Dunn Roadbuilders Provides Smooth Ride in Southeast

Wed April 09, 2008 - Southeast Edition
CEG



Take a construction company with 130 years of experience and mix well with a compaction equipment company with 90 years in the business and life is good on Mississippi and Alabama roads these days.

When railroads were in vogue back in 1878, Dunn Construction opened its doors in Virginia to serve that booming industry.

Since then, the multi-faceted corporation has expanded its areas of operation to include road and other heavy construction projects. They are now among the largest and most diversified construction companies in the Southeast.

Dunn Roadbuilders of Laurel, Miss., owns and maintains a substantial fleet of road building equipment. It also has its own asphalt plants and QCQA labs to ensure a quality end result. And in Mississippi, like most states today, a quality end result drives the bottom line.

Part of Dunn’s success in this area has been driven by its choice of equipment partners. A few years back, Ken Welborn, sales representative of Stribling Equipment, pulled up with a new Sakai double drum roller in tow. Operations Manager Randy Adams and QCQA Materials & Plants Manager Rick Croy were skeptical, but agreed to take a look. They were admittedly impressed.

The Dunn roller fleet, which had been filled with big names and small results, now includes eight Sakais. According to Adams, the company now owns four SW900s, which are the larger 84-in. (213 cm) machine and four 67-in. (170 cm) SW800s.

“When we’re doing mainline paving of state and interstate highways, two of the 900s turn the trick,” Adams said. “With 4,000 vpm high frequency, we’ve had great success with a pair of Sakais in tandem to make breakdown density on some pretty tricky Superpave mixes.”

Both on site and back in the lab and plant, Croy keeps a keen eye on the mixes he designs and how they act in the field. According to Croy, “The paying public rarely applauds a great paving job. But they sure let you know when they don’t like it.”

In tune with that thinking, the state of Mississippi pays bonuses for a smooth ride and imposes stiff penalties for failure to meet density. In addition to these penalties and at times more painful, comes an equally bad reputation.

Using the Sakai rollers, Dunn has enjoyed excellent results and has maintained its strong reputation in the area, penalty-free.

Mississippi mixes come in three different sizes: small, ST; medium, MT; and large, HT — the mix being dependent on traffic volume, size of road, etc. These contemporary Superpave mixes can be difficult to compact, with the mix turning tender shortly after laydown.

“So we have to get on it and off it quickly, gaining density fast,” Adams said.

The Sakai rollers were born for this type of job. Asphalt Compaction 101 dictates that vibratory compaction is best achieved at impact spacings between 10 and 12 per foot.

This impact spacing is key to gaining the highest density in the shortest time. Roll too fast and the impact spacing stretches out, increasing the number of passes required to achieve density, affecting smoothness and the bottom line, losing money. Roll too slow and density is achieved but productivity is lost and thus money in the process.

Sakai introduced 4000 vpm high frequency rollers in 1999. Since the frequency of the roller and the speed of the roller will determine impact spacing, a higher frequency roller will permit higher rolling speeds at the same target impact spacing. And these same higher rolling speeds are what enable Sakai to beat these difficult tender zones while gaining necessary compaction. In addition, the standard counter-rotating eccentrics direct the centrifugal force downward as opposed to interacting the mat at an angle and not gaining full impact effect.

According to Croy, “Other key considerations challenging contractors working with Superpave are distance from the plant to the site, ambient temperature and wind, all of which affect laydown temperature and thus the window of opportunity to compact the mix properly ahead of the tender zone. Sakai rollers help us meet those challenges every day.”

Dunn Roadbuilders President Pepper Beckman sums up the company success philosophy best:

“We’ve come a long way from the words ’hot, black and sticky’ to Superpave. Like any other organization, we are faced with daily challenges. The answers to these challenges — be they in the form of personnel, techniques or equipment — determine the long-term success of the company. Sakai is one of those positive steps we have taken that have enabled us to maintain a leadership role in road building. Their products are well thought out and the consistency of results leads us to bonuses, rather than penalties. Beyond that, we have found their people to be very knowledgeable and their rollers to be incredibly reliable, leading us to far less downtime and a better bottom line.”

For more information, visit www.sakaiamerica.com or www.dunnroadbuilders.com.