VOL 19 ISSUE #2


In 1977, two brothers envisioned owning a company. With two employees, one backhoe, and a handshake, Shaw Brothers Construction was formed. The same founding principles of work hard, satisfy the customer, and respect the people you work with still guide the company today. Since its humble beginning, Shaw Brothers Construction has grown into one of Southern Maine’s largest earthwork contractors for site development, heavy/highway, and utility projects. Shaw Brothers also provides the area with quality aggregates from its various gravel pit and quarry locations. With the addition of Astec’s asphalt plant featuring the newest technology, the company is now operating the greenest plant in Maine. At the helm, brothers Jon and Dan Shaw continue to manage the day-to-day operations, now providing their customers with a variety of asphalt mixes. 

ASTEC PLANT RUNS ON NATURAL GAS

After 18 months of research, design, purchase, and installation, Shaw Brothers launched its new Astec 400 TPH (362 MTPH) stationary asphalt plant in May 2014. The plant, installed at Shaw Brothers’ headquarters in Gorham, Maine, runs on natural gas and processes aggregate from the company’s Brickyard Quarry, also located on site.  

“By locating the new plant by one of our quarries, we lower trucking emissions,” said Jon Shaw, co-owner of Shaw Brothers Construction. “Running the plant on natural gas also minimizes emissions and reduces cost, making the plant eco-friendly.”

Co-owner Dan Shaw continued: “It was important to us to have an asphalt plant with the latest technology, not only for the production of quality mix, but to minimize our impact on the community with respect to emissions and noise. We wanted to be able to maximize the amount of recycle in our mixes to be a good environmental steward of our resources. Astec’s innovative approach to being ‘green’ met our expectations.”

three-mod-reverse-pulse-baghouse
An upsized 80,000 CFM three mod reverse pulse baghouse was added to the configuration to reduce dust.

ADVANCES IN GREEN TECHNOLOGY

Shaw Brothers’ new asphalt plant features the latest Astec technology, including the V-Pack™ Stack Temperature Control System and the Double Barrel® drum mixer with patented warm mix system.

The V-Pack™ Stack Temperature Control System consists of V-flights, patent-pending flights with a deep V-shape. V-flights produce a uniform veil of virgin aggregate across the drum no matter how much material is in the drum, or what the production rate is, or how much RAP (reclaimed asphalt pavement) is used in the mix. Because the V-flights shower material uniformly, they never leave a hole in the veil. More revolutions per minute place more aggregate in the air. 

Astec’s patent-pending V-Pack Stack Temperature Control System monitors the exhaust gas temperatures at the baghouse inlet as the primary reference for control. As the exhaust gas temperature rises, the Control System checks it against a set point. When the temperature exceeds the set point, the Control System speeds up the drum’s rotational speed and controls temperature to the set point. This thickens the veil, which reduces the stack gas temperature. The drum speed can be varied from a minimum of about 7 RPM to a maximum of about 12 RPM. (The normal speed for Astec drums without the system is 8 RPM.) 

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For Shaw Brothers, the V-Pack system improves production of virgin and high-RAP mixes by maintaining temperature while running at higher speeds.

The Astec Double Barrel® drum mixer with the warm mix system enables Shaw Brothers to utilize as much RAP as possible. The drum is known for keeping operating costs per ton of mix low while meeting stringent environmental codes. The Astec warm mix system saves energy and reduces smoke and emissions. 

Other plant features include:

  • 10 ft x 14 ft (3.05 m x 4.27 m) eight-bin cold feed system
  • Three recycle feed bins; two for RAP (reclaimed asphalt pavement) and one for RAS (recycled asphalt shingles)
  • Four 200-ton (181 tonne) insulated storage silos
  • 80,000 CFM three mod reverse pulse baghouse
  • Whisper Jet® burner
  • Three Heatec 30,000 gal (113,562 l) liquid asphalt tanks

“By using the latest technology, we have diminished the noise and smell often associated with asphalt plants,” noted Dan Shaw. “We now have one of the most environmentally friendly plants in New England … the neighbors and town may even forget we’re here.”

  • For customers wanting a custom mix, Shaw Brothers has fine RAP stockpiled on location.

  •  Shaw Brothers utilizes ½-in (1.27 cm) RAP (reclaimed asphalt pavement) in its mixes.

  • The Astec 400 TPH (362 MTPH) stationary asphalt plant has an eight-bin cold feed system.

  • Shaw Brothers included the the Astec Double Barrel® drum mixer and warm mix system in the plant setup.

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