

Get a v-groove crack chaser, pull off any peeled parts, square off the area, sand and solvent wipe, patch crack with a flexible paste or joint sealer, then recoat the squared off area with epoxy. It'll look like a patch but won't peel or crust up on you again.

Edger and GarageGuy are both right.

It's probably a shrinkage crack that will continue to move a bit but if you chase it and fill it with a flexible product, it won't open up again. You might see the repair if you're looking for it but it shouldn't be that bad.

 

[lyonkster]

fill it with a flexible product, it won't open up again.

Do you guys have any leads on what I could use to fill the crack? I can't get the Legacy Industrial gel epoxy shipped to me (and don't have time to get it shipped elsewhere then over to me as I need to do it next weekend at the latest).

Can I get something locally that would work (Sikaflex, thinset as mentioned above, Simpson epoxy, etc)? Or something like this from Emecole? http://www.emecole.com/pages/Emecole-555-Concrete-Crack-Repair-Kit.html

 

[Edger]

Sorry Lyonkster, no suggestions. Not living in USA.