Effect of Nanoclay on the Rheological Properties, Rutting, Fatigue, and Storage Stability of Polymer-Modified Binder

The main purpose of this study is to determine the physical and performance properties of binders modified with styrene–butadiene–styrene (SBS) and/or nanoclay and compare the behavior of polymer-modified binders (PMB) and nanocomposite-modified binders. In this research, classical tests have been used to investigate physical and mechanical properties, and dynamic shear rheometer (DSR), bending beam rheometer (BBR), temperature sweep, multiple stress creep recovery (MSCR), linear amplitude sweep (LAS), storage stability, and aging resistance have been used to determine rheological and operational properties. The results of examining the physical properties of nanocomposite-modified binders showed that the use of nanoclay increases resistance to thermal stresses, reduces temperature sensitivity to climate changes, and improves aging resistance. These changes are directly related to the percentage of nanoparticles. The results of DSR and BBR tests showed that SBS6, SBS3/Nc6, and SBS3/Nc8 binders with performance grades similar to PG82-16 have the best performance at the operating temperature range. The results of the MSCR and temperature sweep tests showed that, due to the increase of surface interaction between nanoparticles and the polymer matrix, nanoclay reduces permanent strains and improves elastic behavior and rutting resistance of PMB. This positive effect becomes more apparent with increasing temperature, stress intensity, and percentage of nanoparticles. I of the LAS test has shown that nanoclay improves the fatigue life of PMB at strains less than 5%. The storage stability test has shown that, despite the positive effect of increasing the percentage of nanoclay on improving the compatibility of PMB, the amount of 4% nanoclay provides a favorable performance for the storage of PMB. The findings from the response surface methodology (RSM) analysis indicate that nanoclay has a significant impact on the temperature characteristics and performance of PMB. The developed model’s predicted results were found to align well with the actual laboratory results. Through the optimization process, it was recommended to use a nanoclay content ranging from 3.9% to 4.7% in order to achieve desired performance and temperature outcomes in PMB. Specifically, for cold weather conditions, a nanoclay content of 3.2% is suggested, while for hot weather and heavy traffic conditions, nanoclay contents of 4.9% and 4% were determined.