STRENGTH in Design

Overcoming Obstacles with Nonreinforced Concrete

The widening and repaving of U.S. 131 and construction of two interchanges is the largest single contract awarded by the Michigan Department of Transportation (MDOT). “The biggest challenge was the sheer size and magnitude of the project, which is a major highway in Grand Rapids,” notes Erick Kind, Delivery Engineer for the Grand Rapids Transportation Service Center, a division of MDOT.

Valued at $140 million, the three-year project involved the construction of 27 new bridges, interchange ramps, and 18 retaining walls, along with the moving of 5.5 million cubic meters of dirt and installation of electrical systems and signage. More than 20 subcontractors worked on the project.

A Substantial Task

Three primary contractors — Ajax Paving Industries, Inc., C.A. Hull Co., Inc., and Kamminga & Roodvoets, Inc. — formed a triventure, an unusual arrangement that worked extremely well, according to Hugh Luedtke, Project Manager at Ajax Paving. Because 131 is heavily traveled, juggling construction with the necessary lane closings and rerouting of traffic on the roadway were the toughest parts of the job.

Specifically, the improvements to 131 called for widening the section of highway extending from 44th to 76th Streets from four to six lanes, with a median dividing the two sections of three lanes, and replacing the old asphalt and concrete roadway with new concrete.

Interchanges were built at 68th Street and also where 131 crosses the new M-6 highway, a 20-mile roadway along the south side of Grand Rapids due to be completed in 2005. The work on U.S. 131 and the 68th Street interchange was completed last November, while the new M-6 interchange is due to be finished June 1, 2004.

Ajax Paving’s primary responsibility was reconstructing the concrete pavement on U.S. 131, as well as all associated ramps and interchanges and two miles of M-6. C.A. Hull built the bridges and retaining walls, and Kamminga & Roodvoets was responsible for the embankment, underground, and excavation. “Because there were so many bridges and other existing structures, the scheduling of each event was crucial, since the bridge contractor couldn’t do the work on his own, but had to be tied to the dirt contractor and to Ajax for the paving,” says Luedtke.

Staging the Project

The project was divided into five stages — the first two for the construction of northbound 131, the third and fourth on southbound 131, and the fifth on the M-6 portion of the interchange. “Up front we agreed to let Kamminga & Roodvoets be the lead contractor, so we’d have a central voice,” Luedtke adds.

Managing the lane closures and rerouting of traffic on 131 was a key challenge, considering that the road is a major artery out of Grand Rapids and that each lane closure cost the contractors $15,000 a day. “Originally, the plan was to close one lane in each direction through 2002 and 2003, but in 2002 we worked with the contractor to widen the existing bridge so that we could fit two lanes of southbound traffic and one lane northbound,” says Michael Guter, Project Engineer at URS Corporation, which represents the MDOT.

The $15,000-a-day savings that resulted from adding an extra lane of traffic resulted with the contractors receiving a $1.5 million bonus. (The lane closure rental costs are figured into the contract, so if the cost is less, as in this case, the contractors get a rebate.)

Managing the traffic in the midst of construction was difficult, notes Luedtke. “With the lanes being narrow, measuring only 11 feet wide, and much of the traffic being tourist-oriented there were numerous accidents during the project,” Luedtke says. It was an added hazard.

The contractors met with the MDOT engineer at least once a week to discuss progress on the schedule and the effect of construction on traffic flow. Meetings were held with local business owners to address traffic concerns and ways in which to direct the detours. Electronic message boards on the freeway redirected the traffic, and closings of ramps and lanes were announced on local radio stations.

Overcoming Obstacles

Guter notes that there were some unexpected delays and cost increases. For example, project engineers became concerned about the stability of the soils at the south end of the job after close examination, which led to a change in the type of bridge foundations. Originally, spread footings, which distribute the load over a wider area, were planned, but instead the contractor installed pile-supported footings, which are rooted deeper in the ground and supported by the underlying soils.

Another change was the decision by the MDOT to switch from asphalt to concrete on the 68th Street interchange. “The roadway is expected to get a great deal of turning movements and concrete is stronger, so we negotiated a new price with Ajax,” says Guter.

In another instance, a change in plans led to $234,000 in savings, which was split between the contractor and MDOT. Originally the design specs for 131 called for reinforced concrete to be used for the paving, but Ajax proposed to MDOT to use nonreinforced concrete instead. Reinforced concrete consists of two layers of concrete sandwiching a layer of steel mesh, which is poured and installed in a continuous process while the concrete is still wet. Joints are sawed into the pavement at 27-foot intervals to control the cracks that inevitably occur with concrete.

Nonreinforced Concrete

“In reality these reinforced pavements end up with cracks between the saw-cut joints and deteriorate quicker than they’re supposed to,” says Luedtke. Nonreinforced concrete lacks the steel mesh, but the sawcuts are made in closer intervals — every 15 feet — which better protects against random cracking. Because of the superior performance, quicker installation process, and lower cost of nonreinforced concrete, all states except Michigan have switched to its use for the building of highways, according to Luedtke. Because Michigan adheres to the older standards and isn’t sure the nonreinforced concrete will last as long, Ajax agreed to a seven-year warranty on the pavement. “Other jobs have been performed with nonreinforced concrete, and we feel strongly that it will last longer,” says Luedtke.

Despite initial doubts, Guter notes that the MDOT is moving to nonreinforced concrete pavements 100 percent. State officials find “it works better." The engineer said that Ajax had also agreed, as part of its warranty, to guarantee not only the materials and workmanship as in other warranty projects, but also the performance of the concrete pavement for a seven-year period. This is two years longer than most other warranties. “If the subgrade was bad, reinforced concrete would be a better material, but the MDOT paid for a strong subpavement underneath, so Ajax is confident the nonreinforced will work,” Guter says.

Ajax also was able to pave the road more efficiently through use of cutting-edge equipment, Luedtke says. Normally, a steel bar, called a dowel bar, is placed beneath each saw-cut by hand. But in this case, Ajax used two types of pavers — a Gomaco 2800 and a CMI — which saved time by automatically inserting the bars as the roadway was paved. “It’s more efficient, and the quality of bar placement is higher,” says Luedtke. The Gomaco paver was used to pave a 24-foot swath making up two lanes, while the third lane and 16-foot ramps were paved with the CMI paver. “We do not pave any wider than 24 feet at one time, because your ride quality suffers when you do,” explains Luedtke.

Ajax received a 100-percent bonus on the strength of the concrete, which was well in excess of the design criteria, Luedtke notes. At the end of 28 days two test cylinders of concrete are broken and compared with the strength specified in the design. If the cylinders are consistently above the design strength, the contractor gets a bonus. In fact, Ajax’s concrete achieved 5,875 pounds psi (per square inch) of average strength, a 67-percent increase over the 3,500-psi specified strength in the design.

“Despite unexpected changes, the immensity of the job, and lots of rainfall in the last year of the project, leading to delays, it happened on schedule and within budget,” says Kind. “The work went smoothly, and you couldn’t ask for a better group of people,” Luedtke adds, referring to the triventure. Even though each contractor is used to working on their own, everyone worked well together. The result is a greatly improved highway and interchange that will be appreciated by motorists for many decades to come.