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Epoxy Solutions / Services / Concrete 101 / Coating Selection September 2014
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Coating Selection

If concrete floor surfaces arenít adequately protected, they are more susceptible to damage by impact, abrasion, and chemicals. Higher maintenance and repair cost are the result. In the last 15 years, however, there has been a dramatic increase in the use of concrete floor coatings and toppings, indicating that building owners want to cut these costs.

The following steps can help coating specifiers and building owners select the best system to meet their needs. Using the right coating and installing it properly can ensure maximum floor surface performance with minimal maintenance.

1. Evaluate the floor surface

The first step in selecting a floor coating is to evaluate the condition of the existing floor surface. Does it have any cracks, spalls, uneven spots, or other surface defects? Is it covered with dirt, old coatings, or other materials that could interfere with the bond of a new coating?

Adequate surface preparation is critical to successful coating performance. The type of surface preparation method used can have a bearing on coating selection. For example, if preparation methods result in a rough surface profile, the floor may need a leveling or fill coat before a thin-film coating can be applied. This can double material cost. In this case, use a thicker coating.

Types of surface preparation methods for concrete floors are mechanical, chemical, or a combination of the two. Because of the possible environmental hazards of floor cleaning chemicals. Contractors often prefer mechanical preparation methods, such as shotblasting. Sometimes, though, acid etching or degreasing is necessary to clean the floor surface adequately.

New concrete surfaces also require surface preparation. Removing curing compounds and surface laitance and roughen the surface to improve coating bond.

2.†Consider performance conditions

The next step in coating selection is to determine the performance conditions the coating must withstand. Following are the major factors that can affect coating performance:

HEMICAL EXPOSURE Coating materials, even those in the same class differ widely in chemical resistance. Itís important, therefore, to identify the type of chemicals the coating will be exposed to. Also consider the degree of exposure. Will the coating be under constant chemical immersion or just subject to occasional chemical spills? Will the spills be cleaned up or go unnoticed?

ABRASION The amount and type of traffic a floor surface receives determines what degree of abrasion resistance a coating should have. Surface exposed to steel-wheeled traffic, for example.† Required coatings high in abrasion resistance for long term wear. Epoxy Solutions Inc. does not warranty any coating (30 mils or less) against steel wheeled traffic.

IMPACT Floors exposed to heavy loads and direct impact need the protection of a coating system or topping. Also heavy loads on steel wheels require the ultimate in a floor topping.

TEMPERATURE EXTREMES The coefficient of expansion and contraction of many coatings is much higher that that of concrete. If a floor is to be exposed to temperature fluctuations or thermal shock, choose a coating system having a similar expansion can contrition coefficient to prevent bond loss. A coating alone cannot absorb enough heat to resist thermal shock.

After analyzing performance conditions, rank their importance. Identifying the conditions most critical to floor protection needs can help narrow the choices.

3. Donít overlook other considerations

Often coating specifiers overlook the considerations described below when selecting a floor coating. Though these factors usually donít affect coating performance, they may affect the speed and ease of installation and the building ownerís satisfaction with the coating.

AESTHETICS How an owner thinks a floor is going to look after itís coated versus the actual final appearance are sometimes widely divergent. To ensure owners get when they want, ask them what decorative appearance and surface textures they prefer. With the variety of coatings available, many looks are possible. Perception in decorative flooring is one of our most difficult obstacles.

SAFETY When choosing a floor coating you must understand that the minimum coefficient of friction is .40 in Ontario. This standard set by the Ministry of Labour requires that employers maintain a slip resistant environment at all times. A little slip resistant aggregate, which cost peanuts at the time of installation, can reduce lawsuits and lost work time dramatically. Expensive systems do not ensure that the minimum standard is maintained. If you are unsure of how this standard affects you please call Epoxy Solutions for a Certified reading at your facility. Accidents are preventable!

INSTALLATION NEEDS †Often floor resurfacing projects have tight installation schedules. This may prevent the use of coating systems that take a long time to install. Also consider the amount of odor of the coating. In occupied areas, for example, the odor of solvent-containing coatings may be too strong. The temperature of the floor surface at the time of coating installation is critical too. Some coatings, such as epoxies, are temperature-sensitive and have variable curing times at lower temperatures.

LIFE EXPECTANCY All building owners want a floor coating system that will last forever and is maintenance free. But all coatings need some periodic maintenance if they are to achieve their maximum life expectancies. Maintenance procedures should be clearly understood and adhered to.

ECONOMY When choosing a floor coating you generally get what you pay for. A low-cost coating may save money initially, but a more expensive system usually provides longer wear and has greater protection against chemical breakdown. Generally, thicker coatings are the more durable and last longer.

4. Specify coating type and thickness

Coatings for concrete can be classified by:

  • Thickness (thin-film, high-build, slurry, and topping or overlay)
  • Polymer type (epoxy, urethane, vinyl ester, acrylic, methyl methacrylates, and various hybrids)
  • Appearance (decorative or functional)
  • Finish (smooth or textured with or without slip resistance)

Surfacing needs can help determine the appropriate coating thickness, finish, and appearance. Polymer type is more difficult to select. There are thousands of formulations of polymer coating for concrete, and each is different.

Epoxies and urethaneís are the most commonly used polymer types. Generally urethanes are thin-film coatings and have excellent abrasion and wear resistance, gloss retention, and stain and chemical resistance. Most urethanes, though, contain solvents and isocyanates. Recent government regulations by the Ministry of Labour, Occupation Safety and Health Administration (OSHA) and the Environmental Protection Agency (EPA) require lower volatile organic compound (VOC) content in these and other products and will eventually ban most urethanes from the market.

Epoxy floor coatings, on the other hand, contain no solvents.† They also have excellent adhesion, good to excellent chemical and abrasion resistance, and excellent mechanical properties (tensile, compressive, and flexural strengths).

Recently, epoxy hybrids have been developed to replace most urethanes. These materials have good to excellent thermal and stress-relieving properties and impact resistance when incorporated with aggregates. They also form the new backbone for secondary containment systems because these flexible epoxies do not contain plastisizers and will remain flexible for the life of the building.

5. Review material properties and application procedures

After choosing some prospective coating products based on the factors discussed so far, review each oneís specifications, performance characteristics, and installation procedures. The coating that best satisfies floor-surfacing needs is the one to use.

Reviewing coating specifications can be confusing because there are no standard specification formats. Formulators test their coating products using a variety of ASTM methods and other. The reviewer often must compare theses different test methods to find difference in reported values. Professional assistance may be needed to understand the data. At Epoxy Solutions Inc. we are N.A.C.E. Certified Coating Inspector and can assist you in coating specification and selection.

6. Choose and experienced installer

Choosing the right contractor to install the coating is as important as choosing the coating itself. For the best results, find a contractor who is trained to install the type of coating to be used.

Robert R. Cain is president of KRC Associates, a consulting firm specializing in the protection o of concrete surface. He also serves on the board of directors of the International Association of concrete Repair Specialist (IACRS).

Epoxy Solutions Inc. are certified installers for Garland Floor Company, Rustoleum, Polymer Science Corporation,† 3M ESD/Conductive, ICI/DEVOE, Sico, LM Scofield, Crossfield Products, Dexotex, Ardex Concrete Toppings, Mapei, & TBS (Technical Barrier Systems).