How to Polish Concrete Steps and Stairs

Polished concrete has become the choice of flooring for interior designers. It is attractive and extremely durable. We are repeatedly asked about polishing steps and stairs or treads and risers.

Primarily, there are two types of stairs: cast-in-place and pans. Cast-in-place steps and stairs are formed using wood or other materials. Once the form is built, concrete is placed and finished within the forms. The treads are finished first. Once the concrete has reached a set (firm), the forms are stripped, exposing the freshly placed concrete. The vertical surfaces will need to be rubbed or trowel finished, creating a smooth, bug hole free surface.

A pan tread is a steel form with a solid bottom and 2” sides forming a watertight pan. These are attached to a steel staircase during construction. Concrete is placed within the pan and the tread is finished like the cast-in-place method. The steel pan is left in place during and after the concrete has cured.

Both systems have other huge advantages over other construction methods. In fire escapes, combustible flooring systems might be illegal in your area. Carpet, vinyl, tile, and rubber are the most common. All of these will sustain a flame, while concrete will not.

If color is what you want, integral color concrete can be used. Integral color is added to the concrete along with the other ingredients. The preferred method is to have the concrete producer add it when all the other ingredients are put into the ready-mix truck. This will ensure there will be a well-blended batch.

Dyes can also be used to add color. A dye is applied during the polishing process. It is a liquid solution that is produced in an array of commonly selected colors. 

Various levels of slip resistance can also be produced. When polishing a tread, you will start the polishing process with a coarse diamond cup wheel. This will level the area and expose the amount of aggregate needed in the design. Coarse diamond cup wheels leave the surface rough. The finer the diamond on the wheel, the smoother the surface will be. This allows you to stop when you hit the right texture. Caution: the rougher the surface, the less gloss is produced. A rough surface will always have a matte appearance unless a high gloss sealer is applied after the final grind.  

Why Choose Polished Concrete Steps?

Concrete is a wonderful building material when installed in an environment that will be subjected to elevated levels of traffic. Europe has concrete surfaces in service that were placed in the 1300’s. If the proper concrete placement procedures are followed, it should outperform other flooring materials.

The one floor system that equals polished concrete is terrazzo. Terrazzo uses two distinct types of binders, cement and epoxy. The binder is the glue that bonds to the substrate and binds the decorative aggregate. Once placed it is polished using the same method as concrete.    

The visual appearance of a polished stair tread can add to the interior design of the space. During the production of the concrete, color can be added moving away from the conventional gray color. During placement, the surface can be top seeded with decorative aggregates. Once cured, the surface can be ground deep enough to expose the seeded decorative stone or glass producing the look of terrazzo.    

Stair safety should be a top concern. The slip coefficient of friction (SCOF) can be increased by stopping the polishing early in the process. The coarser the diamond cup wheel, the rougher the surface. American Disability Act (ADA) recommends a value for all surfaces within a building. Check with ADA to find the value they recommend for your facility.

Once the stairs have been polished and the facility is open to traffic, they will need to be cleaned. Dirty treads can be unsafe to walk on. Concrete has a pH of 9.5. When selecting a cleaning solution, match the pH of the cleaner to the concrete. This is considered pH neutral. If a higher (caustic) or lower (acidic) pH cleaner is used, the concrete surface could be damaged.

After multiple cleanings, the topical protective polished concrete sealer might show wear. The sealer used can be reapplied bringing the appearance back to new. The determining factor will be the gloss. If the gloss level begins to diminish, it’s time to reapply. The application is simple. Right after cleaning, spray a thin coat on the surface. With a dry microfiber cloth, wipe the surface in even strokes moving from your left to your right. One coat should be fine.

Tools & Materials Needed

If the main floor is being polished, you already have the equipment needed. The same equipment and diamond tooling used to polish the edges of a room will be used to attack stair treads.

