Semnan University Press Journal of Transportation Infrastructure Engineering 2423-5350 7 1 2021 05 22 Laboratory Comparison of the Effect of Using Geogrid and Nano-Silica on the Fatigue Behavior of Hot Mix Asphalt Laboratory Comparison of the Effect of Using Geogrid and Nano-Silica on the Fatigue Behavior of Hot Mix Asphalt 53 68 4619 10.22075/jtie.2020.20962.1466 FA Gholam Ali Shafabakhsh Faculty of Civil Engineering, Semnan University, Semnan, Iran Hossein Bahrami Faculty of Civil Engineering, Semnan University, Semnan, Iran Mahdi Akbari Faculty of Civil Engineering, Semnan University, Semnan, Iran 0000-0002-9359-5095 Journal Article 2020 07 26 It is very important to focus on treatments aimed at strengthening and improving the asphalt layer to increase the life of the pavement. Among the methods to increase the life of asphalt concrete pavement against structural failures that have been discussed in this study include the asphalt mixture modification approach (using Nano-silica) as well as asphalt reinforcement approach (using geogrid). In this study, based on the results of previous studies, the increase in fatigue life of these two approaches and their comparison with the fatigue life of control samples has been investigated. To determine the fatigue life of asphalt mixtures, the fatigue test of 4 points bending (4PB) beams under constant strain conditions (at 3 levels of 500, 700 and 900 micro-strains) has been used. The results show that by addition (in wet method) of Nano-silica to pure bitumen, the fatigue life of asphalt mixture is increased for both samples of Nano-silica modified and geogrid reinforced asphalt mixtures. For example, at a strain level of 500 micro-strain, the addition of 5% Nano-silica increases the fatigue life by about 193.9% (equivalent to 2.94 times) and the installation of a geogrid layer increases the fatigue life by about 212.4% (equivalent to 3.12 times). Also, asphalt mixtures reinforced with geogrid at the strain levels of 500, 700 and 900, respectively, increased the fatigue life of the mixture by about 6.5% (equivalent to 1.06 times), 61% (equivalent to 1.61 times) and 1.8% (equivalent to 1.02 times) compared to the samples modified with Nano-silica. It is very important to focus on treatments aimed at strengthening and improving the asphalt layer to increase the life of the pavement. Among the methods to increase the life of asphalt concrete pavement against structural failures that have been discussed in this study include the asphalt mixture modification approach (using Nano-silica) as well as asphalt reinforcement approach (using geogrid). In this study, based on the results of previous studies, the increase in fatigue life of these two approaches and their comparison with the fatigue life of control samples has been investigated. To determine the fatigue life of asphalt mixtures, the fatigue test of 4 points bending (4PB) beams under constant strain conditions (at 3 levels of 500, 700 and 900 micro-strains) has been used. The results show that by addition (in wet method) of Nano-silica to pure bitumen, the fatigue life of asphalt mixture is increased for both samples of Nano-silica modified and geogrid reinforced asphalt mixtures. For example, at a strain level of 500 micro-strain, the addition of 5% Nano-silica increases the fatigue life by about 193.9% (equivalent to 2.94 times) and the installation of a geogrid layer increases the fatigue life by about 212.4% (equivalent to 3.12 times). Also, asphalt mixtures reinforced with geogrid at the strain levels of 500, 700 and 900, respectively, increased the fatigue life of the mixture by about 6.5% (equivalent to 1.06 times), 61% (equivalent to 1.61 times) and 1.8% (equivalent to 1.02 times) compared to the samples modified with Nano-silica. https://jtie.semnan.ac.ir/article_4619_4f387306692658a1654da9b7e1811ac2.pdf