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Do I need wire in the concrete?

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dmac1

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Having about a 6" floor poured with, I think, 3,000 psi concrete in a big garage that houses a couple trucks and our 13,000 lb fifth wheel. Also putting an apron out front of same concrete. The concrete guys says we don't need to reinforce it.

What do you think?

Thanks.
 
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dmac1

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Thanks.

Isn't the purpose to hold it in alignment when it cracks? Note - I didn't say if.

Does the strength of the concrete matter as to whether you use wire or not? I'm totally in the dark on this subject.

Thanks again!
 
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skyking

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It is the only integrity you have in the concrete. It holds the cracks together.It will crack.You need tied rebar. Get a new concrete man.
 
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Farmall450

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I agree that you definitely want some sort of grid interlocking it. I'd go with skyking's advice as well.
 
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FFRKing

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I just had a 30x50 pole barn garage built and the builder swore that wire wasn't needed with fiber reinforced concrete. When we got to talking about it, he said that it was not necessary in their area (Oklahoma) but if I had a lot of clay soil then it would be a good idea to add wire. I had it added along with the fiber in the concrete.
I know you didn't mention anything about fiber reinforced concrete but can't imagine that anyone would pour concrete without that as a minimum.
With the amount of weight your putting on it, I think wire would be a wise choice.
Cracks in concrete are almost as certain as death and taxes. You may be able to control it, but it's going to happen.

Chris
 

theoldwizard1

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Isn't the purpose to hold it in alignment when it cracks? Note - I didn't say if.

That is what I was told also. I paid for it when I had my driveway done 20+ years ago.

This is WIRE, NOT REBAR !
 
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dmac1

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Thanks for all the help guys! Had a different contractor out today and he will be doing the job...with wire. I think wire is adequate. Its on a firm base of some sort of compacted clay, rock mix that has sat for 10 years and been driven on all along. And he'll be using 4000 psi concrete.

In conjunction with this, we're gonna flush mount a BendPak SP-7X lift and it will have a rebar grid under it that will be tied to the main surrounding slab. The concrete for about 1' around it will be 10" thick cuz need 4" under where the lift mounts, then the 6" slab.

Also, this guy talked about putting expansion joint around our pole barn supports just to make sure nothing bad happens if things expand. Much more attention to detail.

Again, thanks!
Dave
 

TheEquineFencer

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Farmville, NC 27828
Having about a 6" floor poured with, I think, 3,000 psi concrete in a big garage that houses a couple trucks and our 13,000 lb fifth wheel. Also putting an apron out front of same concrete. The concrete guys says we don't need to reinforce it.

What do you think?

Thanks.

IMO, at your apron, dig a "footer" about 12 inches deep and 6 inches wide so you don't break a corner off if something heavy get on it.
 
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dmac1

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I asked a friend same question I posed here. Here is part of what he sent me off the Portland Cement Association website which is below:

http://members.cement.org/ebiz55/ProductCatalog/Product.aspx?ID=263

Can fibers replace wire mesh or welded wire fabric in a concrete slab on ground?

To answer this question, it is first necessary to establish why wire mesh or fibers would be used in a concrete slab. One of the main reasons is for crack control. PCA, however, states that cracks in slabs on ground can be controlled with uniform subgrade support and proper joint spacing (as a function of slab thickness). See Table 6-3 from PCA’s Concrete Floors on Ground, EB075.

Reinforcement for Floors on Ground
Is reinforcement necessary?

NO With uniform support and short joint spacing.

YES When long joint spacing is required or when joints are unacceptable in floor use.

Although short joint spacings alleviate the need for reinforcement, wire mesh will allow for increased distance between joints if correctly placed in the upper portion of the slab, at least two inches below the surface. In these slabs with longer joint spacings, the purpose of wire mesh is to hold random intermediate cracks tight.

Plastic fibers should not be expected to replace wire mesh in a slab on ground. However, although not affecting joint spacing, plastic fibers are used to reduce plastic shrinkage cracking.

Plastic shrinkage cracks are those that occur immediately following concrete placement, before the concrete has hardened. Plastic fibers are commonly dosed at 0.1 percent by volume for slabs on grade; this is equivalent to 1.5 pounds per cubic yard.

Although polypropylene fibers are among the most common for controlling plastic shrinkage cracking, there are many types of fibers in addition to polypropylene, including other plastic materials, such as nylon.

Fibers serve different purposes based on the characteristics of the material from which they are made. For instance, steel fibers provide high flexural strengths and impact resistance and are found in heavy-duty industrial floors.
 

Zrexxer

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Does the strength of the concrete matter as to whether you use wire or not?
The strength of the mix design that you're being quoted has nothing whatsoever to do with reinforcement. Whether the mix is specified as 3000 psi, or 4000 psi, or whatever, is compressive strength. It's a function of the amount of portland cement in the mix and the water-cement ratio, and the aggregates used to make the concrete.

Compressive strength is measured by casting a 6" dia x 12" long cylinder under uniform conditions, allowing it to cure a specified time, and crushing it in a special press that measures the force applied. The stress required to break the cylinder is specified in pounds per square inch.

Steel reinforcement is not used to improve compressive strength in concrete. It's there to provide flexural and tensile strength. Coming from a civil engineering background, I wouldn't make any concrete placement whatsoever without reinforcement, and I wouldn't place anything more structurally demanding than a residential driveway with welded wire mesh. A 6" thick 4K psi slab certainly is a candidate for a rebar mat IMO.

But, it's your decision and your money.
 
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BlackTalon

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Alexandria, VA
I would recommend complying with ACI's minimum recommended steel-to-concrete ratio of 0.0018 for temprature/shrinkage control. for a 6 inch thick slab that would mean a steel cross-sectional area of 0.13 sq in per linear foot of slab. So 6x6 -W7.5xW7.5 (0.15 sq in/ ft) at a minimum.
 

jocool1585

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Nov 23, 2008
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Steel in the floor and have them soff-cut it in the green zone. Concrete doesn't have to randomly crack.
 
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