How to Remove Waterproof Spray on Cement Driveways

Remove old waterproofing sealer before applying new sealer.

Masons use cement as a binder for concrete. Cement is the "glue" that holds the aggregate and sand together to form a hard, stable and durable concrete surface. Many homeowners apply waterproofing sealer to their concrete driveway to protect the surface from stains and freeze-thaw patterns that lead to cracks in the driveway. Some types of sealant turn a tan color, flake or peel with age and require removal before resealing the concrete driveway.

Things You'll Need

• Blaster
• Corn husk or walnut shell blasting media
• Eye protection
• Dusk mask
• Chemical-resistant gloves
• Chemical resistant splash shield or goggles
• Chemical-resistant boots
• Concrete stripper
• Paintbrush
• Power washer

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Instructions

Blasting

1. Fill a blaster with ground corn husk or walnut shell blasting media.

2. Put on eye protection and a dust mask.

3. Direct the blaster gun at the concrete driveway, positioned 24 inches away from the surface. Turn on the blaster and make back-and-forth sweeping motions across the concrete driveway. Move the blaster in closer to the surface if the waterproofing sealant does not come away from the concrete surface.

4. Move from side to side across the driveway as you work your way forward down the driveway. Continue to blast the sealant away from the surface until no waterproofing sealant remains on the concrete driveway.

Chemical Stripper

1. Put on chemical-resistant gloves, chemical-resistant splash shield or goggles and chemical-resistant boots.

2. Apply a thick coating of chemical concrete stripper made to remove epoxy, urethane and sealants with a wide paintbrush until the entire driveway has a coating of chemical stripper. Leave the chemical stripper on the surface for two to eight hours, depending on the brand of the chemical stripper and the thickness of the existing waterproofing spray.

3. Examine the chemical-covered concrete driveway every hour for signs of lifting and wrinkling of the old sealant.

4. Aim the nozzle of a power washer at the driveway beginning at the end near the house. Spray the driveway with the water from the power washer until no chemical stripper or waterproofing sealant remains on the concrete driveway.

Tips & Warnings

• Test a hidden area on stained or dyed concrete for colorfastness before applying chemical stripper to the entire concrete surface.

• Clean the area where the chemical stripper and old waterproofing material collects and dispose of it according to your local laws and ordinances.

• Do not keep the blaster gun in one area; you will create a divot in the concrete surface. Always keep the blaster in constant motion.

References

• "Masonry and Concrete"; Creative Homeowner Editors; 2009
• "Masonry"; Time Life Editors; 1977