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Question DetailsAsked on 8/21/2017

My 2 month old stamped concrete seems to be crumbling, is this normal?

We had a stamped concrete patio poured 2 months ago and it seems to be getting a lot of chips in it, they aren't on the top but they are located where the cuts are from the stamp, its literally crumbling in some areas. I can run my fingers across it and it falls apart. Is this normal for a newly poured patio.

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5 Answers

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Common, because many (or for residential sized jobs, probably most) contractors do not know about or care to take the trouble to do proper curing of the concrete, so that could be the problem.

You can see some pictures in similar questions here, FYI - those answers might help you: If these are cracks IN the concrete, see above photos and responses. But if these are real thin flakes, peeling off like sunburned skin, then they probably stamped it a bit wet so there was lattance (basically runny cement-rich water) on the surface - when they stamped the pattern it settled into the stamped cracks and because it was basically just cementy water, it did not cure right and formed basically a "skim" on the concrete, which was initially held in place by curing compound or sealant but is now peeling free. If that is the case, unlike the cracks shown in the first couple of questions above, you will also see it most likely in any formed control joints (straight grooves across the full dimension of the slab) UNLESS they were saw cut after it cured. One similar possibility - they stamped it too wet and retrowel the surface to clean up form "snags" - places the concrete stuck to an unoiled rubber/latex stamp), commonly sprinkling a bit of water on it, and in the retroweling some of the surface water and cement (laittance again) slopped down into the formed grooves, forming a very weak unbonded grout layer as above, which is now weathering out. If just peeling skin - very easily broken like pieces of frosting, not significant flakes or chunks of concrete, probably nothing to worry about - around 1000 psi pressure washing or brushing with a stiff brush or wire brush will likely remove them easily. However, if these are actual flakes of concrete - coming up as chunks with aggregate in them [rather than just very brittle and weak thin flakes or bits of sheet hardened grout], typically forming divots and little potholes in the concrete (and generally all over which you say it is not, not just in the formed grooves) then likely to be from incomplete curing causing the concrete to have failed to reach strength, so it is already weathering away. (Freeze-thaw damage also does this, but I doubt that is the case for a 2 month old slab unless you also have pet penguins and dogsled to work year around). IF you have substantial popouts (not just feather-thin flaking like peeling skin) ONLY in the formed grooves, then I would guess they put curing compound or form oil on the surface before stamping, then stamped - exposing the fresh concrete in the grooves and leaving the grooves unprotected and able to dry out and fail to cure right. [Usually the concrete should be stamped BEFORE curing compound is put on it, though some put it on initially after floating the surface (especially in serious drying conditions), then the form is oiled with form oil or release agent, the stamping done, then the full surface should be sprayed with curing compound and full curing procedure started. IF it is "crumbling", as you can dig more than paper-thickness flaking into the concrete at those points with a screwdriver say, then either it was allowed to lose its mix moisture, which it needs to form the minerals which bond the concrete together [it "cures" by forming minerals bonding the aggregate, using the cement and the water, NOT by drying like common glue for instance], or it was way short of cement or poorly mixed so there are areas (or entire mix) without adequate cement. IF you can dig into it like this, nothing can be done to fix it - will deteriorate fairly quickly (especially in freeze-thaw conditions) and contractor should replace it, or if he refuses you would need to call his bond to get the bonding company to repair it in lieu of him doing it. Hope this helped - if more than just very thin flakes of weak grout, sounds like something the contractor should be repairing.

Answered 3 years ago by LCD


Sorry about the answer being all run together - sometimes the Angies List computer does that - removing all the paragraph breaks.

But from the thumbs-up I guess the response got through OK - hope this was just laittance, not actual surface breakdown.

BTW - if just laittance, once it is scrubbed off would probably be an idea to put on a coat of concrete sealer if the surface does not bead jup and shed water, because if it is chipping off within 2 months I would guess they did not do that.

Answered 3 years ago by LCD


unfortunately this is definitely not just surface, or cracks, Well I guess some areas were cracks at some point then the crack became a chip when it goes all the way through, I hope that makes sense, big chunks of cement or aggragate like you describe would chunk off with a screw driver, it's especially bad on the control joints, looks like they were cut with wavy Scissors and each wave is a chunk out, but of course in no pattern. I can pickup the chunks and hold them in my hand. I wish I knew how to attach photos. The contractor came to the house and pretended not to see anything wrong.... Saying, what? what? That's a control joint. He told me I should have gotten pavers and did more research to know what I was buying.

