Rustoleum Rock Solid will probably not hold up all that long.

Here is the FB link for the company that did our garage last fall. They use a new type of polymer coating that comes with a 15 year warranty. I'm pretty sure it is rated for exterior, as well. It was very reasonable!

Not sure what area of the country you're in, but perhaps he could give you some contacts

All American Garage Floor Coating | Facebook

(He's just an end user of the product, so maybe he will refer you to the parent company for a contact in your area.)

Not actually a garage floor at all so maybe at least post a pic of what it is you are asking about.