Best way to seal crack in concrete slab?

[HerHusband]

I have a very thin hairline crack in my conrete slab, right in the middle of the garage doorway. It is barely visible and is so thin I can't even feel it with my fingers. Unfortunately, water still finds it's way into the crack on the outside of the garage door and seeps along the crack to the inside of the garage. So, I would like to seal up the crack before it turns into a bigger issue.

Any recommendations?

Most crack sealers seem to be made for larger cracks, so I'm not sure they would even get down into my hairline crack.

Thanks,

Anthony Watson

[lawrence.jamesnc]

If it's really that thin I'd try filler superglue from the hobby store. There is gray caulk for concrete if you think it's a little bit more open and you can use a plastic squeegee to force it in the crack and bit like grouting tile.

[Don Y]

Is water getting *into* the crack or simply clinging to it as a "guide" to flow into the garage?

I.e., are you sure the crack is the cause and not just a *symptom* (of a low spot in the floor)?

As a first attempt, I'd try some silicone caulk applied with a trowel (or float). This will tell you if the crack *is* the "low spot" vs. just RESIDING in a low spot.

Once you know what the case is, you can peel the silicone off (or, scrub it off with a wire brush) -- it won't last applied as thinly as your description suggests it would be.

But, based on what this discloses, you might then be able to try an epoxy intended for use with concrete/cement applied using the same sort of technique. Make a serious effort to clean up the crack and surrounding areas before trying to apply it.

[VinnyB]

On Thu, 17 Mar 2016 14:20:36 -0000 (UTC), HerHusband wrote in

See if you can rent one of these.

Use it to clean out and widen the crack. Then fill the crack with grout.

[clare]

Waterglass.

[clare]

Just get some sodium silicate - aka "waterglass". It is sold as a concrete sealer, among other things - and will seep into the crack and seal it up. (or you can make it from drain cleaner and silica-gel dessicant packs if you want to get adventuresome)

[Paintedcow]

How much of he crack is outside the door? You might just drill a hole in it, right inside the door, using a concrete bit. Then fill that hole with some sort of epoxy or JB Weld. That will stop th flow of water to the inside!

[HerHusband]

Maybe 5-6" outside the door, and another 2" or so directly under the garage door itself. Then it extends 3 feet or so inside the garage.

Anthony Watson

[gregz]

I'm inclined to use PL Premium polyurethane. If you warm it up good, and squeege it in. Might be messy though.

Greg

[caitlyn ford]

replying to gregz, caitlyn ford wrote: I think you should just consult a professional about the problem so you could save time and resources while solving it.