Taking care of high-traffic floors has always been hard work.
Even with the advent of high-speed planetary propane stripping systems that can cover upwards of 15,000 square feet per hour, stripping floor finish off vinyl composition tile (VCT) floors is messy, smelly, inconvenient and can be dangerous.
Usually, stripping can only be done during afterhours when a store, plant or building is closed.
The combination of stripping solution and finish sticks to and hardens on whatever surface it touches, including machines, shoes, merchandise and molding or baseboards.
The combination also can be incredibly slippery — 10 to 15 times slicker than ice — which can lead to worker injuries.
It’s no wonder that strip and finish cycles are often extended, causing facilities to look dirty, dingy and unkempt.
The worst part is that, even after a facility has finally decided it cannot delay maintenance any longer and has paid to have a beautiful job of stripping and refinishing done, they will have to do it all over again in six to 12 months.
In a sense, the facility is renting its own floor because it will have to pay every year for the same annual maintenance.
Facilities managers accept this fact because there has been no other good alternative.
Just imagine having to reapply roofing mastic and shingles each year or replacing all of your lighting components annually.
If you stop and think about it, it makes no sense financially to “rent” your floor.
Now, there is finally a good answer for these high-traffic floors: Polished concrete.
Understanding Polished Concrete
The Concrete Polishing Association of America (CPAA) defines polishing concrete as, “The act of changing a concrete surface, with or without aggregate exposure, to achieve a specified level of gloss.”
Depending on the method used, and if done properly, a polished concrete floor can last 20 years with only standard daily maintenance — no additional annual maintenance.
In fact, a properly polished floor is so smooth and flat that it is actually much easier to keep clean because there is almost no texture for the dirt to adhere itself to.
While daily maintenance is still required, you have no annual maintenance, so it’s more like owning your floor than renting it.
To understand why this is true, we need to delve a little into the properties of concrete and the processes that can be used to polish it.
Under a microscope, and quite similarly to human skin, concrete resembles a porous mountain range; there is a huge variety of aggregate particles with numerous peaks and valleys from.
The process of concrete polishing flattens those peaks and fills the pores to achieve a floor that is very flat, very hard and very resistant to surface staining.
With conforming polished concrete floors, the shine is actually generated by how flat the concrete is and the way that flatness reflects the light, not by any topical chemicals.
It is important though to understand that not all “polished” concrete floors are the same.
According to the CPAA, there are four major categories of polished concrete:
- Surface coated
- Bonded abrasive.
Each progressive process more aggressively flattens those aggregate peaks than the prior one; surface coated polished concrete is the least aggressive, while bonded abrasive polished concrete is the most aggressive.
- Surface coated
Non-conforming or surface coated concrete does not flatten the floor at all; it is concrete that has had a chemical coating film applied to it in order to achieve a gloss reading.
It does not conform to the CPAA’s definition of polished concrete, and the durability will depend on the quality of the chemical used, the rate of foot traffic and maintenance procedures.
Concrete polished through burnishing utilizes a multi-step operation of mechanical friction, rubbing a concrete floor surface with or without waxes or resins to achieve specified level of gloss as defined by the CPAA.
This operation yields a less durable finish and requires more maintenance than bonded abrasive polished concrete because mechanical friction cannot flatten concrete the way that bonded abrasive grinding and honing can.
To some varying extent, the peaks of the mountains are being polished, but the valleys remain untouched.
In some cases, parts of the abrasive binding agents get trapped in the valleys, making the floor look smoother than it actually is.
Unfortunately, these agents are quickly dislodged by foot traffic, so the floor can end up looking significantly less shiny after even a short period of time.
Hybrid polished concrete is achieved through a multi-step operation using a combination of standard grinding equipment, lightweight grinding equipment and/or burnishing equipment to combine both mechanical grinding and friction to achieve a specified level of gloss as defined by the CPAA.
Basically, it is a combination of burnished and bonded abrasive processes, hence the term hybrid.
Whether it is more like the former or the later depends on the combination of processes and machines used.
- Bonded abrasive
Bonded abrasive polished concrete requires a multi-step operation of mechanically grinding, honing and polishing concrete with bonded abrasive diamonds to cut the concrete surface and refine each cut to the maximum potential to achieve specified level of gloss as defined by the CPAA.
