Mahmoud Malakouti Olounabadi

Although bitumen only makes up a small portion of asphalt mixtures, it significantly impacts their performance. Over the past few decades, bitumen modifier additives, such as nano-silica, have been utilized to enhance asphalt performance. This research aims to investigate the influence of nano-silica on the mechanical properties of asphalt and bitumen mixtures. The study utilized crushed stone materials with grading No. 4 of the Iran Road Pavement code, 70-60 pure bitumen, and nano-silica in varying amounts (2%, 4%, and 6% by weight of bitumen). Marshall and resilient modulus test were employed to evaluate the mechanical properties of asphalt mixtures, while Marshall's resistance ratio was used to assess moisture sensitivity. Additionally, tests on penetration degree, softening point, and elasticity were conducted to evaluate the effect of nanosilica on bitumen properties. The findings revealed that the modification of bitumen with nanosilica led to decreased penetration, increased softening point, and reduced plasticity. Furthermore, the use of nano-silica improved Marshall strength and reduced Marshall's flow in asphalt mixtures, with a 6% addition of nano-silica increasing strength by 41% compared to the control sample. The addition of nano-silica also enhanced the moisture sensitivity of the mixtures and increased the resilient modulus by 95% compared to control asphalt samples.