Grading of Australian bitumen by multiple stress creep recovery

摘要

primarily on viscosity. Other parts of the world have adopted the dynamic shear rheometerbased multiple stress creep recovery (MSCR) test as the basis for high temperature grading of paving bitumens. The move to MSCR grading of bitumen reflects the ability to test and compare different types of bitumen in an objective way that better reflects field performance. MSCR results were obtained for 42 Australian bitumen samples, spanning 12 grades, falling into five types of bitumen, including unmodified, acid-modified, elastomer and plastomer polymer modified, as well proprietary elasto-plastomeric products. The typical MSCR-based grading of Australian bitumen was determined and the intra-grade variation was assessed. MSCR was found to grade Australian bitumens at lower service temperatures than the older | G*|/ sin(delta) parameter. Further, a high stress sensitivity was observed for the polymer-modified samples. It is recommended that the MSCR test be considered for inclusion in Australia bitumen specification, particularly for high stress and high temperature applications, and that further work be undertaken to understand the generally high degree of stress sensitivity.