AbstractThe aim of this study was to evaluate the impact of nanosilica (NS) and gilsonite on the behavior of asphalt binders and stone matrix asphalt (SMA) samples. An asphalt binder with 60/70 penetration grade, 0%, 3%, 5%, and 7% gilsonite, and 0%, 2%, 4%, and 6% NS by the weight of the asphalt binder were used. The rotational viscosity (RV), linear amplitude sweep (LAS), bending beam rheometer (BBR), multiple stress creep recovery (MSCR), and dynamic shear rheometer (DSR) tests were applied to evaluate the physical and rheological behaviors of modified asphalt binders. Also, the wheel track, dynamic creep, indirect tensile strength (ITS), resilient modulus (Mr), and four-point bending (FPB) fatigue tests were utilized to examine the performance characteristics of mixtures. Moreover, a two-factor analysis of variance (ANOVA) was used to analyze the data. The rheological test results showed that gilsonite and NS enhanced the rutting and fatigue resistances of asphalt binders. Gilsonite also reduced the low-temperature resistance of asphalt binders, while NS improved that. The storage stability test showed that gilsonite enhanced the storage stability of asphalt binders. Also, adding NS led to an improvement in phase separation. MSCR test indicated an improvement in the high-temperature performance of base asphalt binder at different stress levels by the addition of gilsonite and NS. Based on the LAS test, gilsonite and NS enhanced the fatigue characteristics of asphalt binders. The sample test results also showed that gilsonite and NS improved the permanent deformation resistance, MR, ITS, fracture energy, and intermediate-temperature properties of samples.

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