2015 Elsevier Ltd. All rights reserved. A background of evidence of the importance and impact of damage healing in asphalt pavements from laboratory and field studies is presented. Mechanisms of healing that result in a measurable recovery of engineering properties are presented, including descriptions of the impact of crack wetting, reversal of the fracture process, and the influence of molecular morphology. Methods are described to measure intrinsic healing in asphalt binders using a dynamic shear rheometer (DSR). Healing measurements on binders are compared to the proposed mechanisms of healing in asphalt binders, including measurements of surface free energy, which are shown to be consistent with the proposed mechanisms. Later, a continuum model and a concomitant test methodology are used to measure healing characteristics in asphalt mixtures that are independent of the testing conditions, sensitive to the duration of the rest period during which healing occurs, and sensitive to the level of damage that precedes the rest period. Thermodynamic considerations of damage and microdamage healing processes are discussed in considerable detail, concluding with a general thermodynamic framework for derivation of damage and microdamage-healing constitutive relationships, with a focus on accurate estimation of stored and dissipated energies. Finally, incorporation of microdamage healing in constitutive relationships for pavement performance modeling is discussed, and future directions are identified.
