The first thing to understand is that concrete is not a uniform product! Each job will present different conditions and challenges that may require you to modify your normal procedures.
Almost any structurally sound concrete floor, whether new or old, can be polished. However there are some exceptions, for example with new floors no special mix design is required to achieve good results – although the floor should be in place at least 28 days before polishing begins to ensure adequate curing.
Some retail and warehouses facilities that plan to polish their floors after placement may specify a floor that is as smooth as possible to minimise the polishing steps required.
Fail to Prepare, Prepare to Fail
Existing floors typically require some surface preparation prior to polishing to remove dirt, grease, coatings or blemishes. Bear in mind though that floors that are wavy, need extensive patching or are extremely porous may not be good candidates for polishing.
In fact, getting the substrate preparation right is a critical aspect of any polished concrete project, as if the concrete is not up to the task at hand then the finish will never achieve the desired aesthetics or functionality. The concrete should be cleaned, flattened and given a light texture for the new coating to key into – especially if the concrete is old or has seen some extensive use.
Grinding is normally the preferred process to achieve this. Why is grinding the best method to prep a surface you ask? Well, grinding enables you to remove old floor coverings such as epoxy, paint, carpet adhesive and self-levelling compounds while simultaneously levelling out the underlying concrete surface and creating the ideal surface for further treatment of your floor – all in one action!
Wherever possible during a refurbishment, it is better to retain the substrate instead of destroying it along with the previous floor coating. Doing this means that you avoid the need to use a self-levelling compound and incur unnecessary material costs in the form of extra coverings to fill out irregularities, which are both expensive and time-consuming.
When in doubt about the best course of action, consult with your equipment and material supplier’s technical representative for recommendations on how to proceed.