I would use 5/8 or 3/4" epoxy coated rebar on 12" grid with 8" slab. Overkill is good right?

So, care for a dissenting opinion from an engineer?

Concrete cracks when it sees tension loads.  It doesn't take much to crack it either, but it's really good at taking compressive loads.  Steel is really good in tension, you could take your two trucks and attach a piece of 1/2" rebar between them and play tug-o-war all day and not stretch it.  But a kid can bend it, because it's terrible in compression.

When you load a concrete slab it's trying to bend downward, putting the top into compression and the bottom into tension.

If you put your rebar right dead center you might help contain some cracking, but you haven't helped the slab to carry the loads.  You need steel as far from the load as you can get it, and still protect the steel from the elements.  So, 6" slab with the rebar at 3" means the rebar is right in the middle where it will almost never see load and the cracks in the slab have to move half-way through the slab before it becomes active.

8" slab with bar 2" from the bottom edge?  Suddenly you're taking load sooner and keeping the slab together better, especially helpful when dealing with a commercial slab like this where you need a good smooth floor for years.

Dude, hire an engineer.

That is reason enough to do it

I did 5" with rebar and fiber mesh for my driveway that only ever has at most a 2500HD diesel on it for 12 hours at a time.  If its worth doing its worth overdoing.

Don't forget the base over which you pour.  I used to have to pack the wet crushed gravel base with a jumping jack compacter for the heavy concrete pours.  The gravel ended up damned hard and packed down tight.

I went with that fiberglass slab and it started breaking apart after about 6 years, the rebar and wiremesh slab with the thicken edges that it connects to is still perfect 15 years later

I work on mainly post tension suspended slabs, parking garages and high rises. Frequently have 1" of clearance underneath the bottom mat of rebar and to the formed edge of the deck in Seattle.

Curious here-what psi is the threshold for punching shear?  Is it purely PSI or is there some foot area that defines the transition?

Does it help much to use steel plates to spread the load?

I am on the electrical side of engineering.

But i am drinking so i am not concerned woth loads.

Hahaba

Wait maybe i am fuck this shit.

This is the second time I've posted something similar to this today but it bears repeating.


Concrete threads here in GD crack me up.  (No pun, in this case, intended)

LOL

It's assumed that concrete breaks at a 45 degree angle, so if you're 6" thick and have a 12" footprint on top, you've got a ....  Carry the 3.... Divide by shoe size....  Bigger size at the bottom.

All of the paperwork the driver hands the crete inspector and us has the specs and the allowable amount of water we can add on site. I get the same sheet if I'm doing a side job, all I have to do is look at it to see what I can add.

It's not really, and I'll give you a good example.

Take decorative residential concrete.

Great stuff, but it is frequently ripped out and replaced within 20 years. Stamp preferences change, color preferences change with what is in style, and even with perfect upkeep, the surface gets a little beat up and you can't make it look like brand new again without re-doing it, especially here where salt is going to find it's way onto anywhere that sees foot traffic in the winter.

A 4" walkway with only fiber in it will come out easy as pie with a mini-ex, but if you rip into it and find out that it's 6" thick and has a rebar grid inside it, then it's change order time, and the labor to rip it out just went up, because now you need to get a hammer attachment, you have to pay a guy to stand there with a demo saw cutting the grid as you mangle it, the fill needs to be sorted from the scrap and taken away in separate loads if you don't have a place to dump reinforced fill (lots of people are picky about not having steel in the fill)

Over doing it on a job like that costs more money twice.

I'm looking for 95 percent modified or greater, or its back on the jumping jack for you

So the minimum slab thickness is 5"? Or am I not understanding what a formed edge is.

It means all the rebar in your slab needs to be 2" or more away from the forms.

That's your formed edge.

Concrete cover over rebar varies with exposure and rebar size

Concrete poured against earth:  3"

Concrete exposed to earth or weather
 #6 - #18 bar:   2"
 #5 bar and smaller: 1-1/2"

 (i.e. poured against forms, then stripped and backfilled)

Concrete not exposed to earth or weather (indoor slabs)  
 #14 - #18 bar:   1-1/2"
 #11 bar and smaller:  3/4"

Beams and columns:  1-1/2"

Without engineering it and knowing you will be loading it I'd say go with 6" depth with 1/2" rebar on 8" centers on 1-2" chairs.  The rebar and chairs make the pour harder so hopefully you have easy access.  Pumping it gets expensive and the concrete is a different mix with more reliability concerns.  Your biggest loadings could come from the cement truck when you  do a second pour and drive on the fresh concrete for better access.  Moist cure is always the best and wait for good cure if you have to do multiple pours.

I hate cracked concrete.

Helix concrete is what you want. Gov uses it for tanks too so it should easily handle your load.

Fibre and mesh cracks great

If you want rebar and a 4" slab you'd have to put a vapor barrier - 10 mil visqueen, or insulation board under the slab.

Assuming you're local code is based on the ACI 318 code / IBC  / RBC codes.

Walks sometimes, but hardly ever out here commercial.

Exception- steel fibers in earthquake retrofit.

The batchweights out here always show is any added water is allowed.

Its smarter to order the mud delivered at a placeable slump, and hold the ready mix company to that. They can easily deliver a performance mix needing no water added at an 8 if so desired.

I say garage but it will be more like a small warehouse 32 x42

It will have pallet racking and a small forklift.

My placement/finishing cost the same as 4" thick, pump has a minimum I was still under so I'm just out some $$ for the concrete itself.

And the thickness allowed me to put the bar lower in the slab to put it into tension.