Polished concrete
Encyclopedia
Polished concrete is concrete
that has been treated with a chemical densifier
and ground with progressively finer grinding tools. The grinding tools are usually progressive grit
s of diamond grinding cup wheel
s and diamond polishing pads. Typically, concrete is not considered polished before 400 grit
, and it is normally finished to either the 800, 1500, or 3000 grit level. Stains and dyes are often applied to enhance polished concrete as well as other options such as scoring, creating radial lines, grids, bands, borders, and other designs.
flooring
option because it makes use of the materials already present. Most modern buildings are built on a concrete slab; polishing the exposed concrete eliminates the energy and material consumed by applying a floor covering. It is something to consider when building or modernizing towards a more green solution.
Polished concrete floors are low-maintenance, as they are more durable and easier to clean than many flooring options. Its relatively high coefficient of friction can make it non-slippery. Polished concrete reduces dust mite and allergen
problems, and does not support mould growth. Anecdotal evidence suggests highly reflective polished concrete reduces lighting needs and improves natural lighting, but as of yet there has not been a study to confirm this. Polished concrete flooring is hard wearing and will not chip or dent like softer surfaces such as timber and mopping with warm soapy water once a week is the only maintenance required.
LEED 2009 standards contain guidelines for using polished concrete flooring to qualify for LEED credits.
, are used to gradually grind down surfaces to the desired degree of shine and smoothness. The closest equivalent example would be polished granite or marble.
Polished concrete floor installation is categorised into two types: new floors, and retrofit floors.
Concrete
Concrete is a composite construction material, composed of cement and other cementitious materials such as fly ash and slag cement, aggregate , water and chemical admixtures.The word concrete comes from the Latin word...
that has been treated with a chemical densifier
Concrete densifier
A concrete densifier is a chemical applied to a concrete surface in order to fill pores, increasing surface density. Chemical densifiers are used on polished and non-polished concrete to reduce dusting and wear; on polished concrete surfaces densifiers help concrete take a better polish and make...
and ground with progressively finer grinding tools. The grinding tools are usually progressive grit
Grit
Grit may refer to:* GRIT , also known as Arhgap32 or PX-RICS* Grit , a U.S. periodical founded as a newspaper in 1882* Grit , by Celtic fusion musician Martyn Bennett* Grit , by Norwegian rock band Madrugada...
s of diamond grinding cup wheel
Diamond grinding cup wheel
A diamond grinding cup wheel is a metal-bonded diamond tool with diamond segments welded or cold-pressed on a steel wheel body, which usually looks like a cup...
s and diamond polishing pads. Typically, concrete is not considered polished before 400 grit
Grit
Grit may refer to:* GRIT , also known as Arhgap32 or PX-RICS* Grit , a U.S. periodical founded as a newspaper in 1882* Grit , by Celtic fusion musician Martyn Bennett* Grit , by Norwegian rock band Madrugada...
, and it is normally finished to either the 800, 1500, or 3000 grit level. Stains and dyes are often applied to enhance polished concrete as well as other options such as scoring, creating radial lines, grids, bands, borders, and other designs.
Benefits
Polished concrete is considered a good sustainable designSustainable design
Sustainable design is the philosophy of designing physical objects, the built environment, and services to comply with the principles of economic, social, and ecological sustainability.-Intentions:The intention of sustainable design is to "eliminate negative environmental...
flooring
Flooring
Flooring is the general term for a permanent covering of a floor, or for the work of installing such a floor covering. Floor covering is a term to generically describe any finish material applied over a floor structure to provide a walking surface...
option because it makes use of the materials already present. Most modern buildings are built on a concrete slab; polishing the exposed concrete eliminates the energy and material consumed by applying a floor covering. It is something to consider when building or modernizing towards a more green solution.
Polished concrete floors are low-maintenance, as they are more durable and easier to clean than many flooring options. Its relatively high coefficient of friction can make it non-slippery. Polished concrete reduces dust mite and allergen
Allergen
An allergen is any substance that can cause an allergy. In technical terms, an allergen is a non-parasitic antigen capable of stimulating a type-I hypersensitivity reaction in atopic individuals....
problems, and does not support mould growth. Anecdotal evidence suggests highly reflective polished concrete reduces lighting needs and improves natural lighting, but as of yet there has not been a study to confirm this. Polished concrete flooring is hard wearing and will not chip or dent like softer surfaces such as timber and mopping with warm soapy water once a week is the only maintenance required.
LEED 2009 standards contain guidelines for using polished concrete flooring to qualify for LEED credits.
New or retrofit
In simple terms, the process of polishing concrete is similar to sanding wood. Heavy-duty polishing machines, for example concrete grinderConcrete grinder
A concrete grinder can come in many configurations, the most common being a hand-held Angle grinder, but it may be a specialized tool for countertops or worktops. There are also purpose-built floor grinders that are used for grinding and polishing marble, granite and concrete...
, are used to gradually grind down surfaces to the desired degree of shine and smoothness. The closest equivalent example would be polished granite or marble.
Polished concrete floor installation is categorised into two types: new floors, and retrofit floors.
New floors
New floors require less work resulting in lower costs, but there are a few things to be aware of before a new concrete floor can be polished. Firstly the slab can contain a decorative aggregate. The two most common aggregates are river stone, granite, and black basalt mix, however the aggregate can be almost anything. The finished surface of the concrete will need to be finished to a high standard to facilitate the polishing process. During the finishing phase any decorative aggregates such as seashells or car parts can be dropped into the surface of the concrete. Builder needs to be aware as early as possible if the concrete is to be polished so that the final finish is of the best quality.Retrofit floors
Retrofit floors can be done in two ways. The existing floor slab can be cut or sanded and the natural aggregate will be the feature or a topping slab with a minimum thickness of 50 mm can be added on top of the existing slab.Process
Process involved in polishing concrete:- The concrete floor is cut 3–4 times depending on the finished surface. This can be done wet or dry depend on the site situation.
- The surface is then grouted with cement to correct imperfections and fill air bubbles.
- Two more cuts are done after grouting.
- A clear liquid hardener referred to as an indensifier is then worked over the surface for about 1 hour. The indensifier will provide a glossy look to the finished floor. It will also give the floor extra strength.
- The floor is then left overnight for curing before 3 more polishing grit are done.
- Lastly the concrete surface will be sealed with a stain and block out sealer to reduce water and oil staining.
- Timing of delivery depends on the type of equipment that a contractor uses. It can be expected that a 32" grinder will average 600 square feet per hour per grit, and a large Bobcat mounted 3-headed grinder can grind 2,000 square feet per hour per grit. The Bobcat grinders have limited availability on the east and west coast.
Notable buildings with polished concrete
- Solyndra, Fremont, CA – President Obama and Governor Arnold Schwarzenegger walked on this Diacon polished concrete floor in May of 2010
- California Academy of Sciences, San Francisco, CA
- Saddleback Church Teen Center, Lake Forest, CA
- Planes of Fame Air Museum, Chino, CA
- California State University, Sacramento, CA by Pacific Decorative Concrete
- University of New Mexico Arena "The Pit" Albuquerque, New Mexico
See also
- LEEDLeadership in Energy and Environmental DesignLeadership in Energy and Environmental Design consists of a suite of rating systems for the design, construction and operation of high performance green buildings, homes and neighborhoods....
- USGBC
- Burnishing
- Grinding
- Concrete grinderConcrete grinderA concrete grinder can come in many configurations, the most common being a hand-held Angle grinder, but it may be a specialized tool for countertops or worktops. There are also purpose-built floor grinders that are used for grinding and polishing marble, granite and concrete...