Enhancing High-Modulus Asphalt Mixture Performance: The Role of Nano-ZnO and SBS Additives in Bitumen Modification

This study explores enhancing high-modulus asphalt mixture (HMAM) performance with commonly used bitumen with a penetration grade of ۶۰/۷۰ instead of a low penetration grade. To achieve the desired stiffness and mitigate thermal cracking, three dosages of ۳.۵, ۴.۲, and ۴.۹% of zinc oxide (Nano-ZnO) and three dosages of ۳.۲, ۳.۷, ۴.۲% of styrene-butadiene-styrene (SBS) were incorporated as additives. Comprehensive performance tests were conducted, including BBR, LAS, and MSCR for bitumen, alongside low-temperature SCB and moisture susceptibility tests for the asphalt mixture. Statistical analysis using one-way ANOVA was performed to validate the results. The findings revealed that gap-graded asphalt mixtures alone did not yield HMAM; however, Nano-ZnO (۳.۵, ۴.۲, and ۴.۹%) and SBS (۳.۲, ۳.۷, and ۴.۲%) additives significantly improved dynamic modulus and produced HMAM. Based on the flexural creep stiffness and m-value results, the modified bitumen ones exhibited superior low-temperature performance; generally, at least a ۳۰% improvement in mixture performance has been achieved. Moreover, these additives improved damage resistance and fatigue performance, which can be interpreted by demonstrating enhanced orderliness and reduced polar component accumulation. Elastic recovery and non-recoverable creep compliance were notably improved through the modification process, indicating better resistance to both elastic and permanent deformations. Additionally, the modifications enhanced fracture properties and moisture resistance. The optimal percentages for Nano-ZnO and SBS are suggested to be ۴.۲% and ۳.۲%, respectively, underscoring their significant benefits in enhancing the performance of HMAM by improving the physical properties of bitumen, reducing its solubility parameter, and increasing compatibility with SBS.

کلیدواژه ها:

High-modulus mixture ، Nano-ZnO ، Styrene-butadiene-styrene ، Low-temperature cracking ، Gap-graded