Eleven miles of I-39 reduced to rubble;
old pavement is base for new highway
Job guaranteed to hold up at least five years
by Barry Gantenbein, editor, Western builder
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The work on I-39 from just south of Highway 54 near Plover, Wis. to Business Route 51 in Stevens Point started in April. Rubblizing, which is breaking concrete pavement into bits to serve as base course for the new roadway was done by Memorial Day. Paving was finished in August, and bridge work was done this fall to complete the job.
The job is said to be the largest rubblization job in state history, as well as the biggest warranted job in the four years the Wisconsin Department of Transportation (WisDOT) had done warranted work.
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Antigo Construction's multiple-head Badger Breaker did the rubblizing on the I-39 job.
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The concrete pavement that was rubblized and then left in place to serve as the base course for the rebuilt highway was constructed in 1970. The nearly 30year-old pavement was breaking up, with joint repair work done in 1987, 1990 and 1994.
"We were out here repairing on a pretty regular schedule," said Linda Richardson, district pavement design engineer for WisDOT.
The schedule for the job on I39, the major north-south highway in the central part of the state, called for as much work as possible to be done either before Memorial Day or after Labor Day to keep traffic disruptions to a minimum.
For instance, rubblizing started on April 13 and was completed before Memorial Day, while work on bridges didn't begin until after Labor Day. The schedule was set up to avoid lane closures during the peak of the tourist season.
The schedule also had all four lanes open to traffic on weekends all summer long.
"There's a real peak in traffic on Friday nights and Sunday afternoons. If we take one lane away, we've got problems," said John Rock, project development supervisor with WisDOT District 4.
Antigo Construction, Inc., Antigo, Wis., was the subcontractor that did the rubblization of 39 lane miles of existing concrete pavement - the biggest rubblizing job in the state and one of the biggest in the country, according to George Shinners, president of Antigo Construction.
"The size of the project wasn't a challenge as much as the need to be flexible on how much we would rubblize at a given time," said Shinners. "We had days when we did 20,000 square yards. Other days, like when we did off and on ramps, we did a couple thousand yards, maximum."
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Crazy schedule |
Shinners added, "It was the craziest schedule you've ever seen on the days we worked, and many days we didn't work for one reason or another. We couldn't do ramps on Friday, Saturday or Sunday, so we would generally do those on Thursday."
The state wanted to keep traffic disruptions to a minimum, so lane and ramp closures were limited. After Memorial Day, work was prohibited from noon on Friday to Monday morning.
Prior to Memorial day, American Asphalt crews worked six days per week. After Memorial Day, weekend lane closures were not allowed which reduced workdays to four and one-half days per week.
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A close-up look at the hammers on the multiple-head Badger Breaker, and the concrete bits the machine leaves in its wake.
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"The work schedule on Friday consisted mainly of finishing shouldering, painting, cleaning up, and removing lane closures. This meant that the asphalt paving was limited to four days per week," said John Montgomery, vice president of American Asphalt of Wisconsin, a division of Mathy Construction Co. based in Mosinee, Wis.
Montgomery added, "A large portion of the paving work in Wisconsin is done late in the construction season. We had a very aggressive paving schedule which dictated a large amount of equipment and manpower. With this project scheduled early in the construction season it wasn't a problem having enough resources to construct the project."
Paving followed closely behind rubblization of existing concrete.
"We do a lot of jobs where they must pave everything we break by the end of the day. That's typical of real high volume traffic areas," Shinners said.
Antigo Construction rubblized a total of over 274,000 square yards and averaged 12,000 square yards of rubblization a day in the 23 days of rubblizing, not including the days the crews worked on ramps.
Ramps were closed at night for rubblizing and paving, and opened to traffic the following morning. The transitional part of ramps was rubblized starting at 9 p.m., and paved by 1 a.m.
"People would wake up in the morning, and it would be done," Shinners said.
The crew for Antigo Construction used as many as three machines to rubblize the existing pavement, which allowed rubblization and pavement of three miles of pavement a day at the peak.
Antigo Construction used their multiple-head Badger Breakers (MHB) to do the rubblization.
"We had anywhere from one to three MHBs operating. The day we did the 20,000 yards we had three machines. Each one can generally do 7,000 per shift. Most of the time we had two machines working a 10 to 12 hour shift," said Shinners.
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Crushed concrete |
The Badger Breaker breaks concrete into one to two-inch size pieces through the upper three to four inches, with larger pieces farther down in the layer of crushed concrete.
"It's like crushed stone on the top, and the pieces get gradually larger as you do down. At the bottom it varies somewhat, but generally the pieces are nine inches plus or minus in width, and as much as four inches thick," Shinners said. "You get your strength on the bottom, where you have the larger pieces. They're locked together pretty tight."
