Epoxy Coating Floor Prep Methods: Shot Blasting vs. Diamond Grinding

Shot Blasting or Diamond Grinding Your Concrete Floor

Putting a new epoxy or urethane coating on your cement floor is a great investment in your workspace. It would be silly to spend money on the coating product, but neglect the preparation of the surface beforehand. When applying a concrete coating, you will be faced with a decision of either shot blasting or diamond grinding your concrete.

Which is better? Like most questions in workspace improvement, the answer is “it depends.” Important questions you need to consider are cost, how damaged your surface is, and how much time you have.

Shot Blasting

 Over the years, shot blasting has been the go-to method for floor preparation. Steel balls are projected from a machine onto the concrete surface over and over, to crush the top layer of concrete and dislodge any coatings. Most balls are pulled back up and used again, but some do escape the machine. Soft concrete, or laitance, concrete dust and any other contamination are pulled into the machine’s dust collection system for disposal so your workspace stays clean while the shot blasting is going on.

Advantages of Shot Blasting Concrete

  • Shot blasting is chemical-free
  • Dust is not hazardous waste
  • Can use in or outdoor applications
  • Many types of abrasive are available
  • Shot blasting is considered a clean process
  • Can be used in sensitive areas of factories, food prep areas, etc.
  • Wide variety of machines available- ride on, walk-behind, electric, and diesel
  • Can be completed quickly

 Disadvantages of Shot Blasting Concrete

  • Can only remove 2-3 mm of screed or 1 mm of epoxy
  • Shot blasting is hot enough to make some existing coverings sticky
  • May leave overlap marks (also called tram lines)
  • Edges of walls and surfaces can usually not be reached by the machine so 7-9 mm must be handled differently

Diamond Grinding

 Diamond grinding machines use pads or discs coated in specific grits of industrial-grade diamonds to abrade concrete surfaces and remove contaminants. Professionals will utilize dust collection systems to contain the spent grit and the concrete dust so it does not make your workspace a mess. On higher-end machines, the dust collection is incorporated in the grinder.

Advantages of Diamond Grinding Concrete

  • Can use a sequence of grits to create a marble-like finish on concrete
  • Removes high build and multiple layers better

Disadvantages of Diamond Grinding Concrete

  •  Can be very slow
  • Diamond blades and diamond abrasives can be expensive
  • Removing thick layers increases the cost due to the number of blades consumed
  • Metal studs or bolts in concrete can damage the grinder
  • May need to re-cut expansion joints

Some concrete projects may even incorporate both types of grinding depending on the need and desired outcome.

PennCoat, Inc. has been providing industrial painting, commercial painting, epoxy flooring, and polished concrete services for nearly 30 years.  Our experienced installers are trained and equipped with the proper knowledge and tools to ensure that every installation is installed efficiently and safely.  PennCoat, Inc. provides service to Pennsylvania, New Jersey, Maryland, and Delaware.  We cover York, Lancaster, Philadelphia, Chester, Montgomery, Baltimore, Harrisburg, Dauphin, Bucks, Berks, and other counties in the surrounding area.