10/21/09 — State awards contracts for repair work on I-795

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State awards contracts for repair work on I-795

By Staff Reports
Published in News on October 21, 2009 1:46 PM

Contracts totaling almost $12 million have been awarded to two companies to repair pavement damage along the 18-mile section of Interstate 795 between Goldsboro and Wilson.

The contracts require that the damaged asphalt in the outside lanes be removed and replaced by Dec. 31. An additional layer of asphalt will be placed on all lanes on this same stretch by Oct. 15, 2010.

The work could begin as early as next week and at times the highway could be limited to one lane of traffic in each direction during the work.

The North Carolina Department of Transportation awarded contracts Tuesday afternoon to Barnhill Contracting Co. for slightly more than $6 million and S.T. Wooten Corp. for $5.9 million.

The total is $1.4 million less than the DOT's original estimate of $13.4 million.

I-795 was completed in December 2005, and pavement damage began appearing by the summer of 2007. The highway began as U.S. 117. It was added to the Interstate System as I-795 in October 2007.

Meanwhile, a $500,000 "winterization" project on the outside lanes was completed last fall. Those lanes were selected since that was where the most severe cracking was found. Prior to that work the state had patched a section of the southbound lanes just north of Goldsboro.

The DOT began researching the cause of the premature failure and issued a report in July of this year.

To fully correct the damage, the study recommended replacing three inches of pavement on the outside lane and then overlaying the entire roadway with three and a half inches of asphalt to increase the depth of asphalt from slightly more than five inches to over eight and a half inches.

The study attributes the problem to several contributing factors, including asphalt pavement thickness and the use of an extremely dry pavement mix that contained a low amount of the asphalt cement that binds together the stone aggregate and other mineral material together.

According to the study, the pavement's thickness made it more susceptible to the damaging effects of traffic along the route. The low amount of binding cement material may have contributed to the poor performance of the pavement, too.

The findings concluded that, although all work was conducted according to DOT specifications and policies, changes need to be made to prevent reoccurrence.

The changes include immediately switching to use of a "mechanistic" pavement analysis, which evaluates individual site and construction conditions, rather than relying on standard equations to determine the sufficiency of pavement materials.

The report found that employing such an approach to evaluating the asphalt mix used for I-795 would have predicted the early damage of this pavement.

The findings also recommend revising the process used to assess the strength and durability of asphalt mixes and eliminating the use of asphalt mixes with low amounts of binding materials unless extensive field performance history exists.

Recommendations also include reviewing the selection criteria for new types of asphalt mixes and ensuring that engineers are familiar with the performance trade-offs for various mix types.

Reports and other documents regarding the department's findings are posted online on DOT's Web site at www.ncdot.gov/newsroom.