Old garage slab

Discussion in 'Concrete Floor Finishes' started by Don Monfils, May 29, 2017.

  1. Don Monfils

    Don Monfils PRO CARPET Charter Member

    IMG_8089.JPG Were going to rebuild a garage on this old slab after a fire. We tried to clean the slab with some kind of concrete cleaner and it did very little.
    Yesterday I picked up some Muriatac acid
    and put it on the burn marks then scrubbed with a stiff brush. I then used a 4,000 psi pressure washer. I cleaned it up pretty good. I still have some rust marks that won't come out.
    My wife wants to paint the slab. I have seen to many garage floors that were painted (even with epoxy) peel and look like poop.
    She also looked at a concrete dye but I thought that was something put in the concrete mix .
    I have a couple spots where gas ate right into the slab. What could I fill these areas in with? Would the spots have to be primed first ? Also there are some cracks what could I fill them with so water don't get in them?
    I was thinking after filling in the spots using a concrete sealer.
    Has anyone successfully coated an old garage floor.
  2. Mike Antonetti

    Mike Antonetti I Support TFP Senior Member

    That should've been demo'd as well. If relocation is wanted,size changes, multiple reasons.

    Maybe slab in front of that with pass through for that slab for putting equipment, travel trailer parking, nows the time.
    Last edited: May 29, 2017
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  3. Don Monfils

    Don Monfils PRO CARPET Charter Member

    IMG_7094.JPG We're gonna be on a limited budget.
    Slab is staying. We rarely parked vehicles in there , mostly storage for tractor, mower, snowblower, yard tools,beer refrigerator.
    We are building the same size but, with 8'x9' garage doors, so I can get my pickup in there occasionally. Also 10 ' first floor ceilings for overhead storage.
    Like this .
  4. Mike Antonetti

    Mike Antonetti I Support TFP Senior Member

    A stain will somewhat work, other chemicals arrived first and established their ground, for example oil. So concrete stain will not soak in.

    I've seen many attempts at hiding cracks only to magnify.

    Attached Files:

  5. Old garage floors are extremely tricky to put any type of floor covering or finish on. As Mike stated, they get contaminated with all types of chemicals that can remain in the concrete forever. Some of this stuff you can see, like your rust stain, some of it you may not until you cover it and it comes up through what you covered it with. That's where Mike is coming from with saying it should have went with the demo. It's almost as much money to deal with the issues you can have as to replace the slab itself.

    The other issue you're going to end up dealing with, depending on what you decide to do, is that you're most likely going to have a moisture problem if you try to cover that floor. You can overcome this with an epoxy, but the application of the epoxy is going to dictate that the slab be ground or shot blasted to CSP of 3 typically - like a hammered finish - then the epoxy applied.

    epoxyman will hopefully be along and he may have some other thoughts on ways to deal with the issues.
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  6. Incognito

    Incognito No more Mr. Nice Guy! I Support TFP Senior Member

    I can't imagine anything would bond well to that slab without shot blasting the surface and applying an epoxy moisture treatment. So if you're not going to drop the $$$$ on a garage floor I'd probably just go with cheap paint or concrete sealer and get used to recoating every couple of years or so.
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  7. kwfloors

    kwfloors Fuzz on the brain Charter Member I Support TFP Senior Member

    We sometimes use muratic acid and then wash with a cleaner before putting primer and a polyphatic coating on. I have heard you never want to build over a slab that had been in a fire. I don't recall why, maybe the smell never goes away or something. My neighbor built over his but I think its going to fail in the long or short run.
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  8. kylenelson

    kylenelson You'll find me on the floor I Support TFP Senior Member

    I stained my patio last year and it was a pretty nasty slab with paint and who knows what since 1974 on it. I took a diamond cup to the gross spots and did the acid treatment then stained it. Looks good and is relatively cheap.

    Looks like this

    Attached Files:

    Last edited by a moderator: Jun 14, 2017
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  9. Mike Antonetti

    Mike Antonetti I Support TFP Senior Member

    Grey is in, what a coincidence, concrete is grey, just leave block walls, slabs,etc. bare. I dislike grey, my truck interior is grey, in flooring "whitewash" I try not to see grey.
  10. Dave DelGiacco

    Dave DelGiacco Pro Member

    2 Part epoxy high strength sealer should fill that nicely, let it harden in place, scrape off excess, sand and then finish. It will look like a brand new floor. A company called Like Nu concrete does a nice job at repairing old and worn out concrete.

    Attached Files:

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  11. Mike Antonetti

    Mike Antonetti I Support TFP Senior Member

    I have some serious rust stains on my driveway due to washing out ride on scraper battery tray. Randomly put a product on, didn't touch it, but killed the grass just fine. They have products for rust stains?
  12. Kman

    Kman Tile Expert I Support TFP Senior Member Published

    As old as it is, and contaminated as it is with chemicals, you'll likely have to grind it no matter what.

    Epoxy for the cracks, and epoxy finish for the surface. Anything else is going to require frequent maintenance. The heat from car tires will damage most anything else you could put on there.

    And don't go with the cheap epoxy finish from Lowe's. Get something that will hold up in a commercial setting.

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