Minimum thickness for concrete pour 2

[JoeBaseplate]

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?

 

[hokie66]

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.

 

[JoeBaseplate]

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

 

[rowingengineer]

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.”

 

[normm]

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 ?

 

[hokie66]

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.

 

[JoeBaseplate]

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.

 

[SkiisAndBikes]

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.

 

[hokie66]

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.

 

[paddingtongreen]

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.

 

[racookpe1978]

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

Can he just use a floor-leveling compound?

 

[hokie66]

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