epoxy injection - cracks in concrete 1

Good morning a2mfk,

At 1/4" wide it's unlikely there is any reinforcing of significance or what little steel there is has yielded. Epoxy has it's limits and cracks of a 1/4" are probably on the maximum end of what can be repaired using most products. I think this might better be more of a gouge, explore, and full patch approach.

Also there would be a lot of water escaping through a crack that size. The deck probably just hasn't cracked....yet.

regards,
Michel

I wouldn't use epoxy unless I was certain that the wall wasn't still moving.

I would investigate a bit further. Is the visible crack this wide because of raveling or previous repair attempts, but the underlying crack narrow? A typical face repair would require grinding of the crack to allow sealing of the face with a proper 2-part elastomeric (below the water line, it might be tricky to find a product listed for that use.) If you inject, that is done behind a face sealant which can remain or can be removed, but would be unsightly unless removed by grinding.
Unless the reinforcement has deteriorated (which would probably be evidenced by rust staining), it either was improperly placed or the crack is not really all that wide. It would take a tremendous amount of force to yield mesh or bar, and I can't recall ever seeing this in a pool which did not exhibit other distress.

I didn't measure the crack width, this was months ago and it may be less than that. It seemed the width was fairly consistent throughout the height of the wall and was limited to this one spot near the center of the wall longitudinally. It also may have been ground out a bit by the previous repair attempt. No rust staining. The homeowner seemed to think the crack has been pretty stable in terms of width or length. I have no reason to suspect the crack is still widening or there are continued movements of the pool, but it is possible.

The repair is already being done, and it is not what I recommended. From what has been told to me, they are using rebar "staples" along the crack, then they ground out the crack and are filling it with a hydraulic cement pool patching compound. I believe this has little tensile bond strength and is much more likely to crack than epoxy, though maybe the staples will do that job and the cement will do its job as a waterstop. Hopefully for the homeowner it works.

This was just a quick conversation several months ago, I did go and have a look but the pool had water in it. Then I emailed the homeowner a link with a epoxy injection synopsis (similar to a basement wall crack repair). This was just a friendly favor giving her my opinion and making sure I did not think there was a bigger issue at hand (soil problems), not an actual job where I performed an in-depth investigation and did repair drawings or specs.

Its one of those favors you wish you hadn't done, but it was for my boss' friend. He is not an SE...

a2mfk...your first recommendation was correct. Stick with it.

Not that I would necessarily agree with your epoxy injection method, but best to stick with it at this point, as they are not doing it your way anyway.

Hokie, from an educational standpoint, I still welcome your opinion, even though it is from a V Tech'er.... I hardly have a horse in this race at this point. I have always understood that epoxy injection was one of the better ways of repairing cracked concrete walls, but I don't think pool contractors in Florida do it very often. This also ensures them continuous business in my opinion, since they don't offer guarantees on their repairs anyway.

Sorry for my somewhat facetious comment. Seriously, cracks and leaks in swimming pools are rarely straightforward. Filling cracks either involves rigid material (epoxy or cementitious) or a flexible sealant. None of these are foolproof or permanent. Where I am, the preferred method for repairing a badly cracked (I consider a 1/4" crack in a swimming pool to be a bad crack) and leaking pool is to install a vinyl liner. What is the condition of the surface in the pool? Pools generally require resurfacing after 10-20 years, depending on how well they have been maintained, so repairing the crack by installing a liner gives a new, clean, easily maintained surface.

The pool is currently being resurfaced, and the pool contractor came up with this repair. I am pretty sure the homeowner will just go with what they are doing (I told her months ago I recommended epoxy injection, she either forgot or disregarded it). I understand this is a common repair method in Florida, but I think that is based on experience and also there is no pressure to get it right (since no guarantee is offered). I think it is something these contractors find relatively straightforward and easy so why take a risk on a new method. Also, they just may not know about epoxy injection of cracks. But this is not how things change for the better, or how state of the art advances.

I know vinyl lining of existing concrete pools is done here, but it is pretty uncommon. The 1/4" wide crack was an estimate from several months ago, and likely includes the width of the crack after being ground out before the last time it was sealed.

My experience with concrete repair outside of the pool world lead me to epoxy pressure injection, which I have had success with several times, not to mention countless structures using epoxy-bolt applications. My research indicated it is a very common repair for basement walls and many of those repairs are now warrantied by the good contractors. However, we have very few basements in Florida, so contractors who do epoxy injection are likely mostly on the commercial side of things, repairing concrete balconies on ocean side hotels and condos for exampled, not doing residential repairs. They are not to be found in the local yellow pages, hence the problem and disconnect.

Thanks all for the input, its in the books now. I hope for the homeowner's sake that repair holds up. I told her it may indeed work, but it just wasn't my first choice.

Have you looked into any crystalline products. I actually just sat in on a lunch and learn yesterday put on by a rep for Xypex. We have used a similar product on projects and it's legit stuff. They have a whole bunch of different waterproofing and crack repair products. Here is the email for the rep if you want to get a hold of her. sandy.bradford@xypex.com

Sure, the contractor that didn't know anything about epoxy and thinks I am full of crap will love it when I recommend magic crystals....

I will let the homeowner do whatever she wants, which I am sure is whatever repair method they started. Next time don't bother asking me and wasting my time.

xypex works really well for small cracks... used it with success often... but, not so good for large cracks...

As someone noted... it's a matter of determining if the cracks are active... that will dictate the repair.

Dik

Just for posterity...

Here is a link to some guidelines on when to use epoxy or some other method of crack repair based partly on ACI 224:

Excellent link, CAB...

Dik