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Old 08-21-2010, 08:33 AM   #1
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concrete repair cracking


poured 20 X 20 garage a month agofloor 3,000 psi w fiber glass
power trowel looked good did not have time to cut lines in floor
I walked in garage today and noticed spyder cracks going lenghtways and
across middle of floor
can i now cut lines in floor and fill old cracks
looking for all ideas would like to repair so I could get my car project going
thank all

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Old 08-21-2010, 12:03 PM   #2
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concrete repair cracking


what a shame you couldn't find the time to finish the work when it had to be done as those random cracks are the exact result of not doing something right when it was time to do it,,, having creating this mess, you might as well wait while the floor decides where it will crack - those cracks will become joints as the conc changes dimension due to hi-skool physiks laws applicable to temp swings & how they affect solids.

it shouldda been cut into 4 10'x10' squares by sawing 2 20' sawcuts thereby persuading the conc to crk where YOU wanted as soon as it could be sawed w/o excessive raveling,,, you could saw it now ( full depth ) but, imn-s-hfo, why bother just yet as the damage is already done,,, get on w/the car project !


ps - when you do finally get around to sealing cracks, they'll need to be sawed 1st w/1/4" blade to provide the crk sealant sufficient dimension ( sealant ratio ) & space to perform well - all depending on which joint sealant you choose, of course !

pps - have the same situation in our garage but can't blame you,,, that bldr just never bothered to have his sub do it right, either !

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Old 08-21-2010, 03:24 PM   #3
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concrete repair cracking


Thanks for info



I have a few months before I will start using garage I would like to repair will I can
what type of mix
should I use to put in cracks ? epoxy or cement patch
when that is all done will I be able to put epoxy coating on floor ?
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Old 09-26-2010, 01:25 PM   #4
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concrete repair cracking


You can use either a 2 part epoxy or an acrylic-modified cement patch.

The disadvantage of epoxy is that you have to pour it into the cracks. Inevitably there will be some over pour or smearing of the epoxy on the concrete surface. About the only way to get it off is to grind it with a 4" diamond cup grinder. That will scar the surface of the slab somewhat but it won't make any difference if you are going to put an epoxy coating on it. (Make the slab cuts first before doing the coating.)

Cement patch is easier to work with. To clean up and level the surface simply wipe it lightly with a damp sponge while it is still wet.

Patrick
California Concrete Restoration
www.squidoo.com/epoxygaragefloors
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Old 09-26-2010, 02:58 PM   #5
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concrete repair cracking


IF you choose epoxy, still be sure you prep the crk correctly as noted previously,,, include a bond-breaker as you'll ONLY want 2-sided adhesion,,, pick 1 that's got the right coefficient of expansion/contraction, too.

acrylic cementitious filled joints will/usually/might/may reflect the crk up thru your very fine new floor surface w/o doing the prep & crk work right.

' disadvantage of epoxy ' in YOUR garage is that the crk may only measure .005 to .010",,, gravity won't sufficiently fill it meaning you'd have to employ hydraulic pressure to inject it,,, 4" zec wheel will remove laitance & patch junk w/o significantly scarring the crete's surface,,, diamonds will make it a mess as noted above.

agree w/pat's slab sawing advice,,, just saw them full depth & insert backer rod to PREVENT epoxy o'lay from penetrating your newly saw'd jnts,,, don't bother w/apron store epoxies, either,,, they're water-based &, im-n-s-h-fo, junk peddled to ignorant & unsuspecting h/o's - diy'ers.

welcome aboard, pat
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Old 09-26-2010, 04:50 PM   #6
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concrete repair cracking


Quote:
Originally Posted by itsreallyconc View Post
IF you choose epoxy, still be sure you prep the crk correctly as noted previously,,, include a bond-breaker as you'll ONLY want 2-sided adhesion,,, pick 1 that's got the right coefficient of expansion/contraction, too.

acrylic cementitious filled joints will/usually/might/may reflect the crk up thru your very fine new floor surface w/o doing the prep & crk work right.

