Surface Preparation Steps: Clean, Roughen and Repair
Clean the Concrete
Remove all chemicals, oil, and grease from the concrete first. Curing compounds, oils, grease, chemicals, or other contaminants should be removed. Chemicals and oils are often removed with high-pressure washing. Dirt and grime can be removed with a degreaser worked in with a floor polisher. Learn more about cleaning concrete.
Shotblasting is often used to clean the floor- a benefit with this method is that it "profiles" the floor to receive the bond coat at the same time the floor is cleaned. A "water drop" test can be used to determine if a surface is clean. Water beads on surfaces contaminated with sealers, curing compounds, oil, and grease.
Here are some products & techniques you may find useful during the cleaning process:
Roughen or "Profile" the Surface
The most important characteristic for a coating or overlayment bonding is the texture or "profile" of the concrete.
For Concrete polymer-modified overlays:
Contractors and manufacturers are split between roughening the concrete by mechanical profiling or acid etching. Large or difficult surfaces will usually be mechanically profiled.
Related Product: Tek Gel™ for Profiling
For Floor Coatings in Industrial or Commercial Applications:
Mechanical profiling is the method of choice. Thomas Kline of Structural Preservation Systems notes that acid etching can provide adequate surface preparation for horizontal installations of coatings and toppings in areas that are well ventilated and require a spark and dust free environment. But they will not remove petroleum-based products or animal vegetable oils from the concrete.
William Perenchio of Wiss, Janney, Elstner Associates, Inc. notes that acid etching should only be done when no alternative means of preparation is possible.
Again, the safest measure is to follow the floor coating manufacturers installation instructions.
Repair Surface Defects
First, get the specifications from the coating or overlay manufacturer for repair materials to be used under the coating for material compatibility.
Grind or chip all projections from the concrete greater than 1/16 "
Remove unstable concrete, and clean and fill holes or cracks, and other surface defects with an approved material. Understand if the patch should be roughened or smooth, and how long they need to cure before being covered.