Types of Asphalt Plants

Asphalt is used for paving roads, parking lots and roofing. It mostly consists of sand, gravel or stone which is bound together by cement made from crude oil. There are two kinds of asphalt: straight run asphalt used for paving roads, airport runways and parking lots, and oxidized or air blown asphalt which is primarily used for roofing and pipe covering. Asphalt plants are facilities where asphalt is mixed and created. The EPA reports that asphalt mixing plants create 300,000 tons of mixing asphalt annually.

Batch Mix Plant

• In a batch mix plant the sand or gravel is dried first and then taken to a mixer. While in the mixer the aggregate is mixed with liquid asphalt.

Drum Mix Plant

• In a drum mix plant, the liquid asphalt is injected directly into the rotary dryer with the aggregate. The rotary dryer then heats the entire mixture. Higher organic emissions are expected from a drum mix plant because the liquid asphalt is exposed to higher temperatures and open flame.

Environmental Concerns

• Asphalt is a mixture that contains thousands of different chemicals, including volatile organic compounds, carbon monoxide, sulfur, nitrogen oxides and polycyclic aromatic hydrocarbons. These fumes are emitted into the air by asphalt plants and then inhaled into the lungs. As a result, many counties across the United States have regulated asphalt plants.