It would be beneficial to apply your Epoxy Primer on a surface that has a profile, to give a mechanical 'Anchor' to the coating. As you quite rightly state, Hydroblasting
( Or U.H.P. Jetting) does require Abrasive Injection to produce a surface profile. The type of abrasive is crucial to give a profile of given shape and depth. We use GMA Garnet, Australian Grade, this is a naturally occurring hard and very dense Inert Mineral, crushed to the grades suitable for giving the profile we require for the selected coatings.
Hope this helps,