Floor covering over *cracked* concrete slab

Now that we have removed the wet carpet from our basement floor, we can see a few cracks in the concrete.
Although the recent mini-flood was caused not by water coming up through the cracks but by water overflowing into the house from a flooded window well, ought we to fill the cracks before laying new carpet or carpet tiles?
Perce
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Percival P. Cassidy wrote:

Absolutely. And you should also do a test to see if there is some moisture coming up through the slab. Put some plastic down on the slab and tape down the edges. Let it set for a couple of days and then remove the plastic. If the slab is darker where the plastic was, you have moisture issues that need to be addressed.
R
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Percival P. Cassidy wrote:

Let the concrete dry thoroughly. It may take a few weeks. You may need a fan and a dehumidifier.
Fill large cracks with mortar. Every slab has hairline cracks. Large cracks, especially those where the two sides are different levels, should be examined by a foundation expert.
Seal all cracks with something like RedGard.
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Steve Bell
New Life Home Improvement
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On 06/13/08 03:12 pm SteveB wrote:

Thanks for the reply.
The cracks are little more than hairlines. Most of the floor already has some kind of coating on it, but I have no idea what it is. Will the RedGard work on top of an existing coating?
Perce
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I had a long crack in my garage floor. I just blew it clean with compressed air and filled it in with sanded tile grout. In my case the maximum crack width was about 3/4" with most of it under 1/2" the crack is over a decade old so I am taking a chance it will not move more and open the crack again. If I thought it would move, I would have used a flexible concrete caulk. One year and still stable.
I would attempt to remove the coating before applying any new adhesive for carpet, it sounds like residual adhesive. A floating floor may be OK if it is smooth enough. A floor sander might work but if it is too gummy then a solvent (like paint remover) and scraper might be in order first.
It is not necessary to have a dry surface for Mortar or Grout. For a tube dispensed caulking product, read the label.
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Percival P. Cassidy wrote:

It should work just fine, but read the label. I use it mainly under tile and wood flooring. I'm sure other brands will work just as well.
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Steve Bell
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