concrete slab for rv garage

[encantofred]

hi,

i looked at other posts but still wasnt sure what the right thing to do is.

i am going to have a 65x70 shop. i will put 2 55k lb RV's that have 3 axles each on them in it.

currently the contractor is saying 5" and 3500psi, no wire mesh or rebar.

this is not a money no object build but i do want to make sure there is no issues. i do not like the feel of fiber mesh in the concrete.

the ground here in arizona is rock hard and will be compacted as well before pour.

any suggestions from you concrete wizards or PE's?

thanks for you help

tom

 

[Big Gus]

My patio is 5-6" with wire mesh so I would think a shop floor would be more than that. I'm no expert though.

 

[kd3pc]

6" of 6,000 psi test concrete, with mesh or rebar should be just fine

 

[jimp]

I consider my slab to be the minimum, 60X72 red iron framed shop.

6" slab, 3500 psi.
#4-12" on center each way.
10" perimeter to frost line tying all the columu footings together with 3 #4 on bottom and 2 or 3 in the perimeter wall
All opposed column footings tied together with 4 # 4 rebar

I can't see anyone not using rebar in a slab bigger that 10'X10' and I would use it in that size.

 

[Mach5]

Don't know if you are here in the Valley (Maricopa County), but if you are you need to be mindful of the fact that there are several areas in the greater Phoenix metro where there are expansive soil conditions. Your rock hard soil will crack and heave your concrete to pieces when it expands with a heavy rain. I'd say for something that large you really want the opinion of a local PE.

 

[encantofred]

mach5, yea, this will be out in wittman. i think i will probably find a pe to figure it out.

thanks

tom

 

[wssix99]

hi,

i looked at other posts but still wasnt sure what the right thing to do is.

i am going to have a 65x70 shop. i will put 2 55k lb RV's that have 3 axles each on them in it.

currently the contractor is saying 5" and 3500psi, no wire mesh or rebar.

Strength-wise, this is just fine. The pressure on the concrete from your tires' contact patches is just a few tens or hundreds of PSI - no match for 3500 psi concrete. In a parking situation, you don't need the rebar for strength, either.

You DO need either closely spaced control cuts or more widely spaced control cuts with wire mesh or rebar to control shrinkage cracking, which will occur as the concrete cures. Likewise, adding more wire mesh or rebar or more closely spaced cuts will decrease the likelihood that you will have cracks outside of the control cuts.

this is not a money no object build but i do want to make sure there is no issues. i do not like the feel of fiber mesh in the concrete.

You should check out this recent thread, which has a good discussion of fiber vs. reinforcing, etc. http://www.garagejournal.com/forum/showthread.php?t=221030

I highly recommend putting in some wire mesh or rebar in addition to the fiber mesh. (if you like it)