You might think that concrete is a boring material. Not at all. In a very well-documented article, "Concrete Nation," Science News tells us how the limits of this humble material are being pushed. You can now find concrete that bends like metal and which is five times as strong as regular concrete without any reinforcing steel bars. Or you can use concrete which doesn't need a vibration machine to remove the air bubbles inside, which can save lots of time during construction. There are also translucent concrete or concrete incorporating transparent elements, allowing to build floors lit from below. And by adding titanium dioxide to cement, you obtain a self-cleaning concrete that remains the same color for centuries and can even clean the air by breaking down dangerous pollutants. Fascinating, isn't?
Before going further, let's start by some illustrations. The pictures and the legends below come from the site of a current exhibit at the National Building Museum in Washington, D. C., Liquid Stone: New Architecture in Concrete (Macromedia Flash needed).
Below are computer-generated images of the hypothetical Mound Builder Museum designed by Building Studio from Memphis, Tennessee (Macromedia Flash needed).
And this one shows another museum, the MUCEM, in Marseille, France, which will be completed by 2009.
Now, let's look at a concrete that bends like metal.
For instance, consider some of the new materials developed by concrete giant Lafarge, headquartered in Paris.
Vic Perry leads the company's North American operation producing Ductal, one of Lafarge's newest concrete products (Macromedia Flash needed). Unlike regular concrete, which is brittle and can rupture suddenly under a heavy load, Ductal can bend. "It will deflect and show signs of cracking before it fails," says Perry. "You can see in advance that you've got a problem."
What's more, Ductal is five times as strong as regular concrete. That extra oomph comes from the addition of small fibers dispersed throughout the matrix. These fibers, made of either steel or polymer, reinforce the concrete and eliminate the need for reinforcing steel bars, or rebar. A bridge made out of Ductal can be lighter and thinner than a traditional bridge, Perry says.
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Actually, no concrete object lies outside of the poetic sphere as long as the poet knows how to use the object properly.
—Johann Wolfgang Von Goethe (1749–1832)
Because of an aging workforce, there is also the need to reduce the amount of labor during construction.
In response to this concern, Lafarge has developed Agilia. According to the company, laying a 60-cubic-meter slab of regular concrete -- enough for a floor in an office building -- requires eight people and takes about 8 hours. Placing the same-size slab of Agilia could require as few as two people and take a couple of hours.
Normally, after concrete is poured, the mason passes a vibrating machine over the surface to squeeze out all the air bubbles. It's a loud and time-consuming process. However, Agilia contains a mix of additives: superplasticizers that keep the concrete fluid and other chemicals that cut down on the water needed. These enable the concrete to consolidate under its own weight without mechanical vibration.
Other concerns, such as global warming, also lead to concrete innovations. Do you know that the cement industry produces 7% of the global human production of carbon dioxide? There are now efforts to replace cement by 'greener' materials. And new kinds of concrete are specifically designed to reduce pollution.
Scientists at the Italcementi Group in Bergamo, Italy, have developed a self-cleaning concrete that keeps buildings from turning black from pollutants in the atmosphere. Luigi Cassar and his colleagues at the research branch of Italcementi made the concrete by adding particles of the white pigment titanium dioxide to the cement component.
When titanium dioxide absorbs ultraviolet light, it becomes highly reactive and breaks down pollutants that come into contact with the concrete's surface. The reactive material can kill bacteria and fungi and also break down pollutants such as nitric oxide, sulfur dioxide, and many volatile organic compounds that contribute to concrete's darkening.
After reading about all these innovations, do you still think that the ubiquitous concrete is boring?
Sources: Alexandra Goho, Science News, Vol. 167, No. 1, Jan. 1, 2005, p. 7; and various websites
Art is a concrete and personal and rather childish thing after all—no matter what people do to graft it into science and make it sociological and psychological; it is no good at all unless it is let alone to be itself—a game of make-believe, or re-production, very exciting and delightful to people who have an ear for it or an eye for it.
—Willa Cather (1873–1947)
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Architecture
Energy
Innovation
Materials
Technology.