Investigation of the High-Temperature Behavior of Asphalt Binders Modified by Warm Additives through Performance Grade and Multiple Stress Creep and Recovery System

Abstract

Recently, a new test method, multiple stress creep and recovery (MSCR), was suggested to improve the current performance binder tests. In the MSCR test method, the behavior of binders in high temperatures was evaluated. One of the advantages of this new specification was to better capture the rutting behavior of binders. The aim of this research was to investigate the rheological behavior of modified binders through MSCR and a performance grade (PG) test and compare the results of grading binders through two different methods of MSCR and PG systems. In order to modify the original binder, the warm additives (Sasobit, Rheofalt, and Zycotherm) were used in this study. Results demonstrated that warm additives improve the rheological behavior of the original binder. The results of two parameters [nonrecoverable creep compliance (Jnr) and percent recovery (R%)], which derived from MSCR test, indicated that Jnr decreases and R% of binders increase. In comparison with modified binders, binders modified with 3% Sasobit (S) have the lowest Jnr and highest percent recovery value, which gives rise to the original binder to better resistance against rutting. According to the PG method, binders containing 3% additive S can be used in all climatic regions in Iran.