Evaluation of Hybrid Binder Use in Surface Mixtures in Florida

摘要

Binder and mixture tests were performed to evaluate the relative performance of a PG 67-22 base binder and six other commercially available binders produced by modifying the same base binder with the following modifiers: one Styrene Butadiene Styrene (SBS) polymer, three commercially available hybrid binder composed of different percentages of rubber and SBS polymer, and two asphalt rubber binders (5% and 12% rubber: ARB-5 and ARB-12). Results indicated that hybrid binders (modified with more rubber than SBS) that exceed the cracking performance characteristics of unmodified binder and asphalt rubber binders, and have about the same cracking performance characteristics of SBS polymer modified can be produced commercially. Results also indicated that hybrid binder can be suitably specified using existing specification requirements for PG76-22 binder and solubility. Therefore, it appears that hybrid binder has the potential to replace three binders currently used by FDOT in hot mix asphalt: SBS polymer modified asphalt, ARB-5, and ARB-12. It was recommended that FDOT develop a transition plan to accomplish this. The research also showed that existing binder tests do not accurately predict cracking performance at intermediate temperatures, even in a relative sense. A new binder direct tension test configuration was conceived and designed in the study that has the potential to obtain properties from which cracking performance of binders can be predicted. It was recommended that FDOT pursue development and evaluation of the proposed test.