Specification Presents Challenges

By Aram Kalousdian, Editor | September 28, 2010

An approximately 13-mile asphalt overlay project on US-10 in Midland County, MI, includes rubblizing, reconstruction under overpasses in order to get the required clearances, guardrail upgrades, culvert cleaning, and replacement of two bridges over Sanford Lake. US-10 is a four-lane divided highway. Work is being done on the eastbound and westbound sides. The project began in April 2008 and will be completed in the fall.

The wearing course asphalt mix is an open-graded Superpave mix. The project is being done under the Michigan Department of Transportation's (MDOT) percent within limits (PWL) specification. PWL involves test results that show a certain percentage of the hot mix asphalt falls within specified limits. It requires a certain consistency and density in the asphalt mix.

"It was difficult to meet MDOT's specification with that asphalt. I think the temperature during the day and getting the necessary compaction has a lot to do with it. It was pretty frustrating at times," Tim Walker, project manager/estimator for Fisher Contracting Company, of Midland, MI, said. Fisher Contracting Company and Central Asphalt, Inc., of Mt. Pleasant, MI, are a joint venture on the project.

"After a fair amount of testing, placing asphalt and fixing problems, we were able to meet MDOT's specification and get the job paved out up to this point. We still have paving to do this year, but as far as all of the test strips go, they are all taken care of, we just need to go in and finish it," Walker said. The application of the asphalt has also presented challenges.

"The mix is so coarse, meaning that there are a lot of large stones in it, that the application took longer. They had to go at a slower speed in order to keep the mat where it needed to be. In addition, the compaction effort on it was a lot greater. We needed a lot of rollers. The material cools down too fast, so you need a lot of rollers on it to get the compaction before it cools off too much," Walker said.

Walker said that Fisher Contracting has had approximately 30 pieces of equipment on the project. "This is a two-year project, but we rolled most of it into one year. So we needed to ramp up our equipment and people in order to meet the valued engineering schedule that we proposed to MDOT," Walker said. Even though most of the work was rolled into one year, the project will not be done early. The bridge work at Sanford Lake is driving the schedule. They won't be completed until the end of the summer. Walker said that Fisher Contracting needed to rent some equipment for the project.

The project is over $28 million. Subcontractors on the project included Saginaw Asphalt, of Saginaw, MI (wedging, leveling and wear course paving); RMI, of Arkansas (rubblizing); Lois Kay Contracting, of Saginaw (rubblizing) and Posen Construction, Inc., of Shelby Township, MI (bridges).

Material quantities on the project include approximately 340,000 square yards of aggregate base course, approximately 250,000 square yards of rubblizing and approximately 240,000 tons of asphalt.