Warming the mix
Contractor heats Little Rock high-rise slabs during winter construction

By Mark Friedman

Moses Tucker Real Estate Inc. of Little Rock recently unveiled a new mixed-use commercial building in the city's downtown, its second in the last two years.

The $26 million First Security Center, a 12-story, 168,000-sq.-ft. tower, sits on a quarter block in the heart of Little Rock's River Market.

"We think there was a demand for the product," said Jimmy Moses, a partner in Moses Tucker, which also opened the seven-story, $11.5 million Arkansas Capital Commerce Center in 2002 in the River Market.

First Security Center will feature a Marriott hotel on floors one through six, office space for the brokerage firm Crews & Associates of Little Rock on floors seven through 10 and 24 luxury condominium units on the top two floors.

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CDI Contractors LLC of Little Rock began work in June 2003 by demolishing a vacant masonry building at the site.

The general contractor's plan for constructing the building was to "treat it like three different buildings, even though they're all stacked on each other," said John Moore, CDI's project administrator.

Each section was "totally different," Moore added. "And none of the plans for either the hotel or the condos were buildings that had been done before, so this was all a totally customized unit. There's no question this is the most difficult project I've been on."

"The blending of the hotel, office space and condos was a real challenge," said the project's architect, Tom Adams, president of Wittenberg Delony & Davidson of Little Rock. Each of the three building types has its own requirements and requests.

All the mechanical systems had to line up and work together throughout the building, "so it required an unusual amount of mechanical, plumbing and electrical coordination, more so than in most (buildings)," Moore said.

The floor-to-ceiling heights also varied. In the hotel, the ceiling height is 8 ft. 6 in., while it rises to 10 ft. on the condo floors and 14 ft. 6 in. on the office floors.

Adams had to respond to a variety of tenant requests when designing the building.

The condo owners "wanted to have floor-to-ceiling glass as much as possible," he added. "The hotel was the opposite. It didn't want to have that much glass. And the office space sort of fell in the middle."

Everyone seemed pleased with the design, though. During the construction, all 24 condominium units were sold.

From the beginning, CDI was on a tight schedule because Marriott needed to be opened for the ribbon cutting of the William J. Clinton Presidential Library in November.

That meant the tower had to be built during the winter, Moore said.

With the tower slabs being made of post-tensioned concrete, CDI had to cast each floor in place on a temporary plywood table customized for the project.

Typically a project like this would have been built in the summer.

"You can't pour concrete when it gets below 40 degrees, so you have to use cold weather techniques," Moore added.

CDI draped industrial tarps on the sides of the structure and turned on gas heaters underneath the floor where it would be pouring the 5,500-psi concrete.

That's done so the water-based concrete won't freeze, Moore said. "That's why you literally heat (the floor) like a stove," he added. If the slab froze, CDI would have to remove the concrete and start over.

"We had some delays due to freezing conditions (but the slab didn't freeze)," Moore said. "We had to work hard to avoid it."

The contractor also had to make sure the concrete delivery trucks snaking their way through downtown Little Rock didn't get tied up in traffic.

"Those concrete trucks can't be interrupted, because you can't have a slab partially cure," Moore said. To avoid traffic problems, CDI began pouring the slabs around midnight and concluded about 10 a.m.

CDI had to coordinate with the local gas, electric and phone companies to determine where underground pipes and cables were, Moore said.

"In some cases the utility companies didn't even know what was underneath the ground, and we would dig and find something we didn't know was there," he added.

He said CDI uncovered railroad tracks that weren't on any of the maps and workers often hit "huge, round smooth boulders" when drilling through the sandy riverbank soil during foundation construction.

Adams said he chose brick for the building's exterior to give it "a warehouse feel." But trying to place bricks 14 floors off the ground caused problems.

Moore said a Bennu scaffolding system was used to get the job done. The platform scaffold sits on the ground and enables workers to add two-story vertical sections as they work their way up the building.

"It's like the steel frame scaffolding that you see on a lot of high-rise buildings," Moore said. "There would be no way to build the building without (the Bennu system)."

Because of the success of the first two projects, Moses Tucker announced at the end of October that it would build another tower in the River Market, which will be a 17-story, $45 million residential building.

"We believe based on our previous success that there is a demand for high-end luxury condominiums," Moses said. "And there's no better place to put them than on the top floors of a building."

Useful Source

For information on other current and future projects in downtown Little Rock, go to: http://www.downtownlr.com/attractions/