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Permanent deformation is one of the dominant asphalt concrete damages. Significant progress has been made to realistically predict the damage. In the last decade, the mechanistic approach has been the focus of research, and the fundamental theories of viscoelasticity, viscoplasticity, continuum mechanics, and micromechanics are applied to develop the material laws (constitutive equations). This paper reviews the advancement of permanent deformation models including analogical, microstructural, and continuum-based methods. Pavement analysis using the nonlinear damage approach (PANDA) is the most comprehensive and theoretically sound approach that is available in the literature. The model coupled different damages and other phenomena (such as cracking, moisture, and phenomena such as healing, aging, etc.). The anisotropic microstructure approach can be incorporated into the PANDA approach for a more realistic prediction. Moreover, the interaction of fatigue and permanent deformation is the gap that is lacking in the literature. The mechanistic approaches have the capacity to couple these damages for unified asphalt concrete damage prediction. [ABSTRACT FROM AUTHOR]

• Proposed a sequential test procedure for fatigue and permanent deformation damage interaction. • Proposed energy-based permanent deformation failure criterion for post-flow number deformation properties. • Strain hardening in steady state has significant effect on fatigue damage rate. • The effect pre-fatigue (less than 50% of modulus) at low temperature is marginal on deformation rate at high temperature. The dominant load-induced damages, permanent deformation (PD) and fatigue cracking (F), are traditionally predicted separately by taking temperature as a variable of departure. This paper presents an experimental study of the two damages and interaction using sequential test procedure (STP) based on 'sequential damage'. The STP is conducted in PD-F and F-PD sequences on each specimen using a creep-recovery and cyclic fatigue tests. The effect of strain hardening on fatigue cracking is studied in the PD-F sequence, and the impact of fatigue cracking on permanent deformation is explored using the F-PD sequence. First, the shear deformation in tertiary stage of creep recovery is investigated using the dissipated energy ratio criterion and a new fourth creep phase is obtained. Following the PD-F sequence, strain-hardening is found a significant accelerator of fatigue damage rate, particularly on aged and laboratory produced mixes. The fatigue tests without considering the strain-hardening effect underestimate fatigue damage rate. In the F-PD sequence, the effect of pre-existing crack (up to 40% modulus reduction) on permanent deformation is found marginal. The sequential test and damage approach is an effective way to analyze interaction between damage modes and evaluate asphalt mixtures. [ABSTRACT FROM AUTHOR]

• Stress-dependent linear viscoelastic property of asphalt concrete is investigated. • Thermo-piezorheological simplicity of asphalt concrete is validated using the TTPSP. • The fundamental Triaxiality Ratio parameter is used for LVE characterization. • New model proposed that integrates the triaxiality ratio with the TTPSP. The linear viscoelastic (LVE) properties of asphalt concrete is investigated in this paper using a controlled-strain triaxial dynamic modulus test over wide frequency, temperature, and confining pressure ranges. The time–temperature-pressure superposition principle (TTPSP) is applied to validate the thermo-piezo-rheological simplicity of the tested materials using triaxial master curves. The LVE response is found highly stress-dependent at intermediate and high temperatures. The Prony series modeling of time-domain properties ascertains that confining pressure strongly correlates with long-term relaxation modulus, the absolute maximum slope of the relaxation modulus, and viscoelastic damage parameter. The stress triaxiality ratio concept is applied, and a new shift model is proposed that takes the triaxiality ratio as an internal state variable in the TTPSP. The model prediction agrees well with the experimental data. Moreover, a relationship between the long-term relaxation modulus and the triaxiality ratio is established. The triaxiality ratio coupled with TTPSP can accurately describe the stress-dependent response of asphalt concrete in the LVE domain. [ABSTRACT FROM AUTHOR]