Maintenance and Repair Considerations for Concrete Floors
Proper maintenance of concrete floors can save time and money in the long run. Spotting the early-warning signs of deterioration can head off major problems. Better yet, choosing the right protective coating and applying it carefully when the floor is new can prevent problems for years.
Given the varied uses of concrete floors today, there are many excellent coating and patching products on the market. When planning a new floor, a facility manager should know the kind of wear and tear the floor will need to withstand.
The choice of coatings depends on the nature and extent of the expected foot and machine traffic, and the degree to which traffic will be dispersed across the floor or directed along wear-prone corridors. As with most endeavors, advance research and consultation with the manufacturers of floor coatings are worth the time.
Safety is paramount - Some coatings are more slippery than others, but most are slippery when wet. Depending on the anticipated use, a walkway, ramp, loading platform or even an entire floor may require an anti-slip coating. These coatings should contain an additive, such as silicone carbide granules for a rough finish, or grit - such as walnut shells or silica - which can be purchased separately and mixed with the coating prior to application for different anti-slip finishes.
Durability is another prime consideration - Floors that may experience fuels, solvents or other harsh chemicals may need tougher coatings, not only for the durability of the floor but also for ease of routine cleaning and spillage cleanup. Some chemical-resistant coatings are specifically formulated for use on concrete surfaces in the vicinity of chemical storage tanks (piping, dike walls, containment areas, etc.).
Ease of Application
Brushes, rollers or squeegees without special equipment or training can be used to easily apply the best floor coatings. To minimize employee exposure to harmful fumes during application, it is best to choose a 100 percent solids coating, since they contain no volatile organic compounds (VOCs). Self-leveling coatings save hours of labor. For a large job, a coating packaged in containers holding three gallons or more can also save time.
Before choosing a floor coating, it is advisable to study the manufacturer's specific application instructions. Here. the buyer will encounter many variables - curing time, curing temperature, thickness per coat, mixing ratio, pot life, coverage per container and surface preparation, to name a few.
Proper surface preparation is essential to ensure the adhesion of a coating. In all cases, the floor must be sound, rough, clean, oil-free - and dry. Newly poured concrete should be allowed to cure for 28 days prior to preparation. Power washes or steam cleaners are effective and can reduce cleaning time, but multiple cleanings still may be necessary.
If a curing membrane or cap-curing agent have been used on new concrete, they must be removed. The new floor should either be shotblasted or etched with acid to create a porous surface profile. Environmentally safe acids, such as citric acid, are available. However, etching is not a substitute for degreasing, and should come after the surface has been degreased. The floor should be rinsed several times after etching to neutralize the acid.
Before washing a concrete floor, chipping, scarifying, shotblasting, sanding, or grinding for older floors should remove all loose or unsound concrete. After washing with a grease-cutting detergent, the floor should be rinsed several times.
For previously painted or coated concrete, a spot test should be conducted to make sure the new coating bonds to the old surface. It is advisable to wait five days and then scrape the test area with a sharp instrument, or cut an "X" into the surface, place pressure-sensitive tape firmly over the cut, and remove the tape with a hard, fast pull. If the new coating fails either test, remove the old finish with a sander or paint stripper.
Shotblasted or etched concrete usually requires the application of a primer to penetrate the surface prior to applying the protective coating. It is important that the primer be formulated specifically for the chosen coating, and that the manufacturer's instructions be followed to the letter.
By watching a concrete floor for signs of deterioration, a maintenance crew can usually stay on top of the aging process, and ensure that all repairs are minor ones.
Obviously, the choice of a grout or patching compound depends on the nature of the problem. As with choosing an initial coating, effective repair of a concrete floor first requires choosing the right product for the job at hand. Many of the variables to be considered are also the same: Curing time, ease of mixing, ease of application, etc.
The best patching compounds on the market today are 100 percent solids, epoxy-based formulations. With compressive strengths three to five times greater than concrete, these room-temperature-curing compounds are the strongest products available. These are particularly useful where the deterioration was the result of greater or more frequent stress than received by other parts of the same floor. Easily trowel-applied, these nonsagging, nonshrinking products provide excellent resistance to water, oils, solvents, acids and alkalis. Some even bond to wet surfaces. By contrast, water-based compounds readily available at hardware stores and home centers have poor compressive strengths and are not as durable.
High-traffic areas call for a fast-curing formulation; some repair products cure completely in just three hours.
Preparation of an area to be filled or coated is similar to preparing an entire floor. Some repair compounds require the application of a primer to maximize adhesion.
With careful planning, the correct matching of product with expected use, and vigilant upkeep, common pitfalls can be avoided and a concrete floor can last for decades with an attractive, durable finish.