Shot blasting vs. grinding: Which is better for epoxy floor preparation?

Pros of Shot blasting:

1. The shot blasting process is cost effective and environmentally friendly.
2. The steel shot used by the shot blasting device is cycled back into the machine to be re-used again making the process is dust-free.
3. Shot blasting makes it possible to prep 30k sq ft per day. For smaller jobs, a small shot blaster is used to prep.
4. All shot blasting is done standing up which puts less strain on workers.
5. For the majority of projects, shot blasting jobs will give a better profile for adhesion.

Cons of Shot blasting:

1. Shot blasting makes it difficult to fit into tight spaces or close to walls, so edge grinding is always required as part of this process.
2. Shot blasting requires 480v electrical hook up on-site or we will need to bring a generator to power the equipment.
3. Shot blasting will only provide a more aggressive profile. It is unable to be dialed in to provide a lower profile that works for sealers.

Pros of Concrete Grinding:

1. Large planetary concrete grinders can smooth and level surfaces that are uneven.
2. Grinding is a slower process than shot blasting, but it is the best way to fix largely uneven floors.
3. Small concrete grinders work great for small areas, don’t require special electrical hookups, and often work faster for small jobs than a shot blaster.
4. Concrete grinding is a dust-free process.

Cons of Concrete Grinding:

1. Hand grinding is very arduous and requires employees to be on their hands and knees.
   For larger projects, concrete grinding is not a cost effective method of prep.
2. Concrete grinding in large areas is very slow when compared to shot blasting.
3. Concrete grinding will only provide a lower profile (csp 1-4, see picture of concrete profiles)

Is it necessary to shot blast or grind for every epoxy project?

All direct-to-concrete epoxy projects require shot blasting or grinding before installation. The type of prep that is performed is determined by the system being installed. If the epoxy system is a thinner mil system such as a sealer, grinding the surface works best. For epoxy coatings and other thick mil systems, shot blasting is the preferred method of prep.

Think of it this way:

If shot blasting was used for a sealer application, the high points in the concrete left after blasting wouldn’t be encapsulated by the sealer. This leaves exposure points that will cause water or other foreign material to penetrate under the coating leading to early failure of the flooring.

For extremely thick systems, like urethane cements, the concrete requires a heavy profile to “hold on to” the system. This will help prevent the epoxy from delaminating or separating from the concrete.

Could this be done DIY, or should you call a professional?

The most important recommendation is to ensure proper prep! This is the most essential part of our installation process. Those attempting DIY concrete prep won’t have access to the expensive shot blasters, vacuums, and grinders that are required. YouTube might be filled with DIYers detailing their experiences installing epoxy themselves, but they rarely tell the whole story.

One prep method advertised is using muriatic acid to etch the concrete. This may work for thin sealers that require a low profile, but it also requires immediate neutralizing of the surface. The whole process is quite messy and doesn’t provide the right profile required to make a coating last. Also, muriatic acid will kill grass and stain asphalt driveways if used to prep concrete.

Overall, concrete prep for epoxy installation is an arduous and careful process that is required to ensure a long-lasting epoxy system. Whether your project needs shot blasting or grinding, contact our experts at SwedeBro to give you a quote for your project today!