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Thermal Properties of Paving Materials

Paving materials have been used since before the days of the Roman Empire to create better roadways. According to the University of California at Berkeley, numerous classes of materials can be used in paving including asphalt, concrete, granite and even wood. The University of Texas at Austin points out that paving practices are increasingly being examined under the auspices of environmental sustainability. The University of Florida adds that pavers can exhibit a wide diversity of thermal and physical properties that depend on composition.

Asphalt Roadways
- Asphalt is the most common paving substance used in much of the industrial world. A by-product of oil extraction and refining, asphalt contains large quantities of hydrocarbons and is poured onto a relatively flexible and heat absorbent surface. Asphalt is used in parking lots and highways because of its low cost and long lifetime. Thermally, it stores a great deal of heat and contributes to the phenomenon of the urban heat island noted in many cities.
Concrete Thermal Properties
- Concrete is another common substance used in paving but one that is thermally inactive. Concrete is comprised of minerals that have been taken from the soil and mixed with water. Water can absorb a great deal of heat energy which makes it a natural heat sink that doesn't increase in temperature as rapidly as other substances. It also doesn't lose heat easily so a concrete sidewalk will maintain a fairly stable temperature.
Brick Paving Materials
- Bricks are a less common paving material in roadways in the United States but are seen in much of Europe and in newer, more aesthetically-oriented communities in North America. Brick can be made out of certain types of soil and sand and is baked to achieve its notable rigidity. It is a better absorber of heat than solid rock due to its more porous nature, but still remains cooler than asphalt unless subjected to extreme heat.
Granite Pavers
- Granite is an uncommon paving material but still sees use in areas where it is inexpensive. Granite is a mineral material extracted in bulk from rocky areas. Granite paving blocks can be cut directly from stones on the side of mountains and maintain their standard density through installation. There is little room between molecules in a sample of granite and heat does not easily penetrate the surface. Granite reflects most thermal energy, making it a paving material that does not contribute significantly to surrounding temperatures.

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