Asphalt


Kansas City, MO

Lehigh Technologies produces two products that are used in Rubber Modified Asphalt (RMA). MicroDyne™ is a micronized rubber powder produced from end-of-life tires. Rheopave™ is a proprietary formulation of polymers and other components designed for applications in the modification of asphalt binders and for stabilizing ground tire rubber (GTR) in RMA blends.

Micronized rubber powders (MRP) are incorporated into liquid bitumen to gain performance grade advancements in RMA. Lehigh collaborates with asphalt modifiers, manufacturers and contractors to ensure that their asphalt cement formulations meet stringent Federal Highway Administration and Department of Transportation safety and performance specifications. MRP is optimized for ease of use, with consistent particle size, extreme quality and first-in-class flowability, which are essential for RMA performance and cost effectiveness.

Rheopave™ XP10 is a blend of selective polymers and other additives designed specifically to enhance the performance of GTR in rubber-modified asphalt binders.  It disperses easily and networks with the rubber powder in RMA systems to improve dynamic shear rheometer (DSR) performance (lower phase angle), improve multiple stress creep recovery (MSCR) performance (higher percent recovery), and improve GTR storage stability (lower delta-T).  When properly formulated, Rheopave/GTR binders meet all performance requirements for polymer-modified binders. The chemistry is independent of Styrene-butadiene Styrene (SBS) and thus is not tied to SBS supply, feedstock or volatile price indexing.

RMA is a growing application for MRP in the United States and around the world. RMA is already employed or being trialed in over 35 states (including Georgia, California, Arizona, Texas and Florida) and nations such as China, Germany, Korea and Spain.

Benefits

  • Improved durability and increased rutting and crack resistance, which means less maintenance.
  • Increased safety. Some studies show that using RMA boosts traction and reduces the risk of skidding.
  • More cost-effective. Using RMA in road maintenance reduces reliance on oil-based materials and avoids the oil-price roller coaster. RMA also helps maintain a blacker surface, which retains heat better and therefore decreases salt and sand use in winter months.
  • Reduced traffic noise. Studies show that roads made with RMA are significantly quieter than those made with regular asphalt surfaces.
  • Reduced environmental footprint. Using MRP reduces use of oil-based materials and diverts end-of-life tires and post-industrial rubber from landfills.

For more information on the benefits of using RMA in roads, visit the Rubberized Asphalt Foundation website.

Research
To better understand the interaction between MRP and asphalt, Lehigh Technologies embarked on two studies with the National Center for Asphalt Technology (NCAT):

With over a decade of successful commercial use and strong technical support provided by these NCAT studies, the utilization of Cryogenic GTR and MRP in asphalt binder modification and mix designs has grown substantially. Armed with this information, over half a dozen states have modernized their Rubber Modified Asphalt Specifications to incorporate the use of cryogenically ground rubber powders.

For more detailed information and samples please contact Ryan Alleman

          Rubber is a product that            provides long-term supply. [Using RMA] is a more cost-effective and competitive way to modify asphalt, and it provides an outlay for scrap tires that may otherwise end up in landfills."

Peter Wu, bureau chief of technical assistance at the office of Materials and Research for the Georgia Department of Transportation

NCAT

Lehigh partnered with the National Center for Asphalt Technology to perform research to better understand the interaction between MRP and asphalt. This partnership resulted in two published studies:

Effect of Ground Tire Rubber Particles on Open-Graded Mixture Performance, December 2013.

Effect on Ground Tire Rubber Particle Size and Grinding Method on Asphalt Binder properties, October 2012.