Evaluation of select warm mix additives with polymer and rubber modified asphalt mixtures

Warm mix technologies are being increasingly investigated in an effort to conserve energy, reduce emissions, and extend paving season. Most of the laboratory research conducted to date on warm mix technologies has been concentrated on studying the impact of warm mix technologies on unmodified asphalt binders. This research effort evaluates the use of select warm mix additives with unmodified, polymer-modified, and terminal blend tire rubber asphalt mixtures from Nevada and California. The study evaluated two different warm mix asphalt (WMA) technologies: Sasobit and Advera. The experimental program evaluated the resistance to moisture damage and rutting of different mixtures with and without liquid anti-strip and lime. Additionally, fatigue resistance of modified and unmodified asphalt mixtures without anti-strip was conducted. In this research effort, the unmodified WMA mixtures were able to achieve mixing temperature reductions of 26.7 to 29.4 degrees C while the modified WMA mixtures were able to achieve mixing temperature reductions of 16.7 to 25.0 degrees 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. Additionally, the combination of modified asphalt binders with lime will eventually generate better resisting mixtures to permanent deformation. Moreover, the resistance to fatigue cracking of HMA and WMA mixtures was also enhanced using modified asphalt binders. Furthermore, a mechanistic fatigue analysis using 3D-Move software confirmed the outcomes of fatigue testing.