NCAT Study Confirms Benefits of Crumb Rubber in Asphalt

The method of manufacturing crumb rubber, whether cryogenic or ambient, does not impact the performance or quality of rubber asphalt pavements. according to a new study by the National Center for Asphalt Technology (NCAT). The use of recycled tire rubber in asphalt pavement can produce longer lasting road surfaces, reduced road maintenance, lower road noise, shorter breaking distances and add to the long term cost effectiveness of the pavement, the study affirmed.

“We are optimistic that the study findings will accelerate the use of sustainable material in highway construction,” says Richard Willis, NCAT’s assistant research professor. “By increasing the use of ground tire rubber, asphalt producers will benefit from price stability as compared to more volatile oil prices which impact the cost of traditional, oil-based polymers.

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Importantly, ground tire rubber produced cryogenically or ambiently provides high performance and cost benefits in asphalt.”

In recent years, as oil prices have risen, the number of states reassessing the potential of GTR mixtures has begun to increase; however, according to NCAT, little research has been published which characterizes the influence of particle size, grinding technique and blending methodology.

The NCAT study addressed these needs and indicates that surface area and particle size of the rubbers had the most influence on the modified asphalt binder — smaller particle size, which equates to larger surface area, provides better performance.

Based on the study results, researchers also recommend that ground tire rubber should be considered an appropriate asphalt binder modifier to achieve critical high temperature performance in mixtures. Because ambient and cryogenic GTR performed equally in terms of binder modification and separation, specifications should not distinguish between the two types of materials when the GTR is 30 mesh or smaller, researchers said. And, the researchers conclude, ten percent rubber is an appropriate level of loading for asphalt binders.

© Scrap Tire News, October 2012