Finite Element and Mechanical Modeling of Fatigue Behavior of Partial Vapor-Conditioned Viscoelastic Material

Abstract

Past studies have shown that vapor conditioning to 100% Relative Humidity (RH) reduces the fatigue life of viscoelastic materials such as asphalt binder. However, it is not known how partial vapor conditions such as RH 25%, 49%, and 71% affect asphalt binder’s fatigue behavior. In addition, it is unknown which viscoelastic material parameter (i.e. viscus or elastic parameter) is responsible for damage in asphalt binder or Asphalt Concrete (AC) in general and what steps can be taken to reduce fatigue damage. In this study, films of asphalt binders were prepared and partially vapor-conditioned in enclosed chambers containing potassium acetate (25% RH), potassium carbonate (49% RH), and sodium chloride solutions (71% RH). Creep nanoindentation tests were performed on the vapor-conditioned asphalt film samples. The nano-creep test data are fitted using Burgers models. The Burgers model shows that elasticity increases and viscosity decreases as RH% increases. To this end, a Finite Element Method (FEM) model is developed in ABAQUS to examine the fatigue performance of the asphalt binder at 49% vapor-conditioned only. Using the spring and dashpot elements of Burgers model as FEM inputs, simulations are run. Results indicate that an increase in binder viscosity would reduce permanent deformation in the viscoelastic material.