A vibratory compactor followed behind the Badger Breakers.
"It's got a herringbone grid pattern on the drum, which does some final pulverizing of the surface material. It sets the top inch to two-inch sized material and smoothes it out," said Shinners.
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American Asphalt of Wisconsin used a Road-Tec shuttle buggy to feed material into a Blaw-Knox paver.
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A smooth drum vibratory compactor was used just before paving to make sure the aggregate was flat and a consistent shape.
"So when they put the mix down they get an even layer of bituminous to compact," Shinners said.
Antigo Construction didn't rubblize bridge approaches, which often have a great deal of reinforcing steel, or transitional points near structures.
On the I-39 job, crews milled 3 and 1/2 inches of concrete pavement beneath bridges where there were clearance problems.
"You have to be aware that when you're putting four to ten inches of asphalt down, depending on the design, you might have clearance problems in some cases," said Shinners.
Crews used the MHB's breaking pattern instead of saw cutting to separate the main line from ramps. The clean break left the slab intact to separate the rubblized area from the ramps, which were to be left unbroken.
"That saved time, and obviously some expense. We've done this enough, we knew we'd get a pretty clean break in the pavement where the edge of our hammers hit," Shinners said.
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Guaranteed to last |
Paving work on the job is warranted for five years. The I-39 reconstruction is the largest warranty project done in the four years the state has been doing warranty work.
On a warranty job, there are no specifications, other than performance specifications, which gives the contractor doing the work the flexibility to be innovative in construction techniques and the mix used.
For example, on this project American Asphalt of Wisconsin used a 25-mm (SMA type) gapgraded mix for the first lift.
"We hoped that the 25mm gapgraded base mix would reduce the potential for rutting and fatigue cracking," said Montgomery.
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For a more consistent mat, American Asphalt of Wisconsin used a Road-Tec shuttle buggy for the paving on I-39 near Stevens Point, Wis.
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Three lifts of mix were used to pave the mainline. A total of 7 and 1/4-inches of asphalt was placed at the centerline and 5 and 3/4-inches on the outer edge of the lanes.
The existing pavement had a 1 percent cross-slope. The new pavement design called for a 2 percent slope from the centerline, so the first lift of mix was placed about 4 and 1/2-inches thick at centerline and about three inches on the outer edge to achieve the desired cross-slope. PG58-28 asphalt was used in this 25mm gap-graded base mix.
The second lift was paved with one and 3/4-inch thick 12.5mm Superpave mix using PG58-28 asphalt.
The third lift was paved with a one and 3/4-inch thick 12.5mm Superpave mix using a polymer modified PG58-34 asphalt. This mix was also used to resurface the ramps on this project.
Blaw-Knox pavers were used on this project, and a Road-Tec shuttle buggy was used to transfer the mix from the trucks to the paver for the surface course layer.
A wedge joint, rather than a vertical butt joint, was used between lanes. Joints between lanes are tapered, which is safer for the traveling public, so there is a wide joint instead of a vertical joint.
Overlay on bridge decks was done after Labor Day. Doing the bridges before the mainline had been considered, but would have pushed the paving schedule back. Asphalt paving was completed in early August.
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Fast track |
The job was on the fast track from the start. The job got the okay from the state in late August, 1998, and a plan had to be in place by Nov. 1, 1998 for work to be done this year.
The fast pace of the job cut engineering costs. Engineering design costs were 0.6 percent, compared to 12 - 15 percent for typical job.
Every year for the life of the warranty, the state will evaluate the pavement to see if the work exceeds the thresholds set in contract. If any of the threshold levels are exceeded, the contractor must remedy the distress at no cost to WisDOT or taxpayers.
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An overhead view of a Blaw-Knox paver used on the I-39 job. Note the tapered joint that is being put in place.
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The warranty sets thresholds for cracking and rutting, if thresholds are exceeded the contractor must bring the pavement back to the original standards.
If conflict occurs on remedial work, a Conflict Resolution Team made up of two contractor representatives, two State officials, and an independent evaluator will resolve the dispute.
The warranty also calls for the contractor to seal cracks, if any appear, after three years.
From WisDOT's perspective, warranty work is attractive because the state isn't responsible for any maintenance repair work on the pavement for the life of the warranty.
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There's no need for a WisDOT inspector or WisDOT design of paving mix on warranted jobs, so there's less state personnel needed for the work.
"The approach I've taken is to watch what they're doing and document it just so we have some record of it. I might think something should be changed, but you just have to assume they're going to produce a product they feel is good," said Mike Kretschmer, a civil engineer with WisDOT District 4.
The choice of mix design and the ability to start paving in April were significant advantages of the warranty, Shinners said.
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An Ingersoll Rand dual drum compactor followed the paver during work on I-39.
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Source: Western builder Vol.89, No.43
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