new stamped concrete is already cracking.


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Old 05-29-05, 09:07 AM
annie63
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new stamped concrete is already cracking.

We had stamped concrete put around our pool and patio and it has already cracked in several places. The contractors attitude is "oh well there is nothing guaranteeing it not to crack". It has been in only a month or so. We don't know what to do but it doesn't seem like we should have to accept that as an answer. Any help or advice on stamped concrete would be so appreciated!
Annie
 
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Old 05-29-05, 09:33 AM
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Welcome to the forum
Wish I had the answer you are wanting to hear but unfortunatly all concrete is apt to crack. To minimize cracks steps need to be taken before the concrete is poured. Most important is site preparation. Any fill needs to be well packed. [#1 cause of cracks IMO] Stamped concrete is no more or less apt to crack. It may be easier to patch the cracks and have them not as noticable. Unless the concrete was poured to thin or the contractor was negligent in some other way I doubt you will able to do anything about it.
 
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Old 05-29-05, 11:06 AM
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Cracked Concrete

If you have concrete it is going to crack. That is the law of cement and concrete. The stamping had nothing to do with the cracking. Probably neither did the contractor. As mentioned before, a solid base with about 4" of power packed sand is needed for a good base. However, the strength of the concrete has alot to do with it. 3000 psi, 4000 psi, 5000 psi. I never use 3000 psi. Also was rebar used ? Or matted concrete used. These are all items that will make the concrete stronger. I only know of 1 time in 30 years where the contractor redid the job for free. That's just the nature of the beast. Sorry about that. Good Luck
 
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Old 05-29-05, 06:31 PM
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Check with your Better Bussiness Board, and check to see if there is a licencing body in your area or take them to small claims court, Most reliable companies gurantee their work for at least a year.
 
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Old 11-16-05, 03:08 AM
PA_mason
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Cool

Annie, hopefully my response isnt too late for this problem, dont let these people that posted fool you, it IS the contractors fault, i have been in masonry for over 6 years, i've gotten a good hand on how the installation goes with stamped concrete, was it a hot day outside when the stamped concrete was installed? this is one of the biggest problems with cracking, if your installer has cut expansion joints in the walkway, there is no reason for the small/ to hairline like cracks around the faces of the stamped stone. These small, hair-like cracks, occur because of the neglect to stamp the concrete in due time, or the installer waiting too long to stamp it after the dust/color was put onto the poured concrete, the combination of the coloring they use and it being a good hot day outside will make it too dry too quick, then when they stamp the actual concrete, it's cracks the facing while in the process, it gives the concrete a hard crust on the surface. when the stamps are pressed into it, it has been too dry, and not enough wetness to form it correctly into the stamp, and so it cracks. i've seen this too many times, dont let the contracter take advantage of you, it is there responsibility to cut out the walkway and replace it. this stuff is way too expensive for what it is to just let it go. i would suggest pointing out that fact to the installer, after they realize you now know what happened, they should be fixing it in due time, if they dont, i would suggest small claims court, and a bad recommendation to all who inquire, about the contractor. if you have further questions or pictures you would like to send of this, please feel free to contact me, ***********@*******.com



