[gibmaker]

Does it appear that there are fibers protruding from the concrete or is it literally just breaking down and really powdery? If it is just flat out breaking down and becoming powdery you need to etch the concrete with muriatic acid to stop the efflorescence. If you can stop the efflorescence your best bet would be to get a moisture cured urethane and coat the floor, but only if you can stop the efflorescence, otherwise the urethane will fail. Pictures would help.

 

[gibmaker]

The main reason why the slab is doing this is because it sounds like it has a broom finish, they didn't trowel it well, so the cream of the concrete never got as hard as it should have. The efflorescence is basically salt leaching out of the concrete. Don't you live in Florida Bert? Temp wouldn't have been a problem. You don't need a structural engineer to help you, he may be able to tell you what is wrong, but unless he has a vast knowledge of the products available to fix the situation he may only be able to do just that, tell you what is wrong. I have been working for a company for the past 10 years that does industrial/ retail flooring, as well as retail and industrial paint and just about anything else you can think of, I answer these questions from 8-5 Mon-Sat. If you want to check out our web site here it is. http://parkercoatings.com/index.html