Glow-in-the-dark cement could revolutionize how we light cities

Updated 15th July 2016
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glow in the dark cement
Glow-in-the-dark cement could revolutionize how we light cities
Written by By Sophie Morlin-Yron, for CNN
Concrete has never been a conventionally beautiful material.
But that's about to change.
Mexican scientist José Carlos Rubio Avalos has invented a glow-in-the-dark cement (a key component of concrete) that might one day beautify city nightscapes from Shanghai to Seoul.
The energy-efficient material soaks up sunlight during the daytime and begins to emit light as the sun sets.
And it's not just lampposts that the luminous invention could render obsolete.
"It could be used for exterior and interior applications," says Rubio Avalos, a materials scientist at the Universidad Michoacana de San Nicolas de Hidalgo, Mexico.

Cementing a place in history?

Cement is a multi-billion-dollar industry -- in 2014, global consumption of this material totaled 4.3 billion metric tons.
Now, Rubio Avalos' invention has got the industry re-imagining how to use this material.
Coating houses, bike lanes, highways, interiors and even swimming pools with glow-in-the-dark cement are all applications for which Rubio Avalos has received requests, from governments, businesses and NGOs.
He says Doctors Without Borders, for example, wants to use the technology "in bathrooms in areas where there are problems with the electricity and where women can be in danger entering dark public toilets."

A billion dollar industry

Rubio Avalos has patented his "novel cement matrix" -- essentially, a modification of ordinary cement.
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.
In the beginning of the concrete-making process, cement powder is mixed with water and the material starts to gel. The gel makes it form crystals.
"They look a little like cornflakes," he says, and are an unnecessary byproduct.
In Rubio Avalos' concrete, these crystals have been removed, which allows the sunlight to enter the cement matrix without being reflected. The result: a material which absorbs UV rays during the day and releases light at night.
"Some say it is a completely new material," says Rubio Avalos.
Its glow-in-the-dark properties will last "for at least 100 years," he says, and adds that the technology works even on cloudy days. It can work indoors, as long as the UV rays come in through the windows.

A city in red, green and purple

Marine blue and bright green are the colors currently available, but Rubio Avalos is working on cement that can glow white, red and purple.
He is currently building a pilot plant, which he expects will be ready to produce the material within three to five months.
But more funding is needed.
"If we want to commercialize this and cover all the requests from Europe, America, Africa, Asia that I've received, I need around $5-6 million."
Because of its complex structure, glow-in-the-dark cement is around five times more costly to produce than ordinary cement, says Rubio Avalos, who is a nominee for the Mexican National Science Award 2016, which recognizes those whose work has made a global contribution to science.
But entire structures don't need to be made of his material to glow. Rubio Avalos says they can merely be coated with an outer layer of his cement.
Even that isn't cheap.
"A one square meter piece, which is maybe 3mm thick, would cost around $60-70," he says.