Road Constructors Could Improve Tests

Kevin Hall, an associate professor of civil engineering in the University of Arkansas’ College of Engineering, has been testing new quality-control devices used for asphalt pavement construction. The goal was to find new ways to help companies that do road and parking lot construction meet federal testing requirements while managing costs and improving surface quality.

Two of the primary tests required by law in every asphalt construction include measuring the density of the road and the content of the asphalt mix. Traditional tests can be costly and lengthy.

But Hall’s team is bullish on two new products that he said should offer “as good or better” results than traditional tests:

• The new CoreLok vacuum sealing device, made by Instroteck Instrument Inc. of Raleigh, N.C., is apparently ideal for measuring the density of a core cylinder drilled out of pavement. The machine costs about $4,000 and has very nominal operational costs.

“We’re very high on CoreLok,” Hall said.

Traditionally, the density tests have been done using inexpensive scales. But Hall said getting a CoreLok is an investment in greater accuracy.

• New ignition ovens, made by Troxler Electronic Laboratories Inc. of Research Triangle Park, N.C., and the Thermolyne division of Barnstead International in Dubuque, Iowa, also get a thumbs up. Asphalt content determinations are almost universally made now by nuclear test equipment.

But industry experts said it costs construction companies $3,500-$4,000 annually to maintain the necessary gauges, dosimeter badges, training and licenses to conduct nuclear density testing. Plus, new gauges cost more than $9,000 each.

The ignition ovens, which burn the asphalt sample at 1,000 degrees Fahrenheit, cost $9,000 but have continued operational costs of only about 50 cents per usage. And there’s no additional certification or licensing costs.

“Ignition ovens offer an opportunity to get the asphalt content as accurately as radioactive-source devices, but with a lot less hassle, risk or cost,” Hall said.

Hall’s research was developed under the Mack-Blackwell Transportation Center, a joint venture between the UA’s engineering college and the Walton College of Business. Funded by the U.S. Department of Transportation, Mack-Blackwell provides about $650,000 annually for engineering research.