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Epoxy for Slab Crack?

jchri66's picture

Epoxy for Slab Crack? (post #192881)

jchri66 on Fri, 08/27/2010 - 13:22
in

I have a slab crack and wanted some advice on how to repair.  Homedepot said to use Sika Concrete Fix and a concrete guy said to use an epoxy.  I purchased Simpson Set-pac EZ which is an anchoring epoxy so I was wondering if that is the right stuff for the job.  I do not believe the crack is getting wider.  We have lived here for 4 years and a previous owner had put drywall spackle in there and the crack hasn't expanded beyond that cheesy fix.  Any suggestions?  I want to do the right thing here.

-A +A

Just a minor note:  Often a (post #192881, reply #1 of 6)

by DanH in reply to jchri66 [original] on Fri, 08/27/2010 - 16:15

Just a minor note:  Often a guy will say "epoxy" because it's a two-part product.  But when you look at the label it's acrylic or something similar.


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I have used two part anchor (post #192881, reply #2 of 6)

by DaveRicheson in reply to jchri66 [original] on Fri, 09/03/2010 - 03:20

I have used two part anchor bolt epoxy to fill an open  joint at the wall and a concrete floor. It has been in there for two years now and hasn't moved.

I would say your plan should work.

A standard method of repairing cracks in poured foundation walls is to use an epoxy injection technique. The epoxy for that process is a thinner mix than the anchor bolt stuff. So you may need to pour it in slowly and maybe do it in stages to avoid trapping air pockets.

Epoxy will bond and seal, but (post #192881, reply #3 of 6)

by rdesigns in reply to jchri66 [original] on Fri, 09/03/2010 - 06:35

Epoxy will bond and seal, but will not tolerate much movement. You say there's no evidence of continuing movement, so it might be OK.

I would go with the Sika, and save the anchoring epoxy for anchoring.

To thin the epoxy (post #192881, reply #4 of 6)

by mans835 in reply to jchri66 [original] on Fri, 09/17/2010 - 08:39

When filling small cracks I usually add some solvent to the epoxy, it makes it thinner and epoxy fill the crack better.

 


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Maybe the pourable urethane (post #192881, reply #5 of 6)

by Clewless1 in reply to jchri66 [original] on Sat, 09/18/2010 - 06:16

Maybe the pourable urethane (I think that's what it's called)? They use that to seal all kinds of concrete joints and stuff (e.g. for radon sealing and such).

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movement makes the decision (post #192881, reply #6 of 6)

by slykarma in reply to jchri66 [original] on Sun, 09/19/2010 - 10:17

Epoxies like anchoring compounds are rigid and inflexible. You don't mention the size of the slab and whether it is on compacted grade or over framing, so we don't know the circumstances that caused it to crack in the first place. If things are still moving due to settling, slab loading or expansion/contraction, then epoxy or acylic fillers will eventually fail. Sikaflex caulks are designed for jointing concrete slabs and wall panels where movement is a given, but they won't have the hard finish you might be looking for.

If the cracking is extensive and wide, you might try an inexpensive mix of portland cement, fine sand and a concrete bonding agent. (For fine cracks less than 1/8" wide, use a mix without sand). Wet the slab with a spray bottle and keep it damp while you apply the patch mix. Trowel it in, let it cure a few days, then gently grind off the excess. This will also be a rigid patch susceptible to failure if further movement occurs, but a lot less expensive failure than epoxy if the cracks are large. Sikaflex does a great job but will likely not match well the existing concrete for both colour and surface texture.

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