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New slab on grade on top of existing one. 1

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r2d22

r2d22

Structural
Oct 3, 2007
11
Hi,
There is an existing unreinforced slab on grade that has some light cracks. Expansion joints are spaced about 12 ft in both directions. A new slab on grade is planned to be placed on top of this existing one. We have two options in mind, but not sure which one would be the best. See attached drawing.
In both cases, new sawcut joints will coincide with existing expansion joints.
I will appreciate your advice.
options_u3wirj.jpg
 
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If going for the first, I would do a double layer of plastic, but if the surface is uneven if probably won't help.

Friction coefficients for slab on grade from a Norwegian publication:
Smoothed sand: 0,9
Plastic (PE) on sand: 0.7
Two layers of plastic on sand: 0.5
 
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Probably you have more than two options.. What is the reason for unbonded topping?

If the existing slab on grade is in good structural condition , you may consider a bonded topping.Use a good bonding agent, and prepare the existing slab surface and provide control joints in the new slab matching with the olds.

I will suggest you to look to the following doc.






If you put garbage in a computer nothing comes out but garbage. But this garbage, having passed through a very expensive machine, is somehow ennobled and none dare criticize it. ( ANONYMOUS )
 
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If you use a bonded topping, unless you add a fair amount of reinforcing, the cracks in the lower slab will transmit to the new slab, likely.

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So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik
 
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