TEMPERATURE INDUCED STRESSES AND DEFORMATIONS IN ASPHALT CONCRETE

In northern and some desert areas of the western U.S., transverse cracks have appeared in asphalt pavements. These have been attributed, in part, to thermal stresses that exceed the breaking strength of the asphalt concrete surface. The research reported in this paper aimed to investigate the development of thermal stresses and deformations in asphalt concrete under controlled lab conditions and also to ascertain under what circumstances the development of thermal stresses might indicate possible cracking of idealized representations of actual pavements. Utilizing the creep compliance measured for a range of temperatures from -40 to +110 deg F for a particular asphalt concrete, stresses and deformations under conditions of restrained deformation and creep for varying temperatures were predicted by viscoelastic theory. Measured stresses and deformations appeared to agree well with predicted values; thus, the theory was extended to predict thermal stresses due to temperature changes at the surface in a slab of the same material. For temperature changes below 0 deg F, computed stresses at the surface of an idealized representation of an asphalt concrete pavement considerably exceeded the breaking strength for the material. Thus, it could be concluded that temperature changes, especially in the range below 0 deg F, might contribute to the cracking of asphalt concrete pavements.