State test of recycled tire-asphalt mix planned 4-mile section of Route 140 to be repaved

November 22, 1993|By Traci A. Johnson | Traci A. Johnson,Staff Writer

About four miles of Route 140 between Westminster and Taneytown will be repaved as a test section in the State Highway Administration's rubber tire-asphalt research program.

"The . . . section was selected to be paved with asphalt with recycled tires in the mix," said Randy Houck, a SHA resident maintenance engineer for the county. "It is a good area to test the mix."

The section that will be repaved is between Mayberry Road and Taneytown. The surface was repaved about five or six years ago.

But, Mr. Houck said, the road had minor surface problems in addition to being a good place to test the new asphalt mix.

"The road has been selected because there has been some environmental cracking," he said. "When you drive down the road at 55 mph, you don't see the cracks.

"It's being used because, well, it was in good shape, but it was showing a lot of cracks."

The SHA's rubber tire-asphalt testing began in 1991 when scrap tire rubber was used in repaving a small section of Route 543, Ady Road, in Bel Air.

The highway administration recently completed another test site, three miles of Route 340 west of Route 15 to west of Catoctin Creek in Frederick County.

The Route 140 test will give highway officials the opportunity to study the difference between conventional asphalt cement and asphalt rubber mixture. Two types of mixtures -- one wet and one dry -- will be tested on Route 140 to see which is more durable and provides the better driving surface.

The wet mix consists of rubber tires blended into hot asphalt. The dry mix incorporates small pebbles into aggregate, which is then mixed with hot asphalt.

The SHA will try to incorporate scrap-tire rubber into highway projects throughout the state in an effort to dispose of scrap tires, which will not be allowed in Maryland landfills after 1994.

Congress has delayed for one year federal legislation that would require 5 percent scrap tire rubber to be used per ton of asphalt that will be laid during 1994.

The proposed federal goal is the use of 20 percent scrap rubber in paving by 1997.

Hal Kassoff, SHA administrator, said in a news release that the delay can be used to address cost issues -- the scrap rubber asphalt costs more than regular asphalt -- and the environmental effects of recycling tires.

Mr. Kassoff said the process involves shredding the tires; separating the steel and fabric; and grinding, bagging and transporting the materials to an asphalt plant, where it is blended with the asphalt.

"Although this is a complicated process, SHA believes in the value of recycling in order to preserve our environment," Mr. Kassoff said. "We continue to hope that asphalt-rubber pavement will provide quality road surfaces for our customers, while ensuring safety on Maryland highways."

The State Highway Administration, the Maryland Environmental Service and the University of Maryland began research in January on the use of scrap rubber in asphalt pavements.

The university received a grant from the Environmental Service and $310,000 from SHA for the research.

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