Detecting the Durability of Asphalt Concrete through the Deterioration of Stiffness under Dynamic Stresses

The most significant durability issues facing the asphalt concrete pavement are practicing the moisture damage and the ageing processes. An attempt has been made in the present work to verify the deterioration in the initial stiffness of asphalt concrete while practicing such durability issues. Asphalt concrete mixtures were prepared with optimum binder content and extra mixtures were prepared with a variation in the binder content of ± 0.5% within the optimum asphalt contents as a service tolerance during the asphalt mixture preparation process. The mixtures were compacted in a slab mold using laboratory rollers. Beam specimens were extracted from the slab samples and subjected to dynamic flexural stresses under constant microstrain level of 400 and at 20℃ environment. The deterioration in the initial flexural stiffness was monitored through the fatigue life of the specimens. It was observed that the fatigue life of the aged mixtures increases by (1.2, 5.6, and 1.3) folds for mixtures prepared with (4.8, 4.3, and 5.3) % binder respectively as compared with those of the control mixtures. However, the fatigue life of the moisture damaged mixtures decline by (64, 33.3, and 35.7) % for mixtures prepared with (4.8, 4.3, and 5.3) % binder respectively as compared with those of the control mixtures. It was concluded that implementation of optimum binder content can enhance the quality of asphalt concrete throughout the durability issues, and the binder content is the most sensitive issue of the asphalt concrete mixture variables in producing a sustainable pavement