Plant floor coatings review

The types and variations of floor coatings for industrial use today are bewildering. Even if you're a knowledgeable chemist, it's hard to sift through the plethora of names, properties, and recommended applications. Even so, a little knowledge can go a long way in talking with suppliers and installers.
By Richard L. Dunn, Editor, Plant Engineering Magazine June 12, 2003
Key Concepts
Surface preparation is as important as the coating.
There is a coating for every need.
Selection factors
Installation precautions
Basic coating types

The types and variations of floor coatings for industrial use today are bewildering. Even if you’re a knowledgeable chemist, it’s hard to sift through the plethora of names, properties, and recommended applications. Even so, a little knowledge can go a long way in talking with suppliers and installers. This article is intended as a basic review of the major types of plant floor coatings systems.

Selection factors

The conditions under which a floor coating must perform are paramount in the proper selection of a coating. The more definitive the conditions are, the better the potential for selecting a coating that will perform as required and expected. Some of the conditions that must be considered are:

  • Floor traffic loads and concentrations — frequency of vehicle traffic, weights of vehicles and loads, maneuvering, types of wheels or tires

  • Substrate for coating — type of concrete or other material, new concrete, previously applied coatings, cracks, spalling

  • Temperatures — normal temperatures, temperature ranges, rates of temperature change, expansion/contraction

  • Chemicals (and their concentrations) floor has been exposed to prior to coating

  • Chemicals (and their concentrations) floor coating will be exposed to, both known and potential

  • Flatness requirements

  • Slope or drainage requirements

  • Cleaning requirements

  • Slip-resistance characteristics required

  • Appearance/color requirements

  • Abrasion resistance required

  • Impact resistance

  • Conductive properties

  • Concrete moisture content

  • Concrete surface strength

  • Curing properties — duration, vapor release.

    • Many floor-coating contractors offer a variety of coating products to fit various needs and are helpful in the selection process. Coating manufacturers are also excellent sources of guidance.

      Installation precautions

      Surface preparation of the floor to be covered is at least as important as selecting the right coating. And preparation of the floor is actually more difficult than installing the coating. Whether the coating is being applied over repaired areas, an existing coating, or a new substrate, correct surface preparation is critical. Here are some factors to consider.

      Surface to be coated must be as clean as possible. All dust and other particles must be removed before a coating is applied. All traces of wax, oil, grease, and other contaminants must be removed. Clean oil spots and stains with absorbing compounds. Scrub with detergents or solvents to lift contaminants that have penetrated the surface; more than one application may be needed.

      All cleaning materials need to be compatible with the coating to be applied. If an acid cleaning method is used, check the substrate surface pH and moisture content to ensure they are within guidelines of the coating manufacturer.

      Patching and filling materials must be compatible with the coating system. Check with the coating manufacturer to make sure the materials to be used for filling cracks and joints or for patching will not cause any coating problems. Be sure that all concrete surfaces or patches are fully cured. A new concrete floor may need to cure for up to a month.

      Use abrasive blasting or scarifying to remove old coatings or to “resurface” floors in bad shape. Although such methods may disrupt plant operations, they may be a necessary part of substrate preparation to ensure the coating’s performance and long life.

      Verify that the tensile and compression strengths of the substrate match the requirements of the coating. Coating manufacturers can provide detailed specifications and installers should be able to conduct appropriate tests.

      Investigate all scheduling concerns and plan accordingly. Timing and time restrictions are critical. It is likely that installing a new floor coating will be limited to evenings, weekends, holidays, or shutdown periods. And once the project begins, the work area cannot be used until the project is complete. Minimum and maximum cure times vary widely depending on the coating system. Temperatures and humidity nearly always play a role in obtaining proper results; be sure that air and surface temperatures and humidity levels can be maintained at the specified levels throughout the installation.

      Basic coating types

      While there is a plethora of floor coatings available, the most widely used types fall into a few general families. Most coatings are built up in multiple layers. Top coats are a frequently applied option.

      Surface hardeners, sealers, and dustproofers. Surface treatments that harden, seal, and reduce dusting are basic to almost all concrete installations. Common solutions are sodium silicate or fluorosilicate. Other chemical formulations are also used. Curing agents generally fall into this category of coating.

      It is imperative that the final floor coating be given consideration before using any of these agents, because some can have an adverse effect on the bonding of other types of flooring products. For the same reason, older floor surfaces should be analyzed for compatibility with the new floor coating being considered.

      Thin mil coatings. Thin mil coatings are generally roller-applied epoxy or urethane, and may be water based or solvent based.

      High-performance urethane offers excellent shine, durability, flexibility, weatherability, color stability, and resistance to abrasions and chemicals. It is often used as a top coat over an epoxy.

      Water-based epoxies are used as primers, base coats, and topcoats. These two-component coatings are water reducible with low odor. They offer moderate chemical and abrasion resistance and good adhesion properties.

      Solvent-based epoxies are durable, multipurpose coatings with excellent adhesion and resistance to acids, alkalies, and aliphatic solvents.

      High-build epoxy coatings. These 100% solids, two-component coatings will hide minor floor imperfections and can be applied to new concrete floors or over older floors. They cure to an extremely hard and durable surface, which can be smooth, textured, or non-slip. They have minimum odor. They are available in a wide variety of colors.

      Broadcast systems. Broadcast systems are a special type of epoxy coating that includes a layer of aggregate to give the floor decorative coloring and a slightly textured surface. They are good for restoring worn or slightly pitted concrete and exhibit other properties of epoxy for wear and chemical resistance.

      Heavy-duty resurfacers. These relatively thick toppings are used to repair heavily worn or damaged concrete floors and are generally trowelled in place. Common materials include epoxy resins and polyester resins. These surfaces perform better than concrete under heavy traffic and harsh conditions. They can be applied over concrete, brick, metal, and even wood.

      Conductive coatings. Conductive coatings are relatively new to the coatings industry. These systems include special primers and top coats to safely dissipate static electricity charges to ground.

      More Info: Readers anticipating a floor coating project may find the following ASTM standards of interest:

      D4258 Practice for Surface Cleaning Concrete for Coating

      D4259 Practice for Abrading Concrete

      D4260 Practice for Etching Concrete

      D4262 Test Method for pH of Chemically Cleaned or

      Etched Concrete Surfaces

      D4263 Test Method for Indicating Moisture in Concrete by the Plastic Sheet Method

      D4541 Test Method for Pull-Off Strength of Coatings Using Portable Testers

      General guide to floor coating systems

      Heavy-duty resurfacers Thin-mil coatings High-build coatings Broadcast systems Concrete treatment Conductive coatings
      Source: Adapted with permission from information provided by QuestMark Flooring
      Manufacturing/production X X X X X
      Traffic aisles X X
      Loading docks X X X
      Locker/restrooms X X
      Food processing X X
      Bottle/fill lines X X
      Warehousing X X X
      Plating lines X
      Chemical storage X X
      Packaging areas X X
      Laboratories X X
      Airline hangers X X X
      Water/waste treatment X X
      Paper mills X X
      Epoxy recoats X X X
      Coolers/freezers X X
      Battery charging X
      Electronic assembly X
      Testing labs X
      Pharmaceuticals X X X X
      General patching X