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Abstract

Premature failure of flexible pavements has a large problem in many Iraqi roads with drastic increase in truck axle loads. It is necessary to reduce this early collapse and make the best use of the pavement material in the design of economic. In this paper, the control on the properties of binder layer at the expense of wearing layer to achieve better balance between the damage ratio compared to the most design life are adopted. The methodology is based on the damage analysis concept which is performed for both fatigue cracking and rutting on different pavement sections using KENLAYER program.
The investigated pavement components are thickness and elasticity modulus for binder layer and thickness of wearing layer. The results of pavement analysis showed that the design life increases with increasing the thickness of wearing layer when the thickness of binder layer increases more than (3.94 in) and it decreases when the thickness of binder layer increase less than (3.94 in). The fatigue damage ratio decreases with increasing the thickness of wearing layer when increasing the thickness of binder layer more than (3.94 in) and it increases with increasing the thickness of wearing layer when increasing the thickness of binder layer less than (3.94 in). The rutting damage ratio increases with increasing the thickness of binder layer and with increasing the thickness of wearing layer. Finally, the design life increases with decrease binder moduli and fatigue damage ratio increases with increasing the binder moduli and also the rutting damage ratio decreases with binder moduli (330000 psi).

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