A common misconception with shiny concrete floor surfaces is that they are slippery.
Something important to understand right away is that just about any hard and dense surface lacking surface profile, texture or grit, will be slippery when walking in puddled water.
There are many way to achieve a less slippery surface.
– Adding sand to a sealer.
– Trowelling a textured pattern into the concrete or overlay.
– Broadcasting small metal or vinyl grit flakes into a top coat.
These all work fine but when it comes to polished concrete they are not an option. This is because the resulting shine you see after a floor has been grinded, hardened, polished, sealed and burnished, is the result of the concrete itself having been filled with ever increasingly smaller scratches from the grinding and polished phases. The top coat guard ads a little bit of sheen but mostly serves as a stain resistant layer.
This stain resistant top layer also keeps the floor from releasing concrete dust. Polished concrete floors are porous by nature.
In regards to slipperiness, let’s look at some of the differences between polished concrete and sealed concrete.
As indicated above, polishing is the act of scratching a surface with ever smaller and smaller scratches. The floor shines because light reflects off it at many different angles both horizontally and vertically.
With sealed concrete, the shine you see is 100% derived from the clarity and plastic nature of a sealed floor. There is a build up of material on the surface providing lustre and a reflective nature. While beautiful when new, sealed concrete doesn’t shine for as long as polished concrete because it is softer and therefore scratches more easily. Sealed concrete is also more slippery when wet because it is not porous at all which is why it is often necessary to add non slip materials into the top coat of a sealed floor.
When stepping on a polished surface, water is actually able to be pushed down into the pores of the floor a little bit resulting in more traction. On a microscopic level, the polishing process has cut off the high points of the concrete and the hardness process has raised the low points thereby increasing the amount of surface the foot is reaching. The end result is more foot on the floor and less foot on the slippery water.
When choosing a concrete finish be sure to discuss how you plan to use the floor. Sometimes you may want a polished floor but a clear sealer over aggregate exposed concrete with a non slip added in may be a better bet.
There is no golden rule for when to choose one finish over another, so speak with a concrete flooring specialist today to determine your best option.
