Comparison of performance properties of terminal blend tire rubber and polymer modified asphalt mixtures

Incorporation of used tires in asphalt mixtures has been a major advancement in the using recycled materials in asphalt pavements. Tires contain some of the polymeric components that have been used to modify the asphalt binders for decades, but in a solid form. This paper presents the result of a research to examine whether or not the proper application of the tire rubber in asphalt mixtures can enhance the pavement's mechanical properties to the same degree that the traditional polymeric binder modifiers do. The performance of a terminal blend tire rubber mixture was compared to a polymer-modified mixture through mechanical testing at the Asphalt Institute laboratory. Two mixtures in this study were designed with the same gradation in accordance with the California standard specifications, one with polymer, and the other with terminal blend asphalt. Flexural beam fatigue test, Superpave shear test, and disk-shaped compact tension test were conducted to evaluate the performance of the mixtures with respect to fatigue cracking, rutting, and low temperature cracking, respectively. The results revealed that the terminal blend mixture would have a better rutting performance. Furthermore, the terminal blend mixture exhibited a slightly more ductile behavior at the low temperature of-12°C. The two mixtures showed a similar performance with respect to fatigue cracking at 20°C.