During the past 26 years Carl Covington has worked for Dunn Construction, he's been part of the asphalt production transformation this 125-year-old leading Southern road contractor has undergone to maintain its competitive edge in a market that continues to put new and improved asphalt mix designs to the test.

And like the transformation Dunn Construction made from railroad construction to road construction in the early 1900s, improvements in asphalt production have helped the company meet customer demands for quality bituminous products.

Dunn bids and serves as general contractor on projects including industrial roads, storage yards, parking lots, subdivision, municipal streets, airport taxiways and runways, and interstate and other highway construction.

Dunn's road construction is supported by six asphalt production facilities in the northern part of Alabama. The company has expanded its operation through Dunn Roadbuilders, a sister company serving the east central and southeast sections of Mississippi.

The company's quality initiatives reflect the ever evolving technology Dunn addresses to meet the increasing demands of its customers. While "hot, black and sticky" were used to define quality bituminous concrete of the past, "Superpave, smoothness, polymer additives, restricted zones, fine aggregates, angularity, pay factors, warranty work and certification" are some of the terms used to describe today's quality bituminous concrete. In the past 10 years, a national research effort has been underway to determine and implement methods of designing, producing, placing and testing bituminous concrete. The objective of the research is to produce longer lasting, better performing bituminous concrete pavement. Dunn has responded, by not only investing in state-of-the-art equipment and plants, but also by expanding its Quality Control/Quality Assurance Division. Dunn's goal is to produce quality bituminous concrete pavements that exceed the requirements and expectations of its clients.

From the opening of its first asphalt plant in 1915, Dunn recognized the vital role it would play in the construction of quality asphalt roads throughout the Southeast.

From batch to drum

When Covington began his career with Dunn in the late '70s, drum plants characterized the company's asphalt production capabilities. But as Covington worked his way up from laborer, to plant foreman, to plant manager and now Southern Division manager, he helped the company integrate new drum production technology that improved productivity levels and also allowed Dunn to successfully produce the emerging mix designs that characterize the quality bituminous products of today.

One particular Dunn asphalt production facility typifies the continuous improvement business philosophy of the company is the East Thomas, AL 300-tph Gencor UD300 Ultradrum plant, which was brought on-line in 1999. The Ultradrum counterflow design incorporates an isolated mixing section located behind the burner, so there is no chance of liquid asphalt coming in contact with the burner flame. The plant is equipped with an Ultra II burner, which is extended well inside the dryer for maximum efficiency and contact with the wet aggregates. The East Thomas plant is equipped with two 200-ton storage silos and replaced an old batch plant located at the facility since 1978. The upgrade not only allowed the facility to increase production from 160-170 tph (batch plant capacity) to 300 tph, it also provided improved technology required to produce some of the new mix designs, like open graded friction course and Superpave, which the Alabama Department of Transportation was starting to specify on many of its road projects.

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