Performance evaluation of alternative polymer-modified asphalt binders

Styrene–butadiene–styrene (SBS) polymer-modified asphalt (PMA) binder is widely known to provide superior performance, particularly in terms of cracking, as compared to unmodified asphalt binder. In recent years, alternative PMA binders have been developed to meet PG 76-22 specifications and requirements from the multiple stress creep recovery (MSCR) test. However, existing tests/requirements may not be sufficient to ensure the quality of alternative PMA binders. This study evaluated seven types of alternative PMA binders using different tests, including existing Superpave PG binder tests, the MSCR test, and a newly developed binder fracture energy (BFE) test. Results showed that four alternative PMA binders can potentially have equivalent performance to SBS binder. Three deficient binders were identified in both the MCSR and the BFE tests. Superpave PG binder tests, however, distinguished only one as deficient. Compared to the MSCR test, which provides a qualitative assessment (pass/fail criterion), the BFE test brings the added advantage of providing a quantitative assessment of relative binder performance based on fracture energy density values. Findings appeared to indicate that the BFE test can be used as an effective tool for binder specification by state highway agencies.