Translucent Concrete: Lets The Light Shine In

Concrete 

During the Roman Empire, Roman concrete was made from quicklime, pozzolana and an aggregate of pumice. Its widespread use in many Roman structures, a key event in the history of architecture termed the Roman Architectural Revolution, freed Roman construction from the restrictions of stone and brick material and allowed for revolutionary new designs in terms of both structural complexity and dimension. Hadrian’s Pantheon in Rome is an example of Roman concrete construction. Concrete, as the Romans knew it, was a new and revolutionary material. Laid in the shape of arches, vaults and domes, it quickly hardened into a rigid mass, free from many of the internal thrusts and strains that troubled the builders of similar structures in stone or brick. The widespread use of concrete in many Roman structures has ensured that many survive to the present day. The Baths of Caracalla in Rome are just one example. Many Roman aqueducts and bridges have masonry cladding on a concrete core, as does the dome of the Pantheon. Some have stated that the secret of concrete was lost for 13 centuries until 1756, when the British engineer John Smeaton pioneered the use of hydraulic lime in concrete, using pebbles and powdered brick as aggregate. However, the Canal du Midi was built using concrete in 1670, and there are concrete structures in Finland that date from the 16th century. A method for producing Portland cement was patented by Joseph Aspdin on 1824.

                                                

Fluorides Glass

It was invented by Gerhard Bernsee of Schott Glass in Germany in 1973.Fluoride glass is a class of non-oxide optical quality glasses composed of fluorides of various metals. Because of their low viscosity, it is very difficult to completely avoid crystallization while processing it through the glass transition (or drawing the fiber from the melt). Thus, although heavy metal fluoride glasses (HMFG) exhibit very low optical attenuation, they are not only difficult to manufacture, but are quite fragile, and have poor resistance to moisture and other environmental attacks. Their best attribute is that they lack the absorption band associated with the hydroxyl (OH) group (3200–3600 cm−1), which is present in nearly all oxide-based glasses. An example of a heavy metal fluoride glass is the ZBLAN glass group, composed of zirconium, barium, lanthanum, aluminum, and sodium fluorides. Their main technological application is as optical waveguides in both planar and fiber form. They are advantageous especially in the mid-infrared (2000–5000 nm) range.

                                           

                                           

                

                                              Silica 

Dr. W. A. Patrick invented silica during World War one.Silica exhibits fairly good optical transmission over a wide range of wavelengths. In the near-infrared portion of the spectrum, particularly around 1.5 μm, silica can have extremely low absorption and scattering losses of the order of 0.2 dB/km. Such remarkably low losses are possible only because ultra-pure silicon is available, it being essential for manufacturing integrated circuits and discrete transistors. A high transparency in the 1.4 um region is achieved by maintaining a low concentration of hydroxyl groups (OH). Alternatively, a high OH concentration is better for transmission in the ultraviolet (UV) region. Silica can be drawn into fibers at reasonably high temperatures, and has a fairly broad glass transformation range. One other advantage is that fusion splicing and cleaving of silica fibers is relatively effective. Silica fiber also has high mechanical strength against both pulling and even bending, provided that the fiber is not too thick and that the surfaces have been well prepared during processing. Even simple cleaving (breaking) of the ends of the fiber can provide nicely flat surfaces with acceptable optical quality. Silica is also relatively chemically inert. In particular, it does not absorb water.

Phosphates Glass

Phosphate glass constitutes a class of optical glasses composed of meta-phosphates of various metals. Instead of the Sio₄ tetrahedra observed in silicate glasses, the building block for this glass former is. Phosphorus pent-oxide (P₂O₅), which crystallizes in at least four different forms. The most familiar poly-morph comprised of molecules. Phosphate glasses can be advantageous over silica glasses for optical fibers with a high concentration of doping rare earth ions. A mix of fluoride glass and phosphate glass is fluoro-phosphate glass. 

Optical Fiber 

Fiber optics, though used extensively in the modern world, is a fairly simple, and relatively old, technology. Guiding of light by refraction, the principle that makes fiber optics possible, was first demonstrated by Daniel Colladon and Jacques Babinet in Paris in the early 1840's. John Tyndall included a demonstration of it in his public lectures in London, 12 years later. Tyndall also wrote about the property of total internal reflection in an introductory book about the nature of light in 1870: "When the light passes from air into water, the refracted ray is bent towards the perpendicular... When the ray passes from water to air it is bent from the perpendicular... If the angle which the ray in water encloses with the perpendicular to the surface be greater than 48 degrees, the ray will not quit the water at all: it will be totally reflected at the surface.The angle which marks the limit where total reflection begins is called the limiting angle of the medium. For water this angle is 48°27', for flint glass it is 38°41', while for diamond it is 23°42'. Unpigmented human hairs have also been shown to act as an optical fiber.

Translucent Concrete 

Translucent concrete (also: light-transmitting concrete) is a concrete based building material with light-transmissive properties due to embedded light optical elements - usually Optical fibers,silica,phosphate glass,and fluride glass. Light is conducted through the stone from one end to the other. Therefore the fibers have to go through the whole object. This results into a certain light pattern on the other surface, depending on the fiber structure. Shadows cast onto one side appear as silhouettes through the material.Translucent concrete is used in fine architecture as a façade material and for cladding of interior walls. Light-transmitting concrete has also been applied to various design products.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..Translucent concrete has been first mentioned in a 1935 Canadian patent. But since the development of optical glass fibers and polymer 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 product popular today with fine & layered patterns were developed.

^Sources

Mckee, R. (2000, December 23). Phosphate Glass for Photonics. Oak Ridge National Laboratory. Retrieved November 19, 2012, from http://www.ornl.gov/info/ornlreview/rev27-3/text/phoside2.htm

Light Transmitting Concrete.. (2009, February 14). Crookedbrains. Retrieved November 19, 2012, from http://www.crookedbrains.net/2009/02/light.html

 

See-Through, Light-Transmitting … Concrete?! | Designs & Ideas on Dornob . (2001, September 15). Dornob | Modern Home, Interior & Furniture Designs & DIY Ideas . Retrieved November 19, 2012, from http://dornob.com/see-through-light-transmitting-concrete-material/

OFS: Optical Fiber. (2012, March 12). OFS, a Furukawa Company. Retrieved November 19, 2012, from http://www.ofsoptics.com/fiber/

What are phosphates - Phosphate Forum of the Americas. (2002, May 10). Phosphate Forum of the Americas - Home Page. Retrieved November 19, 2012, from http://www.phosphatesfacts.org/what.asp