Investigation of the Rheological and Bonding Characteristics of Crumb Rubber-Modified Asphalt Binders Mixed with Warm Mix Asphalt Additive and Antistrip Agent

This research study evaluated the influence of crumb rubber modification and the addition of warm mix additive and liquid antistrip agent on asphalt binder properties. The experimental plan consisted of evaluating the virgin asphalt binder and crumb rubber-modified asphalt binders (CRMABs) at different doses of crumb rubber (CR). The test results were used to select an optimum content of CR that would lead to a CRMAB that meets the local specifications for polymer-modified asphalt binders. The CRMAB at optimum dose was further evaluated to assess the influence of warm mix additive and liquid antistrip agent on the asphalt binder’s resistance to moisture damage and fatigue cracking. The laboratory evaluation included the binder bond strength (BBS) test in accordance with AASHTO TP 91 and the estimation of damage tolerance of asphalt binders using the linear amplitude sweep (LAS) test following AASHTO TP101. The laboratory evaluation showed that the CRMAB with 8% CR met the local specifications for polymer-modified asphalt binders. The test results also showed while the increase in CR can have a positive effect on the rutting resistance of an asphalt binder, it may jeopardize its resistance to moisture damage and fatigue cracking. Further evaluation showed that the addition of a warm mix additive along with an antistrip agent can minimize the detrimental effects of CR on asphalt binder. In summary, this study demonstrates that a CRMAB can be engineered to meet asphalt binder specifications and result in an acceptable performance and durability. The findings from this study are highly beneficial for agencies with limited access to asphalt binder sources or performance grades but are interested in using recycled tire rubber from waste tire in their asphalt mixtures.