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I have a fifth wheel parked on dirt (only option I have), I cannot pave the entire section due to cost mostly.

I'm planning on making a few 1' x 1' slabs 4" thick to set the jacks on, and probably 1' x 2' 4" thick for the wheels.

Is there any issue with this? Also, should I be adding mesh/rebar or just do straight concrete? Any extra input is always welcome as well.

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  • Why bother to make a concrete block? You can simply build a brick pavement to handle light load.
    – r13
    Dec 31, 2021 at 18:13
  • It's a 10,000-pound trailer, wouldn't the 2" bricks break? Being a fifth wheel weight would be supported from the 4 tires and the front jacks. I see 4" as the minimal on other forums so thought that was pretty much what I had to get but can't buy 4" slabs ready made around here. Dec 31, 2021 at 20:28
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    I would rather use brick, or solid block, for ease of replacement, as frost heave and rain/ponding can soften the ground and dislocate the pads. BTW, for 10,000 weight spread over 5 points, each will support 2000 pounds. Given your soil can support 1500 lb/sf without excessive settlement, and with a safety factor of 1.5, you will need 2 square feet of pad under each wheel/jack.
    – r13
    Dec 31, 2021 at 20:54
  • Thanks for the comments, ended up going with the solid block pilers for the jacks as you suggested, still gotta find/make a slab for the wheels. Will be adding the gravel underneath the slabs as suggested in the answer which from what I found is 5000 lb/sf. Jan 1, 2022 at 0:20
  • I like that answer too, but suggest at least 6" coarse gravel to reduce the chance for ice forming, and maintain free drainage. Good luck.
    – r13
    Jan 1, 2022 at 1:03

2 Answers 2

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Since we're in december, do not pour concrete when it freezes. If the weather is too cold it will take longer to set, and if it freezes, it will crumble.

Dig hole. Try not to loosen the dirt too much below the bottom of the hole, otherwise it will compact later when you park the vehicle on it and the slab will sink in.

Pour a layer about 2-3" thick large gravel on the bottom. This is mostly for drainage, to keep your concrete dry so it doesn't freeze and crack in winter. It'll also give more even support.

If you want it to look nice, make a rectangular form with some planks. You can oil them with rapeseed oil.

Put in some mesh rebar. You'll need a bolt cutter, or a hacksaw and lots of sweat. It should be in the middle of the concrete, because if it is too close to the edges, it will rust, expand, and crack your concrete from the inside. So you can mix a bit of concrete to make a few heaps and rest the rebar on them.

Mix concrete. If you use a cement mixer, you can throw some reinforcing fiber into the concrete for extra strength. If you mix it by hand, only use fiber if you have big arms and enjoy a good workout.

Pour concrete, work it with trowel, etc. Make sure there are no holes, "vibrate" it with the trowel to help it set, hit the planks with a hammer, etc. Basically vibrations help it set and fill voids.

Next, do the surface so it looks nice. There must be a slope so water drains, so you can make it a bit higher in the middle. If you expect it to sink into the ground a bit, you can make it higher by about 1/2", but then if it doesn't sink, watch your toes when you walk around.

Next wait long enough for it to set, and remove planks.

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If you can make them slightly bigger by 4" each way the off the shelf 3/8" rebar will fit into the pour properly, with 2" away from the forms. 2 pieces each way on the 1'X1' and 3 across the 2' way

Immediately after pouring tap the edges of the forms with a hammer or heavy block to vibrate the air out of the edges. Do round over the edges so when the forms are removed the concrete will be less prone to chip off at the corners.

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