"JimT" writes:
In other words. If YOU examined the product the implied waranty no longer
exists.

If you examined the product, "there is no implied warranty
with regard to defects which an examination ought in the
circumstances to have revealed to him."

How, praytell, could the OP's examination of the product in
the store have revealed to him that it would flake his
concrete? On the contrary, his examination of the product in
the store, as well as his conversation with the associate,
suggested that it would not. In short, the warranty of
fitness for purpose is in effect, because the defect which was
subsequently discovered could not have been discovered by
examination before purchase.