How to Repair, Seal and Waterproof Concrete Cracks

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concrete patio crack repair

Sealing and waterproofing cracks in concrete. Over time and exposure to the elements, exterior concrete can develop cracks, due to temperature changes, ground movement, improperly placed joints and excessive loads. Find out what causes a crack in a concrete patio in your home or other slabs, and what the options for concrete patio crack repair. 

Once a crack develops, it is important to seal the crack from water, to prevent further deterioration. QUIKRETE Polyurethane Concrete Crack Sealant is a non-sag, flexible sealant that will stretch up to 700%, without failing. This allows for ground movement and expansion and contraction from temperature change. Concrete crack sealant's matte gray color and textured formula is designed to match the surrounding concrete surface, and its non-sag formula can be used on both horizontal and vertical surfaces.

Concrete crack sealant dries to a permanently flexible, durable material. As with any concrete repair, proper attention to crack preparation is essential to achieving a successful result. Using a chisel and hammer, widen the crack to a minimum of 1/4 inch and break away any deteriorating concrete. The edges of the crack should be vertical or beveled in an inverted "V." Then, remove the loose material with a brush. For large cracks, over 1/2 inch deep, backer rod, which is a foam rope, should be placed in the crack, before applying the sealant.


Concrete Patio Crack Repair

Always wear eye protection and waterproof gloves, when working with polyurethane sealant, and work in a well-ventilated area. To apply concrete crack sealant, simply cut the nozzle tip at an angle, with a utility knife, to match the width of the crack, and load it into a standard caulk gun. Slowly draw the gun down the crack, forcing the bead of concrete repair caulk deep into the crack.

When filling the crack, make sure the polyurethane sealant extends, edge-to-edge. A concrete crack sealant can be tooled with a trowel to remove any excess material and to match the surrounding surface, immediately after placement. The concrete crack sealant will be tack-free in about two hours, depending on temperature, humidity and crack depth. The excess sealant should be removed, immediately, with a citrus-based cleaner or mineral-spritz and a cloth. Polyurethane sealants are temperature sensitive and should not be used when temperatures are below 50 degrees.