Astec Double Barrel^® Drum Mixer

Overview

Sequential mixing ensures ingredients are added to the hot mixture in an order that allows better temperature equalization and even distribution of all particles throughout the mix.

The Double Barrel sequence begins when aggregate enters the drum from the conveyor and passes through the flop gate, which minimizes air leakage into the drum. From there, it passes through a series of veiling flights that transfer the heat from the burner to the aggregate. The aggregate then exits the inner drum, dropping down into the outer drum shell, where paddles sequentially mix in RAP, liquid AC, and dust/filler in a flame-free environment. In this zone, the constituents are mixed for the remainder of the drum length before exiting to the drag.

Astec Double Barrel Drum Mixer

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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Recycled Asphalt Pavement

Recycled asphalt pavement (RAP) is asphalt paving material recovered from old road beds either by milling or excavation.
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Downloads

Astec Double Barrel Brochure English
Download (pdf) 10 MB
Astec Double Barrel Drum Brochure French
Download (pdf) 14 MB

Key Specifications

Portable Drum Size (m)	Portable Mixing Chamber (m)	Portable Metric Tons Per Hour (MTPH)
1.8m x 10	5.8	181
2.1m x 11	5.8	272
2.4m x 11.6	6.4	363

Portable Drum Size	Portable Mixing Chamber	Portable Tons Per hour
6' x 33'	19'	200
7' x 37'	19'	300
8' x 38'	21'	400

Relocatable Drum Size (m)	Relocatable Mixing Chamber (m)	Relocatable Metric Tons Per Hour (MTPH)
1.8 x 10	5.8	181
2.1 x 11.6	6.7	272
2.4 x 12.2	6.9	363
2.7 x 14.3	6.9	454
3 x 15.2	6.9	544

Relocatable Drum Size	Relocatable Mixing Chamber	Relocatable Tons Per Hour
6' x 33'	19'	200
7' x 38'	22'	300
8' x 41'	22' 5"	400
9' x 47'	22' 5"	500
10' x 50'	22' 5"	600

UNITS:

All specifications subject to change without notice.

Features

Double Barrel Trunnions

Adjustable steel trunnions with railroad duty bearings.
Double Barrel Drum Tires

Hot-forged from solid billets of alloy steel and precision machining provides ultra-smooth operation.
Double Barrel Thrust Rollers

Thrust rollers on either side of the tire restrain the drum.
Mixing Paddles

Bolt-on mixing paddles allow for easy maintenance.
Astec V-Flight

The v-shaped notch allows material to start pouring out of the bucket at the beginning of each revolution. The material in the bucket continues to pour out until the rotation is complete. This is what provides an even veil of material. The v-flight is also larger than a traditional flight, allowing it to carry the same amount of aggregate even with the notch.
Double Barrel V-Flight Veiling

Provides greater uniformity of the aggregate veil through the gas stream during the drying process, across a wide variety of mix designs and tonnage rates.
Double Barrel Hydraulic Access Door

A large hydraulically operated access door allows easy service of mixing shanks and tips from the outside of the drying drum.
Insulation

4" thick insulation under the outer skin of the mixing chamber minimizes heat loss and increases efficiency. In addition, temperature-resistant ceramic fiber insulation is used in critical high-heat areas.
Temperature Sensor

Once heated and dried, the aggregate leaves the drying chamber and enters the mixing chamber. At this point, an infrared sensor measures the temperature of the hot aggregate and automatically adjusts burner output to keep aggregate at the required temperature. This unique Astec feature makes it easier to control mix temperatures and to consistently produce mix that conforms to specifications.
Portable Double Barrel Drum Mixer

The Double Barrel drum mixer is also offered in a portable configuration.
Astec Warm Mix System

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 warm mix system injects a small amount of water into the liquid AC to create microscopic steam bubbles. These small bubbles reduce the viscosity of the liquid AC, allowing the mix to be worked at lower temperatures.