Hair line cracks in garage slab - need recommendation

[General Lee]

What do the good folks here recommend to fill/seal cracks in my garage floor? I have some cracks forming after roughly 15 years. The worst is about a 1/16 inch thick. I'd like to go ahead and fill and seal them hoping to stop or slow down their mission of expanding.

Which products have you all found to be superior?

 

[jeff9366]

You have moisture moving under the concrete.

Until you correct this, cracks will continue to appear, gradually spreading out.

It could be something as simple as dammed gutters.

 

[ovrszd]

When I built my shop I had the concrete "cut" into 10ft squares. I filled the cuts with DAP Concrete/Mortar filler and sealant. Came in caulking tubes.

I've heard of a liquid type, but never worked with it and can't remember the name. Sorry.

 

[s219]

Filling the cracks might make it look neater, but it won't fix the problem or prevent future cracking. You can buy a Quickcrete crack filler at Lowes, Home Depot, etc, which is a thick gray goop that you squirt into the cracks and it hardens (it's in a plastic bottle with a pointed tip). You should first fill the cracks with sand to about 1/2" from the top before using the goop. It works well.

If you're cracks are only 1/16", that's going to be tough to fill and may not be worth the effort.

 

[CalG]

Filling the cracks might make it look neater, but it won't fix the problem or prevent future cracking. You can buy a Quickcrete crack filler at Lowes, Home Depot, etc, which is a thick gray goop that you squirt into the cracks and it hardens (it's in a plastic bottle with a pointed tip). You should first fill the cracks with sand to about 1/2" from the top before using the goop. It works well.

If you're cracks are only 1/16", that's going to be tough to fill and may not be worth the effort.

Regular household builders/painter's calk. So what if it doesn't harden? The crack is only 1/16thinch now. But it will get wider ;-)
Blow out the crack with compressed air before you squeeze in the calk.

PS Color match! It will look better when you are done ;-)

 

[Dave M7040]

If you did not saw cut the slab very soon after it was poured you are doomed to suffer cracks unless a very special water reduced mix was used and the wet curing done properly for at least 7 days.
The slab will respond to change in moisture or humidity levels as well as temp changes opening or closing the cracks.
Because the changes in temp and moisture do not occur uniformly throughout the depth of the slab, there are curling forces which bend the slab up or down at the cracks.

The timing of the initial cutting has been found to be very critical and there is now a special saw called a "Green Cut Saw" to do the job.
The Green reference is describing the curing state of the concrete, i.e. barely firm. It has special shoes to prevent the blade from pulling up the barely firm concrete as the blade proceeds.

You cannot stop the cracks from moving. Now the only measures are just cosmetic.

Dave M7040

 

[tamu94]

If they are just hairline cracks I would not worry about them (cosmetic). Every concrete/foundation guy I have spoken to about this says the majority of slabs will develop some over time. Make sure your foundation is correctly drained maintains a consistent moisture content. Drainage and drought is a big problem for slabs here in Texas.

 

[Alan L.]

Every slab I have ever seen has hairline cracks. I have them in my shop and on porches of my house. I am sure there are plenty under the flooring also. 1/16" is a little bigger than "hairline", but probably not structurally significant. If those "not hairline" cracks get any bigger I'd probably have a pro take a look.

 

[Industrial Toys]

I have them in my couple year old building around the man doors. I too thought, it would be nice to pour something (very liquid) in to seal them. Not for any structural reason, just to kep water and dirt out and give a nicer appearance. I notice the same thing in our barn, built in 89. Cracks in the same place, where the slab extends over the poured wall.

 

[deerefan]

What do the good folks here recommend to fill/seal cracks in my garage floor? I have some cracks forming after roughly 15 years. The worst is about a 1/16 inch thick. I'd like to go ahead and fill and seal them hoping to stop or slow down their mission of expanding.

Which products have you all found to be superior?

Can you provide some details? Thickness of slab, type of reinforcement used, sub soil conditions- was it compacted and what is the make up (sand, clay, limestone, etc). Location? Any expansion or construction joints in the slab? All concrete cracks to some extent, hair line cracks are going to happen. 1/16" may be a bigger issue. Give some of the details above and I may be able to help you.