Concrete is synonymous with hardness, yet is fluid. It is by definition a hybrid – with no intrinsic form and despite its generic reputation, finished concrete can assume almost any colour, texture and pattern. Concrete is a chameleon. It is most often gray, but can just as easily be made white, brown or even vibrant red. It is these characteristics,however that make it such a tantalizing medium for many architects today. Like clay in hands of a sculptor, concrete allows architects to create structures that are uniquely evocative, referential or geometrically adventurous.
The art and science of building is greatly affected by the development of materials. Among other construction materials, when understood and applied, the inherent qualities of concrete can lead to distinguished expressions in architecture as it combines fundamental and highly desirable qualities that makes it an excellent building material. Tado Ando, the Japenese architect who made Concrete a contemporary material to work with says, “Concrete is a true structural material that represents its own time. When constructed and maintained properly, nothing can surpass concrete”.
Sujatha Thampan delves deep into the varied facets of this building material.
GLOW IN DARK CEMENT
Imagine concrete that looks like ordinary, plain gray concrete during the day, but after the lights go out, it will generate a luminescent glow that will last all night long without being connected to any power source. José Carlos Rubio Ávalos, a researcher at Michoacan University of San Nicolás de Hidalgo in Mexico, and his team have designed a new type of phosphorescent cement that could illuminate highways, bike paths or buildings without using electricity. The energy-efficient material soaks up sunlight during the daytime and begins to emit light as the sun sets. Rubio Avalos has patented his “novel cement matrix” – essentially, a modification of ordinary cement.
Using the same raw materials with which cement is manufactured and by adding certain additives, scientists modified the optical properties of the material, and it became phosphorescent. “Cement is an opaque body, it does not allow the passage of light to the interior, so we must make a change in its microstructure to allow a partial entry of light into the interior for it to have this behaviour,” Rubio Ávalos says. By using additives, scientists are able to prevent the formation of crystals that occur normally during the production of cement, creating a material with a non-crystalline structure— similar to glass—that allows passage of light inside. Rubio Avalos added photoactive materials to the cement to absorb and emit light, but the greatest challenge was to make the cement, an opaque material, soak up UV rays. To do this, he had to alter its microstructure.
And although it is manufactured like ordinary cement, the change in the microscopic structure needed to make it glow modifies the structural properties of the material—thus it may not have the same applications as the ordinary kind, and is intended to be used on surfaces as a coating material. Because of the inorganic nature of the cement components, the material can have a very long shelf life when compared with other phosphorescent materials such as plastics or paints—but this will always depend on how it is used.
Phosphorescent materials absorb energy from radiation such as the ultraviolet light emitted by the sun—or by lamps, if indoors— energy they later emit as light, which can be seen after dark. As it loads up energetically with ultraviolet rays, even on cloudy days the cement will be able to absorb enough energy to glow during dark periods for up to 12 hours.