Part of I-385’s Asphalt to Include Rubber Tire Scraps

Wed July 05, 2006 - Southeast Edition
Gwenyth Laird Pernie

Reconstruction of 7.8 mi. of I-385 in Laurens County, SC, will bring the busy stretch of highway up to federal interstate standards. In addition, this project is testing the viability of incorporating ground scrap tires into asphalt for paving.

According to Drew McCaffrey, resident construction engineer with the South Carolina Department of Transportation (SCDOT), reconstructive work began on the $24.9 million project in February 2004.

The primary contractor for the project is F & R Asphalt Inc. of Gaffney, SC. Frank Reeves (father of current owners Randy Reeves and Scott Reeves) opened the company in 1968 and in 1990, the Reeves brothers reorganized the company under the name of F & R Asphalt Inc.

Today it employs 150 full-time workers and has four asphalt plants throughout South Carolina.

Upgrades to the interstate will include widening the shoulders and emergency lanes, upgrading the slopes and cross sections and lifting and repairing four bridges.

According to Randy Reeves, president of F & R Asphalt, in order to modify the slopes and prepare for the new asphalt between 270,000 and 350,000 cu. yds. of borrow and between 250,000 and 300,000 cu. yds. of unclassified borrow was required.

“ In order to achieve clearance standards, the four bridges were elevated between 24 and 32 inches; and, because the bridges were all over 55 years old, they were in need of some asphalt repair,” Reeves said. “United Bridge Company of Great Falls, SC, was subcontracted to handle the bridgework.”

New Machine Assists in Job

To improve the overall paving efficiency and final product quality on the I-385 project, F & R purchased a Cedarapids CR 662 RE material transfer device (MTD).

The surge capacity built within the hopper of the Cedarapids feeds the paver’s hopper, which establishes a continuous paving process but at a slower speed than without a transfer device (which requires a stop-start paving process). This both increases production and reduces material and thermal segregation.

“Utilizing the Cedarapids on the I-385 project has improved overall paving efficiency, increased production and laid a higher quality, more uniform mat than on projects where we didn’t use an MTD,” Reeves said.

According to McCaffrey, the total amount of asphalt needed for the project is currently estimated at 237,000 tons.

Test Section Includes Rubber Tires

According to Chad Hawkins, state bituminous materials engineer of SCDOT, SCDOT is working with Asphalt Rubber Technology Service (ARTS) to test the performance of rubber-modified surface course and rubber-modified open-graded friction course (OGFC) compared to the performance of polymer-modified surface course and polymer-modified OGFC, along a 6-mi. section of this I-385 project.

ARTS is a partnership between South Carolina’s Department of Health and Environmental Control (DHEC) and Clemson University that promotes, designs, and tests uses of recycled scrap tires in rubberized asphalt and other civil infrastructure applications.

“The test sections will be the right lane [which receives the most truck traffic] of southbound I-385 between miles 20.5 and 14.6,” explained Hawkins. “There will be three test sections: one will include rubber-modified 12.5-mm with a polymer-modified OGFC overlay, the second will include rubber-modified 12.5-mm with a rubber-modified OGFC overlay, and the third will include polymer-modified 12.5-mm with a rubber-modified OGFC overlay. The remainder of the project [all lanes for the miles preceding the test sections, and the center and left lanes next to the test sections] will be the standard polymer-modified 12.5-mm with a polymer-modified OGFC overlay.”

According to Mary Corley, program administrator for ARTS, approximately 3,000 tons of rubber-modified 12.5-mm mix and approximately 1,500 tons of rubber-modified OGFC mix will be used for the project.

According to ARTS, 280 million 20-lb. (9.1-kg) scrap tires are produced annually in the United States (235 million are passenger car tires, 42 million are truck tires and 3 million are aircraft and equipment tires), which equals 5.6 billion lbs. of scrap tire waste every year. Most states do not allow whole tires in landfills because they are excellent breeding grounds for insects (especially mosquitoes) and are also fire hazards. Furthermore, buried tires tend to work their way up to the top of the landfill, becoming exposed over time.

“The method and time needed for laying both the rubberized asphalt and standard polymer asphalt are about the same; however we anticipate that the rubber modified overlay will be sticker, and possibly have a slight color difference than standard asphalt, ” stated Reeves.

Costs Between Methods Vary

“Project costs depend on a number or variables including how familiar the contractor is with the technology, the size of the project and haul time from the hot mix asphalt [HMA] plant,” Corley explained. “Typically, rubber-modified HMA costs are the same as polymer-modified HMA, but 30 percent more than conventional HMA. However, several studies of life-cycle costs of the rubberized asphalt pavements have shown that it is more cost-effective than conventional HMA because it requires less maintenance cost and has a longer life.

“The cost for the rubber-modified HMA portion of the project is approximately $250,000,” continued Corley. “This includes 4 lane-miles of rubber-modified 12.5-mm Superpave surface course and 4 lane-miles of rubber-modified open-graded friction course (OGFC).”

SC Doesn’t Process Scrap Tires

“The major drawback to utilizing scrap tires in asphalt in South Carolina is that we do not have a local processing plant to process the locally-collected tires, so currently we import the ground tire material from out of state,” Hawkins said. “ For the I-385 project, Blacklidge Emulsions Inc., a major producer of rubber-modified asphalt binders in Florida, is producing the rubber-modified asphalt binder for the project. F&R is then using that rubber-modified asphalt binder to produce the rubber-modified HMA, both for the surface course and OGFC.

“Because of this, the cost savings for utilizing this method is not in the South Carolina taxpayer’s favor,” Hawkins said. “However, from a performance standpoint, the method seems to be working quite well.”

But officials believe the results of the new technique will outshine its cost.

“Highway noise reduction can be accomplished using rubber-modified asphalt in porous asphalt mixtures like open-graded friction course,” stated Corley. “In addition, rubber-modified asphalt stress absorbing membranes [SAM] and stress absorbing membrane interlayers [SAMI] fill a unique niche in the asphalt industry by reducing pavement maintenance needs. Rubber is also a viable alternative to other polymers for use on high-volume roads that require mixtures made with modified binders for rut resistance.”

In South Carolina, the SAMI process has been used on portions of highways 261, 76, 52 and 17.

Paving of the test portion of I-385 will start in mid-July and should take approximately 30 days. The original date of completion of the reconstruction of the 7.8-mi. section of I-385 was June 2006; however, an extension has been granted and a new date for completion has not been established. CEG

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