A major innovation in the hot-mix asphalt (HMA) industry was delivered to Tennessee Asphalt Co. of Knoxville, Tenn., in 1974: a highly portable drum-mixer production facility from Astec Inc. That HMA production facility was the first version of what would eventually become known as the Astec Six Pack HMA facility.
Prior to that development, the paving industry did not have the advantage of moving HMA production facilities from one location to another in an easy and cost-effective way. Transporting a stationary plant was very time-consuming and costly—so if a new paving job opened up 50 miles away, the only alternative was to increase haul times of the finished mix from the stationary plant to the jobsite.
But then Astec developed its portable Six Pack facility, an innovative design that provided producers with everything they needed to make high-quality mixes anywhere. The original setup of the plant included a parallel-flow drum mixer, a cold-feed system, a liquid asphalt cement tank, a scalping screen with inclined conveyor, a baghouse and a self-erecting surge bin. Later models incorporated the Astec Double Barrel dryer/mixer technology.
The self-erecting surge bin (SEB) is perhaps the most intriguing component of the Six Pack facility. The SEB reduces the number of loads by combining the surge bin, drag conveyor, truck scales and control house. A thick steel truck-loading platform is part of the frame, eliminating the need for concrete foundations. Two large hydraulic cylinders are used to raise the SEB from transport position to production position in less than 15 minutes. The name “Six Pack” was used because an entire production facility could be moved on the road as six different units. Upon arrival at the jobsite, the six units could be quickly and easily arranged to work together. Many producers have stated that they could move the plant from one location to another and have it operational in just three days. One thing that makes this possible is the self-erecting feature on the components.
The Astec portable Six Pack quickly became the world’s best-selling portable asphalt plant. Since its introduction in 1974, Astec has delivered more than 600 Six Packs in North America and around the world. Today, producers who are interested in purchasing a Six Pack facility have a wide range of options, including the Double Barrel dryer/mixer or the Double RAP drum with production capacities of 200, 300, 400 or 500 tons per hour.
