STEP 1: REMOVING OIL, GREASE, AND DIRT
Dirt, dust, and other loose contaminants will inhibit bond formation and can be removed first by sweeping, vacuuming, air blasting or water spraying.
Hydrophobic materials, like oil, grease, and form-removal lubricants will also inhibit bonding and should be spot-removed. The recommended methods of removal are scrubbing with a brush, water and detergent, steam cleaning, and low-pressure washing (under 5000 psi).
With the concrete sound and contaminant-free, all that’s left is to adequately roughen the surface, but to what degree?
STEP 2: TEN GRADES OF SURFACE ROUGHNESS
With the concrete sound and contaminant-free, all that’s left is to adequately roughen the surface, but to what degree?
Grinding
Grinding removes laitance, protrusions, surface contaminants and produces a smooth or polished surface, depending on the roughness of the abrading discs.
The discs move at right angles to the surface, and may leave circular patterns or gouges in the surface. Floor grinders are used for horizontal surfaces. Hand-held grinders are used on vertical surfaces.
SHOTBLASTING
Shotblasting propels steel shot against the concrete surface by means of a wheel. The impacts of the shot pulverize concrete and contaminants and roughen the surface. Spent shot is separated from waste products and recycled. Shotblasting is a preferred method for cleaning and profiling horizontal surfaces and has the same applications as abrasive blasting. In some special situations, robots can shotblast on horizontal planes.
SCARIFYING
A scarifier consists of rows of toothed washers assembled on steel rods that are mounted to a rotating steel drum. As the drum spins, the washers strike the surface, fracturing and pulverizing concrete, and producing a striated pattern. Scarifying only works on horizontal surfaces.