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Another Slab on Grade Question

Another Slab on Grade Question

Another Slab on Grade Question

(OP)
A coworker is designing a slab on grade for a warehouse, about 12,000 SF; heavy forklift loads. She's of the opinion that T&S steel is needed no matter what. I'm of the opinion that it's a cost trade off between sawing and sealing joints in an unreinforced slab versus placing bars and sawing and sealing fewer joints.

The project is in a location where I doubt the concrete supplier would be capable of providing shrinkage compensating cement or fibers.

Any thoughts?

Thanks

RE: Another Slab on Grade Question

bridgebuster - I agree with you. Instead of spending money for reinforcing, consider suggesting to spend an equivalent amount of money for additional concrete (make the unreinforced slab thicker). Grading, forming, finishing, curing, and even placing the concrete are essentially unchanged for a thicker slab. Strength of the slab is more or less proportional to the square of the depth - a lot to be said for 8" vs. 6". We often made this tradeoff for certain slabs at electrical generating stations.

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RE: Another Slab on Grade Question

Inclusion of fiber reinforcement is something that could be considered as well.

BA

RE: Another Slab on Grade Question

In some parts of the world, post-tensioned SOG are common for such applications. It gets rid of the long-term maintenance of multiple slab joints.

Intermodal facilities and large warehouses in Australia, for example, are often constructed with bonded (grouted) PT.

I know this does not answer your question, just thought I would add it to the discussion.

RE: Another Slab on Grade Question


bb...agree with you and SRE. I'm not a fan of steel in slabs on grade. A very flat subgrade, larger aggregate in the concrete; and proper location, depth and timing of the sawcuts are the better mitigation techniques.

I use 24 to 36 times the concrete thickness for joint spacing, 1/4 x thickness for depth and sawcut same day as placement....no matter how late that might be! No waiting till next day!


FAQ for Preventing Random Cracks in Slabs on Grade

RE: Another Slab on Grade Question

(OP)
SRE & Ron - As always, thank you for your helpful advice.

BA - I'd like to try the fibers - I've heard good things about it - but I don't think the concrete supplier would be able to do it. A few years ago at the same site the local supplier couldn't provide a mix with Type III cement. Another project I'm involved with is going to use fiber reinforced UHPC for the joints between precast panels.

Ingenuity - post-tensioning is a good idea but it would be beyond the capability of the contractors in the area. At the same site there was a contractor who thought bending a#6 bar would break it.

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