Polished concrete is strong, durable and low maintenance while having that earthy texture of stone with a polish equal to granite. Here is how it is done.
It is similar to traditional polished terrazzo which is very flat and poured as a special mix to make the finish more successful. Polished concrete floors can also look almost bumpy and have little or no aggregate showing. Flatness and polishing are not necessarily the same thing which is a good point to clear up before agreeing to your project.
It costs extra time and diamond wear to cut floors with a concrete grinder until they are flat. They can either be ground flat to fully expose the aggregate like terrazzo, or the aggregate can be partially exposed, or the concrete grinding can expose no more than the fine sands at the surface. It often takes skill and experience to control the process of polished concrete floors and the quality of the concreter’s original laying work is also a contributing factor in the quality of the finish. Where the aggregate is a feature special materials can be added to the wet concrete mix such as coloured pebbles, metals and glass to enhance the final appearance.If you would like to learn more about this, visit their website at polished concrete gold coast.
Most people are unaware that there are ten to fifteen steps for polished concrete floors which takes a long time to complete and can be quite expensive.
Typically it takes many grinding passes to finish a highly polished floor although there are other ways as explained later. The general rule is to double the diamond grit size under the concrete grinder for each pass so a contractor might start with very coarse, 16 or 32 grit size diamonds, then use 60 grit diamonds followed by 120, then start again with a 50 grit diamond resin pad instead of a metal segment. Using the resin pads the steps may be 100, then 200, 400, 800, 1500 and finally 3000 grit. That would be ten separate grinding passes which does not count the two other essential steps.
Two more essential steps:
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.