How thick a slab for a bus?

[belfert]

Do I really need anything more than a 4" concrete slab to support a bus? 

One of the cities I'm looking at for a lot to build a house requires a asphalt/concrete driveway and I don't want asphalt again.

Brian Elfert

[Beatenbo]

Not if you like to look at big cracks!! I mean in the concrete. The front of a bus may be OK but a MCI has 10 tons on the rear. I wouldn't think of less than 6" with reinforcement. You could probaly hear 4" breaking under you.

[Jerry32]

In my Garage I poured 4" on the car side and 6" on the bus side. Jerry

[Iver]

Shop floor 50'x28' with 40' pit...... conc. 4" to 5" thick,  3/8" rebar at 18"centers both ways,  hard concrete with fibers on a good solid base.....
Two MCI-9's parked on it and no cracks in 3 years....
        Iver.

[niles500]

Iver has it right - What's your sub-base (soil condition)? With the proper sub-base and 3000 psi fibered concrete 4" MIGHT BE DOABLE - FWIW

[tomhamrick]

I have a 300 foot concrete driveway, a 100 X 50 concrete pad between the house and the garage, and the 30 X 50 garage where the bus is parked. All of this is a 4" slab that is 10 years old with no problems. I also have hydraulic jacks on my bus and have had all wheels off the ground for extended periods placing all weight on the the jacks. The base is important.  Of course I do have an Eagle and some of you would say that since half of it has rusted away, it doesn't weigh much!! 
Tom Hamrick
1984 Eagle 10S

[Stan]

Along with the question of good base, I notice Iver says 4" to 5" of concrete. Most contractors use a 2 x 4  (3 1/2") for a form and then tend to push a little extra dirt toward the center. The 4" slab you pay for may be less than 3" where you put the wheels.

[Ace]

On the property/house we just purchased there is a 310 foot long driveway (concrete) and a pad off the house that measures 75x50. This is where we are building a shop combined with 2 car garage. The contractor had to cut out part of the slab for footers and he measured 6 inches thick and while cutting and digging he had to cut thru rebarb and wire mesh. It was a job to say the least. Our neighbor tells me that the previous owner had a small business that involved trucks. Don't know how large but the slab is not hurt in any way. I think it will handle the buss easy!

Now my old house had a 4 inch thick driveway about 45 foot long. Just long enough for the bus, but after making a stone pad for the bus I noticed where the driveway has cracks in it where they weren't before!

If you can afford it, do the better thing and make it right for the bus! It's a lot more expensive to fix it later!

Ace

[kyle4501]

The base is all important in determining the type of pad on top. So is the quality of the work in pouring the slab.

I poured 7" thick & paid extra for 4000psi concrete. 1 year later, I had cracks & shifting. The contractor isn't in business any more (I can't imagine why), so I'm stuck with it. 

[zimtok]

I did my own driveway about 2 years ago. I didn't have the bus at the time.
I dug it out to at least 4" and in most places it was 5".
3000lb concrete.

I had cracks before the bus, but they have not gotten worse since the bus.
Most driveways I see in this area have cracks.

Around here they pour directly on the clay ground.


.

[brojcol]

Brian,

As long as you have good preparation before you pour, and use the fiber reinforcement, you should be ok with the 4" slab.  The problem with concrete cracking is when it is on poorly prepared soil and/or not reinforced properly.  Concrete generally cracks when there is movement beneath it, or it's uneven somewhere. 

But if it really concerns you, pour an extra foot near the rear where the bulk of the weight will be.

I'm not an expert on concrete, but I did stay at a Holiday Inn Express last night

[bobofthenorth]

If you could place the concrete & more particularly the rebar perfectly then 4" is likely enough.  Perfectly for a 4" slab means 1/2" rebar exactly 1" up from the base on probably a 1' grid.  Since we live in the real world and concrete placers get the rebar "somewhere" inside the slab as opposed to perfectly located in the bottom 1/4 of the slab, I would bite the bullet and pour 6".  If you are going to go with the 4" then be absolutely anal about the position of the rebar inside the slab.  And as you have already been advised compact the living H out of your base.

[JerryH]

Brian:
In addition to concrete thickness, I'd personally use 4,000 psi and certainly rebar.  One key element is site preparation.  Your pour/pad will only be good as the area you prepare.  3/4" modified which has been compacted with a vibatory roller would be ideal.  Get the base in which you are going to pour on compacted, stable and tight.  No voids, etc.  Oh ... and yeah, I'd do 6" min.

Just my $0.02,
Jerry H.

[scanzel]

  I am in the process of building an area for my bus 12 x 75 feet beside my garage and though I am not doing concrete I dug down 12 inches with my bachhoe and put in the 1 1/4 inch processed stone like they use for highways and compacted it. This was done last fall so it could sit all winter and get further compacted by the bus and also by being rained on which will settle it more. Then this year the contractor will be using the highway base blend which has larger stones and is coarser and will support more weight. If you live in the west where your rain fall in near zero, I would compact like they said and then soak it with water and let it sit for a few months to settle more. Don't be in a rush to get it done. My orginal driveway has lasted 20 years before I saw some cracks showing up,  I initially put in a 12 inch base when I built the house. Most contractors will say a few inches is good but when it cracks later they have your money and you have the problems.
Good Luck.

[belfert]

Good info.  I may need to look for a lot in a city that doesn't require a paved driveway.  The budget for my house project is already stretched to the limit.  I don't think I could afford a 6" concrete driveway and I really don't want asphalt with a bus.  My project includes a 1100 square foot home with basement plus a 2600 square foot building for the bus and a shop.

I assume I will need a 6" slab in my bus garage/shop too then.  The current plans for the garage/shop only specify a 4" slab.

Brian