I am a firm believer in the adage “the right tool for the job.” The best piece of equipment for a project is not only dictated by the desire to produce a quality product at a cost-effective price, but also by what you are polishing.
Having been a concrete flatwork contractor for 30 years and a polishing contractor for the past eight years, I realize that no two slabs are identical. Concrete hardness and flatness can have a great influence on your polishing process. In addition, residential concrete polishing projects require different equipment options than commercial slabs. We’ll take a look at what factors you’ll need to consider when choosing polishing equipment for both types of projects.
Residential concrete projects
For the majority of installations, residential concrete slabs are struck-off (“screeded” or “pulled”) by hand. Whether you’re using a wooden 2x4 or a vibratory screed, the result is a floor with relative flatness that’s still wavy. Most residential slabs are also hand-troweled. This requires the finisher to get on the floor when it’s in a relatively soft state and finish by hand. The process invariably leads to low spots and high spots caused by the finishers’ use of knee boards to support body weight on concrete that’s soft enough to finish. A hand-trowel floor can also produce a “softer” concrete surface.
I suggest that you work with these complications rather than against them. With that in mind, choose a machine with relatively flexible heads to hold your segments or pucks. Head flexibility allows the machine to follow the flow of the surface to produce more uniform aggregate exposure. This applies to both salt-and-pepper and exposed aggregate finishes. A rigid-head machine would require you to grind through the high spots before you can achieve a scratch pattern on the low spots, which can result in an inconsistent floor finish containing both areas of large exposed aggregate and areas of little to no exposure.
Another factor to consider is transportability. When polishing basements or interior residential areas, it’s best to use a machine that can fit in narrow hallways and be carried up and down stairs with relative ease. There are polishing machines on the market that allow you to remove the weights required for grinding, making the unit lighter. You can then easily attach the weights when the machine is in place. An added benefit is you can also add or remove weights based on the desired finish and density of the concrete.
One final and very important consideration for residential projects is the power required to run the polisher. In the U.S., most residential power is limited to 120-volt, 15-amp breakers. A portable generator with a 30-amp breaker works well because the breaker does not pop that often, and the generator isn't an expense that will set you back that much. If you buy a piece of equipment that requires 240 or 480 volts, there’s a good chance that you will need to supply your own tow-behind generator. That’s an added expense.
When it comes to edge work for residential projects, most of your needs can be met with a stand-behind edger attached to a vacuum. But you’ll also need a hand polisher to fit in tight spaces and work around plumbing penetrations and other obstacles. A 7-inch polisher with 5-inch pads fits that need. Be sure that you buy a hand “polisher” and not a hand “grinder.” A polisher offers variable speeds at much lower rpms. A hand grinder has one fixed, high speed that can ruin your finished product.
As for dust control in a residential setting, there are excellent smaller units available to address the limited work space. Keep in mind that, especially in tight quarters with many nooks and crannies, the slightest amount of dust can become a hassle for the homeowner. Consider doing any aggressive grinding in restricted areas wet to eliminate dust and reduce noise. There are products available from companies like Gelmaxx and Diteq Corp. that can turn cement-based slurry into reusable water and recyclable solids.