A Simple Damage Approach to Modelling Fatigue in Bituminous Materials

Abstract

Results from laboratory fatigue testing indicate that the effective stiffness modulus of asphaltic material can be reduced significantly under repeated loading without the presence of visible cracking. This indicates that damage is accumulating in the asphaltic material thus reducing the effective volume able to carry the applied load (and hence reducing the effective stiffness modulus). Damage mechanics characterises the state of a material under mechanical loading by a dimensionless scalar variable (known as damage). This paper describes the application of continuous damage mechanics in a simple way to model fatigue of asphalt mixtures. A specimen for uniaxial testing has been developed and a set of stress controlled fatigue tests have been performed over a range of temperatures and stress levels. The results have been used to determine a simple evolution law for the rate of damage accumulation. Trapezoidal cantilever (2-point bend) tests have also been performed and the results have been compared to results from the uniaxial test. For the covering abstract see ITRD E118503.