too g join:2014-08-28 Delhi, NY |
too g
Member
2014-Aug-28 6:07 am
need some concrete slab informationSo I finally got this slab poured yesterday, by the guy who is my contractor friend. Let me preface my question(s) with the disclaimer that he had put an addition on my barn which included pouring a slab for the floor that turned out just fine.
It's in front of the house. I have a packed item 4 driveway. I wanted an area where I wouldn't need to be on my back in the dirt under my car. Have had enough of that. Also, when we get out of the car when it's raining we won't be tracking so much mud into the house. And I can wash the car without standing in mud.
I heat with an outdoor water fired boiler. The driveway is a loop and tri axle trucks will be passing over the slab, as will the propane truck and, in rare instances, the fuel oil truck.
He used rebar for this job. The slab was ~six in., ~35X30. The slab is in four "squares." As regarding the rebar, he laid it out in a grid which extended under the cross forms (not the perimeter). That is, each square did not have its own grid and the bar was laying on the ground. I brought to his attention that there wouldn't be much reinforcement that way and he assured me that they would lift it up during the pour so it would end up in the bulk of the concrete. Seeing as how the grid was on the ground under the cross forms I didn't really see how that was going to work so well. And in fact I don't think it did.
While pouring the second square they had too much concrete and so shoveled the excess into what turned out to be square four. In the mean time it was walked on, a lot, and by the time square four was poured it was pretty hard. Is that concrete now part of the slab, or is the slab thinner in those areas by the thickness of the hardened material?
In two of the squares they didn't do such a good job screeding and there are undulations. I mean, put a level across the top and there is an 1/2 - 3/4 in. space underneath. Is this something I should make an issue of? I really don't consider this to be acceptable but if it sounds like it's within some industry acceptable standard I can live with it. If it isn't, how can it be made reasonably flat?
He used pressure treated 2X4 for the cross frame, which means there is concrete beneath the wood. Is that an issue, like is that now a two inch slab with a piece of wood on top of it? The wood was left in place as the expansion joints. Also, the wood sits proud of the concrete surface for some lengths depending on how well they screed. Should I ask that it be knocked down? It looks to me that it's going to be a problem the first time I plow this winter.
I'd like to hear some comments, mainly constructive in nature if possible.
Thanks,
G |
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A couple of pictures would really help. |
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said by bmilone2:A couple of pictures would really help. Agreed. Having a hard time picturing a pro job turning out as described. |
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Msradell Premium Member join:2008-12-25 Louisville, KY |
to too g
As the previous posters mentioned, some pictures would be very helpful. From your description it sounds like there are some things that definitely need to be corrected. |
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BubbaGIT-R-DONE MVM join:2002-08-19 St. Andrews |
to too g
Just curious if you have spoken to your "friend" about your concerns ?
A couple of the issues you have described....properly lifting the rebar(which is not an issue if done properly at the right time during pour), the undulations would definetly cause me to say Crap more than once, the expansion joint could be an issue but without seeing the before pour, it would not be proper for me to express much of an opinion !
