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 mechani-cal 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 val-leys remain untouched. In some cases, parts of the abrasive bind-ing 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 Hybrid polished concrete is achieved through a multi-step operation using a combi-nation of standard grinding equipment, light-weight grinding equipment and/or burnish-ing 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. ■ Bonded abrasive Bonded abrasive polished concrete requires a multi-step operation of mechani-cally 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 Since the CPAA recognizes that bonded abrasive polished concrete yields the most durable finish and requires the least mainte-nance, 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 con-crete 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 uti-lize 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 succes-sion 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 pro-cess 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 tex-ture 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 con-crete, 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 environmen-tally 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 week-ly 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 busi-nesses 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 signifi-cant benefit for facilities pursuing Leadership in Energy and Environmental Design (LEED) certification. If the process is done correctly, you will save money on labor, on annual mainte-nance and on your utilities. 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 con-crete is the floor of the future. CM www.cmmonline.com 21
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