I know that dusting the development of a powdered material at the surface of concrete is associated with weak concrete at the surface. I've also learned several ways to prevent dusting during new construction. However, besides grinding the surface, I've never heard of any methods to correct dusting once it has occurred. Are there any?
Dusting can be remedied by applying a floor-sealing product based on sodium metasilicate (water glass) or silicofluorides. When a dilute solution of sodium metasilicate soaks into a floor surface, the silicate reacts with calcium compounds to form a hard, glassy substance within the pores of the concrete. The degree of improvement depends on how deeply the silicate solution penetrates. For this reason, dilute the solution with water to make it penetrate deeply. Apply three or four coats, allowing the previous coat to dry before applying the next coat. For the first two coats, use 4 parts water to 1 part silicate. The third coat should be a 3-to-1 solution applied after the second coat has dried. The treatment is completed as soon as the concrete surface gains a glossy, reflective finish. Zinc, sodium, and magnesium silicofluoride sealers are applied in the same manner as water glass. These compounds can be used individually or in combination, but a mixture of 20% zinc and 80% magnesium gives excellent results. For the first application, dissolve 1 pound of silicofluoride in 1 gallon of water. For subsequent coatings, use 2 pounds per gallon of water. Mop the floor with clean water shortly after the preceeding coat has dried to remove encrusted salts. Carefully observe all safety precautions when applying silicofluorides because they are toxic. It is important to note that sealing products will not convert a poor-quality floor into a good-quality floor. They simply are a means of upgrading a dusting floor while improving its wear resistance. Reference ACI 332, "Guide to Residential Cast-in-Place Concrete Construction," ACI 332R-84.