concrete thickness and psi and reinforcement

[encantofred]

hi all,

what is the recommendation for an rv garage for the thickness of the concrete pad and the psi of the concrete and what type of re-enforcement. (lots of debates on re-bar or mesh i have read here).

the rv weighs 55,000 pounds.

no overkill, just what is necessary.

thanks

tom

 

[rburke65]

Re: concrete thickness and psi and re-enforcement

4" of concrete on a well compacted base.

 

[ConCretin]

Re: concrete thickness and psi and re-enforcement

I agree with rburke65 - the base material under the concrete is what's most important. 8-12" of well graded, granular material is generally adequate.

A 4" slab is adequate - you could go to 5" for peace of mind but more than that is probably overkill.

3000 psi concrete would be structurally adequate but you'll get a more durable surface with a richer mix. For a slab, I'd opt for at least a 3,500 lb mix and no more than 4,000.

For reinforcing, I prefer rebar over mesh for the simple reason that it's easier to support. #4's at 18" centers can be supported every 4' and will stay put when the finishing crew traipses all over it. It won't do you any good if it's laying on the ground.

Good luck with your project.

 

[The Boss]

Re: concrete thickness and psi and re-enforcement

^ Above is good advice. Concrete is great under compression, lousy under tension.

 

[budss396]

Re: concrete thickness and psi and re-enforcement

what you really need to know is the tire pressure on the slab, you need to the perimeter of the contact patch the tires. take the tire pressure and divide by the strength of the concrete and that will give you the thickness of the concrete. the amount of rebar will be specified in your local building code for temperature and shrinkage. if you cannot find in your local code look up an ACI manual at your local library or college library. at 55000 pounds you probabily have a pusher with singles in the front and 2 axles with duals in the back. to get a rough estimate of the tire pressure take 55000 and divide by the number of tires.

 

[encantofred]

Re: concrete thickness and psi and re-enforcement

i assume by tire pressure you mean the actual weight of each wheel on the concrete.

front tires are capable of 10,500lbs each (yea they are humongo micheline's 365/70r22.5)

tag axle tires are 6000lbs each tire and drive axle with 2 tires each side are 6250lbs each for the 4 of them.

the original fronts were rated at 9000lbs each and that is how i used the 55klbs total.

with the new upgraded front tires and wheels, that capacity goes up to 57klb.

it is a newell coach if anyone is interested.

so if i used the most heavy ones (fronts) at 10,500lb each, and 3000psi crete, that comes up with 3.5"

is that how you guys look at it?

thanks

tom

 

[ConCretin]

Don't over complicate this by worrying about the pressure exerted by the tires and for God's sake don't go looking for an ACI manual.

Think of it this way, when you're driving your RV on asphalt pavement, how often do you break through and get mired in the ground underneath. Concrete is a lot stronger than asphalt paving so parking your RV on it is not overly demanding.

Just build a good durable slab on a proper sub base. If you want to focus on what's important, focus on controlling mix water and curing. That's where problems are more likely to occur.

 

[Yorkisquared]

I would use 8" x 8" perimeter footing with 2 - #4 rebar and 4" slab with mesh.

 

[tncatadjuster]

Don't over complicate this by worrying about the pressure exerted by the tires and for God's sake don't go looking for an ACI manual.

I've been on both sides of these types of remarks.

 

[encantofred]

i am an engineer, so by definition i over analyze and over complicate everything.....

it is a curse....but a blessing in that i can figure just about anything out...

thanks for all of your comments.

later

tom