Performance of Tire Rubber-Modified Asphalt Binder in Warm Mix Asphalt Mixtures



Warm mix technologies are being increasingly investigated in an effort to conserve energy, reduce emissions and extend paving season. This research effort evaluated the use of warm mix additives with unmodified, polymer-modified and terminal blend tire rubber-modified asphalt mixtures from Nevada and California. The study evaluated four different Warm Mix Asphalt (WMA) technologies: Sasobit, Advera, Evotherm, and Foaming. The experimental
program evaluated the resistance to moisture damage and rutting of different mixtures with and without liquid anti-strip and lime. This research effort showed that the unmodified WMA asphalt mixtures were able to achieve mixing temperature reductions of 27 to 29°C while the modified WMA asphalt mixtures were able to achieve mixing temperature reductions of 17 to 30 °C compared to their corresponding HMA control mixtures. The results showed that the use of modified binders with WMA technologies and anti-strip additives can result in mixtures with a better resistance to moisture damage compared to unmodified mixtures the same anti-strip additives. Additionally, the combination of modified asphalt binders with lime will eventually generate mixtures with better resistance to permanent deformation. A mechanistic analysis was conducted to evaluate the performance of the various WMA mixtures in typical asphalt pavements. The mechanistic analysis showed the improved performance of WMA with the terminal blend tire rubber-modified asphalt binder.

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