There are a wide range of concrete sealers available, each with a different set of performance criteria. When applied correctly, sealers are durable and long lasting. However, all are subject to ageing as well as mechanical and chemical damage.
Regardless of the type of sealer used, coatings will eventually lose flexibility, become brittle and lose some adhesion properties with age. Sealers require re-application after a period of time, subject to coating thickness, weather, moisture exposure and wear characteristics. This makes it important to use the right type of sealer for the job to ensure the longest possible performance.
In this blog post, the experts at Allcon take a look at three of the most popular types of sealers used on concrete - acrylic, epoxy and polyurethane.
This is by far the most common type of sealer used. Acrylic sealers work by forming a protective film atop the concrete. The film protects the concrete in much the same way that a raincoat protects its wearer. The sealer simply covers the concrete surface with a water-resistant barrier.
Acrylic sealers come in both water based and solvent based formulations. In both cases, particles of acrylic solids are suspended in a liquid carrier (either water or a solvent such as xylene or acetone). The wet sealer is applied to the slab, the liquid carrier dries or evaporates, and the solid particles are left on the surface to form a film.
Solvent based acrylics darken the surface and are typically glossier. Those who want more subdued colours or a matte finish while still retaining some gloss should opt for a water based acrylic sealer.
External use such as on pathways, driveways and patios.
Epoxy sealers are often referred to as “two pack” epoxy. This is because most epoxy sealers come as two separate components which need to be mixed together before they can be applied to the surface of the concrete. Mixing the two components together initiates a chemical reaction which cannot be reversed and will begin to set. The pot life is usually between 30-60 minutes.
Epoxy coatings produce a very hard, long lasting, abrasion resistant finish. They adhere very well to concrete and cement based overlay applications. A mid level of sheen or a high gloss look can be achieved.
Epoxies are available in both clear or coloured options. However, they are generally limited to indoor use as they are not UV stable and may yellow in sunlight.
These sealers are much harder than acrylics. Unlike acrylic sealers, epoxy coatings are nonporous and don’t allow moisture to pass through the coating. This means the surface and the concrete must be completely dry and free of any moisture to avoid blistering or bubbles forming afterwards.
Internal use such as on floors in factories, garages, workshops and food preparation areas.
Like epoxy sealers, polyurethane sealers also typically come as a two pack system. When mixed together, it forms a tough UV resistant coating that provides excellent resistance to abrasion. Typically, the surface needs to be primed with an epoxy before applying polyurethane.
Polyurethane has a higher resistance to chemicals than epoxy. This includes resistance to petroleum products and solvents, such as methylene chloride, which is the primary ingredient in paint stripper.
They are available in water and solvent based versions and a range of sheen levels. They can be used on both interior and exterior concrete to impart a transparent, non-yellowing, highly durable finish.
Despite its many advantages, polyurethane has a thin dry film thickness which means that it is not a high build coating. It will not work well to fill in small cracks and divots in the surface.
Floors in high-traffic areas, wet areas such as bathrooms and laundries, concrete countertops, enhancing the beauty of coloured, stamped or exposed-aggregate concrete.
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