To eliminate the imperfections in the pile caps, columns and barrier walls, DPR Construction used four Stinger electric flex shaft vibrators on the job site from Minnich Manufacturing,
Charlotte, N.C., is a rapidly growing city full of both history and charm. It currently ranks as the third-fastest growing major U.S. city, but growth hasn't only occurred over the past few years — Charlotte has been on the upswing for over a decade.
South End is a particularly booming Charlotte neighborhood, home to some of the city's best restaurants and nightlife. The Rail Trail, an 11-mi.-long public trail, runs through the area, giving runners and cyclists a great way to explore the neighborhood, and the nearby Blue Line light rail brings visitors in and out of the South End by way of public transportation.
Adding even more clout to the district is the city's newest retail and office tower, The Line. The recently completed 16-level building was designed to bring the community together and foster connection among residents and visitors. It houses 298,600 sq. ft. of office space above 304,500 sq. ft. of structured parking, along with breathtaking views of Uptown Charlotte. The ground floor includes 24,400 sq. ft. of retail, restaurants and a brewery.
DPR Construction is the commercial contractor on the project, a widely respected company ranked among the top 50 general contractors in the country since 1997. DPR Construction has 27 regionally based offices across the country and three international locations.
The Charlotte branch of DPR Construction performed the concrete scope of The Line, which included 25,000 cu.yds. of concrete and 4,000,000 lbs. of rebar. Unlike a traditional office building, much of the concrete was left exposed, prompting DPR to focus heavily on a quality finish.
"Our team enjoyed working through the unique elements of this project," said Paulie Estrada, concrete superintendent of DPR Construction. "The new structure is going to create a space for the community, and visitors, to shop, unwind and see new views of the city. Building The Line didn't always come easy, though."
Working Through Challenges
To break up the 16-level structure between parking and retail space — and add architectural appeal — a sky lounge was included on level eight. Not only did this create a unique look for The Line, but challenges, too.
Starting on the ninth level, The Line includes two towers that sit on top of the sky lounge, with the tower floors extending past the face of the structure and parking deck — posing a challenge due to how the floor defies gravity.
The main core of the structure, otherwise known as the shear walls, and columns were an integral part of the structure and crucial to get right the first time. The vertical concrete elements start at ground level and extend all the way to the ninth floor. Not only are they important to the structure, but the 17-ft. shear wall is exposed in the sky lounge, creating a center piece of the structure.
"It was tough to make sure we consolidated the concrete well because there was a lot of rebar inside the walls and columns," said Estrada. "These were critical pours. The walls were very high, making it hard to look down the side of the column and be confident that we were vibrating everything to our standards."
Choosing the Right Equipment
To eliminate the imperfections in the pile caps, columns and barrier walls, DPR Construction used four Stinger electric flex shaft vibrators on the job site from Minnich Manufacturing, an industry leader in drills, vibrators and vibrator monitoring systems.
The Stinger is a 14.5-lb. double-insulated universal motor that can drive the full line of Minnich vibrator shafts and heads from ¾ to 2½ in. Available in a 15-amp (115-volt) version, it offers a more compatible speed range of 10,000 to 13,000 vibrations per minute (vpm) to meet today's concrete placement challenges.
The size of the Stinger is ideal for carrying around the job site and maneuvering into small spaces, according to the manufacturer. It also has a fully adjustable harness that fits over the operator's shoulder to help reduce strain.
The unit is equipped with a durable protective frame, which extends vibrator life with urethane end caps that absorb shock while supporting easy-to-grip handles.
The Minnich Stinger provides quiet operation, meeting Occupational Safety and Health Administration (OSHA) A 29 CFR 1910.95 standards.
DPR was able to work efficiently and provide a quality finish on the concrete. The Stinger's versatility was beneficial while pouring support columns and beams.
"The Stinger is by far one of the most important pieces of equipment that we rely on to consolidate concrete," Estrada said. "It helped create a beautiful center piece of exposed concrete."
Seeing the Difference
Estrada has been in the concrete industry for decades and immediately noticed the advantages the Stinger brings to the job site.
"It's really dependable. Before the Minnich Stinger, I was using a different brand and had problems with it day after day. I even had situations where I had to rework the concrete after the vibrator didn't consolidate as needed. That's why we switched to Minnich," explained Estrada. "The Stinger has minimized issues and re-work dramatically. It works efficiently and can handle the workload we put it through day in and day out on the job.
"My experience working with the Minnich team has been great, too. Tech support visited the job site and troubleshot one of the vibrator heads for us — and it was back working in no time. That kind of support is invaluable for keeping a project on schedule."
The developer who worked in conjunction with DPR Construction on this project is Portman Holdings.
For more information on DPR Construction, visit www.dpr.com/company/culture. For more about Minnich Manufacturing, visit www.minnich-mfg.com.
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