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Old 11-16-05, 04:13 AM
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I have been a concrete finisher for over 20 years and the last 10 have done stamped concrete exclusively. Everyone posting so far is partially right, but about different things. First, all concrete will crack. Stamped concrete, although more expensive, is just concrete and will crack for the same reasons. These include but are not limited to:
1) Poor substrate preparation. If the area was not levelled and well compacted, the concrete can sink and crack. Have you noticed any settling?
2) No reinforcement. Did they use wire mesh, fiber in the mix, or rebar? These things will not definitely stop cracking, but can minimize it or hold the slab together when it does crack.
3) Crack control joints. These are the cut "lines" in all decent concrete. They are a place where the contractor makes a groove, (usually by saw cutting it in stamped concrete applications) or by tooling it in with a joint tool. These create a weakened line in the plane of the concrete to control where it will crack. Proper placement, such as off all inside-pointing (re-entrant corners) is crucial. Also around anything poured into the concrete such as a skimmer box cover. If the joints are correctly spaced and cut, the concrete should crack there. They should be cut as soon as the slab will not chip or ravel around the saw blade. We do ours early the next day in the summer, and after 2 days in cold weather. You have to do it before the slab can crack on its own. There should not be any area over about 10' x 10' that does not have a joint in it.
4) Concrete slump. This is a measure of how "wet" the concrete is. If concrete is poured too wet, such as if the contractor added a large amount of water to the truck to make his job easier, then the mix has been weakened and is more likely to crack. These cracks occur due to shrinkage as the concrete sets up. They usually happen within a day or two of pouring. This is my personal guess as to the cause of your cracking. Ask to see a copy of the batch ticket from the concrete plant. It will say what the slump was when it was batched, and the drivers are supposed to write down any water that was added on site. They don't always do it though. If they added a lot of water on site, or the mix was batched out in excess of a 5 inch slump (with no plasticising admixtures) then it was probably too wet and you may have some recourse.
5) Improper finishing. Sometimes the concrete sets up faster than it can be stamped. If the finishers were stomping hard on the stamps to get an impression, or using a pounder to hit the stamps hard, then it may have been too hard. The pounding could have actually caused the cracks. These will usually show up only around the edges of the slab. However, you can also pound hard to get an impression with no ill effects.

Are these cracks long, separated cracks, or little tiny fractures around each "stone" in the pattern? Do they originate at corners? Are there many crack control joints (grooves) in the slab? If I knew more, I could answer the question better. Keep in mind though, that there are several causes of cracking, and no one I know of guarantees against it. I doubt you would win a court case unless the cracks open up more than 1/8 inch, exhibit differential settling between pieces of the slab, or you could prove that the contractor was negligent, and that would be very hard to do.

Pecos
 
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Old 11-16-05, 04:22 AM
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Pa Mason,
The small, hairline cracks around the "stones" in a pattern can occur even if your timing is right when stamping. They are caused by the concrete drying out on top and creating surface tension. When somthing like the edge of a "stone" in the stamp is pressed down into the slab, the over-dried top wiil split open, like the crust on a baked pie. These cracks are strictly cosmetic, not structural. They don't go all the way through the depth of the slab like a structural crack.
They are caused by closing the surface of the concrete too soon (with a steel trowel or even a magnesium float), while it is still wet underneath. They are usually compouded by windy conditons that dry the top of the concrete before it is set up underneath. They are easily fixable by a knowledgeable contractor.

Pecos
 
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Old 11-16-05, 05:28 AM
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Wow! I just looked at the original posting date. Sorry for the long-winded reply, but I thought this was a fresh thread.
 
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Old 11-27-05, 01:38 AM
Huni
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Hello all.

I am new to this forum so if I do something stupid....

I was googling "new stamped concrete cracked" when I stumbled on this thread. I noticed that some of the replies are fairly recent so I hope my question is still fresh.

I am writing this on behalf of my aging mother.( I am not lying) Unbenounced to me, she decided to go ahead with a huge patio project which included a flagstone-like pattern stamped into the concrete. It was also colored. All that I have uncovered so far is that the colorant was tossed on top and the job was done in late June/early July of this year.

When I first saw it, I was not impressed. I am an exotic hardwood refinisher, working on mostly very high-end yachts but I temper my anality when it comes to residential work. This being said, it looked like crap.

First, about 75% of the 630 sq. ft. poured has double lines where the mold or stamp perimiter met the perimiter of a previous effort. This made for very wide "grout" lines usually with a raised thin line in the middle. There are also many "missed" stamps that cut the corners of the patterns or bisected some edges of the pattern. Then there areas that the pattern and grout lines are barely visible. On some of the walkway and close to the step, it is smooth, no pattern at all. To add to the fun, a partial hand print, several deep brush-like marks, and areas that look pockmarked, which on closer inspection, are tiny pebbles. Oh!, I almost forgot, a nice crack close to where the patio ends and the walkway begins.

The patio does have several grooves cut into it. At every 10 square, I have not measured. I had the contractor out today to look at this and 50 other things. When asked to explain the reasons of why I considered this an inferior stamping job,(I had not discovered the crack yet or found you guys), his response was that it can't be perfect everywhere. To which I asked, "Can it be perfect somewhere?" It was obvious that he was not going to crack, pun intended, under my pressure.