Can only hope this "friend" will accept your questioning of his work given your description ! |
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robbin Mod join:2000-09-21 Leander, TX
1 recommendation |
to too g
said by too g:He used pressure treated 2X4 for the cross frame, which means there is concrete beneath the wood. Is that an issue, like is that now a two inch slab with a piece of wood on top of it? The wood was left in place as the expansion joints. Rather late to be asking for advise on the proper material for expansion joints. This should have been addressed before the pour. |
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DataDocMy avatar looks like me, if I was 2D. Premium Member join:2000-05-14 Hedgesville, WV
1 recommendation |
to too g
Regardless how this turns out, every time you look at that slab, you'll think of your friend. |
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MaynardKrebsWe did it. We heaved Steve. Yipee. Premium Member join:2009-06-17
1 recommendation |
to too g
Wood embedded in the concrete is a no-no. Your slab is MUCH thinner there and WILL crack in those locations - probably the first time a heavily loaded truck rolls over it. If he wanted a crack-control joint, the concrete should have been poured either monolithic and then saw-cut afterwards, or poured as separate pads with proper expansion joint material placed between each pour. The rebar placement is all WRONG. Steel rebar and concrete have about the same density. There's no way that the rebar would magically 'float' into the correct depth in the concrete. The rebar should have been sitting on rebar 'chairs' set at the correct depth from the surface ( see » www.polylok.com/showprod ··· e-chairs for but one example). I'll bet the rebar isn't epoxy coated either - though in fairness, that's not common in residential slab-on-grade use. The undulations will pose a trip hazard - there's a reason sidewalks/driveways are poured flat/uniform slope. Ever walk along a sidewalk where a driveway cutout is and feel the pavement 'fall out' beneath your step? 1/2"-3/4" of an inch difference is enough to buckle a knee or twist an ankle if you have any pre-existing knee/ankle problems. Suggest you re-check your homeowners insurance policy for adequate coverage. Then there appears to be the matter of the missing 6"x6" wire mesh which should have been embedded in the concrete - about 1-1/2"-2" below the surface to help prevent cracking. This is a classic example of a job being done without written specs (do you even know what the compressive strength of the concrete is, whether it's properly air-entrained for freezing exposure, what type of base is there and whether it's compressed enough to support the loads you expect, no specification as to 'flatness' or slope), and done via a drinking buddy who says "Don't worry". |
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Msradell Premium Member join:2008-12-25 Louisville, KY |
Msradell
Premium Member
2014-Aug-28 6:38 pm
said by MaynardKrebs:Then there appears to be the matter of the missing 6"x6" wire mesh which should have been embedded in the concrete - about 1-1/2"-2" below the surface to help prevent cracking. The one thing the contractor who did the country did correctly was to leave out the wire mesh!! The only thing it does is hold the broken pieces of concrete together and make it harder to take a slab apart. The OP said in his original post that the contractor used rebar which is much better anyway. The fact that the rebar wasn't done correctly and placed on chairs is a completely different matter, it's always stronger and holds up better than the wire mesh does. |
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to too g
That is a classic "bubba with a 12 pack" job. Wooden expansion joints are going to rot away. Wet wood will freeze and expand in the winter which isn't going to do you any favors.
They should have poured it as one huge slab and cut expansion joints or poured each piece separately using rubberized expansion joints. The rebar setup sounds like a fubar. Did they use remesh and rebar? Or fibermesh in the mix? |
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Hellrazor |
to Msradell
said by Msradell:The one thing the contractor who did the country did correctly was to leave out the wire mesh!! The only thing it does is hold the broken pieces of concrete together and make it harder to take a slab apart. DUH! That is the whole idea of using remesh. It prevents cracked or damaged concrete from heaving all over the place. Jackhammer and bolt cutters to remove it later. |
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natedjElected Premium Member join:2001-06-06 Irmo, SC |
to too g
From reading the OP's post, I think the the OP is confusing WWF ( welded wire fabric) as rebar when actually they are not the same. If the contractor had plans to " pull up" the reinforcement during the pour, then it is most likely not rebar.
Frankly, the wire mesh ends up to the bottom of the slabs more often than not, due to pour placement. My take is this. Since the OP opted for a Six inch slab and it would be used for a residential application, I wouldn't worry too much about the reinf.
The 2x4 as a slab joint is cause for concern. I've seen this done using 1x material and even that is not right because it will eventually succumb to mother nature and you will end up with a trough that weeds will thrive in.
As far as the uneven slab goes, you'll have to show us a photo of the areas because I'm not sure if the contractor was trying to crown the slab to provide drainage or if he was in a hurry to get the job done. |
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too g join:2014-08-28 Delhi, NY |
too g
Member
2014-Aug-29 8:35 am
I spoke with my guy yesterday and voiced my displeasure. His response to the 2X4's is that if there is going to be any cracking it will be there. More or less a stress relief type of thing. I decided against telling him about martensitic phase transformation toughened zirconia.
