Rubber-Modified Asphalt for Roads
More than 200 million pounds of rubber-modified asphalt (RMA) are used on US highways today. In fact, RMA is used right here in Georgia as well as many other states, such as California, Arizona, Texas, and Florida to name a few.
RMA provides environmental and economic performance for roads, state departments of transportation, taxpayers and drivers.
- More durable, less maintenance – using RMA makes roads more durable, improving rutting and crack resistance, which means less maintenance, which, in turn, requires less resources (think taxpayer money).
- Safer – using RMA helps prevent slippage and offers added skid resistance.
- More cost effective – asphalt is an oil-derived product. Using RMA in roads helps lessen dependence on oil as well as keeps the cost to maintain roads more stable and less expensive. Furthermore, RMA helps maintain a blacker surface which helps retain heat better, allowing for less use of salt and sand in winter months.
- Reduces traffic noise – studies have shown that roads made with RMA are 90% quieter than ordinary asphalt (source: Yokohama Rubber Company). As more people move into urban areas, this becomes a big advantage to those who live near busy streets and highways. Currently several states are using RMA to help with noise reduction.
- Environmentally sound – using end-of-life tires in roads is being green; using this highly engineered product in a productive and beneficial way is better than discarding it in landfills.
For more information on the benefits of using rubber modified asphalt in roads go to the Rubberized Asphalt Foundation website at http://www.ra-foundation.org.
It’s More Technical Than You Know
Using RMA in asphalt requires more than just taking end-of-life tires, shredding them into pieces, and then mixing it into the asphalt mixture. Technology is applied with removing the fiber and metal, putting the rubber through a cryogenic process (as the case with Lehigh Technologies), and then separating it into the appropriate particle sizes. This process coupled with industry leading quality offers a micronized rubber powder that is clean (metal and fiber free), properly sized, and manufactured to meet specific State Department of Transportation’s specifications.
Lehigh’s small particle size has big advantages in asphalt. The micronized particle size in asphalt helps keep the rubber in suspension longer. The result is increased storage stability and easier mixing and processing of the asphalt blend.
It’s About Surface Area
To better understand the mechanisms and utilization of rubber powder in asphalt for hot mix applications, Lehigh Technologies, along with two other industry partners, embarked on a study with NCAT (National Center for Asphalt Technology). This study was complete in October 2012. The results from this study can be found at: http://www.ncat.us/files/reports/2012/rep12-09.pdf.
Lehigh Technologies rubber powder particles can be studied by reviewing our SEM (Scanning Electron Microscope) photos in our Application & Development section of the site. These photos demonstrate the precision of the cryogenic turbo mill process (through the uniform particle morphology). Our micronized rubber powders employ a broad distribution of particle sizes to offer tight packing (high bulk density). This, coupled with a high proportion of fine particles (high surface area), means better stress distribution and more interfacial bonding opportunities.
To learn about using Lehigh’s micronized rubber powders in asphalt roofing, click here Construction.