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Minimum thickness for concrete pour
2

Minimum thickness for concrete pour

Minimum thickness for concrete pour

(OP)
Is 1" too thin a thickness for concrete slab on grade (using fibermesh)? It's an odd situation, the pour thickness slopes from a 3" at one end to 1" at the other with aprox 4 ft width across. The pour is going to be on top of an existing concrete floor (basement underneath). The concrete floor has been roughened to a ¼" amplitude. The pour being suggested is 3/8" chip mix with 5" slump and no fly ash (all cement). The floor will get tiled or carpeted eventually.

So is 1" too thin a thickness to pour?
 

RE: Minimum thickness for concrete pour

You said it was a slab on grade, then said it is poured on an existing slab with basement below.  Which is it?  What you described is a topping.  I would leave out the plastic fibre, as it will do no good.  Otherwise, sounds doable.

RE: Minimum thickness for concrete pour

(OP)
hokie, sorry for the confusion. Its not a slab on grade but rather a floor infill.

RE: Minimum thickness for concrete pour

You need to spec a concrete with approprate sized agg and contents, the concrete supplier should be able to help you out here.

ANY FOOL CAN DESIGN A STRUCTURE. IT TAKES AN ENGINEER TO DESIGN A CONNECTION."
 

RE: Minimum thickness for concrete pour

Can you not apply a chemical bonding agent on top of existing floor that will ensure that the whole depth acts as one to take any point loads ?

RE: Minimum thickness for concrete pour

normm,
The best "chemical bonding agent" is Portland Cement.  With the other stuff, there is too much chance that it will act as a debonding agent.

RE: Minimum thickness for concrete pour

(OP)
Update:
The topping may actually be 1"-1/2" thickness and now I am wondering if I should just have them use non-shrink grout.

RE: Minimum thickness for concrete pour

Surface preparation is critical for success. The surface may have been roughened to 1/4" amplitude but how has it been cleaned (water blasting, sand blasting, shot blasting?

A portland based sand/cement slurry can be an effective bonding agent as long as the surface has been prewetted (no ponding water) and is scrubbed into the surface. For thin cementitious toppings I am a fan of matching the properties of the base slab.

RE: Minimum thickness for concrete pour

Joe's topping strip is only 4 feet wide.  Why the big issue with preparation?  He's not depending on composite action as far as I know.  Joe, just use the small aggregate concrete as intended.  Non-shrink grout is overkill in this case and not the best solution.   

RE: Minimum thickness for concrete pour

Joe, do not use grout!!! grout is designed to be contained between surfaces. Use one of the commercial polymer modified topping materials.

Michael.
Timing has a lot to do with the outcome of a rain dance.

RE: Minimum thickness for concrete pour

Indoors, non-load bearing.  Or am I interpreting the statement wrong?   

Can he just use a floor-leveling compound?   

RE: Minimum thickness for concrete pour

No, floor leveling compounds are for small irregularities, not 1.5 to 3 inches.  Nothing better than concrete.

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