Concrete floor paint peeling

HELP! I need to do a high quality job on this floor and am at a loss how would be the best way to do it. This is a concrete slab floor that was poorly painted. I don't know what kind of paint was used. The living area appears to have been rolled with polyurethane varnish but for all I know it could have been a glossy sealer. The garage area was painted with your typical speckled garage floor paint. Both areas have several large areas where the paint or varnish or "whatever" is peeling in small patches. We suspect that water on the floor from flooding has caused moisture to come up through the concrete causing the paint to peel.
The clear coated area has to be refinished. It needs to be re-painted with a clear coating and look like it was never "fixed". What do I need to do to prepare it for re-painting (re-varnishing) and what kind of paint/varnish/sealer do I need to apply? I've considered renting a floor sander but don't want to mess up the surface... not sure which is my best way to go about this job... really would appreciate suggestions. Doing a chemical paint removal seems possible but I'm afraid to do that on this type of surface.

 

Did the floor coatings hold up fine prior to the flooding? how long ago were they painted? Is the concrete good and dry now?

I don't know a lot about sanding concrete floor finishes but the damaged areas will need to be sanded smooth. Since it's unlikely that you can make any non noticeable touch ups - the entire floor would need to be sanded lightly to promote good adhesion.

I'm not real familiar with the coatings used with acid stains. Check with your local paint store [not a big box paint dept] or masonry center - they would know what sealer is to be used. It is not the same poly typically used on wood floors.

 

Yep. The floor is as dry as it's going to get, especially this time of year. I know the paint has been on the floor for at least 5 years, probably about 7. IMO, it was a crappy job to begin with and never should have had the type of paint that was applied which I believe is polyurethane. It's a high traffic area at a lake house which tells me a lot of kids with sand on their shoes will be running around and playing foosball or shooting pool... and probably drinking at the bar. I'm thinking just give it a good sanding and in a hidden spot see if stain or a sealer will absorb into the concrete. I don't think a regular paint made for wood or normal porch paint would work. I was also wondering about using muriatic acid to clean the concrete with before painting...

 

I don't know a lot about acid stains but they chemically react with the concrete to get the color so I don't think there would be a need to add any stain. There are a few in the masonry section of the forums that know about acid stains. You might try asking there for more help - Bricks, Masonry, Asphalt and Concrete - DoItYourself.com Community Forums

I wouldn't use muratic acid - it has no effect over any type of paint coating. It is only used over bare concrete when the finish is too slick for the coating to adhere well.