Polished concrete is a versatile material that is easily customizable in its appearance, using stunning aggregates, quartz, and colors to create a sense of industrial sophistication in both homes and commercial buildings. Its reflective surface creates an evocative quality under light, which can be suitable for a variety of programs.
While still mainly used as a material for interior flooring, architects have been pushing the limits of polished concrete for years, using it for feature walls, patio floors and even large exterior panels such as in David Chipperfield’s extension to the Saint Louis Art Museum.
Polished concrete can be created in a variety of ways, from the least expensive "grind and seal" method to honed concrete, which uses a penetrating sealer to create a reflective surface. Mechanically polished concrete is the type usually used in commercial projects, as it is long-lasting and more durable under heavy foot traffic. It is created by applying a chemical hardener that densifies the porous concrete, and then grinding it to the desired gloss and smoothness. Using a series of progressively fine tools (similar to the process of sanding wood), the concrete can be ground to 800, 1500 or 3000 grit level. Another consideration is the concrete's "exposure level"—that is, the amount of the original surface which is ground away and thus how much of the aggregate material is exposed.
One of the main selling points of polished concrete is how easy it is to maintain. Its smooth, hard surface makes it easy to clean, as well as durable and hard to damage. Although concrete can be prone to cracking through moisture and the building settling, patching materials can disguise these cracks.
Polished concrete is also very versatile, and is customizable thanks to the option to use a variety of finishes, and different aggregates and cement colors in the concrete itself. It can be created to mimic different materials, such as stone and ceramic tiles while being lower-maintenance and more durable. Colors are usually mixed into the concrete before the slab is placed, but can also be applied with dye, stain, or waterproof paint afterward. Patterns can also be carved into the surface while the concrete is setting in order to create a faux tile effect.
In terms of sustainability, polished concrete can be seen as a “green” material as it makes use of the existing floor slab without the use of any extra material. It also works as an effective thermal mass, retaining heat in summer and keeping cool in winter. However, concrete has a higher carbon footprint associated with its production compared to other materials such as timber and steel. Cost-wise, polished concrete has a broad price range depending on the refinement of the finish. However, its long life and low-maintenance means that it is more cost-effective than polished floorboards or quality floor tiling.
Below are some examples of how it can be effectively used in architectural projects: