The characteristics of the particles of seven riverbed and three quarried rockfill materials have been determined quantitatively in terms of uncompacted void content and unconfined compressive strength of the rock from which the particles have been derived. Drained triaxial tests have been conducted on three sizes of the modeled rockfill materials of each rockfill material. The constitutive model based on disturbed state concept, which is normally adopted to depict the behaviour of solid materials such as rock/concrete, has been adopted to characterize the behavior of the particulate rockfill materials. The constitutive model has been found satisfactorily to predict the behaviour of the modeled rockfill materials. This model appears to be suited to characterize the behaviour of rockfill materials. A procedure has been presented to determine the material constants of the constitutive model for the prototype size rockfill materials using uncompacted void content and unconfined compressive strength of rock particles. This approach is better than the extrapolation techniques commonly adopted on the basis of the maximum size of the particles of rockfill materials.