Astec Green System

Overview

The benefits of warm mix asphalt, such as reduced energy consumption, lowered emissions, and elimination of visible smoke, are well-known in the asphalt paving industry. Warm mix technology allows mix to be prepared and placed at lower temperatures than conventional hot mix. To achieve this, the viscosity of the liquid asphalt cement (AC) must remain low at the reduced temperatures. Maintaining a low viscosity at lower temperatures allows mix to flow freely through storage, transfer, and placement equipment and is more easily compacted.

The Astec Green System achieves a lower temperature at a lower cost by eliminating the need for additives or special asphalt cement. Instead, the Astec Green System injects a small amount of water into the liquid AC to create microscopic steam bubbles. These small bubbles act to reduce the viscosity of the liquid AC, allowing the mix to be worked at lower temperatures.

Astec Green System

Applications

Asphalt Mixing

A thermal mixing process is required to turn aggregates and liquid AC into an asphalt pavement mix for road construction. This makes an asphalt mixing plant necessary for road construction. The complete line of Astec asphalt mixing plants, and its range of capacities and features, gives you the choices and flexibility to create your optimum solution.
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Aggregates
There are two main classes of aggregates: natural and manufactured. Deleterious material needs to be removed from both classes. Processing these materials typically requires various steps including reduction and sizing and also may include dewatering and sorting. Producers can use a variety of crushing, screening, dewatering and conveying equipment to meet their desired specifications.
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Downloads

Astec Green System Brochure
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Features

Better Compactibility

Low-viscosity mix achieves easier compactibility.
Producing asphalt mix at lower temperatures leads to less oxidation resulting in longer pavement life. Every 25°F increase in temperature doubles the rate of oxidation of liquid AC.
Solenoid Injection

Water is accurately metered into the system by a feedback-controlled positive displacement piston pump. Using feedback controls, the pump speed is modulated to maintain the appropriate flow of water based upon the flow of the liquid AC. PLC controls provide for smooth and consistent water flow as production rates increase or decrease. Water is injected into the liquid AC through two stainless steel water injectors which continuously inject high-pressure water into a foaming chamber.
Improved Liquid Asphalt Coating

Foamed liquid AC has a greater volume, which allows it to cover a greater surface area, while using the same amount of liquid. This means that the liquid is better distributed over the aggregate. Lower mix temperatures can also increase maximum production rate.