How to Waterproof & Prepare Portland Cement


Portland cement, or what is referred to as common cement, is the most universally used cement product. The material can be mixed to various densities and is suitable for road and building construction as well as poured cement foundations and driveways. Before treating Portland cement with a silicone waterproofing, it should be tested. If a cementitious waterproofing is used, no such test is necessary.

Things You'll Need

  • Muriatic acid
  • Natural bristle brush
  • Gloves, coveralls, boots and paper dust mask.
  • Garden sprayer
  • Silicone based water proofing coating
  • Heavy-bristle 4-inch brush
  • Cementitious waterproofing
  • Bucket and large paint mixing paddle

Preparing Portland Cement for Silicone Waterproofing

  • Sprinkle a few drops of water on a new concrete surface. If the surface absorbs the water, no further preparation is needed. If the water beads up on the surface, the cement should be etched before being coated with clear silicone waterproofing.

  • Mix a solution of 50 percent water, 50 percent muriatic acid in a plastic garden sprayer while wearing protective gloves, coveralls and boots.

  • Spray the concrete with the solution with a garden sprayer, and thoroughly wet the surface of the concrete.

  • Brush the concrete with a natural bristle brush to etch the concrete and prepare it for waterproofing. Keep the surface wet while etching. Re-wet the concrete as necessary.

  • When complete, thoroughly wash the surface with pure water and allow it to dry before proceeding.

Applying Silicone Waterproofing

  • Apply the silicone waterproofing, such as Thompson's Waterseal right out of the container. No dilution is needed or recommended.

  • Apply the silicone waterproofing with a garden sprayer. Thoroughly wet the surface of the concrete, and continue spraying the surface until the entire area is covered. Allow it to dry.

  • Repeat the process if the area is a high-traffic area such as a basement floor, or walls in a room which will encounter repeated contact with water. Be aware that silicone waterproofing on a cement floor may become slippery when wet.

Applying Cementitious Waterproofing

  • Mix the cementitious coating in a plastic 5-gallon pail according to the manufacturer's instructions. The compound will be white, or off white, and the consistency of thin toothpaste. You do not need to etch the walls if using this type of waterproofing.

  • Apply the coating to a cement wall with a heavy-bristled, 4-inch paint brush. Brush the coating into the pores and pits of the cement wall.

  • Allow the coating to dry thoroughly according to the manufacturer's instructions. This coating does not need two coats, however, the walls can be top coated with latex paint once they have cured. Do not apply this coating to floors.

Tips & Warnings

  • Muriatic acid is highly caustic. When working with muriatic acid and patching concrete floors, wear proper safety gear, including rubber gloves and rubber boots to protect your skin from the acid.

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