The three Cs of surface preparation—Clean, Check, and Condition—are the foundation of every successful concrete repair project. Taking the time to clean the surface thoroughly, check for absorption issues and structural integrity, and condition the surface using one of the approved methods is crucial for achieving a strong and long-lasting repair.
The Three Cs of Surface Preparation: A Concrete Expert’s Guide to Successful Concrete Repairs
In the world of concrete repair, there’s an old adage: “Surface preparation is 98% of the battle.”
It’s a simple statement, but a critical message. Neglecting or shortcutting surface prep will inevitably lead to repair failures that waste time, money and hard work wasted time and resources. To ensure success, concrete experts follow what we call the three Cs of surface preparation: Clean, Check, and Condition.
Let’s dig into each of these crucial steps.
1. Clean the Surface:
Cleaning the surface might sound like a straightforward task, but doing it right means much more than a spring-cleaning session. The goal here to remove any and all contaminants, stains, or substances that can inhibit bond – think oils, grease, sap, as well as the usual dirt and grime.
Proper cleaning should use some sort of a surfactant and high-pressure water, which will also help to identify any loose or damaged areas of concrete that need to be addressed.
2. Check the Surface:
Once the surface is clean, we move to step two: checking the surface. In this step, we’re focusing on two aspects: absorption and structural integrity.
Absorption: Look for signs of water beading on the surface. If water beads up, it indicates the presence of contaminants that weren’t removed during cleaning. Re-clean any areas where beading is present before proceeding. On the flip side, pay attention to areas that absorb water particularly fast, which indicate high porosity and require additional conditioning prior to repair.
Structural Integrity: A successful repair must start with a sound concrete surface. Damage may be obvious, like chunks of concrete removed during pressure washing, but damage can also be hidden. To verify integrity, tap the surface areas with a hammer or drag a chain across the surface and listen to the sound it makes. A solid “thunk” indicates a good, solid substrate, but a hollow or ringing may suggest delamination. If you hear anything out of the ordinary, the surface will likely require further prep work – possibly including grinding, scarification or full-scale demolition to remove all unsound concrete before before proceeding with repairs.
3. Condition the Surface:
Once the surface is clean and checked, it’s time to condition it properly for concrete repair. There are three methods for surface conditioning, and it’s essential to choose just one and stick with it to avoid interference between methods.
Saturated Surface Dry (SSD): The simplest – and bare minimum – approach involves soaking the repair area with water and allowing it to absorb before applying a repair material. The goal is to bring the surface to a neutral state that neither adds water to the repair (which could act as a bond breaker) nor absorbs water from the repair (which could lead to cracking or delamination). You’ll know you’re at SSD when the concrete looks wet, but is dry to the touch.
– Pro: Simplicity, speed, low cost
– Con: Provides the bare minimum conditioning performance.
Slurry Coating: In this approach, the repair material itself is used as a bonding agent. A slurry of the repair material and water with a consistency similar to loose grout or paint is applied to the surface being repaired. It’s crucial to work the slurry into the pores to prevent off-gassing and ensure a proper bond. Allow the slurry to dry slightly, then follow with the full repair.
– Pro: No additional materials required, provides enhanced performance over SSD
– Con: May not deliver sufficient performance for some non-porous surfaces.
Priming: The most effective method for surface conditioning involves using a bonding agent, such as Sakrete’s Bond Strength Primer. Liquid primers are applied to the surface using a roller or paintbrush, then allowed to dry slightly before applying the repair material. As with all other conditioning methods, it’s important to avoid puddles, as they can act as bond breakers. Pay close attention to the absorption rate of the primer – highly porous surfaces can absorb primers quickly and may require additional coats for peak performance.
– Pro: Ensures peak performance of repair materials
– Cons: Adds cost to the project
With these critical steps completed, you’re ready to move to the fourth (and most fun) step: pouring concrete.
For more advice on surface prep before starting your next repair, contact the Sakrete Technical Team at 866-SAKRETE or via Live Chat on Sakrete.com.