Pouring over an exsiting slab

[Big Builder]

This must be a tough question........I havn't been able to get an answer anywhere. I will post it again hoping someone will take a stab at it.
We pured a basement slab then we got a freak thunderstorm and while walking through the concrete the clay under the stone contaminated the slab. Now water pressure pushed through the bad spots and we have a wet sopts on floor. I had thought about laying blueskin over the entire floor and then ouring another 2 1/2 slab or maybe even 6 - mil plastic.
Any thoughts out there?
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It must be pressure. The grade is seven feet above the slab.

To much I think to just be moisture wicking up. We took great care with the drainage around the foundation because it is in an area of clay.
We removed the native and backfilled with sand. The water table is high
and a rock face is present on one side. We also wrapped the entire foundation ( including the existing home with delta wrap too.

[Sweep]

I don't think the water issue is related to the damaged slab but it might be related to the use of sand under the slab (the compacted base should have been crushed stone or gravel) and the possible absence of a moisture barrier membrane under the slab. But the most important issue at this point is the sump. If you don't have one you need to install one before making any other decisions.

[Big Builder]

We have 6" of 3/4 clear under the slab. Continuouse drainage around the footings and into a sump ( with back -up0.

We had poly over the stone but as we we walking around in the rain
it was puuled out of place.

I was concerned about the hi water table when I built so
water proofing was taken very seriously. In hindsite I should have put weeping tile under the slab as well and tied it into the perimeter tile.
You know what they say about hindsight.

We arn't prepared to bust up the slab to do that so I was hoping for
surface treatments?

[Sweep]

If there is hydrostatic pressure under your slab you will need a waterproofing membrane like:

Carlisle "MiraCLAY" Bentonite waterproofing (best for hydrostatic pressure)
http://www.carlisle-ccw.com/PRODUCTS/pr_detail.asp?pid=9

or

Polyguard "Underseal"
http://www.polyguardproducts.com/products/architectural/home.htm

or

W.R. Grace "Procor" liquid membrane
http://www.na.graceconstruction.com/product.cfm?mode=c&did=11&id=78#3038

These materials may be difficult to purchase in small quantities and to install yourself. You may need to find a good waterproofing contractor.

[Big Builder]

Thanks Sweep.

I am going to try one of those options.

I will let you know how it turns out.

[Sweep]

Here is a good description of the issues involved:
http://www.buildinganalysts.com/newsletter/winter99.html