Sensitivity of the Fatigue Life of Asphalt Concrete to Testing Variables

Abstract

The serviceability of flexible pavement is related to the fatigue life of asphalt concrete mixture. However, the loading, environment, ageing can influence the fatigue life. In the present investigation, asphalt concrete slab samples were prepared using laboratory roller compaction, beam specimens were extracted from the slab samples and tested under repeated flexural stresses. The beam specimens of 400 mm length and 50 mm height and 63 mm width were extracted from the slab samples. The beam specimens were subjected to the four-point repeated flexural bending beam test. Fatigue life of asphalt concrete mixture was assessed at three microstrain levels, (250, 400, and 750), three test temperatures, (5, 20, and 30) °C, and three asphalt binder contents, (optimum, optimum +0.5, and optimum -0.5) %. It was observed that the fatigue life declines after ageing, moisture damage, low testing temperature, high microstrain level, and lower binder content. However, the stiffness also declines at lower binder content. At 400 micro-strain level, the fatigue life declines by (30.3 and 57) % after practicing short-term and long-term ageing processes respectively. However, the fatigue life declines by (59.6) % after practicing moisture damage process. The fatigue life increases by (480, and 1370) % when the testing temperature rises from (5 to 20, and 30) °C respectively. The fatigue life of asphalt concrete increases by (43.4 and 67.7) % when the asphalt binder content rises from (4.4 to 4.9, and 5.4) % respectively.