Rheological Performance of Asphalt Binders Under Different Creep and Recovery Periods in MSCR Test

Abstract

The present study was undertaken to evaluate the effects of creep and recovery periods on rheological responses and grading of the modified (polymer and crumb rubber modified) and unmodified binders in multiple stress creep recovery (MSCR) test. The MSCR test was conducted considering two creep periods (i.e., 1 and 2 seconds), three recovery periods (i.e., 9, 18, 27 seconds) and at three different temperatures (i.e., 52˚C, 64˚C and 76˚C). A total of 162 binder samples were tested in the laboratory using dynamic shear rheometer. The polymer modified binder showed increase in percent recovery (R) with an increase in a recovery period, while R value did not show variations with increasing creep recovery periods for the crumb rubber modified and unmodified binders. The stress sensitivity of modified binders showed mixed trend with an increase in creep recovery period. The effects of recovery period were minimal with longer creep period for modified binders. The grading based on AASHTO MP 19, could increase adequate traffic level of modified binders, when subjected to longer recovery time. The study shows that loading time in MSCR test may be relooked into for polymer and crumb rubber modified binders.