Determination of Critical Bending Stresses in Portland Cement Concrete Layer with Asphalt Overlay

An asphalt concrete overlay of a jointed plain concrete pavement is intended to extend the service life of the existing pavement structure. Also known as composite pavements, these structures exhibit features of both rigid and flexible pavements. Whereas the behavior of rigid pavements is mainly elastic, the behavior of an asphalt layer is dependent on load duration. At the same time, temperature curling causes nonlinear interaction with the foundation. The available structural models for composite pavements ignore the behavior of the asphalt layer that is load duration dependent when the composite pavement is subjected to a combination of temperature curling and traffic loads. Research was conducted to address the improvement of structural modeling of composite pavements that were subjected to slow-developing temperature curling and instantaneous traffic loads. A simplified procedure was developed that maintained compatibility with the Mechanistic–Empirical Pavement Design Guide. The procedure used a different asphalt modulus for curling than it did for axle loading and determined the total stresses in the pavement as a combination of the stresses from solutions of three elastic boundary value problems. The simplified procedure was compared with the existing design guide structural model for fatigue cracking in a jointed plain concrete pavement overlain with asphalt concrete. A framework for implementing the proposed procedure into the design guide was developed.