A bicycle lane inspired in Van Gogh’s Starry Night can be found in the Netherlands. It was built using phosphorescent tiles, so at night passersby see where they are going without the need of electricity-consuming lighting. But despite the beauty of the scene, only a handful of constructions worldwide have this kind of lighting, because the microscopic structure of common building materials—such as cement, concrete or brick—prohibits adding this property.
But this could soon change. 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.
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 behavior,” Rubio Ávalos says.
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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 noncrystalline structure—similar to glass—that allows passage of light inside. Varying the proportion of additives added while manufacturing the cement regulates both its luminescent intensity and color—so as not to dazzle drivers, if used on roads, for example.
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.
According to Carmen Andrade, researcher at the Spanish National Research Council (CSIC) Institute of Building Sciences in Madrid, “It’s an application that can be worth developing in countries and areas with poor access to electricity in communities with poor life levels, as it doesn’t consume electricity.” But she also adds, “cement is a very alkaline material, so the stability of these compounds should be studied [...] and also how to repair it.”
The project, which represents the first patent for Michoacan University is in commercialization phase. Rubio Avalos’ plans, however, go beyond cement;, he wants to develop a range of products capable of luminescence, this one is just the first.
