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Gen. Contractor
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How do you all tell a Customer when the flatwork you just poured gets a few cracks in it?

Let me give some background- it's a windy hot ***** here. We pour as early as the batch plant will show up, I put fiber, rebar, delay, joints as soon as it will hold the mark, cure/ sealer like a sob.
The batch plant says sorry it passed brake test must be surface drying out to quick- duh- no shiz.

What do you say when you did everything you know to do and it still doesn't come out perfect? Even if I offered to replace it what garuntees it doesn't crack again?
If I had the magic mojo to make concrete not crack I'd be rich.
 

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You must surrender to the shrinkage, Grasshopper.

You're trying everything you can to get it to not shrink, but it's gonna shrink and when it does, that's when it will crack. We recently placed a 40,000 sq ft shop floor at 8" thick with no control joints and no cracks. We're not ready to say we can pour crack-free slabs, but we have been have great success by doing a few simple things.

1) Pour on properly compacted road base, graded as close to pool-table flat as you can get.

2) Use a 10 or 15 mil vapor barrier sealed as tight as possible, and then a layer of regular visqueen on top of that as a slip-sheet.

3) Spray glue a good bond breaker like sill seal (or something a little thicker if you can find it-but NOT expansion joint material. Apply this to everything; foundations, columns, pipes-anything and everything sticking up out of the slab. What you are trying to do is allow the slab to shink without getting hung up on anything. This is why you want to use a foam of some kind instead of exp jt material-it needs to crush as the slab shrinks against it.

4) And last but not least-use a double dose of Macro Fiber-the stuff that looks like chopped up little chunks of baler twine. Yes, it will look like a lawn when you first lay it down, but once it's burned in with a machine most of it is gone. Hit it with a weed burner (carefully) after a few days to get rid of the rest.

More and more owners are opting for polished and stained concrete floors in public building for ease of maintenance, but cracks are the worst thing in the world for that look, so they are demanding innovative ways of achieving this.
 

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I explain concrete as Griz d described to everybody before we pour. In fifty years (knock on wood) my grandpa, dad or myself or brother have never had a structural crack in a foundation. Deep footings, beams, plenty of steel properly sized, tied properly and the right mix prevent that.

Every slab over the last 50 years has cosmetic cracks. It is what it is.
 

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I'm a believer in the Dayton Superior product J-74 aquafilm.
Im going to check that out :thumbsup:

We just use 6 mil. Small slabs near a lake, a shower liner. Shower liner is high :eek:
 

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How do you have a choice? I have no say in what goes in a structural slab.
If an engineer specs 6 mil, and I request an upgrade ( as I have with a shower liner) I have never been denied. If so, get a new engineer :thumbsup:
 

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If an engineer specs 6 mil, and I request an upgrade ( as I have with a shower liner) I have never been denied. If so, get a new engineer :thumbsup:
If an engineer specs something here, it's all that is needed. We have to get soils engineering as well. I trust my engineers enough not to feel the need to re-engineer it myself.
 

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If an engineer specs something here, it's all that is needed. We have to get soils engineering as well. I trust my engineers enough not to feel the need to re-engineer it myself.
I do stuff engineers don't require all the time.

I just gutted the inside of a house and built an elevator shaft in a four story house this spring. I put a shower liner in because it was 17 feet from the drink, and all the steel in the foundation was 5/8, instead of doing #5 in the beams and #3 in the field. He didnt say a word at inspection. I sleep a lot better knowing there will never be seepage.
 

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If an engineer specs something here, it's all that is needed. We have to get soils engineering as well. I trust my engineers enough not to feel the need to re-engineer it myself.
I get you though. Its the engineers call :thumbsup:

I just reserve the right to over do whatever I want on my projects if it makes me rest easier. :thumbup:
 

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I explain concrete as Griz d described to everybody before we pour. In fifty years (knock on wood) my grandpa, dad or myself or brother have never had a structural crack in a foundation. Deep footings, beams, plenty of steel properly sized, tied properly and the right mix prevent that.

Every slab over the last 50 years has cosmetic cracks. It is what it is.


In addition to the above,let me add. Many moons ago,I came across a publication pertaining to foundations produced by the Portland Cement Association. In that publication they advocate control joint installation / spacing vertically in poured walls. The joints are formed by placing triangular pieces of wood on interior of forms,directly opposing each other,total depth of joint to be 1 / 4 of pour thickness (same as flat work) In said publication,recommended spacing / location of joints are called out.


Adhering to this publication has provided me with many foundation pours free of unsightly random cracks. By the way,I'M a huge proponent of plasticizers / water reducers.
 

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We always champher (the 3/4 by 3/4 triangle wood mentioned) Architectural walls for crack control, but you usually don't see it in residential. I did sometimes when I did res, depended on how long the wall was. Over 30 feet or so and I would usually slap a CJ in the middle.

Oh-and the only guarantee I ever made on concrete was against theft and fire :laughing::laughing::laughing:
 

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when it gets to be a hot windy ***** where i am I try to pour on a non or less windy day early as possible in the morning, use a mag float vs the usual wood / resin , construct wind barriers if they can work and put a good evaporation retardant after the bull float , then put a good cure/seal on it . you have to really research and educate yourself on the evap redard and sealer before sing it so you fully understand it and can effectively use it . cut your losses and accept the reality all concrete cracks but now you know you need to take more precaution when pouring in such extreme conditions (or wait them out) and just fil the crack up with some simpson crack pack epoxy
 

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Utah high desert - 90F +, 15-20% RH. Am I right?

Tell them you did everything possible to minimize it due to conditions. You prevented having structural cracks, but you still have fine cracking that you'll fix.
 
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