There are a lot of products that are used with concrete. One newer item that causes some confusion is concrete densifiers. Are they a sealer? Are they the same as epoxy? Just what is a densifier?
Concrete Densifiers Explained
Concrete densifiers are chemicals that are applied to the surface to:
1) Fill in the pores at the surface
2) Increase surface density
3) Improve the wear resistance
4) Reduce dusting
Concrete densifiers are typically water based and include sodium, potassium or lithium silicates. The densifier causes additional cementitious materials to form (in combination with the lime in the cement) and tighten the pores. This creates a harder surface and decreases staining. The depth of the densifier’s effect is impacted by the initial porosity, densifier makeup and concrete’s construct.
Typical Densifier Usage
Concrete densifiers are often used in newly placed concrete exposed to high wear, such as warehouses and loading docks. They are also often used to new, ultra-flat slabs found in big box stores that may or may not later implement polished concrete.
They can be applied to polished and non-polished concrete. When we used to polish concrete, we always used concrete densifiers. For some slabs, we may apply them after the initial “metal bond” grinding was complete, but before any polishing began. In other systems, the densifiers may be applied at the last or next to last polishing step.
Densifiers are not typically used in residential garages or basements. The next section explains why.
Densifiers vs. Sealers vs. Epoxy Coatings
Densifiers are not the same as sealers. They may help improve the stain resistance, but will not compare to a soak-in or topical sealer. Densifiers do not behave or perform in the same fashion as topical, epoxy (or other polymer) coatings.
Thin-mil and high-build epoxy coatings provide a truly sealed surface and often provide chemical resistance far beyond the normal concrete (densified or not). Epoxy coatings create a sacrificial surface, thereby taking the wear and tear in lieu of the concrete. Densifiers just extend the wear ability of the native concrete surface.
Epoxy coatings are still the normal product to protect residential garages and basement floors. Coatings are also the norm for food processing, service bays and chemical storage.
Densifiers may be used on concrete prior to the preparation and application epoxy systems, though it is not common to do so. There are sealers which may be used after the application of a concrete densifier. A few manufacturers now have concrete densifiers that also contain sealers for a 1-step application. But, these sealers are often soak-in, hydrophobic sealers and do not provide any topical build. The sealer's longevity is tied directly to the wear and tear on the concrete surface.