By: Dan DeGraaf, P.E., and Bob Risser, P.E. Contributing Authors
The new M-6 freeway in Grand Rapids was one of the largest road projects in Michigan’s history and was recently opened ahead of schedule. M-6, also known as the Paul B. Henry Freeway, will carry a majority of the truck traffic around Grand Rapids, helping to alleviate congestion problems in the downtown area. The $650 million M-6, which crosses scenic southern Kent and Ottawa counties, was opened ahead of schedule to traffic by the Michigan Department of Transportation (MDOT) on Nov. 17, 2004. The freeway was built to handle 70,000 to 80,000 vehicles per day—a volume that some experts expect will be reached in the near future. In addition to the scope of the project, the technical aspects of M-6 are quite impressive as well.
This project had been a focal point for the debate between concrete and asphalt pavement for a number of years. The debate culminated with the use of alternate bids, which gave each bidding contractor the option of using concrete or asphalt pavement. In order to be sure of an even playing field during the bidding process, the development of the alternate bid specifications required a number of changes to the normal bidding process. All non-pavement items were included in a separate contract so they would not skew the results of the alternate pavement sections. Both concrete and asphalt were bid by the square yard, requiring MDOT to develop a set of specifications for bidding full-depth asphalt in that manner. Maintenance predictions and life-cycle cost analysis adjustment factors were determined by the MDOT and published prior to the letting so they could be applied to the initial cost in the bid. Ajax Paving Industries submitted the winning bid using concrete pavement. The concrete pavement bid not only won the life-cycle cost battle, but it also was lowest in initial cost.
Material and workmanship warranties are standard fixtures on most DOT projects in Michigan, but this contract also included an extra warranty covering the mix design itself. Since the contractor was given control of the mix design, they were required to provide a five-year performance warranty covering that part of the project. The performance warranty specifications also included distress threshold values that represented the very best performance of pavements in Michigan.
Total aggregate
Combined with the responsibility of the performance warranty, Ajax also was aware of the importance of this project to the citizens of West Michigan, the concrete industry and their own bottom line, and took specific steps to insure the projects success. They recognized that in order to meet the strict performance criteria for the project, they needed to use a concrete mixture that not only met the strength requirements to carry the traffic, but also one that would stand up to Michigan’s harsh freeze-thaw climate. Typical paving specifications in Michigan have focused on strength only. Ajax knew that durability elements such as permeability also were going to play a key role in their success.
Although not required by specification, Ajax requested and received permission to utilize a total aggregate gradation-based mix design as part of this project. The Michigan Concrete Paving Association has been working with MDOT to incorporate this procedure into the specifications for use on premium pavements. The design is based on the Shilstone analysis of the total aggregate gradation and utilizes two sizes of coarse aggregate to produce a combined uniformly graded aggregate matrix. This combined gradation produces a concrete mix that is not only more dense, it also is easier to place and less prone to segregation. To further ensure the durability of the mix, a premium limestone was shipped to the project site from over 350 miles away. Additionally, 30% of the cement was replaced with ground granulated blast furnace slag cement producing a very dense concrete.
According to Chris Poe, vice president of the Ajax concrete division, the company had developed new ways to test the total gradation in real time as part of their quality control process.
“We literally had to evaluate every aspect of how we handled the individual aggregates and other components of the mix under this system,” she said. “Even though you developed your mix design in the lab prior to construction, it’s not until you see the actual gradation results from the plant on paper that you understand how handling activities are affecting mix consistency.”
A time to be thankful
Despite the complexities, quality was always the primary focus on this massive project.
“We emphasized quality with every aspect of this job,” said Mark Johnston, president of Ajax Paving. MDOT project engineer Suzette Peplinski added, “When contractors are committed to a high level of safety and quality, everyone benefits.”
Ride quality was another area of importance that received added attention on this project. The warranty included a ride component, so Ajax knew that initial smoothness would be a key to maintaining that smoothness during the warranty period. Production volume was maintained to minimize paver stops and thus improve ride quality.
During a portion of the project, Ajax even utilized a new GOMACO profiler in the paving train to analyze the paving equipment and placement process. Using non-contact sonic sensors, this new equipment allows a contractor to measure ride quality on the fresh slab directly behind the paver or the finishing operations. By not having to wait until the following day to get data on their ride quality, Ajax was able to have the best opportunity to determine and correct ride problems immediately.
With all the attention focused on quality, the project still had to be constructed on time. The Ajax crews were able to open the project several months ahead of schedule. Early completion was no small scheduling matter because the mass grading work for this project had been constructed under five separate contracts. The area covered by the five separate grading contracts were each turned over to Ajax at different times in the construction season and each needed to be coordinated and scheduled accordingly.
This project is a leader and many of the things accomplished on it will eventually be incorporated into the pavements of the future. The citizens of Michigan, the industry as well as Ajax Industries have much to be proud of.
The new M-6 should provide Michigan motorists with more than 30 years of service. Roger Stafford, MDOT Grand Region Engineer, further added, “We have received numerous calls from customers expressing their thanks for the new, smooth ride. We, in turn, are grateful to our M-6 contractors for building a quality product.”
It is anticipated that the final segment will be the best performing segment of M-6 by far.
About The Author: DeGraaf is director of engineering, West Michigan, for the Michigan Concrete Paving Association. Risser is executive director of the Michigan Concrete Paving Association.
