Quantitative evaluation of the effect of dynamic pore water pressure on fracture and fatigue damage of asphalt mixture based on semi-circular bending (SCB) and digital image correlation (DIC) technology

The durability of asphalt pavement is closely related to the fracture and fatigue performance of asphalt mixture after moisture damage, and it is crucial to quantitatively analyze the effect of water on the deterioration behavior of asphalt mixture. The aim of this study was to quantitatively assess the effect of dynamic hydraulic pressure on the fracture and fatigue behaviors of AC-20 graded asphalt mixtures and to compare the differences in mechanical degradation between base course and SBS modified asphalt mixtures by using Moisture Induced Sensitivity Tester (MIST) and Digital Image Correlation (DIC) techniques. First, MIST was used to simulate the pore water pressure on asphalt pavement, then based on DIC combined with semicircular bending (SCB) test, multi-dimensional indices were obtained from both the meso and macro levels to comprehensively evaluate the fatigue and cracking resistance of asphalt mixture. The results show that: the application of cyclic pore water pressure during dynamic water scouring deteriorates the adhesive bonding at the asphalt–aggregate interface, facilitates the early initiation and accelerated propagation of microcracks, and ultimately compromises the fracture toughness of the asphalt mixture. Compared with unscoured specimens, the peak load and fracture energy of scoured specimens (5500 cycles) decreased by over 10 % and 32 %, respectively. Fatigue analysis revealed that water scouring shortened the stable propagation stage (Stage II), hastened the transition to the rapid crack growth stage (Stage III), and significantly reduced fatigue life. At a stress ratio of 0.1, Exx max , D E , and G DE declined by 33.7 %, 35.7 %, and 56.1 % for base asphalt, and 31.5 %, 24.3 %, and 55.2 % for SBS-modified asphalt.