This Job Is Hard Enough

August 25, 2006
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GRAND RAPIDS — With a goal of erecting a floor a week for 14 weeks, exactly how does a contractor get the cement to those heights? And how does the gooey material ultimately surge two dozen stories above ground without hardening on the way up?

Those questions have been answered by Granger Construction Co., which was awarded a $10 million contract to do the concrete work for the new JW Marriott Hotel that Alticor Inc. is building at the corner of Pearl Street and Campau Avenue NW.

Jim Connor, Granger's West Michigan regional manager, said his work crew uses a high-pressure pump to push the cement up a five-inch diameter steel pipe. The pipe runs through the center of the building shell, where an elevator shaft is, and then through openings that have been cut in the middle of the floor areas.

"We pump it up straight through the center of the building. We use a placing boom on top and that allows us to pump vertical. And that big arm-like device, the placing boom, reaches around and then we're able to pump the concrete and place it where we need to," said Connor.

The pump is driven by a diesel motor with an output of 450 horsepower, the equivalent of a tractor-trailer engine. Connor said the amount of pressure needed to push the concrete increases the higher it has to go, and the force also changes depending on the cement mix that is used. Different areas need different mixes. So the pressure load needed to shove the concrete up the pipe ranges from 1,000 to 4,000 pounds.

Getting the cement up the pipe is one task, but keeping it from clogging up inside the pipe is a separate challenge — even more so on very hot and humid days.

"When the pipe is empty, it's just sitting there and the sun is baking it. If it's 100 degrees outside, it might be 130 degrees inside the pipe. If we stop pumping because we have to move something around, it doesn't take very long for that concrete to set under those higher temperatures," said Connor.

If a clog in the pipe develops, the Granger crew has to find exactly where it has hardened and do so quickly. That gets tougher to do the higher the pipe has to go because the pipe is actually a series of 6- and 8-foot-long steel sections that are fitted together. And the sections just may have to be taken apart to find a clog, no matter how high it might be above ground.

"You can't find it with a hammer. It sounds solid all over because it's full of concrete. You have to find where you think the clog is and get sections rinsed out quickly, or put a new one in there that is empty and keep pumping," said Conner.

"The idea is, once you start pumping, you try not to ever really stop for any amount of time. You want to try to keep (the cement) moving along all the time."

At the end of each day, the pipe has to be cleaned from the top down. To do that, Connor said a large Nerf-like ball is stuffed into the pipe. The ball, which is a bit squishy, is then hooked to a compressed-air line. The air forces the ball down the pipe, driving the excess concrete out the bottom.

"We have what we call a diverter valve that will send all the concrete into a bucket. Then we use a crane to hoist that last bucket back up on the deck to use. We run that ball through there one or two times, and it kind of flushes that line out pretty clean," said Connor.

Eventually, Granger will have to build the pipe as tall as what the hotel will be — 24 stories or roughly 240 feet high. At an average of 7 feet per section, it will take about 35 pipe sections to reach the top floor of the JW Marriott.

Connor said this is the largest concrete job that he has ever been involved with, as his crew will use about 10,000 yards of concrete to pour the four-star hotel's floors.

"This is a great job. It's a high-profile job and a fun one to be involved with. It seems to come up in conversations in a lot of places," he said.

Connor had managed projects for Granger before taking over as the company's regional manager about 18 months ago. But Granger, which is based in Lansing, has done quite a bit of work in the region for quite a while. GVSU's Eberhard Center was one of its projects.

"We're excited about the West Michigan market. We're planning on being a definite contender in the area and doing good things in West Michigan," he said.

Pepper Construction of Chicago and Rockford Construction of Grand Rapids are managing the hotel project. The JW Marriott should be open in the fall of 2007.

Granger, which was started by Keith Granger in 1959, recently won three awards from the Construction Association of Michigan's Magazine. The magazine only handed out a dozen honors at the association's 2006 Design and Construction Exposition, and Granger walked off with a quarter of those.

The Diagnostic Center for Population and Animal Health on the MSU campus, Saline High School in Saline, and the Granger Center for Construction Management Technology and HVACR Programs at Ferris State University in Big Rapids were the company's three award-winners.

"It's always an honor to be recognized by our peers and even more so to receive 25 percent of CAM Magazine's annual awards," said Glenn Granger, company president.

"It's a tribute to the dedication of our team members who worked on these projects and the remarkable customers we had the privilege to serve," he added.

Another trade publication, Engineering News-Record, ranked Granger Construction at No. 275 on the 2006 listing of the Top 400 General Contractors in the nation. Granger moved up six spots on the latest list from its position of 281 in 2005.    

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