This method yields the most durable finish and requires the least maintenance because every one of the aggregate peaks has been cut down to the lowest valleys so that the concrete is almost perfectly flat.
Bonded Abrasive As The Best Choice
Being environmentally friendly is all about less being more.
You want to minimize chemicals, minimize labor, minimize environmental impact and minimize maintenance expenditures.
Since the CPAA recognizes that bonded abrasive polished concrete yields the most durable finish and requires the least maintenance, it is the best environmental choice, so we will focus on that method.
Remember that floors polished with other methods will not last as long and may not share all the same characteristics.
Polishing concrete is similar to the process of sanding wood: You start with the most aggressive bonded abrasive diamond, just like wood sanding starts with the coarsest sandpaper.
The lower the number of the bonded diamond abrasive, the more aggressive it is.
This first cut will go as deep as any part of the process, while the rest of the process will serve to smooth the texture of the concrete and take it all down to the depth of that first cut.
The grit that you start with depends on how rough the starting condition of the floor is.
A 50-grit abrasive is a common starting point, but there are also 30-grit, 16-grit and eight-grit abrasives as well as pads that utilize diamond impregnation technology.
After the first cut with a 50-grit abrasive, follow the same procedure with a 100-grit and then a 200-grit abrasive.
After the 200-grit abrasive has been used, a lithium densifying chemical is applied to the floor with a microfiber mop.
The densifier actually penetrates into the concrete — particularly, the pores and softer particles — and dries.
As it dries, it hardens, doing what its name implies, making the concrete denser.
After the densifier has dried, a propane burnisher is run over the surface to further cure and harden the densified concrete through heat.
To understand why this is important, I usually tell people to imagine cutting meat: It is easier to cut lightly frozen meat into much thinner slices than it is with raw meat.
In a similar way, the densifier hardens the surface of the floor so that finer and finer slices can be taken off of it with diamond abrasives.
After the floor is densified, and depending on the level of shine desired, it can be polished with up to a maximum of a 3,000-grit pad.
After 3,000-grit diamonds pads are used, the floor is so flat that it appears wet.
If all of the steps were followed in succession and performed properly, you should be able to count the number of light bulbs in the ceiling by looking at the reflection on the floor.
Finishing The Environmentally Preferable Argument
Once this bonded abrasive polishing process is complete, the floor is both incredibly flat and incredibly hard from the densifier.
Because it is so flat, the maximum amount of light is reflected, making the floor appear wet.
Also, because it is so flat, there is no texture for dirt to adhere to, so soils are easily wiped away.
The densifier has sealed all the pores and hardened all of the soft material in the concrete, so liquid soils will be resisted for much longer periods.
While routine maintenance is still needed to remove dry soils and any grease, oil or other foreign matter, the floor will not require additional annual maintenance for decades.
A polished concrete floor is environmentally preferable for a variety of reasons.
For one, it is effectively a chemical-free care process; the only chemical that you have put onto the floor has penetrated into the floor and become a part of the concrete.
Because there will be no more grinding or polishing needed, the densifying chemical will not be released, nor will any concrete dust become airborne.
If polishing, burning and honing, there is no need to put any finish on the floor, buff the finish or remove the finish — again, nothing to get into the air to affect indoor air quality.
No additional chemicals are necessary to treat a properly polished concrete floor except for a neutral cleaning agent for weekly maintenance.
Additionally, because the floor is so smooth, a microfiber dust mop will glide over it as effortlessly as it would over fine marble; dirt will have no surfaces to cling to, so even typically messy soils will be easily cleaned.
Lastly, because the floor is so reflective, your entire facility will be brighter; many businesses have found that they can halve the number of light fixtures when they transition to polished concrete.
Not only does this reduce a business’ carbon footprint, but it also reduces their electricity bill.
The energy savings can also be a significant benefit for facilities pursuing Leadership in Energy and Environmental Design (LEED) certification.
Retail industry leaders like Kroger and Wal-Mart are adopting polished concrete — maybe you should too.
If the process is done correctly, you will save money on labor, on annual maintenance and on your utilities.
You may pride yourself on operating like Kroger and Wal-Mart, or you might pride yourself on not operating like them.
Either way, you owe it to yourself to find out more about polished concrete and how it can work for your facility.
Believe me when I say that polished concrete is the floor of the future.