Concrete Densifiers for Polished Concrete

Densifiers are used for polished concrete floors. When added to the concrete, a chemical reaction causes the surface to get extremely hard. While we touched upon densifiers in an earlier blog, we’d like now to examine their characteristics in detail. As is our custom, we’ll zoom in on a product we regularly use at PennCoat, in this case AmeriPolish 3D HS Densifier.

Densifiers for Polished Concrete

Polishing densifiers penetrate the surface of a concrete structure, such as a floor, to give it a better shine and harden it against wear and damage. The densifier helps to solve two problems encountered when polishing concrete:

  1. New concrete “bleeds” water, which rises to the surface and softens it. This can lead to micro-chunking of the surface during polishing. Densifiers bind to the concrete’s lime in a pozzolanic reaction to form cement-like compounds that harden the surface.
  2. Concrete’s porosity makes it vulnerable to unwanted staining. Densifier tightens the concrete’s pores, helping the surface resist liquid spills that would leave stains or streaks. A properly densified polished concrete surface shouldn’t need further sealing, although it might be good idea in high traffic or vulnerable areas.

Physicochemical Characteristics

The key to densifier action is the presence of silicon compounds:

  • Silanes: Polarized compounds with a general formula of SiH4. The compound has a sharp, vinegary smell, and is the basis for many compounds via the substitution of hydrogen by halide and methyl groups.
  • Siloxanes: Compounds with a functional group of Si2O, in which the oxygen atom is shared by two silicon atoms. Siloxane compounds have low glass-transition temperatures that help achieve glossiness. They are often polymerized into highly branched hydrides and silicones.
  • Silicones: Polymers of siloxanes with the general chemical formula of [R2SiO]n, in which R is an organic group. Silicones repel water, inhibit the growth of microbes, resist UV radiation and ozone, and are chemically unreactive.

Proprietary formulations of all three compounds are found in AmeriPolish Densifier, along with surfactants, hydroxides and UV-absorbers such as derivatives of piperidyl sebacate (C21H39NO4).


Densifier can be applied on existing or new porous concrete floors. It quickly penetrates and seals the concrete, increasing the floor’s durability, stain-resistance and gloss. It usually darkens the concrete and helps to enhance its color and clarity, while locking in dyes to extend their lifetimes. AmeriPolish Densifier is odorless, low-VOC and non-flammable. It is water soluble, with a milky appearance and a pH of 10.9 (alkaline). It acts to minimize dust and efflorescence (salt residue), and has a shelf life of one year. Porous concrete floors treated with AmeriPolish Densifier can be polished to a high gloss with diamond pads and can extend the coverage rate of optional sub-surface stain resistors.

Application of Densifiers for Polished Concrete

Prepare the concrete by grinding with diamond-resin grits up to 200, then scrub down the floor and let it dry. Spray on AmeriPolish Densifier in an overlapping circular pattern, then spread with a microfiber pad for even coverage. Keep adding densifier until the floor is saturated, and keep the floor wet for 15 minutes before allowing to dry. Grind and polish with higher grit diamond and microfiber pads. You can apply additional stain resistors and/or sealers at this time.

Alternatively, you can apply the densifier via a high-speed system in which you burnish the first coat with an 800-grit diamond pad, and then a second coat with a 1,500-grit pad. Apply any additional sealers.

Keep the concrete floor looking good by periodically using an automatic floor scrubber and a rejuvenating cleaner.