A concrete pump with a telescoping boom section – one of the first such models in North America — is enjoying steady employment in Colorado, specializing in tight-quarter jobs with overhead obstructions.

Southwest Concrete Pumping, Denver, purchased the new Schwing 31-HT truck-mounted boom pump following the Bauma show in Germany, where the first-of-its-kind model was introduced to contractors and pumpers. Southwest’s Vice President Bob Rosendale says the new unit has worked every day since the company took delivery in June.

“The pump has nearly 20,000 yards of mix placed since we acquired it,” adds John Hyre, the company’s vice president/marketing. “We’re averaging about l,000 yards a week on a variety of jobs, and the pump has performed superbly on about a dozen projects.”

A unique design
With the addition of the 31-HT, Southwest Concrete Pumping’s equipment fleet has been rounded off at an even 40 pumps. “They are all Schwing models,” says Pete Degrood, sales representative. “We’ve got 29 pumps at our Denver headquarters and another 11 at our Greely branch.”

While Rosendale, Hyre and Degrood are enthusiastic about the low-profile 31-HT, the individual who likely is most appreciative of the functional capabilities of the new pump is its operator, Larry Ranum:

“When we’re working inside buildings with interior walls that create a number of bays, the telescoping action lets me work around these obstacles by extending or retracting the boom. This eliminates a lot of excess hoseline and it means I don’t have to reposition the pump as often.”

With the same horizontal reach as the standard 31-meter boom of 87 ft (and vertical reach of 102 ft), the telescoping section enables the the 31-HT to unfold in an overhead clearance of just 18 ft 7 inches.

Ranum says the retraction ability of the l5 ft 2 in. telescoping section offers indoor pumping advantages that other pumps can’t provide. “You eliminate a lot of labor when you don’t need four guys pulling hose across the mat,” he maintains. “And it results in more square footage covered in the same time a standard boom or line pump would require.”

Project proven pump
Among the jobs already completed by the 31-HT are an indoor slab for a gymnasium floor and a series of highway retaining-wall pours. On August 14, R.R. Concrete, subbing for general contractor Roche Constructors, called on Southwest Concrete Pumping to make a continuous pour for a basketball court at a recreation center in Longmont, Colo.

“We drove the pump inside the building through a 13-ft-high door and unfolded the boom with 5 ½ ft of clearance remaining below the 24-ft height of the rafters,” recalls John Hyre.

Ranum positioned the 31-HT at a 90-degree angle to the pour and boomed the entire 120 cu yds without relocating the pump. The corners were reached by adding 20 ft of line system.

“We finished the job in a little over three hours,” says Ranum. “The long haul for the ready-mix – about 40 minutes – slowed us down a bit. Under ideal conditions the pump can put out 171 yards an hour. Without a low-profile pump like this, we would have had to use a trailer pump with a lot of line and extra labor.”

On a highway widening project for C-470 in south Denver the 31-HT made retaining wall pours 15 ft high under a bridge. Only 20 ft of clearance existed between street grade and the overhead span. Four separate pours, each 80 ft long, were made during three days last September to complete the 160-yd project for general contractor Concrete Works of Colorado, which also supplied the ready-mix.

Southwest Pumping needed only the 4-ft tip hose of the 31-HT as the telescoping boom retracted and extended on each separate pour below the bridge, reaching out the full 80-ft on each pour. The one-sided Simmons forms (the shotcreted embankment formed the back of the wall) required that the mix be placed in l-ft lifts to prevent form blowout. The maneuverable pump made return passes every 30 minutes on succeeding lifts to complete the walls that are l4- to l5 in. thick.

“We made each 40-yard pour without additional line system,” Ranum says. “A pump with a conventional boom of this size couldn’t have maneuvered under the bridge. You’d have to position it away from the pour and run in a lot of line.”

Elevated mezzanines and warehouse docks and bays are other examples of projects ideally suited to the versatile new Schwing pump, Ranum says. And, adds Hyre, “We’ve kept the pump busy. It’s made at least one pour a day since we acquired it last June.”