Luther Stem Concrete Pumping of Fort Smith, AR, and Jensen Construction Company of Des Moines, IA, once again teamed up for “Part II” of the bridge crossing the Arkansas River at Sallisaw, OK.
“Part I” of the bridge project included pumping more than 7,000 cu. yds. (5.351 cu m) of concrete for piers and web walls. The piers out in the water were 12 ft. (3.6 m) in diameter and more than 100 ft. (30 m) deep. Each of the 12 piers took around 425 cu. yds. (325 cu m) of 4,000-psi concrete to fill.
In addition,the majority of work was done while pumping from a barge in the river using Luther Stem Concrete Pumping services.
As a recap, this was the third bridge to be built on this site in the last 65 years. This was because of the implementation of the Arkansas River Navigation System and increased truck traffic with the coal industry.
Also, the existing bridge was growing old and needed repairs.
Having completed the pier work in the latter part of November 2001, Jensen Construction crews worked throughout the spring and summer of 2002 setting bridge beams, welding sub-plates and tying steel on the 1,600-ft. (487 m) bridge crossing.
With the beam work and a majority of the sub-plate and rebar work completed, work began on the first of the 12 deck pours in the latter part of August 2002. The pours were sequenced in a way that one pour would be made on one end of the bridge, then the next pour would take place on the opposite end. Sections were then leapfrogged over to get to a pour farther out over the water.
This was not a problem because the deck was accessible with Stem’s long-reaching 118 or 141 ft. (36 or 43 m) Putzmeister pumps.
The bridge deck was 84 ft. (26 m) wide with a center barrier wall. It was mandatory that both sides were done in a continuous pour. To accomplish this, Jensen Construction used a Bidwell unit with screeds and rollers on both sides of the center barrier wall. To get the concrete to the screed, a ConForms 60-ft. (18 m) deck placer was attached to a 5-in. (13 cm) deck line using a 20-ft. (6 m) hose between the placer and the hard line.
A ConForms quick connect was used to speed up the process of breaking down the deck line every 30 ft. (9 m). As the pour got closer to the boom pump and the deck placer was no longer needed, it was removed by a crane sitting on the barge below the bridge.
The majority of these pours had 150 to 200 ft. (46 to 61 m) of system connected to the 141-ft. (43 m) Putzmeister pump. The system was laid out flat over the front of the pump and consumed an average of 400 cu. yds. (306 cu m) of concrete per pour.
The concrete was supplied by Mid-Continent Concrete Company of Tulsa, but delivered out of their Sallisaw branch approximately 9 mi. from the construction site.
All pumping was rather routine with the exception of one pour in the very center of the bridge. Because of sequencing and in order to load the center beams first and avoid arching, the 300-ft. (91 m) center span had to be pumped before a lot of the adjoining pours could be made.
Therefore, the equipment would have to pump a combined distance of nearly 800 ft. (244 m) from the back of the pump down through approximately 600 ft. (183 m) of 5-in. (13 cm) system and then through the 60-ft. (18 m) placer and onto the deck to reach the center span section. Amazingly, at one point, 80 yds. (73 m) of concrete was placed in one hour through the 800 ft. of system.
Although cleanup of 600 ft. (183 m) of deck pipe can be daunting, the process selected was quick and easy. Instead of cleaning each of the 60 separate adjoining pipes, the crew unhooked the hose from the boom’s end, inserted a pig with a blow out cap and forced air through the line using an air compressor. They then blew the pig through the line with the residual concrete falling into a 3-yd. (2.7 m) bucket, which a crane on the barge held in the air.
“These are the type of pours where you lie awake nights thinking about things that can go wrong and what you need to do to prevent it,” Luther Stem, owner of Luther Stem Concrete Pumping, said. “I knew it was going to be a tough pour. We put three yards of 9-sack grout and almost three yards of concrete in the pump before anything ever came out of the other end of the placer. When you’re pushing concrete extremely far, with the slumps the contractor wanted, and the pressures needed, anything can go wrong. However, without even so much as a small bump, the pour went like clockwork.”
At one point during the center span pour, Ron Barnes, job superintendent for Jensen Construction, approached the back of the Putzmeister pump and looked at the pressure gauge, which was hitting 360 bar. Grinning, he said, “Luther, what are you worried about, you’ve still got 40 bar left?”
Of the 10,000 cu. yds. (7,645 cu m) used on the project, more than 70 percent were used for the piers and 30 percent for the bridge deck. The $20-million project was slated for completion by mid-2003.
“You can prepare all you want for a job like this, but you have to have confidence in your equipment. We only had a back-up pump for the one long pour and it wasn’t needed,” said Stem. “We pumped over 10,000 yards of concrete on the entire project without so much as a blown 90.
“Some might say that we were lucky, but more realistically, we have confidence in the reliability of our Putzmeister pumps and know they are thoroughly maintained and ready for whatever we put them up against.”
Proud of the company’s accomplishments, he added that, “We’re a small company with just four pumps, but we’ve handled some fairly good size jobs that were both difficult and complex. Sure the big companies do the big mat pours with 10 or 15 pumps, putting down 10,000 yards in one day. While that is very impressive, I would put our smaller company up against anybody when it comes to hard work, trained and competent employees and overall customer satisfaction.
“Contrary to what some might think, there is a place in our industry for the smaller owner-operator pumping company.”