Laboratory evaluation and FEM modeling of the rutting behavior of CR-enriched rejuvenator-modified RAP mixtures

Economic and environmental issues have increased the use of Recycled Asphalt Pavement (RAP) in asphalt mixture construction worldwide. The use of RAP materials results in increased hardness and reduced crack resistance of asphalt mixtures. This prompts the recommendation of rejuvenators to settle this problem. While rejuvenators enhance crack resistance, they also increase rutting potential by reducing mixture hardness. Modifying the rejuvenators with crumb rubber is one method to solve this problem. To this end, two kinds of recycled oils, namely cooking oil and engine oil, were modified by crumb rubber. They were employed as rejuvenators in asphalt mixtures with 25%, 50%, and 75% RAP. The laboratory test results indicate that rubber-modified rejuvenator mixtures exhibit better rutting resistance. Subsequently, to predict rut depth in various mixtures, a 3D finite element model (FEM) was defined in the Abaqus software. In this model, asphalt mixture behavior was defined as viscoelastic, and the effects of various factors such as the intensity of tension applied to the surface, asphalt layer thickness, and asphalt mixture temperature were investigated. The FEM analysis reveals that an increase in tension intensity, temperature, and asphalt layer thickness leads to a rise in rut depth. Furthermore, a meaningful correlation exists between FEM analysis and dynamic creep test results.