Influence of Ageing on Deformation of Asphalt Concrete

Abstract

One of the major negative issues facing the flexible pavement throughout its service life is the decline of the quality while ageing. The present investigation deals with the permanent deformation and resilient modulus of wearing course asphalt concrete. Asphalt concrete mixtures were prepared at optimum asphalt content and at 0.5 % asphalt above and below the optimum. The mixtures were subjected to short-term ageing, then Marshall specimens were prepared and subjected to long-term ageing. Control specimens before ageing were also prepared for comparison. The specimens were subjected to 1200 repeated indirect tensile stresses at (25 and 40) °C using the Pneumatic Repeated Load System PRLS. The permanent deformation was monitored by Linear Variable Differential Transformer LVDT. The resilient modulus was evaluated. It was concluded that significant decline in permanent deformation could be detected after short and long-term ageing process regardless of the binder content or testing temperature. At optimum binder content of 4.7 %, the permanent deformation increases by (84.7, 7.2, and 43.6) % when the specimens are tested at 40°C as compared with those tested at 25°C for control, short-term aged, and short and long-term aged specimens respectively. However, the resilient modulus increases after the ageing process. At optimum binder of 4.7 %, the resilient modulus declines by (4.7, 5.2, and 12.5) % when the specimens are tested at 40°C as compared with those tested at 25°C for control, short-term aged, and short and long-term aged specimens respectively. The ageing process can decrease the susceptibility to permanent deformation and can improve the resistance to fatigue in asphalt mixtures.