An innovative approach to characterize the micro- and macromechanical damage phenomena resulting from fatigue cracking and relate them to the design and durability of pavements has been developed. In this approach, crack propagation and its associated damage are considered as irreversible processes, and hence the general framework of the thermodynamics of irreversible processes is used to model fatigue crack propagation behavior. A constitutive equation, the modified crack layer model, is used to extract material parameters characteristic of the pavement’s resistance to fatigue crack propagation. These parameters are the specific energy of damage, γ′, and a dissipative characteristic, β′, of the paving mixture. The general applicability of the proposed approach has been extended to examine fatigue crack propagation data of concrete reported in the literature. It is found that the proposed model describes fatigue crack propagation behavior of concrete pavements over the entire range of the crack driving force.