putting equipments on top of existing concrete paving 1

[AskTooMuch]

If existing reinforced concrete paving is at least 6" thick, can I consider it as slab on grade and just check the soil bearing if i need to put equipments on it.

For example, I have a 15' diameter tank, can i put 1'+/- thick pedestal and dowel to existing paving as long as it meets soil bearing and concrete shear check?

 

[JStephen]

I was curious to see the responses, and there seem to be none.
My thinking-
If you treat the pavement as "disposable", then yes, provided allowable bearing is adequate, you can set the tank on it, and the tank will be fine- you're just using the concrete as fill. You may get some damaged concrete, and may have drainage towards the tank due to deflections.

If you're concerned about the integrity of the pavement after it's loaded, then you'd need to evaluate deflection, shear, moments in the pavement, and in that case, it might or might not be adequate- but you couldn't just assume that it was.

I suppose you could sawcut around the pedestal so that little section of pavement could move independently.

 

[JoelTXCive]

How tall is the tank? Whats the unit weight of it's contents (water?)? And will it be filled all the time?

Even if the bearing pressure is acceptable; a geotech might need to look at long term consolidation settlement under the tank.

 

[Ron247]

If you mean you will size the pedestal plan view dimensions to meet soil bearing and shear of the concrete only, I would think you need to check more if you are not allowed to damage the slab. As pointed out, you will affect more than just those two items.

Also, the moment capacity to me may be a big deal since you are putting a fairly high concentrated load on a fairly thin slab with respect to tank loading.

 

[AskTooMuch]

I guess it's better to saw cut the pavement and treat it as a fill/lean concrete and put a new pedestal/footer above it. I'm not sure if I need to dowel the new pedestal/footer to pavement that was saw cut though. Flexible hose will be used connecting to tank to account for tank settlement.

 

[EDub24]

That could work but you should analyze the existing slab. Depending on the subgrade modulus of the soil you could have issues with shear and flexure in the existing slab.