5" floor fibermesh only

[wewiserangers]

I'm not a Concrete guy so I need some expert input.

Quoted a 5" floor for my shop with fiber mesh. No rebar or wire mesh. This is for a farm shop. I have a 10,000 lb tractor.

Concrete was quoted as 3500 psi. With 1' of base rock compacted.

Will this be adequate.

 

[Rusted Nut]

What’s the base below the 1” of rock? That’s the most important part. Fibers will somewhat help with small spider cracks, but IMO, not much else. Mesh/rebar will hold things together if it cracks, but doesn’t prevent cracking. Proper water control, expansion/control joints, and curing will minimize cracking. Search the forum for ConCretin, he has an excellent write up on slabs.

 

[wewiserangers]

Level well drained area. Clay base mostly

 

[Rusted Nut]

What is the compaction of the clay? I would think with clay, you would want rebar. Hopefully someone with more clay experience will weigh in here.

 

[slomaro3.4]

This is interesting, my 14'x24' is exactly this 4000psi 5" slab fiber mesh only (based on the amount of concrete poured I wound up closer to 6" avg), ~7" of gravel fill on a fairly sandy soil composition vapor barrier underneath as well. The concrete guy talked me into it citing the soil composition in my development and included . My use is fairly light, right now it's got a 2800lb fishing boat and eventually it'll get a 4 post lift.

Now IF I were parking a 10000lb vehicle in there, I would have probably wanted wire mesh or rebar, or IF I wanted a 2 post lift I would have done whatever the lift specs call for.

 

[Shiftless]

Concrete was quoted as 3500 psi. With 1' of base rock compacted.

What’s the base below the 1” of rock? That’s the most important part.

Let’s get this straight. Unless it was a typing error, the OP said one FOOT of base rock compacted… not one INCH. Big difference!

 

[wewiserangers]

Yes 1'. 12 inches of rock

 

[Rusted Nut]

Let’s get this straight. Unless it was a typing error, the OP said one FOOT of base rock compacted… not one INCH. Big difference!

Yea, I read that wrong. But still whatever is under the rock needs have good compaction.

 

[ScaldedDog]

I'd never place a slab, or even a sidewalk, without rebar. It's just a terrible place to cheap out. As others have said, the slab will crack. The questions are, will the cracks expand, or not? Will the slab shift so that the lip of the cracks are higher on one side than the other? Without rebar the answers to both will likely be 'yes'. With it, they'll likely both be 'no'.

Mark

 

[ericm]

If you're planning on installing a lift, check some lift manufacturer's specifications for concrete. The 10k two post lifts I'm looking at usually require rebar. That said if it was me I'd get a different quote with rebar.

 

[Sturgeon]

Half to go with the rebar and expansion joints. Unfortunately concrete cracks and all we can do is try to keep the cracks tight by using rebar. Also not many crack repair products that produce a neat alternative for to little rebar used. Look at it this way, you will be set for the future lift?

 

[Codyboy]

I'd never place a slab, or even a sidewalk, without rebar. It's just a terrible place to cheap out. As others have said, the slab will crack. The questions are, will the cracks expand, or not? Will the slab shift so that the lip of the cracks are higher on one side than the other? Without rebar the answers to both will likely be 'yes'. With it, they'll likely both be 'no'.

Mark

For a sidewalk at the least use some mesh.
Slabs and driveways always with rebar, yes.

OP has a 10k lb tractor.
Meh.
10k lb tractors have large tires and a large contact area. I wouldn't worry about that weight at all.

But as you mentioned the rebar will keep the inevitable cracks from separating or being uneven.
Fiber will not do that.

I cannot understand a reason why rebar wouldn't be used.
Cost?

It's a small price to pay up front , compared to shifting concrete and have to rip it out and start over.

No mention of digging out beams at least around the perimeter or piers where columns will be.
My 40x60 has a beam of 12x24 deep around the perimeter that sits on piers where the corners are and in where the I beams are located at 20ft o.c.
Further there is a grid 20ftx20ft of 12x12 beams for the whole floor.

Rebar is 3/8, 16" o.c. in the field , in the beams is 4 or 6, 1/2" rebar can't remember and piers are a spiral rebar with 6(?) Vertical members.

Do not skimp on concrete and reinforcement for it.

 

[Kaizen]

did my 30x36 with rebar in the thickened edge. OP are you not in a frost area?
I only had mesh in the middle 6" with 4k. I wanted a lift so i spent some time figureing out lift and door placemets and that dictated where I made my cuts. A 10k tractor carries and pulls some heavy stuff so make sure you account for the added weight or if you are storing that in there.

 

[ConCretin]

I realize the OP asked this question a month ago and has probably moved on but I'll add this for those that are interested. The most important question shouldn't be fiber vs rebar vs mesh, it should be how will the base under the slab be prepared. If the base under the slab is stable and able to support the loads placed on the slab, you don't need reinforcing at all. A 5" slab on a good base is plenty stout enough for virtually any use.

Fibermesh helps prevent or reduce shrinkage cracks but doesn't add much protection against loads. Steel reinforcing won't prevent a slab from cracking under load either and can actually increase the likelihood of shrinkage cracks. It's somewhat expensive insurance that if you do overload the base, the resultant cracks will be restrained from moving and the slabs basic integrity will be maintained. If however, your base is inadequate and continually overloaded, your slab is still in trouble regardless of how it's reinforced.

Before anyone gets exercised by the blasphemy, I'm referring to slabs on grade, which are basically non- structural work surfaces that depend on the soils below for support rather than thicker structural elements that are self supporting and do require rebar.