Permanent deformation in idealized bituminous composites

Abstract

Abstract

This paper describes tests undertaken to characterize the deformation behaviour of idealized bituminous mixtures and the development of a model to describe the permanent deformation exhibited by these mixtures in a wheel-tracking test. Steady state uniaxial and triaxial tests are used to characterize the deformation behaviour of the idealized mixtures over a range of stress levels, strain rates and temperatures. Results show that at low stress levels the deformation mechanism is linear viscous flow whereas at high stress levels the deformation mechanism is non-linear viscous flow with a power-law creep exponent of approximately 2.4. Wheel tracking tests have been performed over a range of applied stress levels and temperatures. Results indicate that the accumulation of permanent deformation in these idealized mixtures is non-linear. The measured uniaxial and triaxial properties have been used in a viscous model to predict the permanent deformation measured from wheel tracking tests. A method is presented for incorporating the observed non-linear behaviour of these materials in a linearized viscous approach. The results indicate good agreement between predictions and measurements, indicating the applicability of this type of model.