Investigation of Gilsonite-, polyphosphoric acid- and styrene–butadiene–styrene-modified asphalt binder using the multiple stress creep and recovery test

The multiple stress creep and recovery (MSCR) test has been proposed as a replacement for the existing high-temperature binder test (G*/sin δ). However, most studies concerning the MSCR test focused on the polymer-modified asphalt. The primary objective of this study was to investigate rutting resistance of non-polymer (Gilsonite and polyphosphoric acid [PPA])- and styrene–butadiene–styrene (SBS) copolymer-modified asphalt using the MSCR test and compare the results with the dynamic shear oscillatory test. Besides, the Hamburg Wheel Tracking Test (HWTT) was conducted to provide a benchmark to examine the rankings based on parameters G*/sin δ and MSCR compliance value Jnr. The test results indicated that there was a linear relationship between phase angle and MSCR percent recovery for the selected binders, but this relationship was dependent on modifier type. In addition, there was divergence in ranking rutting resistance of Gilsonite-, PPA- and SBS-modified asphalt binders according to G*/sin δ and Jnr. HWTT proved that the rutting resistance ranking based on Jnr was more reliable in the present study. For highly modified binders with SBS and Gilsonite, G*/sin δ overestimated the rutting resistance of Gilsonite-modified asphalt if compared to SBS-modified asphalt.