Cement coating.

[kyle4501]

Does the concrete have a good vapor barrier under it? If not, the moisture migrating up thru the concrete will push a barrier coating (like epoxy) off.

Lay a large piece of plastic over the concrete for a few days. If dry on the bottom of the plastic, you're good. If there is condensate on the bottom, you don't have a good vapor barrier & most any top coat will not last. There may be some 'breathable' sealers that can be used, but, as I remember, they were pricey.

Since the contractor messed up my vapor barrier, I've decided to go with the garage floor tiles.

[luvrbus]

Kyle, you are right about the lifting. The math never worked for me folks paying 4 bucks a sf for a floor and installing a high priced epoxy for 6 bucks a sf for looks that don't last.A power washer and concrete cleaner will keep his floor looking good also but it makes a mess if he doesn't have floor drains    good luck

[Len Silva]

How is it that Roman concrete as inferior as made seem compared to modern concrete outlast's it?

Roman concrete for several plaster in composition or age toughness instead implies overall hardness years cannot be made to rugged as yesterday for durability. Structural more in even plenty decades done even firmness today.

Thank you for that explanation.  I have never understood why Italian cars were so much faster than American.  Now I finally get it.