The understanding of the behavior of a concrete road under fatigue loading is vital for the design and the performance prediction. A lean concrete sub base is used, especially in case of higher traffic intensity, for concrete roads for effective distribution of stresses in the pavement and sub grade. But there are apprehensions regarding utilization of bond between pavement quality concrete and lean concrete for design of rigid pavements. The present investigation presents a study on behavior of high volume fly ash concrete composite sections under flexural fatigue loading. A cement replacement level of 60% with low calcium fly ash was used for both pavement and lean concretes. A total number of 50 composite beam sections were tested under constant amplitude non reversed cyclic loading. Fatigue life distribution followed lognormal distribution at all the stress levels. Relation between stress level and fatigue life was developed for composite section. Bond between two layers of concretes proved to be beneficial from the criteria of load carrying capacity and fatigue behavior.
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