The main piece of power equipment is a hand grinder. Hand grinders come in 2 sizes, 5” and 7”. Seven-inch grinders are usually used in the first polishing steps. They run at high speed (7,000 rpm) and use a 7” cup wheel. If you are not comfortable using this size of grinder, a 5” hand grinder will work just as well. A 5-inch is easier to manage and has the same diamond cup wheels as a 7-inch but on a smaller platform. There are models that have speed adjustments. This works well moving from grinding and on to the honing and polishing steps. These steps are performed at a lower speed than grinding.

When dust is generated, a quality industrial dust extractor must be connected to the dust-generating equipment. An industrial vacuum has multiple filters capturing the dust. The final filter before the clean air is expelled is a High-Efficiency Particulate Air (HEPA) filter. A HEPA Filter will remove the smallest particulate.

Diamond cup wheels come in grits like the ones used on the large, walk-behind grinders. Grinding is done with metal bond abrasives; honing uses a transitional bond and polishing a resin bond. The most critical steps are with the metal bonds. They cut the fastest and deepest of all the tooling. It is easy to develop gouges on the surface to the point they cannot be removed.

During the process, a densifier can be applied. Densifiers react chemically with concrete. This reaction enhances the hardness of the surface increasing the abrasion resistance. This step is important on the treads. The level of constant abrasion is high and by having a harder surface, the service life will be increased.

All porous wear surfaces need a level of protection. Dirt, oil, grease, and food are contaminating substances that will negatively affect the appearance of a polished surface. The polished concrete sealer is very thin and repairable. On a tread with moderate traffic expect 6-12 months of use.

Construction sites can be dangerous, and safety needs to be consideration for not only you but also your employees and other workers in the area. Protective eyewear, leather boots, work gloves, and a dust mask are essential Personal Protective Equipment (PPE) that needs to be worn when on site. Grinding concrete produces dust-holding silica. Silica, once inhaled, will negatively affect your lungs.         

How to Polish Concrete Steps and Stairs

• Surface Preparation
  • Clean the steps thoroughly removing dirt and debris.
  • Use DiamaPro® Diama-Clean 30 for all general cleaning.
  • Rince well with clean water and extract the water with a wet vacuum.
  • Grinding Process
    • Using a hand-held grinder, start with Coarse 50-grit metal bond cup wheel.
    • Honing Process
      • With the hand grinder move on to a 50-80 grit transitional cup wheel.
      • Move onto a 120-grit transitional cup wheel.
      • Densifying
        • Apply the DiamaPro® Diama-Hard to harden the surface and enhance durability.
        • Polishing Process
          • Hone with a hand grinder and 100-grit resin bond pad.
          • Polish with a hand grinder and 200-grit resin bond pad
          • Polish with a hand grinder and 400-grit resin bond pad (matte finish)
          • Polish with a hand grinder and 800-grit resin bond pad (gloss finish)
          • Sealing and Protecting
            • Apply DiamaPro® Diama-Guard HG to protect the surface and provide an easier-to-clean surface.

Maintenance Tips for Polished Concrete Steps

• Regular Cleaning
  • Daily
  • Add DiamaPro® Diama-Clean 30, neutral pH cleaner, to the freshwater.
  • Clean with a soft cloth.
  • Resealing
    • Protective sealers will eventually need to be reapplied.
    • After cleaning the floor, reapply DiamaPro® Diama-Guard HG
    • Allow to cure for a minimum of 2 hours.
    • Immediate Stain and Debris Removal
      • Wipe spills promptly to avoid permanent stains.
      • Mop or vacuum scratch-producing debris regularly.
      • Avoid Abrasive Tools
        • Use non-scratch pads for cleaning.
        • Always start cleaning with the least abrasive system reducing the chance of damage.

Conclusion

Stairs and steps or treads and risers can have a similar appearance and durability as a polished floor. Color and texture can be emulated on almost any concrete surface with the floor. With proper training and practice, concrete treads and risers can be a durable, decorative element within the design when polished.

There are pieces of equipment that will be needed to polish stairs and steps. Hand grinders, diamond tooling, and commercial dust extractors will be used throughout the process. Niagara Machine is a supplier that has you covered when selecting equipment. We represent quality manufacturers that specialize in polished concrete, whether it be a floor, stair tread, or riser. Give our office a call or speak directly with one of our outside field representatives for guidance.