' disadvantage of epoxy ' in YOUR garage is that the crk may only measure .005 to .010",,, gravity won't sufficiently fill it meaning you'd have to employ hydraulic pressure to inject it,,, 4" zec wheel will remove laitance & patch junk w/o significantly scarring the crete's surface,,, diamonds will make it a mess as noted above.

agree w/pat's slab sawing advice,,, just saw them full depth & insert backer rod to PREVENT epoxy o'lay from penetrating your newly saw'd jnts,,, don't bother w/apron store epoxies, either,,, they're water-based &, im-n-s-h-fo, junk peddled to ignorant & unsuspecting h/o's - diy'ers.

welcome aboard, pat
Itsreallyconc:

Not sure that I or other readers understand all your contractions and abbreviations. I'm sure "saw-d jnts" means 'sawed joints" and that "epoxy o'lay" means "epoxy overlay". What the heck is "im-n-s-h-fo"?

RE: Hair-line cracks. The homeowner won't have to use hydraulic pressure to inject epoxy into them if he takes your previous suggestion to open them up with a 1/4" diamond crack chasing blade.

RE: Backer rod. Since the homeowner will undoubtedly be rolling down the epoxy, I doubt that much of it will leak down into the newly-cut tension relief joints. Even if a bit of it does leak down, I can see no harm. Doubt that you can even find backer rod to fit into a 1/16" saw cut. If the homeowner is paranoid about this issue, I'd suggest that he just fill the cuts with sand up to about 1/4" below the surface of the slab. The sand would quickly soak up any minor epoxy leaks in the cut and prevent it from penetrating down into the remaining 3 1/2+ inches of the cut.

Patrick
California Concrete Restoration


PS I prefer "Patrick" to "Pat"
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Old 09-26-2010, 05:03 PM   #7
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concrete repair cracking


apologies, patrick,,, i'm from noo yawk where everyone has a nickname - even brooklyn's joey pots 'n' pans & jimmy 3-fingers.

btw, good points,,, forget to note small stuff as we do this work all the time,,, it translates as ' in - my - not - so - humble - f'n - opinion ' they may not say that often on the left coast

saw-d jnts" IS 'sawed joints" and "epoxy o'lay" means "epoxy overlay",,, yes, ' IF ' homeowners yada-yada-yada,,, if a frog had wings, it wouldn't bump its *** when trying to fly across the floor.

as i recall, sika & others have high-weight-methyl-methacrylates w/viscosity of wtr suitable for crks down to .003" but its $ 225 per gal,,, usually only bought when the engineer sez ' do it or replace it ! '
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Old 09-26-2010, 06:06 PM   #8
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concrete repair cracking


Isrealconc:

Yes, you are talking to a larger audience than New York. Your reference to "brooklyn's joey pots 'n' pans & jimmy 3-fingers" falls on deaf ears outside of New York city.

Patrick
California Concrete Restoration
]
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Old 09-26-2010, 08:01 PM   #9
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concrete repair cracking


that's possible,,, suppose its like being from san fran, marin, or la

relax, pat - we're all friendly in here ( even moi ) altho you should watch out for a guy posting as ' jomama '
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Old 09-27-2010, 06:01 PM   #10
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concrete repair cracking


thanks to all fom every where

Im going to rent walk behinh saw from rental place
It cuts wont be deep enough to cut trew complete pad
than i have some 2 part epoxy that the state uses to repairs
should i epoxy or cut expansion lines first ?
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Old 09-27-2010, 06:26 PM   #11
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concrete repair cracking


if you use a 12" blade, you should be able to saw 3.5 - 4" deep,,, saw 1st, then epoxy,,, bear in mind the state's mtl may NOT be the proper mtl for your floor,,, all epoxies have different qualities & are picked for the relative repairs.
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Old 09-27-2010, 08:34 PM   #12
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concrete repair cracking


I used the Quickrete water-based in the garage after powerwash/etching/etc and did not like! Very thin and didn't fill small holes, poor coverage, is like a skating rink with any water, and is now peeling two years later after minimal use.

Also heard hot-tire peeling was an issue with the Behr epoxy as well.
Supposedly they've changed their formula since.

Many years ago I used the non-water brand(bought by Valspar), with very good results. Brake cleaner, oil, etc. barely made a stain in it. Color not consistent but it has held up well.

There are also very expensive ones like Sikkens, but not for a working garage.

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