The effects of aging on asphalt-aggregate mixtures is a topic that has been gaining attention in recent years. Of special interest is how the fatigue performance of asphalt concrete mixtures changes with time because of changing material properties. The fatigue performance of a mixture is related to its viscoelastic material properties. An investigation of the effects of aging on viscoelastic properties of an asphalt-aggregate mixture, such as creep compliance, relaxation modulus, dynamic modulus, and phase angle, is discussed in this paper. The framework for including the effect of aging in an existing uniaxial constitutive model is established, and the applicability of Schapery’s elastic-viscoelastic correspondence principle to aged mixtures is validated.