Almost any structurally sound concrete floor, whether new or old, can be polished. But there are some caveats.
For new floors, no special mix design is required to achieve good results. However, the floor should be in place at least 28 days before polishing begins to ensure adequate curing. Some retail and warehouse facilities that plan to polish their floors after placement may specify the installation of as smooth a floor as possible to minimize the polishing steps required.
Existing floors typically require some surface preparation prior to polishing to remove dirt, grease, coatings, or blemishes. However, floors that are wavy, need extensive patching, or are extremely porous may not be good candidates for polishing.
An experienced contractor usually can determine a floor's suitability.To help solidify and densify polished concrete surfaces, some contractors apply penetrating hardeners to the concrete, normally after the first step of the grinding process. These products, which can be applied to new or existing floors, work by reacting chemically with the concrete to form a hard, crystalline structure. They also prevent dusting of concrete and offer extra protection from water penetration and staining.