WHAT IS TILT-UP CONCRETE
Concrete is a mixture of Portland cement and water that coats and binds the surface of fine and coarse aggregates, that through a chemical reaction called hydration, hardens and gains strength to form the rock-like mass known as concrete. Concrete is malleable when newly mixed and strong and durable when hardened. Concrete is a very commonly used in the construction of skyscrapers, bridges, sidewalks, superhighways, houses and dams.
Tilt-up concrete is poured and cast on the job site in concrete forms. Once the concrete has cured, a mobile crane will tilt up the concrete slab and move it into place; where it is braced and secured.
“To prevent the concrete from adhering to the molds, contractors apply release agents, or bond breakers, to the mold before the concrete is poured. These release agents can be solvent-based, water-based, oil-based, silicone-based, silicone-free, silicone water-based and many other proprietary combinations. But, they all perform the same function—they create lower surface energy between the concrete form and the concrete to mitigate adhesion.” (concreteconstruction.net, 2020) Unfortunately, these release agents will prevent paints and coatings from adhering to the concrete surface.
PAINTING TILT-UP CONCRETE
For paints and coatings to properly adhere to the tilt-up concrete, all the form release agents, dirt, grit, grease, grime, laitance and any foreign contaminants must be removed prior to application. Typically, a thorough pressure washing of the surface at a minimum of 2400 PSI will remove water-based bond breakers, but will sometimes require solvent cleaning, acid etching or even abrasive blasting to ensure complete removal. To ensure proper removal, pressure washing should be performed from the bottom of the panel to the top, then flood rinsed back down the panel. This will reduce the chances of missing spots on the wall that can lead to coating failures. Always check with the manufacturer of the bond breaker on the proper means of removal.
After the building has been cleaned and allowed to dry, a “splash test” should be performed on the walls at a rate of at least 2-3 tests per panel, or a rate agreed upon by the general contractor and owner’s representative. The “splash test” is simply splashing clean water from a bottle, low pressure sprayer or hose, to check to see if the water quickly is absorbed into the concrete. This should not take longer than a few seconds. If the water beads or runs down the wall, the area must be cleaned again and retested to ensure adhesion of the coatings.
SPLASH TEST FAIL
SPLASH TEST PASS
After the concrete has passed the test for the removal of bond breakers and cleanliness, it should be primed with a quality acrylic or styrene acrylic primer, such as Florida Paints 3850 SunFlex Exterior Acrylic Primer. For a textured surface, apply a coat of Florida Paints 1960 TropiTex Acrylic Wall Texture in the desired color. For optimum performance and color retention, apply a finish coat of SeaSide 1220 Premium 100% Acrylic Exterior Satin.
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After the concrete has passed the test for the removal of bond breakers and cleanliness, it should be primed with a quality acrylic or styrene acrylic primer, such as Florida Paints 3850 SunFlex Exterior Acrylic Primer. For a textured surface, apply a coat of Florida Paints 1960 TropiTex Acrylic Wall Texture in the desired color. For optimum performance and color retention, apply a finish coat of SeaSide 1220 Premium 100% Acrylic Exterior Satin.
