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New Shop Concrete Thickness
- Thread starter Wenglish120
- Start date
- Replies 32
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Orange Vise
Titanium
- Joined
- Feb 10, 2012
- Location
- California
A properly done 6" slab should easily handle the weight of the forklift + a 30K pound machine, IME.
Overland
Hot Rolled
- Joined
- Nov 19, 2017
- Location
- Greenville, SC
Summary:
Digging out that much dirt, you may/should be down to good dirt. Test it: an engineer, or maybe a fully loaded dump truck and see if it pumps (moves).
If you're bringing in gravel, get the truck to run over your area a few times before it dumps.
Vapor barrier.
Get actual foundation spec from Mazak, no point in making it thicker than necessary.
Rebar top and bottom, surround by 3" of concrete, no point to put in middle.
Don't let riggers bring machine in on forklift; use skates, with plates under them. United Rentals has plates in my area.
Post your location - you'll get better advice and references from locals.
Good luck !
Bob
Digging out that much dirt, you may/should be down to good dirt. Test it: an engineer, or maybe a fully loaded dump truck and see if it pumps (moves).
If you're bringing in gravel, get the truck to run over your area a few times before it dumps.
Vapor barrier.
Get actual foundation spec from Mazak, no point in making it thicker than necessary.
Rebar top and bottom, surround by 3" of concrete, no point to put in middle.
Don't let riggers bring machine in on forklift; use skates, with plates under them. United Rentals has plates in my area.
Post your location - you'll get better advice and references from locals.
Good luck !
Bob
BT Fabrication
Stainless
- Joined
- Nov 3, 2019
- Location
- Ontario Canada
As for gravel, you need to go as deep as the top soil is, idiot that built my shop left 6" of topsoil (its 24" thick) for the 6" slab on grade and 12" thickened edge and 6" of gravel.
For any concrete build, id recommend 12" gravel minimum, like 3/4" clear stone and compacted for drainage under the slab. Depending on the terrain you can also get away with 3/4 minus if you are in not a cold climate.
if a good base is put down, 6" concrete with 6x6 wire mesh in it will be plenty,3500ksi concrete, I have had water tank firetrucks drive over my 6" driveway 2 months after i put it in. they weight approx 38K lbs or so on 4 points.
biggest point as said above, let it cure slow, if its warm out, keep water on it to keep it physically wet and don't drive on it for 28 days min. ive broken 6" of concrete after 7 days of rain on new concrete with a single tire of a 9000# skidsteer. on the edge...
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Rob F.
Diamond
- Joined
- Aug 5, 2012
- Location
- California, Central Coast
Don't just pour a flat slab, I would form and pour a 6"tall curb all the way around, integral with the slab. (Openings for doors of course)
This is good for many reasons, first is iit is an easy way to do water cure of the concrete. Just block off the door openings and fill it with a few inches of water for the first week. Later the walls are built up above floor level. If you wash the floor with water hose no water to rot or rust the wall. If you ram the wall with pallet jack or forklift forks they wont poke through. Helps keep outside water from coming in as easy in flood. as well as the siding can be higher off the outside ground.
This is good for many reasons, first is iit is an easy way to do water cure of the concrete. Just block off the door openings and fill it with a few inches of water for the first week. Later the walls are built up above floor level. If you wash the floor with water hose no water to rot or rust the wall. If you ram the wall with pallet jack or forklift forks they wont poke through. Helps keep outside water from coming in as easy in flood. as well as the siding can be higher off the outside ground.
cnctoolcat
Diamond
- Joined
- Sep 18, 2006
- Location
- Abingdon, VA
Be cautious with concrete contractors, as they are generally not use to prepping and pouring super-strong slabs!
Inevitably they will try to cut corners on the prep, and possibly shave an inch or two of concrete depth.
I've never been ceased to be amazed by "professional contractors", there only mission seems to be to finish the job as soon as humanly possible, with just good-enough quality to keep the customer happy.
ToolCat
Inevitably they will try to cut corners on the prep, and possibly shave an inch or two of concrete depth.
I've never been ceased to be amazed by "professional contractors", there only mission seems to be to finish the job as soon as humanly possible, with just good-enough quality to keep the customer happy.
