Integration of MSCR Asphalt Designations in the AASHTOWare Pavement ME Design Software

Abstract: The “AASHTO M 332-23, Multiple Stress Creep Recovery (MSCR) test” has been implemented by multiple agencies throughout the USA and Canada. It overcomes the disadvantages associated with traditional ‘grade bumping’ method of M 320, especially regarding modified binders. The objective of this study is to incorporate MSCR binder grades in the AASHTOWare Pavement ME Design (PMED) software for a better evaluation of asphalt binder modifications. The inclusion of Level 3 binder grade selection corresponding to the MSCR characterization will allow users to select binders that are more representative of their current practices and naming conventions. Binder data has been collected from Wisconsin, Virginia, and Missouri to investigate how the MSCR grading system is related to the rheological and empirical properties of asphalt. After analyzing the data, MSCR asphalt designations has been integrated into PMED in two input levels. The binder viscosity parameters, A and VTS (AVTS), were used to characterize and define the MSCR binder grades for input level 3. Binder stiffness and recovery parameters from the DSR and MSCR laboratory tests were used to develop an empirical equation to determine the MSCR binder grades for input level 2. This new feature will help pavement designers and practitioners with using more modified and unconventional binders.