Recycled rubber asphalt modified

Recycling rubber from tires for use in asphalt pavements is a promising technology. Asphalt pavements incorporating tire rubber are claimed to have twice the lifetime of ordinary asphalt, but they can cost twice as much. Pavements with crumb rubber additives consume over one million tires per year now, and both asphalt-rubber and rubber modified asphalt concrete have considerable potential for expansion. If Federal, state, and local governments promote much broader use and demonstration of this technology, perhaps the technical issues will be resolved and usage will expand. 

One of the concerns regarding both RUMAC and A-R highways is their recyclability. Old asphalt is typically heated and mixed with fresh material to create new asphalt. There is concern that when the rubber modified asphalt is reheated, it may catch fire or produce noxious smoke. The industry claims that this will not occur, and that recycling of rubberized asphalt has been successfully done in Sweden. However, many state highway departments are not yet convinced. 

A number of methods [11,13-17] have been applied in an attempt to solve the problem and to find more effective ways of tire rubber recycling and waste rubber utilization. These methods include retreading, reclaiming, grinding, pulverization, microwave and ultrasonic processes, pyrolysis, and incineration. Processes for utilization of recycled rubber are also being developed, including the use of reclaimed rubber to manufacture rubber products and thermoplastic-rubber blends and the use of GRT to modify asphalt and cement. 

Research on the use of crumb rubber in asphalt paving needs to be intensified and brought to a conclusion. Research on newer forms of rubber and asphalt mixtures, some without patent protection (thus available at lower cost), needs to be continued. Research on how asphalt-rubber and rubber modified asphalt concrete can best be recycled should be performed. 

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