Two Essential Steps During Polished Concrete Process

2021-06-30

It often takes skill and experience to control the process of polished concrete floors, especially there are two essential steps that cannot be ignored during polished concrete process.

1. Hardening the surface

Polished concrete floors usually have the surface hardened with a chemical before the second, third or fourth grinding pass. The chemical soaks into the floor to a few millimeters (up to half an inch) and causes a chemical reaction to take place that makes the floor harder and easier to polish to a high finish. These floors are very strong and durable without having a surface coating.

2. Filling holes

After the first concrete grinder pass removes the top layer of concrete paste it will expose millions of tiny air holes. If these are not filled before the hardening process then the final polished concrete floor will show these unsightly imperfections. The holes are usually filled with an acrylic tile adhesive type of product mixed with either the grinding dust or cement powder which is hand scraped across the floor using a trowel. The preferred way to fill the holes is to spray the acrylic adhesive ahead of the grinder so that the diamonds mix it into the holes with the grinding dust on the third or fourth pass at around 120 grit. This method is faster and the dust matches the colour of the floor to hide the holes better than when using cement powder.

Typically it takes many grinding and polishing steps to finish a highly polished floor. The general rule is to double the diamond grit size under the concrete grinder for each pass. It might start with very coarse, 10 or 20 grit size diamonds, then use 50 grit diamonds followed by 100 grit.  And then start again with 50 grit resin diamond pads instead of metal diamond tools. When using the resin diamond pads, the steps may be start with 100, then 200, 400, 800, 1500 and finally 3000 grit.