Concrete is durable, but it’s not indestructible. Over time, cracks can develop from weathering, ground movement, or heavy use. If you’re considering a concrete resurfacing product to refresh your driveway, patio, or walkway, proper crack repair is essential to ensure a smooth, long-lasting finish.
In this post, we’ll cover the top two most effective methods to repair cracked concrete before resurfacing.
1. Epoxy Injection for Structural Cracks
Best for: Deep, structural cracks that go through the concrete.
Why it works: Epoxy is incredibly strong and creates a permanent bond between concrete surfaces. It doesn’t just fill the crack—it actually restores the structural integrity of the slab.
Steps:
- Clean the crack: Use a wire brush or compressed air to remove debris and dust.
- Seal the surface: Apply epoxy surface sealant along the crack and attach injection ports (usually spaced every 6–10 inches).
- Inject epoxy: Using a dual-cartridge epoxy gun, inject the resin slowly from the lowest port upward until it begins to ooze from the next port.
- Cure and remove ports: Allow 24–48 hours to cure, then remove the ports and grind any excess epoxy flush with the surface.
Pro Tip: Epoxy injection is ideal for cracks wider than 1/8 inch and in areas where structural integrity is a concern.
2. Polyurethane Caulking for Non-Structural or Hairline Cracks
Best for: Surface or hairline cracks, and areas with some movement or expansion.
Why it works: Polyurethane caulk remains flexible after curing, allowing it to move with the concrete and prevent future cracking. It’s also waterproof and adheres well to prepared concrete.
Steps:
- Prepare the crack: Clean out the crack thoroughly. For cracks larger than ¼ inch, use a chisel to widen the crack slightly into an inverted “V” shape to help the filler bond better.
- Apply backer rod (if needed): For deeper cracks, insert a foam backer rod to reduce the amount of filler needed and improve flexibility.
- Apply polyurethane sealant: Use a caulking gun to fill the crack, slightly overfilling it.
- Tool the surface: Smooth the surface with a putty knife or trowel, feathering it out to blend with surrounding concrete.
- Cure fully: Allow the caulk to cure per manufacturer instructions—usually 24–48 hours—before resurfacing.
Pro Tip: Choose a UV-resistant polyurethane sealant for outdoor applications to prevent discoloration.
Final Note: Why Crack Repair Matters
Failing to repair cracks before resurfacing leads to premature failure of the overlay. Resurfacing products like concrete microtoppings or polymer-modified overlays are only as good as the base they adhere to. Cracks will telegraph through new surfaces if not properly treated.
By taking the time to repair cracks correctly, you’re extending the life of your resurfacing job and improving the overall appearance and durability of the concrete.
Ready to Resurface?
Make sure your crack repair method suits the type of damage you’re dealing with. Whether you need the strength of epoxy or the flexibility of polyurethane, a solid foundation is key to a flawless finish.
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