High-Albedo Pavements May Have Environmental Benefits

Pavement Preservation Journal, Fall 2013, Vol. 6, No. 3
Yetkin Yildirim, P.E.

Heat energy behaves differently depending on the color of the surface that it comes into contact with.

Light, white colored surfaces tend to reflect heat energy, while dark, black-colored surfaces absorb much of this energy. The degree to which a surface reflects this energy is called its albedo, which can be expressed as a numerical value from 0 to 1 (where 1 means 100 percent reflectance, and 0 means total absorption).

Asphalt materials have traditionally been black, and thus, the majority of our world’s roadways are dark in shade. As a result, the earth’s natural surface has become extensively covered by dark roadways. The solar reflectance of a freshly installed asphalt pavement is about 0.05; this means that fresh asphalt absorbs 95 percent of the sun’s energy. Slightly lighter, aged asphalt pavements have a solar reflectance between 0.10–0.18, depending on the type of aggregate used in the asphalt mix.

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