Visco-Elastic Behavior of Asphalt Concrete at Various Constant Strain Levels and Binder Content

The visco-elastic behavior of asphalt concrete mixture is known to be highly susceptible to the variation in the binder content and strain level. Using laboratory roller compaction, samples of asphalt concrete slabs with the ideal binder requirement were created for the assessment. Additional samples were prepared with ± 0.5 % binder other than the optimum requirement. Beam specimens were obtained from the slab samples and tested under dynamic flexural stresses for fatigue life at 20 ℃ using three constant strain levels of (250, 400, and 750) microstrain. The variation in the visco-elastic behavior in terms of the fluctuation in the initial flexural stiffness of asphalt concrete beam specimens was assessed. The visco-elastic behavior of asphalt concrete was monitored and its sensitivity to the variation in the binder content and strain level was evaluated. It was noticed that for mixture prepared with optimum binder content, the initial flexural stiffness declines to (10, 20, and 40) % of its original values when the implemented constant strain level is (250, 400, and 750) microstrain respectively at the end of the visco-elastic stage of failure. On the other hand, such stages of failure occur after (3500, 550, and 110) seconds of loading respectively. Higher or lower binder content than the optimum requirement exhibits decline of the initial flexural stiffness to (2, 30, and 60) % and 50 % of its original values when the implemented constant strain level is (250, 400, and 750) microstrain respectively. On the other hand, such stages of failure occur after (5000, 700, and 200) seconds and (1700, 400, and 100) seconds of loading respectively.