A study on permanent deformation and fatigue damage interaction in asphalt concrete

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.

Automated summary

This paper presents an experimental study on the interaction between permanent deformation and fatigue cracking induced by load. The study found that strain hardening significantly accelerates the fatigue damage rate, while pre-existing cracks have a marginal effect on permanent deformation. The sequential test and damage approach is an effective method for evaluating asphalt mixtures.