Computational analysis of the creep behaviour of bituminous mixtures

This report introduces a visco-elasto-plastic constitutive model for the characterisation of stress-strain behaviour in bituminous mixtures. With the introduction of the Helmholtz free energy and using the concept of internal variables, it has been possible to express a plastic flow law, characterised by isotropic hardening. The formulation of the constitutive relationship has been developed in such a way as to verify a priori the universal dissipation principle, expressed by the Clausius-Duhem dissipative inequality. The model has been calibrated and validated on the basis of the creep recovery response of two different bituminous mixtures under various stress levels and loading time.