Does this slab need to come up, be redone?

I have a new house with a 2 in. concrete slab on the main floor (garage and utility room underneath), with radiant pipes. The floor is defective. The contractor poured the slab, stained it a few days later (water-based stain), and sealed it 11 days later--at a time when the outside temp was around 30 degrees (and the house was not yet heated except by contractor diesel/propane heaters). The three main problems are 1) white blooms everywhere--moisture trapped under the sealer, 2) whole huge areas of stain and sealer peeling up, leaving white chalky calcium carbonate, and 3) serious cracking. On the later, the house is extremely well-built but some of the cracks are almost 1/4 in. wide, and the cracks are numerous in the hall areas, including right next to where deep expansion cuts were made to supposedly minimize cracking.

I have had numerous experts look at the floor and/or photos of it and get extremely diverse opinions. My main concern is does the entire slab need to be removed and repoured, or will grinding up the stain and sealer, then putting down tile (rather than more stained concrete since the concrete surface will then be destroyed), suffice? At least one contractor expressed concern that with the wide cracking on such a new house means the concrete pieces may well rub against the radiant tubes and at some point cause a leak--which would of course be the dead of winter when I'm out of state for a few weeks.

I need to get the floors done right, and since this will be a contractor's insurance issue, need to figure out what must be done soon.

Can tile effectively (and durably) be put over defective concrete that was never allowed to dry and has cracked seriously and has lots of calcium carbonate on the surface now? Or does the whole floor need to come up (meaning removing all the cabinets and a lot more to get at the radiant tubing that will have to be redone)? Remember I need to end up with a top quality floor to go with the rest of the extremely well built top quality home.

First of all, I can't tell you what to do, so you're on your own in terms of making the best decision for you.

But here are my thoughts, based on what you described: I think the majority of white deposits you're seeing are carbonation, which is often caused by the presence of excess carbon dioxide (combustion product in all portable heaters in use today) in the air adjacent to the soft and curing concrete. The carbonation will get worse over time, regardless of how much or what type of sealer you apply, to the point of the concrete actually crumbling, getting soft and becoming quite powdery in consistency. Covering it with tile or anything else will not solve the problem.

If it were my hard-earned $$$ paying for a new house, the floor would be coming out entirely and replaced with properly placed and cured concrete. The initial minor inconvenience of doing so would be small in comparison to months and years of living with a potential disaster. If the contractor wants to fight about it, small claims court would be the venue for getting my money back (if I had to pay for the replacement). Along with a testy submittal to the local BBB and Angie's List, as well, describing in detail the grief your contractor put you through.

Good luck.