Viscoelastic Analysis of Top-Down Crack in Geosynthetic Reinforced Asphalt Pavements Using FEM

The Top-Down crack (TDC) initiates at the pavement surface and propagates downward. One of the major causes of TDC is due to stress resulting from the interaction between truck tires and the pavement surface. Various factors such as tire pressure have a significant effect on the tire-pavement contact area and can lead to the initiation and propagation of TDC. The reinforcement of pavement by geosynthetic can increase the resistance against cracking. However, the geosynthetic performance depends on some parameters such as their elastic modulus. A 3D finite element model utilizes to evaluate the influence of different tire pressures and geosynthetic modulus (that placed at the bottom of the asphalt layer) on TDCs and Bottom-Up cracks (BUCs) in geosynthetic reinforced and unreinforced pavements. In this study, the HMA layer was characterized as a viscoelastic material. The result shows that the variation of geosynthetic modulus has more effect on BUC than TDC. The study also indicates that the timing of the appearance of the cracks be latter as the geosynthetic modulus is increasing. It’s also found that the interval of initiate between BUC and TDC is reduced with increasing the geosynthetic modulus. In addition, the effect of variation of tire pressure on BUC is more than TDC.