Which is Right for the Job? Grind and Sealed Concrete or Polished Concrete
Many people are unaware of the differences between polished concrete and grind and sealed concrete floors, which can often make deciding on one confusing for someone who is not a flooring expert. For example, some customers might come across a sealed concrete project that sparks their own interest, but then might request the application of polished concrete when searching for a flooring contractor for themselves. There are a few things to consider when choosing the application that best suits your project. The main factors that should be examined are aesthetics, performance and cost.
What is the difference between polished concrete and grind and sealed concrete?
POLISHED CONCRETE
Definition: The act of changing a concrete floor surface, with or without aggregate exposure, until the desired level of finished gloss is achieved by using one of the following methods:
- Bonded abrasive polished concrete - The multi-step operation of mechanically grinding, honing and polishing a concrete floor surface with bonded abrasives to cut a concrete floor surface and to refine each cut to the maximum potential to achieve a specified level of finished gloss as defined by the Concrete Polishing Association of America (CPAA). This yields the most durable finish and requires the least maintenance
- Burnished polished concrete - The multi-step operation of mechanical friction-rubbing a concrete floor surface with or without waxes or resins to achieve a specified level of finished gloss, as defined by the CPAA. This operation yields a less durable finish and requires more maintenance than bonded abrasive polished concrete.
- Hybrid polished concrete - A multi-step operation, using either standard grinding/polishing equipment, lightweight equipment, high-speed burnishing equipment or a combination of all three to combine the mechanical grinding, honing and polishing process with the friction rubbing process by utilizing bonded abrasives, abrasive pads or a combination of both to achieve the specified level of finished gloss as defined by the CPAA.
GRIND AND SEAL CONCRETE
The grind and seal process can be achieved several different ways. Factors that dictate the grind and seal process include: the concrete substrate conditions, durability requirements and desired finished appearance. In most cases, the concrete is first passed with a grinder to remove contaminants from the surface. Imperfections such as cracks and divots are then patched with a cementitious patch repair. Subsequently, the concrete is ground for a second time with finer diamond tooling to smooth the floor (in cases where the concrete is porous and free of contaminants, grinding is not required). Next, the surface must be properly cleaned and then there’s the option to color the concrete with a stain or dye before sealing the floor with a wide range of sealers or seal systems.
Aesthetics
Sealed concrete will achieve a higher level of gloss than most polished concrete applications. The option for satin and matte sealers is also available. The concrete can be ground differently to expose more aggregate if desired. Concrete stains can be used to achieve a “mottled look” where there are color lows and highs. In addition, using acid and water-based stains can create multiple color hues that can result in a variegated texture effect. Products like Super-Krete® Products S-9500 Color Stain™ act as a diaphanous coating that help mask the existing concrete’s imperfections. Another reason to choose sealed concrete is that it has a relatively consistent appearance from project to project. A high build sealed system’s level of sheen stays consistent on each application because it’s not dependent on extraneous factors such as the existing concrete’s level of hardness.
Bonded abrasive polished concrete will expose larger aggregate since a typical application will have several passes with the concrete grinder. Also, customers prefer this process when the goal is to have a natural concrete finish because it avoids any kind of film on the surface.
Performance
Sealed concrete can better protect against unwanted stains and penetration of viscous liquids and oils. Spills can be cleaned easily from chemical-resistant sealers such as polyurethanes and polyureas, which could cause permanent damage to other types of flooring. In environments such as kitchens and bathrooms, sealed concrete can better protect against grease and urine stains. In addition, chemical-resistant sealers can block out saturation of animal byproducts that cause odor and chemical deterioration. Perhaps the biggest performance benefit of sealed concrete is the ability to incorporate a skid-resistant additive: aggregate can be applied in different sizes and amounts to achieve the desired level of slip resistance.
Polished Concrete is excellent in high foot traffic environments, because of its superior scratch resistance and low maintenance requirements. The permanent densifying of the concrete allows polished concrete to have a high level of performance between reapplication of the polish guard. Also, polished concrete is breathable and allows vapor transmission to pass through the floor.
Cost
Sealed concrete and burnished polished concrete cost less than traditional polished concrete. Labor hours are reduced because not as many passes with the grinder are required. Downtime length is also reduced because these concrete applications are faster. When the concrete substrate is in good condition these methods will provide the customer a durable modern floor for a very low price.