His response to the rebar was that doing it that way would prevent differential heaving of the squares, and stands by the lift as you pour. I could see how if each square had its own grid the lifting technique might work. However it was continuous (hence his heaving argument) and under the expansion joint 2X4s and lifting didnt accomplish much. The slab was poured on top of the existing hard pan, there's no layer of crushed stone underneath, which was my decision. I also mentioned it being inadvisable to leave ferrous metals in contact with the ground.
The rebar was rebar, not mesh or similar product. It was 3000# concrete according to the invoice, that's the only information I have. No fiberglass. I'll post some pictures.
My main concern here is to what extent has the structural integrity been compromised. We didn't get too deep into the cosmetic issues, which to the extent that they can, will be fairly easy to remediate.
BTW, I have a M.S. in ceramic engineering and intuitively know the answers to my questions but I need to hear it from those who can provide informed opinion. That way I have reinforcement for my argument and be better educated, both as a dumb homeowner and a dedicated DIY'er
I left it that I would get back to him next week after having had a chance to consult with my go-to concrete guys, namely, you guys.
I'm still a film guy but my sister in law is here with a digital camera and I'll get some photos.
G |
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tp0dyabbazooie Premium Member join:2001-02-13 Bulger, PA |
tp0d to too g
Premium Member
2014-Aug-30 3:53 pm
to too g
I think your biggest problem was going cheap and hiring a 'friend' to do it.. Gonna prolly end up with a shitty job, and might lose a friend.
-j |
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too g join:2014-08-28 Delhi, NY |
too g
Member
2014-Sep-3 10:23 am
Posted some photosI posted photos here: » www.flickr.com/photos/to ··· 2446120/My friend further states that expansion joints accommodate expansion/contraction through the thickness, not horizontally. Is that true? His solution is to remove the wood and replace with appropriate expansion joint material, cut the slabs loose from one another and grind out the surface discontinuities with one of those grinders that looks like a floor polisher. And provide a five year warranty that if it fails he'll then remove the slabs and redo the job correctly. |
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gbwalsh join:2010-07-25 Burlington, ON |
I don't know the answers to your questions but If that was mine I would be very disappointed. The waves in the first 3 pictures are awful. I am having a house built and the concrete work I thought was bad but looking at your pictures make me feel a little better. Sorry. |
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chamberc Premium Member join:2008-08-05 Addison, TX |
to too g
That is a complete disaster. If it was free, then I wouldn't complain. If you paid, you need to have it ripped out and done correctly. |
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to too g
Re: need some concrete slab informationThat looks very rough. |
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psiu join:2004-01-20 Farmington, MI |
to too g
Just looked at the pictures...holy...
Let's just put it this way: I've never done my concrete work. Don't know dick about it. But I WOULD do a better job than that.
The fact that it is supposedly done by a professional makes it all the worse -- if you're a pro, your work will always be professional (and I don't care if it's just for beer).
Maybe lesser grade materials on a residential job versus a commercial or industrial job, but the workmanship should be the same.
edit: I mean...YOU would have done a better job, without the experience and access to the tools and equipment and manpower, and that's basically the whole problem, right there. |
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67845017 (banned) join:2000-12-17 Naperville, IL |
to too g
Re: Posted some photosHoly WTF! I don't know anything about concrete really, but I know a poor job when I see one. I'm not sure what recourse you have at this point, but I'm sorry you're having to deal with it all. It's really a botched job. |
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guppy_fish Premium Member join:2003-12-09 Palm Harbor, FL |
to too g
What a cluster *&^%
I do know some about concrete and whom ever did the job is clueless. There should be no wood in the expansion joints, which by the way are made when doing the finishing. The screen work was done by people that at best have never used the tools before.
Worst job I have ever seen posted in 11 years of being a member of this site for concrete work.