ToolCat
I replaced some shop floor this past summer with the intent of making it suitable for setting machine tools on it. Asked the dealer I bought a mill from how thick their warehouse floor was, figuring it had to be pretty thick to handle the weight of machines setting there. He kinda shrugged. “6 inches I think.” No problem with that I asked? “Haven’t seen it crack.” Pause. “And we carry machines over it all time with a 45,000 lb forklift.” 
I poured my new floor 8” thick with 4” of fill gravel under it, all on reasonably compacted dirt. Some bar in it, not a crazy amount, and kept the surface wet for at least a week. The old floor was cracked and heaved 4” concrete and it has’t caved in under my old crane that weighs 20 tons. One thing about pouring concrete, you will only need to do it once, if it is done right. Amortize that cost out over the expected life, and spending a little more per square foot to make it right is a very small cost long term. It will be cheaper to do it right once than do it twice.
I poured my new floor 8” thick with 4” of fill gravel under it, all on reasonably compacted dirt. Some bar in it, not a crazy amount, and kept the surface wet for at least a week. The old floor was cracked and heaved 4” concrete and it has’t caved in under my old crane that weighs 20 tons. One thing about pouring concrete, you will only need to do it once, if it is done right. Amortize that cost out over the expected life, and spending a little more per square foot to make it right is a very small cost long term. It will be cheaper to do it right once than do it twice.
Tyrone Shoelaces
Diamond
- Joined
- Apr 19, 2006
- Location
- Manchester, England
Another vote for the vibratory poker to settle the concrete. You’d be amazed how much the level goes down once the poker goes in. Keep the foundation wet, we used wet sacks laid down on the concrete and we kept them wet.
Rdgards Tyrone.
ncjeeper
Cast Iron
- Joined
- Jan 20, 2015
- Location
- SW Virginia
I did 6 inch thick 4000 psi for my shop floor and dug out a 10x12 area 10 inches deep for a future HBM to sit.
david n
Diamond
- Joined
- Apr 13, 2007
- Location
- Pillager, MN
I swear what's under the slab has got to be 70-80% of the equation. I've been to places where the old buildings had 4"-5" of crete.........places buzzin with forklifts, VMCs, lathes, press brakes, shears, heavy assembly, etc...................floors are holdin up just fine...............
Here at my place I'm lucky enough to have great soil for foundations(crummy for growin' anything).............the excavator came out and scraped off the corn stubble and leveled out a pad. Basically poured the slab right on the ground. The "top soil" is only bout 12" of a light clay and gravel composition. It's all straight coarse gravel below that............. Basically class 5 gravel............pack it and it just doesn't move and doesn't get muddy....................
Here at my place I'm lucky enough to have great soil for foundations(crummy for growin' anything).............the excavator came out and scraped off the corn stubble and leveled out a pad. Basically poured the slab right on the ground. The "top soil" is only bout 12" of a light clay and gravel composition. It's all straight coarse gravel below that............. Basically class 5 gravel............pack it and it just doesn't move and doesn't get muddy....................
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For heavier machines better to have them on their own pad. If you know where they'll go pour it now, if not, make sure you can do it later.
Thickness depends a lot on base too.
When I called last year about concrete it was $138/yard(CAD$) and 10% fuel surcharge, not sure if it's gone up since. Sounds like you guys are getting some crazy high prices. I know rebar had gone up about 3X, not sure if that started coming down with all the construction happening still.
Thickness depends a lot on base too.
When I called last year about concrete it was $138/yard(CAD$) and 10% fuel surcharge, not sure if it's gone up since. Sounds like you guys are getting some crazy high prices. I know rebar had gone up about 3X, not sure if that started coming down with all the construction happening still.
Wenglish120
Plastic
- Joined
- Aug 28, 2020
- Location
- Toccoa, Ga
We have one main concrete company that controls the bulk of the market in whole northeast Ga area. They pretty much have the market as a take it or leave it type thing cause the nearest concrete facility besides them is about 30 minutes away. There are smaller guys, but they probably wouldnt be able to supply large amounts of concrete at one time like the big company can thats 10 minutes up the road.
