While contractors have used concrete as a construction material since Roman times, it has mainly been used for structural integrity, rather than aesthetics. This is particularly true in flooring, where wood, carpet and tile have been a flooring staple for residential and commercial buildings for years. However, more recently, customers are requesting polished concrete floors to achieve a minimalist and contemporary appearance. Its durability makes concrete a great, low maintenance flooring choice for high traffic environments, such as commercial and industrial spaces. Concrete floors also offer additional benefits, such as creating a reflective floor surface that increases natural light in the building, reducing energy usage. 

Get to the Substrate

Every concrete floor is different, so when approaching a new job, contractors should take the time to understand the customer’s individual requirements and desired finish. Visiting the site before the work begins enables contractors to review the existing floor to see the type and condition of the current floor covering, the adhesive bonding the covering to the substrate, and the quality of the concrete underneath. 

This initial visit to the site gives contractors an opportunity to remove a small area of floor covering to understand the work they’ll need to complete to help them manage the expectations of the customer. The final finish of polished concrete flooring is heavily dependent on the condition of the concrete at the start of a project, so contractors should highlight any issues that could negatively impact the final product, such as cracking, at an early stage. 

Once they’ve determined the size of the project and the condition of the floor, contractors can begin removal of the existing covering. Floor scrapers will remove material and adhesive quickly and efficiently — the size and requirements of the job will determine which machine and blades are best to use. Ride-on floor scrapers are suitable for heavy goods removal in rooms with large floorplans, whereas walk-behinds are more suited to smaller rooms or confined spaces to remove soft goods such as carpet. 

Concrete surface profile

Once contractors reveal the substrate, they can determine the condition of the concrete and its surface profile to determine how to prepare and polish the material. 

Concrete surface profile (CSP) is a standardized measure for the roughness of a surface defined by the International Concrete Repair Institute (ICRI). To understand CSP, think of the concrete surface as a landscape with mountains, where the CSP indicates the average distance between the highest peaks and the lowest valleys. This measure ranges from one to nine ― the higher the number, the rougher the surface. 

Depending on its original versus desired CSP, concrete may require a simple polishing of the top surface, or a deeper grinding that reveals the aggregate stones. When revealing the aggregate, the type, distribution and colors in the mix can vary. Hand grinding a small sample area early into the job will give a good indication of the finished result. Evident cracks can be left and stabilized or filled and color matched for a more uniform result. 

When choosing a machine for concrete profiling, contractors commonly choose between shot blasters and scarifiers. In this application, contractors should consider how these techniques impact the concrete, for example a shot blaster will leave marks that are difficult to remove. Scarifiers — cutters loosely fitted on lateral shafts and placed inside a drum housing — could be a better option. Once a scarifier is switched on, the drum rotates to generate centrifugal force, which throws the cutter at the surface, causing a mechanical cutting action. Like with shot blasters, dust and contaminants are moved to a dust collector and only heavier debris might remain on the floor. 

Grinding and Polishing

After profiling the concrete, contractors can move on to grinding and polishing to achieve the desired finish. 

Depending on the job, contractors can pick from a single headed disc or planetary grinder. The former performs a multitude of tasks, from light texturing to opening the pores of the surface or removing paints and thin coatings. Planetary grinders are equipped with three grinding plates, which ensures that the grinding head will always follow the floor to give the best possible result. 

Once they’ve selected a machine, contractors can look into diamond tooling. When beginning to grind down the concrete, it is best to select a tool with a higher grit. From there, contractors can gradually reduce the size of the scratches as they get closer to the desired result before moving to polishing. 

Concrete acts like a sponge and, when left untreated, can stain easily. To prevent this, contractors must densify the top layer of the concrete once polished. This is a vital step in grinding and polishing because it will harden the surface and protect it from stains, slowing the degradation of the concrete. 

The durability of concrete means that it can resist erosion, weathering and more with little maintenance — enabling structures built thousands of years ago to remain standing today. While concrete continues to be a great choice for construction, it is also becoming more of a popular choice for interior design. By taking the time to efficiently remove existing floor coverings and profiling the substrate, contractors can deliver a floor that showcases the beauty of this versatile material. 

Need advice on choosing the right machine for your next surface preparation job? Contact the experts at National Flooring Equipment by visiting nationalequipmentdirect.com.