Evaluation of fatigue life of semi-flexible pavement with cement asphalt emulsion pastes

Abstract

Semi-flexible pavement (SFP) has been receiving more attention in pavement engineering due to its excellent rutting resistance. However, conventional SFP has a lower cracking fatigue resistance than conventional asphalt mixture due to its brittleness. To improve its fatigue resistance, cement-asphalt emulsion paste (CAEP) is employed as a more suitable grouting material to prepare SFP, and the effect of asphalt emulsion content in grout on the fatigue resistance of SFP is investigated. Since the elastic modulus of SFP with different CAEPs differs significantly, the typical tensile stress response of different SFPs in pavement structure varies greatly; thus, the fatigue resistance of SFPs is influenced considerably. To reasonably evaluate the fatigue resistance of SFPs, the fatigue life of SFPs at the typical tensile stress is studied. To this end, firstly, the fatigue models of materials were established for long-term performance evaluation and fatigue life prediction by employing indirect tensile fatigue test. Secondly, the tensile stress at the bottom of surface layer materials under realistic tire-pavement interactions was estimated by a three-dimensional (3D) finite element method (FEM). Finally, obtained tensile stresses from pavement response analysis were used in fatigue models to select an ideal SFP in terms of fatigue performance. The fatigue evaluation results indicated that conventional SFP with cement paste has much lower fatigue resistance than conventional asphalt mixture. The fatigue resistance of SFP can be greatly improved when CAEP is used as grout in SFP. When the asphalt emulsion to cement ratio by mass (AE/C) is 0.4, SFP can have better fatigue resistance than conventional asphalt mixture. Therefore, CAEP with AE/C at 0.4 is recommended as the best grout in SFP to obtain the best fatigue resistance.