My question to you professionals is this: since the entire job, not just the concrete, has numerous other defects and re-do's, how can I incorporate the lousy stamp job as a re-do, or can it be fixed? I now know what he is going to say when I show him the crack, but if he thinks this is of industry standard quality, should I get a second opinion?

Also, with what limited and poorly described information I have given, are there any probable causes? I know one: he slipped while reaching for his beer and stuck his hand in the mud. I wish I could laugh.

Any help in this matter will be greatly appreciated!

Huni
 
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Old 11-27-05, 07:16 AM
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Huni,
Everywhere I go I notice defects in workmanship. Jobs that other people think look good, I think look like crap. Because you are a high-end tradesman yourself, it is natural for you to notice all the defects. Did anyone else notice them before you said something about them? Is your mother satisfied with the job? Has she paid the contractor in full? If so, maybe it's best to let it go.
There are several possible causes for the poor workmanship. Most of them are probably due to the stamper's inexperience. The lack of texture at one end of the job is a classic example of the concrete setting up before the stamper could get to it. The double lines and overlaps are because the stamper did not keep the stamps butted together properly. It takes a lot of patience to do a great job, and concrete won't wait for you.
Thousands of contractors get into this field each year because it looks like easy money. Thousands drop out after a bad job or two. You can only lose so much profit before you realize you're in over your head. How long has your guy been stamping? How many successful jobs has he completed?
Unless the concrete is unstable or you could prove negligence, I doubt that you would win a court case against this guy, even if you deserve to win. Get some opinions from other stamp contractors close to home. If you're still holding back some money from the contractor, maybe one of them would be willing to try fixing this job for the difference. If not, then maybe they could tell by looking at it exactly what went wrong. There is very little that a highly experienced stamp contractor can't fix, including the problems you outlined. The crack is another matter. It can be patched, but most likely it will come back quickly. Good luck.

Pecos
 
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Old 11-27-05, 07:25 AM
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As a side note, I made a lot of money this year fixing jobs that were botched by other contractors. I charged the homeowners a fair price for my labor, but they still ended up paying a lot more than they would have if they had hired a competent contractor in the first place.
Homeowners, PLEASE check references and look at prior work before hiring a contractor. I know it's attractive to go with a low price, but this practice usually ends up costing you a LOT more money in the long run.

Pecos
 
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Old 11-27-05, 06:55 PM
Huni
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New Stamped Concrete Problems

Pecos:

Thank you for your prompt reply. You are correct in the assumption that do to my line of work, I can see a flaw on an flea. Trust me when I say I GREATLY relax my standards when looking at residential construction. In these instances, I also rely heavily on the eyes and opinions of others instead of my own.

The items in my last post were noticed by everybody. My mother is satisfied but she has rarely, if ever, complained about the quality of anything. Plus, if this job goes south in a hurry, it will be me who will have to come back and pick up the pieces. This is why I need to address the plethora of other problems incurred now, along with the concrete.

The contractor gave a one year warranty on the entire job, so I guess the patio concrete would be included. She lives in the Bay Area and was charged $7,000 for 736 sq. ft. of concrete poured. This price was ONLY for forming, pouring, stamping, and coloring. The 4" excavation of the dirt etc., was extra.

One last thing, I found out where the new crack originated. There is a purposely made deep groove( to prevent cracks, I think), where the end of the patio stops and the walkway begins. It is from this groove, that the crack starts and works it way back into the patio portion for about five feet all the way to the edge.

I realize that cracks are common, but what could cause it to emanate from the groove that is suppose to prevent this?

Thanks for your help,

Huni
 
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Old 11-27-05, 07:26 PM
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To be effective, a joint should be cut or tooled 1/4 way through the slab. That is, for a 4" slab, the joint should be at least 1" deep. If it is shallower than that, it could be the reason for the crack.

Pecos
 
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Old 11-28-05, 10:56 PM
Huni
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New Stamped Concrete Cracked

I measured the depth of the expansion joint, where the crack started, and the thickness of the slab itself. Thickness was 3.75", joint was .5" deep. Looks like the concrete guy should have cut the grooves a bit deeper.

Thanks for your help,

Huni
 
 

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