25 September 2006

Innovations in Pavement

I must admit, I don't really pay a lot of attention to the surface beneath my feet unless I'm roller-skating (which I do rarely, and poorly). But I read about some nifty pavement-related inventions, and I have a new-found respect.

The first idea that caught my attention is the use of titanium dioxide as a coating for pavement and roof tiles. Titanium dioxide is sensitive to light, and in the presence of light and water vapor, turns nitrogen oxide (one of the emissions that causes smog) into harmless vapors. Pavement with titanium dioxide has been in use for several years in Japan and is now being tested in England and Italy.

Another interesting pavement innovation: porous pavement. Pervious Pavement is a type of concrete that has the same capacity as regular pavement material but can drain water at a rate of 8-12 gallons per square foot per minute. This eliminates the needs for storm drains, minimizes the risk of flooding in urban areas, and helps to prevent erosion.

New kinds of concrete are made from recycled materials, which is always a good thing. Sulfur concrete is made from sulfur (a byproduct of refining petroleum) and coal ash (a byproduct of, um, burning coal). Other types of concrete being studied are made from blast furnace slag, sludge from paper mills, agricultural waste such as rice husks, used rubber tires, and recycled soda bottles.

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