Examine the Surface - The surface should be checked for barriers such as existing sealers, curing materials, grease, oil, efflorescence, and dirt that must be removed.
Test the Concrete - A "water drop" test can be used to determine if a surface is clean.Note: New concrete must be cured at a suitable temperature for at least 28 days.
Clean Uncoated Concrete - Remove any chemicals, oil, and grease from the concrete first.
Previously Painted Surfaces - If the paint is peeling or degrading in any way, it should be completely removed.
Repair Surface Defects - Remove any loose concrete, and clean and fill holes, cracks and other surface defects with an approved method.
Shot blasting - Shot blasting is principally used to roughen horizontal surfaces in the preparation for the application of sealers, coatings, or polymer overlays.
Diamond Grinding - This method may be used on horizontal surfaces to remove deposits or coatings, and to reduce or smooth a surface profile.
Scarification - Scarifying is the rotary action of the cutters (toothed washers). It impacts the surface at a right angle to fracture or pulverize the top surface of the concrete to expose a clean, fresh surface.
Acid etching - is the process of applying an acid solution to a concrete surface, allowing the acid to react with and 'etch' the concrete.Acid etching of concrete is an acceptable, but less popular method for commercial concrete surface preparation than shot blasting.

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You can find some surface preparation machines at links below:
Profesional floor covering tools and eqiupment for epoxy flooring
Floor preparation equipment: scarifying and grinding machines

More about this topic you can find in "The Best Web Epoxy Links" eBook.