You probably see how beautiful and effective epoxy coatings are. Have you ever stopped to think how much work goes into preparing the concrete surface to produce such magnificent work?
Many clients complain that the work is taking too long, it is too noisy or very dusty. Surface preparation takes up to half the person-hours allocated to the project.
Here are some surface preparation steps.
Concrete Surface Preparation Methods for Epoxying
Etching
Etching is roughening the concrete surface using chemical action. Usually, muriatic acid was poured on the surface until it had eaten into the surface resulting in a rough profile. Epoxy floor coatings need a rough surface to attach.
Shot Blasting
Shot blasting is more aggressive and produces a rougher profile than grinding. The method involves hitting a concrete surface continually with steel shots from a high-velocity centrifugal machine.
Shot blasting can prepare concrete floors for coatings, application of sealers, and polymer overlays. This surface preparation method is advisable when faced with tough 1/8 inch epoxy coatings or methyl methacrylate systems. You’ll have to blast the surface several times for thicker coatings. You can also get rid of 10 mm thick polyurethane coatings through shot blasting.
The good thing with shot blasting is that it produces negligible amounts of dust or air pollution compared to other surface preparation methods. The machine sucks up everything into an internal blast chamber where dust is separated from reusable steel shot. Some companies attach filters to some models to lower dust production further.
Diamond Grinding
Grinding involves smoothening the substrate surface with a mechanical grinder. Grinders use diamond or stone abrasive discs of varying grits. You just attach the discs to the grinder, switch it on and press the rotating discs to the concrete surface at right angles. You then use circular motions to go over the entire work surface.
Diamond grinding can be used to remove light coatings or surface deposits and to smoothen the surface. For thicker coatings, use solid carbide scarifying cutters.
Diamond grinding usually results in a smooth profile than shot blasting or scarifying and can be used to even the surface. You can grind off raised spots or uneven joints from 1/16 inch to 1/8 inch high.
Scarification
Scarifying is primarily eating deep into the concrete floor. You have to do this when faced with deeply contaminated, horrible-looking floors. Machines with toothed wagers at the end of high-speed rotating drums are placed on the floor at right angles to crash and fracture the contaminated concrete surface. You are then left with a fresh substrate to work on. The methods work up to 1/4inch deep.
Scarification can also be used to create a non-slip profile by cutting deep grooves into the concrete.
Scabbling
Scrabbling is similar to hitting the work surface continuously with a hammer, resulting in a rougher profile than grinding or scarification. Scrabbling machines hammer the surface repeatedly using bits mounted on pistons run by compressed air.
You can use scabblers to prepare deeply contaminated surfaces as they can remove coatings up to 1/4 inch deep.
Scabbling is applicable for removing thick epoxy coats, spalled concrete, or preparing a deteriorating concrete surface.
Cleaning the Work Surface
After all the above surfaces have been completed, it is time for some cleanup. Sweep the big and medium debris with a push broom. Next, go over the surface with a shop vac and vacuum every bit of dust and impurities.
Wash the surface with house cleaning detergent and water. Scrub the surface thoroughly with a stiff brush to reach all the crevices and shallow cracks. Use a grease-cutting detergent to remove all grease and oil stains.
Cleaning is important because laying a new epoxy coat on impurities such as dust and grease will cause the new coat to rise or peel in the future, spoiling all the hard work.
Priming
The last stage before epoxying is priming. Primers are substances applied to the concrete surface, usually with adhesive characteristics. They help the new coat to cling faster to the concrete than it would have done without a primer.
Bottom Line
Surface preparation for Epoxying is as important as the epoxying process. You ought to take it seriously to avoid epoxy failure pitfalls in the future. All the above methods are meant to provide a clean, even rough substrate for proper epoxy adhesion.
