Concrete dusting is caused by weak concrete, surface abrasion, or a combination of the two. In most cases, concrete dusting can be reduced with the use of a densifier, but in more severe cases a coating may be required.
If you want to maintain the natural, unsealed look of the concrete and prefer to use a penetrating concrete sealer, then you want to use a concrete densifier. Concrete densifiers penetrate into the surface of the concrete where they chemically react to form a calcium silicate hydrate (CSH) barrier within the pores. This barrier, which resembles white crystals, will fill in the pores to increase density and reduce porosity. Concrete sealed with a concrete densifier sealer can experience an increase in strength of up to 45%. Most concrete surfaces will require 2-3 coats.
The two most common types of densifier sealers are sodium silicate concrete sealers and lithium silicate concrete sealers. Both types of silicate sealers spark the same chemical reaction and form the same CSH structure. There are a few minor differences between them:
Armor S2000: The Armor S2000 is a concentrated sodium silicate concrete sealer. It has a slighly larger molecule size than a lithium silicate and is commonly used to seal old or porous concrete surfaces.
Armor L3000: The Armor L3000 is a concentrated lithium silicate concrete sealer. It has a slighly smaller molecule size than a sodium silicate and is commonly used to seal dense concrete surface. Lithium silicates will also react faster which is why they are commonly used as part of the concrete polishing process.
Before sealing the concrete, you want to make sure it is clean, and after sealing, you will re-clean again after a week. A silicate sealer will push up excess dust within the pores as it reacts. The reaction time with a silicate can be anywhere from 72 hours to 90 days.
In severe cases where heavy dusting is present, or if you want to stop all dusting and not just reduce it, then you want to consider applying a coating. A concrete coating will provide a protective film over the surface. The three main types of concrete coatings are: