Slab on Grade design data 1

[UBbaja]

I know...another slab on grade design post, sorry. I have to designn a slab on grade foundation. The loads are all pretty much dead load, theres some pumps, compressors with moving parts that will go on it, but for all practical purposes, its all dead load. I have read as many posts on SOG as a i can on here, and some reference books as well ( i am a mech. eng so I was a bit lost at first).
my footprint is 24'x36'. It seems the way to go here is to over design it. The soil bearing is 2700 psf. I was thinking of 6" of compacted 2" crusher run, then 6" of reinforced concrete, with the reinforcement being wire mesh 3" up from the finshed grade of teh 2" Crusher run stone. WHat about joints? Joints on 48" on center? I need to back this all up with numerical data, calculations, ect. ANy ideas?

 

[dik]

There's lots of info on the site regarding SOG

For a 6" slab, I'd likely sawcut yours into 12' panels, 1 down the middle, and two transverse.

I'm not sure what is common in your area, but I generally use 6" granular min below the slab. Other than for uniformity of thickness, test data indicates that slab strength is generally independent of the sub-base.

I generally spec 6mil PEVB between the slab and fill to keep moisture from wicking into the conc slab.

If you use WWF, use it in flat sheets and properly chaired... don't believe that the contractor can lift it as the concrete is being poured. Use reinforcing steel at 14" min centres so that concrete placers can step between the bar.

I generally spec that the rebar has 2" cover and sawcut the slab 1-1/2" X 1/4". The added width is used for joint filler. This is needed to support the edge of the concrete from loading. The timing of sawcutting is critical... should be about 8 hours or less after finishing or earlier if a sofcut saw is used. Sawcutting should occur as soon possible without the sawblade 'kicking up' (ravelling) aggregate.

Dik