It should be removed and redone. |
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Msradell Premium Member join:2008-12-25 Louisville, KY |
to too g
Re: need some concrete slab informationI certainly agree that that job looks far from professional but the fact that wood was used in the expansion joints may or may not be a problem. That is done quite often in the area where I live, especially for residential driveways. Obviously the local contractors think it gives a nice look. It does work very well to ensure that the cracks happen in the joints and as long as the wood is sealed along with the driveway it holds up very well. There are many driveways around here that are 20+ years old and the wood looks like new! As for the rest of the workmanship, it's terrible as everyone else has mentioned. |
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gaforces (banned)United We Stand, Divided We Fall join:2002-04-07 Santa Cruz, CA |
to too g
Not acceptable, uneven surface is a tripping hazard. Could have been worse I guess. I have seen worse homeowner DIY jobs. |
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to Msradell
said by Msradell:I certainly agree that that job looks far from professional but the fact that wood was used in the expansion joints may or may not be a problem. That is done quite often in the area where I live, especially for residential driveways. Obviously the local contractors think it gives a nice look. It does work very well to ensure that the cracks happen in the joints and as long as the wood is sealed along with the driveway it holds up very well. There are many driveways around here that are 20+ years old and the wood looks like new! As for the rest of the workmanship, it's terrible as everyone else has mentioned. +1 Contractor used 1x4's in my driveway at my old home when it was built in 1984. Still look like new and no cracks. One section however has spalling. Must have been a bad batch as the other sections are fine. |
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to too g
Re: Posted some photossaid by too g:His solution is to remove the wood and replace with appropriate expansion joint material, I suppose you can do that. Though the "expansion joint material" will be 1x, and you have 2x4s in there now, so its going to look silly when he stuffs 2 pieces in there to fill the gap. said by too g:cut the slabs loose from one another ok said by too g: and grind out the surface discontinuities with one of those grinders that looks like a floor polisher. When you take off the surface, you'll have exposed rock. There is a reason concrete is "finished" on the top. Even IF he can somehow get the surface leveled out that way, its going to look like crap. said by too g: And provide a five year warranty that if it fails he'll then remove the slabs and redo the job correctly.
What is his definition of failed? Because from your pictures, it looks like the "failure" on this project occurred the moment you hired him. |
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PacratOld and Cranky MVM join:2001-03-10 Cortland, OH |
to too g
Re: need some concrete slab informationJust my $.02... that has to be, by far, the crappiest-looking "professionally" poured concrete job I have ever seen. It doesn't even look like he used a bull float on it at all. Was he short of manpower or what?!?!? There's no real excuse for that job if the guy is a pro. "Hey, Bubba... hold my beer while I finish this paving job!" comes immediately to mind. The heaviest "expansion" joint material I have ever seen is around ½"... and it looked like tar-impregnated Celotex. certainly not a damn 2x4. I'm afraid you're pretty screwed... and likely to lose a "friend" if you demand it be made right. With friends like that, you don't need any enemies. |
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BubbaGIT-R-DONE MVM join:2002-08-19 St. Andrews
1 recommendation |
Bubba
MVM
2014-Sep-3 4:27 pm
said by Pacrat:"Hey, Bubba... hold my beer while I finish this paving job!" Can't rite now, I'd have to put my beers down As for the concrete job, in all my 40 odd years of construction work, I honestly would be ashamed if I slept good at night knowing I charged someone for that job. I will say however, there is nothing wrong with wood as an expansion joint if the proper wood type is used. |
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said by Bubba: there is nothing wrong with wood as an expansion joint if the proper wood type is used. Right, usually 1x whatever the concrete depth is. 1x4 in a 4" sidewalk slab is common around here. But a 2x4 in what looks like a 6" slab is just creating a very deep and wide crack joint, not an expansion joint. |
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to 67845017
Re: Posted some photosWhat he said... That is not acceptable for a contractor job. The uneven areas at the wood is caused by a pour job at leveling each concrete slab. They tried to fix the height issue by tapering it to the wood in a 4" wide area. You could talk to a concrete grinding contractor and see if they can level it out. It will expose aggregate but it would smooth it out. |
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