Answered 3 years ago by Acaswell


Answered 3 years ago by Acaswell


More pictures

Answered 3 years ago by Acaswell


OK -- excellent photos BTW.

NO, not normal for new patio (nor should you be seeing things like that for 10 or so years, and that soon only in serious freeze-thaw country. One the joints with big popouts on one side and smaller, pretty minor edge breakoff on the other, the lesser damaged edges are probably about the limit between "normal" concrete behavior (though not usually by 2 months life and before any winter weather) and "excessive breakouts".

Hard to tell from a couple thousand miles away probably, but it appears from the photos that it is occurring all along but predominately only on one side of a given joint - or is that just because of the limited sample of photos ? I would say, if basically on one side of a given joint, that is has to do with the pulling of the stamp - that it lifted the edge of the concrete when it was pulled up, either due ot inadequate release agent on the stamp, or because the concrete was a bit too cured so instead of slipping out of the joint it was sticking to it and tearing the upper edge away - which would also explain the extreme straight and vertical edges and lack of concrete infill of the joints - so my guess is the concrete was a bit too far along the curing process when the stamping was done.

Could also be the concrete was not properly water cured, so the surface concrete and joints dried before the concrete was cured (needs free water for proper curing), making the concrete weak and prone to spalling. If that was the case, the general surface would also be weak and prone to popouts from impacts or sometimes even high heels and furniture legs.

Actually, some of those look like AWFULLY deep pattern joints - usually the stamped joints are much more rounded and shallower. Is there a chance the worst of those are not stamped joints, but rather saw-cut expansion joints - in which case perhaps the saw blade was catching at the back of the kerf on one side (either not tracking straight with the cut line, or possibly warped or not straight-mounted blade) so on one side of the cut it was catching and lifting the edge of the cut, cracking the "green" (cured enough to be coherent and stiff but not yet "hard) concrete. This happen much more easily on slopes and on concrete that is not as hard as it should be when it is cut. Some professional concrete cutting companies doing this on commercial jobs- Oh - OK - blew up the photos and some do look like saw cuts, but some like bottom photo are obviously stamping joints - which have some of the spalling but does not look as bad as at the saw cuts so might be two problems in workmanship there.

Another possible cause - at the stamped joints, not the saw cuts, is if they overfloated the concrete, bring cement to the surface as a wet cement slurry, which smooths and works easier (and this is a trick for concrete setting too fast) but it is in effect bringing a weak cement-only layer to the top, which then spalls and cracks easily. Looks like there might be some areas of this laittance in the field of the stamped areas too.

As for solution - I can't see a good solution for a "repair" of the chipouts themselves.

One (subject to your approval and maybe not acceptable color-wise if that is a surface dust-on coloring rather than mixed into the concrete full thickness - would be for him to come back and grind a bevel on the joints, beveling the edge so the chipouts are not noticeable.

Another solution, again quite potentially a color issue (I have only seen it in gray and black), is cleaning and filling the joints with elastomeric joint sealant to near concrete surface.

Other solution of course is, if he says he cannot do the job without the popouts, is for him to refund your money so you can go to a contractor who can do it acceptably, and if he refuses then contact his Bond company to call his bond for inadequate workmanship.

Unfortunately, from many years (OK, to be honest many decades) of inspecting concrete work and serving as a reviewer to the American Concrete Institute, probably about 60-70% of concrete jobs have significant, quality or safety-related errors in workmanship or technique (rarely in the concrete mix unless working in extreme weather conditions), and probably only about 10% are done professionally and per code without procedure or workmanship being called out and corrected by the inspector (if there is one on the job). Because almost all residential jobs have no on-site inspection during the concrete work, and the average contractor is both less qualified and has not been snubbed up by inspectors to doing top-notch work, those numbers are even worse for residential work, and a lot of those have to do with adding water to the mix or over-floating, doing surface treatment at the wrong time in the curing process, or failing to properly cure the concrete.

Answered 3 years ago by LCD

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