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.