Characterisation of fatigue resistance of alternative pavement design for the state of Qatar

Asphalt mixtures have been designed in the past in the State of Qatar to safeguard against permanent deformation associated with high temperatures. These mixtures are typically designed to have low content of unmodified binder. Consequently, there is a concern based on field observations that theyare susceptible to fatigue cracking. During the pasttwo years, a comprehensive study was conducted in Qatar to evaluatethe performance of full-scale trial sections. These sections involve the use of six different asphalt mixtures in the base course. This paper reports on the evaluation of fatigue resistance of asphalt cores that were recovered from the sections by using a continuum damage mechanics approach. The analysis hasfocused on comparing the dissipated pseudo-strain energy (DPSE) and crack growth index (R(N)). Results are used to develop guidelines for the design of fatigue-resistant mixtures in Qatar and to relate the mixture design to the structural design in order to optimise performance.