Concrete Thickness Recommendation

[8V149 Detroit]

I am new to the form and shop talk seemed like where this should go. I'm going to be building a shop in the future and wondering what would be thick enough for heavy equipment, I was thinking 8 inchs thick but The biggest machine I have is a 300 series machine currently but will probably get something bigger in a few years

 

[repowerguy]

I’d say that 6” should be adequate but it depends on a variety of different factors as well. The soil type in your area and the mix design of the concrete as well as how it’s placed are a considerable to how it holds up.
I would recommend that you call your local r-mix company and ask them for their opinion and maybe talk to their representative/engineer.

 

[Delmer]

The quality of the mix and the reinforcement is just as important as the thickness. Of course that all depends on the base also.

There's no shortcuts. And 8" is an expensive solution with no guarantee if the subsoil has soft spots.

 

[Former Wrench]

Whatever you do, I would suggest imbedding steel rail or thick angle iron to beef up areas where tracked equipment would be brought in. Also, install rings or other that can be used for anchors when something needs to be pulled against.

 

[8V149 Detroit]

Thanks for the help, I was thinking about putting anchors in not sure how to go about that or embed the steel, to google I go to do some research then

 

[alskdjfhg]

What goes under the slab is more important than the thickness IMHO.

I've got about 75tons of machine tools in my 40x80 barn on 6" of concrete. No issues yet, but there is about 1500 yards of fill below it.

 

[doublewide]

At least 18" at the perimeter if not 24". Tapering to 6" at the center. At least 2 if not 3 continuous #4 rebar at the perimeter, lapped at least 2' and tied at all laps. You can set the rebar on 3" x 4" cement bricks to keep it elevated. 6 x 6 wire fabric throughout the slab, make sure you pull it up into the slab as it is being poured. Angle iron with anchor j bolts welded to the inside corner for reinforcement at all openings. All on at least 12" of compacted processed gravel.

 

[DIYDAVE]

There are several concrete calculators out there. I would think 6" is plenty, if properly reinforced, for most rubber tired equipment. Most air tired equipment only puts whatever the max tire air pressure of the machine in question, as ground PSI. I would certainly do some research, as to what is recommended, I see too little and too much, in the replies here, IMHO...

 

[8V149 Detroit]

Definitely doing research, most of our machines are rubber track and tire but we have two metal track machines and plan to get more probably a actual dozer and a bigger excavator. Plan is to build an 80x120 building just a little more than double what we have now 30x60.

 

[lumberjack]

80x120 is 5x bigger than 30x60.

I agree that the fill under the slab is very important to a successful foundation.

 

[8V149 Detroit]

Whoops in that case its 5 times bigger don't know why I thought double, we have our own dirt pit with really good dirt better than most around so we are good there

 

[curb guy]

You should really look into “Macro Fiber” reinforcement. I have used it extensively in place of re-bar and, it works. If memory serves me, 20 lbs. of macro fiber per cubic yard of concrete, is a replacement for 2 mats of #4 re-bar on 12” centers, in an 8” slab. There is a difference between “micro” and, “ macro” fiber. In my opinion, it’s money very well spent. That and, in floor radiant heat.

 

[curb guy]

Almost forgot what the original question was. 6” will be more than adequate, especially with the proper reinforcement, for most applications. Unless you’re working on REALLY heavy stuff.

 

[repowerguy]

Macro fiber will make it hard to get a slick finish, it makes for a strong pad though.

 

[doublewide]

Like this;

 

[doublewide]

At least 4000psi if not 4500. Blend of 3/8 and 3/4" stone.

 

[92U 3406]

IIRC my old man went either 10" or 12" with rebar every foot lengthwise and widthwise.

 

[crane operator]

IIRC my old man went either 10" or 12" with rebar every foot lengthwise and widthwise.

I really like that, but I'm probably too cheap to spend that much, but it would be nice to have.

I think wire mesh is a waste of time, I've torn out a lot of old grain bin slabs that had wire mesh and they spread all over.

I'd probably go 8" concrete and 1/2" rebar on 18" or 2' centers. 4,000 psi mix. If you've got tracked equipment, pouring railroad rails in the concrete is really nice, (like some other guys suggested) with the top 3/8" just barely out of the concrete so you can still sweep it nice and roll creepers over it. I'd probably run the rails all the way outside the doors onto your apron. That way you're never tearing up the concrete with the tracks.

 

[RZucker]

I really like that, but I'm probably too cheap to spend that much, but it would be nice to have.

I think wire mesh is a waste of time, I've torn out a lot of old grain bin slabs that had wire mesh and they spread all over.

I'd probably go 8" concrete and 1/2" rebar on 18" or 2' centers. 4,000 psi mix. If you've got tracked equipment, pouring railroad rails in the concrete is really nice, (like some other guys suggested) with the top 3/8" just barely out of the concrete so you can still sweep it nice and roll creepers over it. I'd probably run the rails all the way outside the doors onto your apron. That way you're never tearing up the concrete with the tracks.

I've walked D9L's and D10's in and out of shops on concrete for many years. As long as it's flat and you move slow there was never an issue, we would lay some 2x6s at the edge between the outside apron and shop floor. Otherwise we barely left a mark on the floor.
I did work in a shop with rails sticking out of the concrete and they were a total PITA to be around. Even the Cat dealer sticks with nice flat floors and moves crawlers slowly.

 

[Theweldor]

If you want to harden the surface a bit. Why couldn't you power trowel some iron powder grout into the surface while it is being finished?