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Frequently Asked Questions
Thank you for visiting Polished Concrete 1 Inc. we hope that we can answer some of your questions.
The answers below are general and may not be applicable to all situations. The answers may be used as a broad reference.
What is Polished Concrete?
A polished concrete floor is a regular concrete floor where the surface has been ground by a series of diamond tools designed to mechanically refine the concrete surface so that it produces consistent gloss, clarity and shine. The polishing process is similar to the one used for granite and marble.
A concrete floor typically needs to be ground 6-8 times, reaching at least an 800 grit finish, to achieve a polished surface. The surface appearance of a polished concrete floor is created through the diamond polishing process and not by the use of a surface coating or sealer. There is no surface material to peel, chip or crack. This allows the concrete slab to breathe and maintain a healthy state.
Polishing concrete creates a surface with a teflon-like resistance to marking and dirt which makes them easy to maintain and keep clean. This is one of the primary advantages over other concrete flooring options.
A self-levelling polished concrete topping is another type of polished concrete flooring. Ardex PC-T is a well known concrete topping that is designed to be polished. Concrete toppings, otherwise known as polishable overlays are typically used when a concrete floor has been damaged too badly to be polished. It may also be poured onto wood floors to create a concrete floor. Once the topping has been poured and reached the minimum curing time, it will be diamond polished like regular concrete.
Polished concrete floors are available in different levels of sheen. The first level is an 800 grit finish, it has the lowest level of gloss, clarity and shine. It’s commonly used for industrial floors because it has the lowest cost while still providing a like-new appearance.
The 1500 grit finish is the mid level and can be found everywhere from industrial floors to art galleries. It provides improved gloss, clarity and shine over the 800 grit for a nicer aesthetic appearance.
The 3000 grit finish is the highest polish level providing excellent gloss, clarity and shine. It is excellent for high traffic applications like retail stores, offices, universities and other institutions that need to maintain a professional image.
Are Polished Concrete Floors Slippery?
No, polished concrete floors are not slippery. They exceed the minimum dynamic coefficient of friction level (ANSI A137.1) at all grits (800, 1500, and 3000 grit). Architects, designers and plant managers can find detailed information about slip resistance (DCOF) on the Concrete Polishing Council’s website. Slip resistance problems for a polished concrete flooring system will primarily be caused by poor maintenance of the floor. Poor maintenance can cause any flooring type to become unsafe so it’s important to have a structured program in place. Stain guards and floor coatings can decrease the slip resistance of a polished concrete floor so test data should be consulted before use.
What are the Advantages and Disadvantages of Polished Concrete Floors?
Advantages
- a beautiful but understated appearance allows merchandise or other elements in the room to remain the focus
- extremely durable, will stand up to high traffic environments
- existing concrete floors can be polished negating the need to bring in new flooring
- teflon-like polished surface resists marking and dirt making it easy to clean and maintain
- exceeds the slip resistance minimum dynamic coefficient of friction (ANSI A137.1)
- environmentally friendly and VOC free
- low cost to install and maintain
- increases ambient light up to 30% through reflection
- no coating to scratch, chip or peel
Disadvantages:
- Concrete is porous and will absorb liquids which may stain or damage the floor. It is not suitable for environments that are regularly exposed to liquids.
- Concrete is susceptible to acidic substances. It should not be used in areas with regular exposure to any type of acidic substances including fruits and vegetables, beer and wine, chemicals, oils, and acidic cleaners.
- It does not have a consistent, homogenous finish. You will see variations in the amount of fine and large aggregate on the surface. The colour may also vary from region to region.
Can Any Concrete Floor be Polished?
Any existing concrete floor where the cementitious portion (cement paste/gel) of the concrete retains its integrity can be polished. If the concrete slab has been compromised by chemical contamination, or other factors, the floor will not retain its polished surface for an acceptable length of time.
Concrete floors that have integrity but have been physically damaged may also be unsuitable for polishing because the final finish may be blotchy and inconsistent. The expectations of the customers would determine whether or not this second scenario would be suitable for polished concrete flooring.
The general rule for determining if a concrete floor can be polished:
- It should be free of oil and other chemical contamination
- There should be minimal surface damage
- The floor should not have a large number of repairs or trenches
Concrete floors that were covered with carpet, tile or wood floors can normally be polished without issue, after an adhesive removal grinding process. Concrete floors that had VCT tile will retain a checkered board pattern in the floor but may be polished if the customer deems it acceptable.
A professional concrete polishing process begins with an aggressive diamond tool that removes the surface concrete and exposes a clean, new layer. It’s important to remove any surface contamination or soiled concrete.
All of the proceeding grinding steps are finer grits that progressively hone and polish the surface. It is a best practice to use a lithium silicate densifier with the polishing process to enhance the durability of the surface.
The hardness or MPa of the concrete surface will predominantly determine the durability and life of the floor.
How Long do Polished Concrete Floors Last?
A polished concrete floor should last between 2-7 years depending on these primary four factors:
- hardness of concrete (MPa)
- type of traffic
- traffic volume
- exposure to substances.
High strength concrete (35, 40, 45MPa) will have the longest lasting polished concrete. It’s more difficult and expensive to polish these floors but it is worth the effort due to their extreme durability. These floors are suitable for high volume and intensity environments.
Low to moderate strength concrete (25-30MPa) is suitable for low volume and intensity traffic.
The type of traffic will affect the life of the floor. Light pedestrian traffic has little wear on a floor while high pedestrian volume can cause high wear.
Forklifts and vehicles are moderate to heavy traffic depending on the type. They will demand more from the floor.
Volume is often overlooked when specifying flooring. A low traffic area poses few problems but a shopping mall or high volume industrial space requires a highly durable floor. Traffic volume is a critical consideration.
Exposure to substances is the wildcard. Certain chemicals or substances can damage polished concrete on contact and need to be limited. Exposed concrete floors are particularly susceptible to acidic liquids.
Other substances like deicing salts can also damage the surface. Salt-proof densifiers can minimize salt damage if applied during the installation. Oils and solvents should be generally keep away from the surface.