Launch Slideshow

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The asphalt QC challenge

The asphalt QC challenge

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    National Center fo Asphalt Technology

    Kristi Connor, a former student at Auburn University, prepares an asphalt sample to run a specific gravity test. Photo: National Center for Asphalt Technology.

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    Kansas DOT

    Technicians with the Kansas DOT take an asphalt sample behind the paver.

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    National Center for Asphalt Technology

    Robert S. James, a civil engineer working in the lab at the National Center for Asphalt Technology, prepares to run a bulk specific gravity test on a sample of hot mix asphalt.

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    Milestone Contractors

    Milestone Contractors technician Dan Brown prepares to gyrate a pill specimen of hot mix asphalt in a Pine Gyratory compactor.

The Indiana DOT, meanwhile, does not have a statistically based acceptance specification, but the state's asphalt contractors would like to establish one so that contractors could be paid based on their own tests. “The state is trying to find six to 12 projects in the 2006 construction season to apply PWL, said Brad Cruea, quality control manager, Milestone Contractors L.P., Indianapolis. Milestone owns and operates 13 asphalt plants in central Indiana.

One of Milestone's challenges is to resolve differences between the contractor's test results and the state's. “We use the same models of testing equipment, but at times we get different results,” said Cruea. Milestone appeals the pay decision if the state's tests result in a pay deduction, but the contractor's tests do not. “About 10% to 15% of our test samples get appealed,” said Cruea. “We have an appeal process in which the state runs the backup sample, and that becomes the pay sample.”

Four asphalt properties make up pay factors for asphalt in Indiana. The test results on the air voids spec (target 4%) determines 35% of pay; core density figures for another 35%; asphalt cement content is 20%; and voids in the mineral aggregate (VMA) is 10% of pay. (VMA is the voids content in the aggregate blend with no asphalt binder present.) Pay bonuses are possible. For example, if air voids run between 0.035 and 0.045, the contractor gets 105% of pay for the air voids portion of the total.

Finding enough workers to be QC technicians—then training them—is a constant challenge, Cruea said. “The state has downsized and wants the contractors to do more, so we've had to hire more personnel,” he said. Milestone currently has 20 technicians, nearly double the number it had 10 years ago. Technicians become certified to do state tests by attending a one-week course at Rose-Hulman Institute of Technology. The qualification program is run jointly by Rose-Hulman and the Indiana DOT.

To find technicians, Milestone first looks within its own ranks. “We're a union company, so we have laborers, operators, people on a paving crew, who may apply,” said Cruea. “If that doesn't work, we run ads in the local newspapers. We also network among the people we work with.”

Many states offer incentives for good contractor performance on material properties and pavement smoothness. “In some cases, if a contractor has a good operation and he knows it, he can factor the incentive into his bid and that gives him a competitive advantage,” said Newcomb. “That applies to material characteristics and to smoothness.”

— Brown is a freelance writer in Des Plaines, Ill.