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joeyboy 02-12-2008 12:57 PM

How can I smooth my bumpy slabs in preparation of epoxy paint/coating?
The problem is that I cannot do an overlay!! No time to wait for the 30 day cure!!!

I had this thread in flooring, but no replies :( .

I have a bunch of concrete slabs (walkways, garage floor, etc) that I am in the process of giving epoxy paint coatings. However, many have cracks/voids/bumps/etc.

So, I'm basically looking for something to use on the slabs, before the epoxy, that I can work with like I'd work with spackle/joint compound on a wall. Something I can just grab a blade and work my slabs with to make smooth and to fix voids/bumps/cracks.

I did my first slab with a mastic product by lanco, "concrete and mortar patch", but this product was soo porous that any spots I had done with it now stand out like crazy! The only slab I did has patches everywhere from the rough mastic compound, contrasted against the smooth slab!!

Any help would be huuugely appreciated!!! :thumbsup:

slickshift 02-12-2008 04:45 PM

I know of no spackle type product that works for this type of repair
...not effectively anyway

The SOP is to put a skim coat over the whole thing
That helps with prep too, as it's now new concrete

Maybe someone around here has used something out there that works like you are looking for....

joeyboy 02-12-2008 07:50 PM

sorry but what's SOP?

I *think* I may have come up with a solution, albeit a PITA one lol, but may work nonetheless.

Since I've got the slickshift in here I may as well ask this ;).

I've been messing around with that lanco mastic stuff in the garage, trying new approaches with it. What I found that worked was to put down some of the mastic and, when it's dried, it's all rough/textured, which is the problem. However, if I put a heavy coat of bonding primer* over it, when it dries, the bumpiness is almost negated. Is this something practical for larger areas? I've only been trying this on chunks of concrete for practice before doing anymore real slabs.

(*the bonding primer I refer to is 'lanco bonding agent' or something, it's the stuff I was using for stucco, I'd use it as the primer for stucco, just roll it on my walls, wait til it dried a bit, then apply the stucco. The stuff seems just like a big 5 gal drum of elmer's glue hahah!)

joeyboy 02-12-2008 07:53 PM

Also, I've been thinking of some unorthodox approaches. For instance, pure epoxy is very expensive (well, in the lil dual tubes I buy lol), but I have to imagine that I could use that with great results (not the epoxy paint, just your normal epoxy glue stuff). That would be good, but I'd need like 50 of the $4 dual tube things of those.

I thought of just using joint compound or spackle, but that'll never do good on outdoor slabs.

My mind wandered to things like bondo and body filler products, but I'm just not versed enough in those to know if it'd be okay or not.

And lastly, my final thought was fast setting cement products. I cannot use cement based stuff, or at least it says I cannot w/o waiting 30 days (which isn't acceptable here), but then I thought of the 20min set time concrete/mortar products. If those set that fast, do they do a full cure faster too? If so, then when the epoxy says "don't use on concrete that's less than 30 days old", can I circumvent that by using a much faster setting concrete? << I just don't know how directly related set time is to cure time I guess! >>

sirwired 02-13-2008 06:04 PM

Well, if porosity/bumpiness is your only issue, maybe a block surfacing primer would do the trick? I'd stop by your local Sherwin Williams and ask if they think Loxon Block Surfacer would work for this application.


joeyboy 02-13-2008 07:12 PM

I hate you. I KNOW I need to go to S&W sooooo bad right now but my car isn't cooperating with me!!!!!!!! Plus I'm almost (hah, not almost, 'am') embarrassed to even explain to the people there that I'm prepping for a 1-part epoxy acrylic made by behr <shudders>.

But yeah, I just got back with a $14 bag (40lbs only too!) of a really fast setting cement (I presume it's just calcium chloride fortified or something) and some sand, so I'm gonna use this, and instead of waiting the 30 day period for curing, maybe give it a week. We'll see, if it works, great, then public knowledge now knows a 30 day period can be reduced to 7 days if you're using a hyper-accelerating cement mix. If it doesn't, and my epoxy starts getting bubbles (from the hydrostatic pressure I'd presume), then the worst case scenario is really a non-issue anyways - I'll just touchup the spots that have issues (this all goes back to my reasoning on why a crappy, 1-part epoxy is better for my personal needs than the 2-part I really wanted!).

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