Paving Tight-Radius Curb


Curb and Gutter Paver

Ever since Black Diamond Group, Inc., Oak Creek, Wis., started in the construction industry in 1959, the company has maintained its vision of being the easiest company to dobusiness with.

That philosophy includes not only business with customers, but also with material suppliers, subcontractors and equipment providers.

When the company decided to expand by adding a concrete division in 2005, it chose to rely on GOMACO curb andgutter machines.

"We try to live our vision every day," said Mark Pichler, Black Diamond's concrete division manager. "The construction industry is challenging, especially in Wisconsin's four-season climate. You have to be on top of your game."

"We separate ourselves from the competition by being easy to do business with." Pichler said. "GOMACO has the same values. That's why we've picked them as a trusted partner."

The company currently owns three GOMACO GT-3600s that is uses to slipform a variety of applications.

The company's subdivision and parking lot work includes several profiles for curb and gutter, sidewalk and barrier wall.

One recent project was the Wheaton Franciscan Hospital in Franklin, Wis., where Black Diamond used two of its GT-3600s, including a new 2007 model, to slipform approximately 5,000 feet of sidewalk and 25,000 feet of curb and gutter.

The locally supplied concrete for the project had 395 pounds of cement and 170 pounds of fly ash in its mix design, and an average slump of 1.25 to 1.5 inches.

The project's non-reinforced sidewalk measured 5 feet wide and 4 inches thick, with tooled joints every five feet and expansion joints every 100 feet.

The GT-3600 simultaneously trimmed 6 feet wide through 4 inches of crushed limestone base.

"On this job, we averaged 1,000 feet of slipped sidewalk per day," said Stan Maertz, concrete project manager. "Our production depends on jobsite conditions. On a good subdivision, we average about 2,000 feet per day," he said.

The second GT-3600 working on the project slipformed the 18-inch-wide curb and gutter.

Municipal requirements for green space on developments increase each year in the state, so more projects involve more and more islands.

The Wheaton Franciscan hospital parking lot has about 50 islands, including several with tight two- and three-foot radii.

"We construct numerous parking lot projects yearly with a variety of different island profiles and complexities," says Black Diamond President Deb Teglia. "Customers count on us for quality, timeliness and attention to detail. We take pride in being the contractor of choice for these types of projects."

Continued success with tight-radius work enables Black Diamond to confidently slipform an 18-inch curb and gutter around a 2-foot radius.

"We just slide our GT-3600's right-front leg out and go with a 12-inch offset," Maertz explained. "We use string line on the straightaways and fiberglass rods to set theradii," he said.

Pichler added, "We also trim a little deeper out in front, so the mold doesn't catch as we go around the radius. We lose a little bit of concrete on a tight radius, but that's not a big deal. We just send the machine right around and if we've got a good mix design, we have minimal tearing around a 2-foot radius with an 18-inch curb and gutter."

Curb-and-gutter production averaged 1,600 feet per day on the job, even with all of the radius work. Finishers working behind the GT-3600 cut joints every 10 feet, with expansion joints every 300 feet, or one per island.

The project's largest challenge wasn't the number of tight radii, but simply jobsite logistics and tight working spaces.

"It was a good-sized site, but in some of the smaller sections, we were dealing with 10 subcontractors working in a quarter-acre," Pichler said. "Keeping those guys out of our way and out of our curb and gutter was a challenge."

After the hospital job was complete, Black Diamond and its GT-3600s moved on to tackle the next challenging project.

Always searching for innovative ways to improve, Black Diamond is currently looking into stringless paving.

"We want to be innovative," Pichler said. "We want to find ways to be easier to do business with and we envision stringless as being a way to do that. We like to be in the forefront. So even though our customers aren'tdemanding stringless right now, we want to be ready whenthey do."