Sealing Concrete

Whether concrete is stamped, stained, or overlaid it should be sealed. Sealing your decorative concrete not only protects your investment, but brings colors and patterns to life. Most sealer manufactures recommend applying sealer after the concrete has cured for 28 days. They can be applied through a sprayer or can be rolled on with a short nap roller cover.
 
There are multiple types of sealers that can be used on decorative concrete depending on the surface, location, and amount of money the homeowner wants to spend. Sealers typically fall into two categories: Film-Forming Sealers and Penetrating Sealers. 

Film-forming sealers are the type most often used for decorative concrete work, and they do just what the name implies - form a protective film on the surface of the concrete. Most of them also impart a sheen that highlights the beauty of colored or exposed-aggregate concrete. In the category of film formers, you'll find three primary types, each possessing different advantages and limitations:

Acrylics

Available in both solvent- and water-based formulations, acrylic sealers are generally the easiest to apply and the most economical. They are widely used on exterior surfaces because they are UV resistant, non-yellowing, and provide good protection against water and chloride intrusion. However, they usually are much thinner than polyurethanes and epoxies, so they wear faster and usually require reapplication sooner.

DIY Rating - 3* Applying these sealers can easily be done by homeowners and are as simple as rolling them on with a paint roller.

Polyurethanes

These sealers are also available in water- and solvent-based versions. They are nearly twice as thick as an acrylic sealer and provide excellent resistance to abrasion and chemicals. But most polyurethanes are moisture intolerant until they cure. That means if any water is present on the surface when the sealer is applied, a chemical reaction will occur that results in foaming and bubbling.

DIY Rating - 7*

Epoxies

Like urethanes, epoxies also produce a hard, long-wearing, abrasion-resistant finish. They bond well to concrete and cement-based overlays and are available clear or pigmented if you wish to add color. However, epoxies have a tendency to yellow with UV exposure, so they generally are limited to interior applications.

DIY Rating - 7*

Penetrating sealers - Move through the voids and capillaries at the surface and penetrate into the subsurface of the concrete. These sealers are silane, siloxane, or siliconate-based products that react with silica and silicate materials in concrete and with each other to form a hard resin that bonds with the concrete. Their primary function is to repel water and water-based stains, keep salts and chlorides (which promote corrosion in steel reinforcements) out of slabs, and, when used in conjunction with polymers and fluorinated compounds, they can also repel greases and oils. Penetrating sealers can be brushed, sprayed, or rolled into the surface. After the solvents evaporate, slabs have a natural concrete look, which is why some owners like them.

How They Work

The surface of a concrete slab repels water when water is unable to move into the pores and capillaries. Silane-based sealers cause this to happen in one of two ways. They either form a continuous film on the capillary walls and pores in the concrete, causing them to repel water, or they plug the pores so that there can be no movement of water through them. Though specifications usually require the concrete to cure for 28 days before application (to ensure good penetration), these sealers do require some water content in a slab in order to react.

Solvents, which can be either water-based or organic, act as a medium to evenly disperse the active ingredients and, depending on the solvent, to determine the depth of penetration.

DIY Rating - 5*

*We have developed the following rating scale based on the difficulty of the installation and steps involved. For those of you who are venturesome DIYers, this scale may help you rethink that project you had in mind and contact one of our trusted installers.