ABSTRACT
Fatigue life assessment of bituminous mixtures has a great significance in the design of asphalt pavements which may be more susceptible to fatigue cracking if the asphalt binder is prone to environmental issues such as ageing and moisture damage. Therefore, it is important to incorporate these environmental conditions into the assessment to ensure an accurate in service pavement fatigue life prediction. Currently, not enough data exists regarding the moisture effects on the fatigue susceptibility of asphalt concrete mixtures. In addition, ageing has not been considered in any detail in the current fatigue life prediction relationship. Consequently, this study aims to investigate the susceptibility of asphalt concrete mixtures to fatigue damage incorporating ageing and moisture conditions. The effects of ageing and moisture using British Board of Agrément (BBA) protocols on the stiffness and fatigue of asphalt mixtures were carried out using ITSM (Indirect Tensile Stiffness Modulus) and ITFT (Indirect Tensile Fatigue Test) in strain controlled mode respectively. After moisture conditioning, the ITSM test results show that the stiffness of control asphalt mixes increased significantly at 20°C and slightly at 10°C. Similarly, there was a slight increase in the stiffness of wet-aged asphalt mixtures at both temperatures. On the other hand, ITFT results show a decrease of the control and aged asphalt mixtures fatigue life at 10°C and 20°C due to moisture effects compared to that of dry condition. Finally, there was an observed increase in the fatigue life when those mixtures become stiffer due to LTOA.
