Performance evaluation of high modulus asphalt mixtures for long life asphalt pavements

This paper describes the results of laboratory and full scale performance tests for a high modulus asphalt binder (HMAB) and mixes (HMAM) developed in this study for long life asphalt pavements. Various binder tests were first conducted on the HMAB and test results showed that the stiffness of the HMAB was significantly increased compared to the conventional binder without changing the low temperature properties of the binder. Laboratory tests for the mixes included dynamic modulus, moisture susceptibility, wheel tracking and fatigue tests.Dynamic modulus test results showed that the modulus of the HMAM was 50% higher than those of the conventional mix at the high temperatures. The results of performance test indicated that the resistances of the HMAM against moisture, rutting, and fatigue damage were better than those of the conventional mix. It was also found from the full scale test sections that the tensile strain values at the bottom of the asphalt layer for the HMAM sections were lower than those of the conventional mix sections although the asphalt layer thicknesses of the HMAM sections were thinner than those of the conventional sections. All the tensile strain values measured from the HMAM sections were within the fatigue endurance limit of 70 microstrain which is the fatigue criterion of a long life asphalt pavement. Similar to the wheel tracking test results, the rut depth occurred in the thick HMAM test section was two times smaller than the conventional pavement section.