ارزيابي خستگي مخلوط هاي آسفالتي بر اساس پارامترهاي انرژي

EVALUATION OF HOT MIX ASPHALT FATIGUE USING DISSIPATED ENERGY CONCEPT

Fatigue cracking is one of the most prominent distresses in asphalt pavement. Different researcher have devel¬oped some various approaches to evaluate fatigue in hot sro mix asphalt. In the constant strain mode, the fatigue life failure at 50 percent reduction in initial stiffness is widely used by asphalt professionals. In this paper, the criteria based on the dissipated energy concept consistency of energy ratio, reduced energy rate and rate of dissipated energy change were compared with the 50 percent re¬duction in initial stiffness by four point bending beam. The loading pattern used in bending fatigue test was a semi sinusoidal load. The method based on rate of dis¬sipated energy change indicates the actual fatigue life, while this is most different from the one that was indi¬cated by the method based on 50 percent reduction in initial stiffness. In order to determine the asphalt mix¬tures fatigue life, the criteria based on stiffness reduction percent in equivalent to "true failure" was suggested as a new criteria.