Translucent concrete (also: light-transmitting concrete) is a

concrete Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wi ...

based

building material Building material is material used for construction. Many naturally occurring substances, such as clay, rock (geology), rocks, sand, wood, and even twigs and leaves, have been used to construct buildings. Apart from naturally occurring materia ...

with light-transmissive properties due to embedded light optical elements — usually

optical fiber An optical fiber, or optical fibre in Commonwealth English, is a flexible, transparent fiber made by drawing glass (silica) or plastic to a diameter slightly thicker than that of a human hair. Optical fibers are used most often as a means to ...

s. Light is conducted through the stone from one end to the other. Therefore, the fibers have to go through the whole object. This results in a certain light pattern on the other surface, depending on the fiber structure. Shadows cast onto one side appear as silhouettes through the material. LUCEM Translucent Concrete

Translucent concrete is used in fine architecture as a

façade A façade () (also written facade) is generally the front part or exterior of a building. It is a Loanword, loan word from the French language, French (), which means 'frontage' or 'face'. In architecture, the façade of a building is often t ...

material and for

cladding Cladding is an outer layer of material covering another. It may refer to the following: *Cladding (boiler), the layer of insulation and outer wrapping around a boiler shell *Cladding (construction), materials applied to the exterior of buildings ...

of interior walls. Light-transmitting concrete has also been applied to various design products. Several ways of producing translucent concrete exist. All are based on a fine grain concrete (ca. 95%) and only 5% light conducting elements that are added during casting process. After setting, the concrete is cut to plates or stones with standard machinery for cutting stone materials. Due to bends in the fibers and roughnesses on the cut surfaces of the fibers, light transmission is generally a bit less than half the incident light on the fibers, so given five percent fibers, about two percent. As the human eye's response to light is non-linear, this can still give useful

daylighting Daylighting is the practice of placing windows, skylights, other openings, and Reflective surfaces (climate engineering), reflective surfaces so that sunlight (direct or indirect) can provide effective internal lighting. Particular attention is ...

. In theory, the fibers could carry light around corners and over a distance of tens of meters, with the rate of loss with increasing length depending on the type of fiber and how it is bent. Working with natural light it has to be ensured that enough light is available. Wall mounting systems need to be equipped with some form of lighting, designed to achieve uniform illumination on the full plate surface. Usually mounting systems similar to natural stone panels are used — e.g., LUCEM uses perforated mounting with visible screws, undercut anchors with

agraffe An agraffe is a part used principally on grand piano The piano is a stringed keyboard instrument in which the strings are struck by wooden hammers that are coated with a softer material (modern hammers are covered with dense wool felt; some e ...

s or façade anchors.

History

Translucent concrete has been first mentioned in a 1935 Canadian patent. But since the development of optical glass fibres and

polymer A polymer (; Greek '' poly-'', "many" + ''-mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...

based optical fibers the rate of inventions and developments in this field has drastically increased. There have also been inventions that apply this concept to more technical applications like fissure detection. In the early 1990s forms like translucent concrete products popular today with fine & layered patterns were developed. Today several companies produce translucent concrete with very different production systems. Some manufacturers are: * Florak Bauunternehmung GmbH, Heinsberg/Germany * LBM EFO, Berching/Germany * LiTraCon Bt, Csongrád/Hungary * LUCEM GmbH, Aachen/Germany * Luccon Lichtbeton GmbH, Klaus/Austria * LiCrete, by Gravelli/Czech Republic

Variants

Apart from fine fiber patterns due to the use of optical fibers or textiles some products with much coarser light pattern are available. The main advantage of these products is that on large scale objects the texture is still visible — while the texture of finer translucent concrete becomes indistinct at distance. Further

pictogram A pictogram, also called a pictogramme, pictograph, or simply picto, and in computer usage an icon, is a graphic symbol that conveys its meaning through its pictorial resemblance to a physical object. Pictographs are often used in writing and ...

s and lettering can be realized with this technology. An approach that does not use waveguides involves using transparent aggregate and binders. However, chemically this would not necessarily resemble

, and might resemble

fiberglass Fiberglass (American English) or fibreglass (Commonwealth English) is a common type of fiber-reinforced plastic using glass fiber. The fibers may be randomly arranged, flattened into a sheet called a chopped strand mat, or woven into glass cloth ...

. Unlike materials requiring alignment of optical fibers, however, it might be transported and poured using existing infrastructure.How to see through walls: Transparent concrete is encouraging architects to rethink how they design buildings
The Economist. Sept. 20, 2001.

References

{{DEFAULTSORT:Translucent concrete Concrete

History

Variants

See also

References