Concrete is one of the most useful materials utilized
Concrete sealers are beneficial for many reasons; they:
Come in a sheen range from matte to high-gloss, adding just the right touch to your concrete surfaces;
Block the penetration of chemicals, dirt, mold, water, UV rays and more;Reduce musty odors, cracking, spalling, efflorescence, crumbling, etc.;
Make the concrete easier to clean, maintain, and increase your concrete's durability, making your investment last longer;
Can penetrate deep into the surface, densifying your concrete and protecting it from harmful freeze-thaw cycles, rust corrosion and more;
Not only protect your concrete, but they can beautify decorative concrete surfaces by making the colors 'pop' even more;
Now that you understand some of the benefits to sealing your concrete, let's talk about the different types of concrete and masonry sealers so you can make the right choice. Remember, there is no concrete sealer that is right for every project and you will get what you pay for. Also make sure you check with the manufacturer for specifications on how to install the sealer properly. Installing a sealer correctly can be just as important as choosing the right type of sealer for your project.
Acrylic Sealers are either water or solvent-based and are a 'film-forming' top coat sealer. They do not penetrate the concrete; rather they form a protective film on the surface. Acrylic sealers are formulated for interior or exterior use, but solvent based acrylics may be more ideal for exterior use as they can be more durable. Acrylics are great for outdoor use because they still allow the concrete to 'breathe'. Acrylic sealers are popular for their low VOC content, toxicity and odor. As they are a soft, film-forming sealer, maintenance coats will be required depending on the wear and tear.
Polyurethane Sealers are also available in water or solvent-based formulas and may be one or two component kits. Although they are also film-forming sealers, they are not as soft as an acrylic sealer and will provide good protection from chemicals and abrasives. Polyurethanes can be used on interior or exterior surfaces and can even be used on concrete countertops. These sealers are typically 50-60% solids content. Be careful not to allow any moisture to come in contact with the sealer until it has fully cured or you may see foaming or bubbling.
Epoxy Sealers create a hard, long-lasting finish. The higher the solids content the stronger the finish. For example, a 100% epoxy finish is incredibly abrasion-resistant and durable. Epoxies are generally suggested for indoor use as they struggle to resist UV rays and can yellow in the sun. You may be able to treat the epoxy with a UV resistant coating if exterior use is necessary. Most are two component kits that you mix just before applying. Some epoxies may be 'tinted' with pigment to provide a semi-transparent color. Epoxies are also a film-forming sealer and can be very slick when wet. Check with the manufacturer if a non-slip grit additive may be used.
Penetrating Sealers do a good job of strengthening your concrete surface from the inside. The tiny particles are able to pierce and then seal the substrate permanently as they expand into the pores of the concrete, leaving a waterproof finish. There are several different types of penetrating sealers. Some are 'paintable' and some are not, meaning they may permanently seal your concrete so thoroughly you will be unable to get paint, stains, dyes, etc to adhere. If you or your customers are interested in decorative concrete work, use a penetrating sealer that can be 'painted'. Penetrating sealers do not typically change the surface appearance but may become slippery when wet.
If you are sealing decorative concrete work, be sure to read up on the maintenance requirements of the sealer. While some sealers can be stained, others may have to be stripped or sandblasted before a new or maintenance layer of stain, dye, etc. can be applied.
ConcreteNetwork.com, a great source for all things concrete, lists several questions you should ask before you purchase a concrete sealer: