Asphalt concrete inverted section pavements for long-life roads

The set-up of new pavement design methods and construction techniques, able to enhance the performance of road infrastructures and in particular of overlay systems, is a problem that is faced by design engineers involved in the road maintenance. To increase the service life allows of reducing the frequency and the costs associated to the pavement rehabilitation, ensuring safety and comfort to the users. The knowledge of the mechanical behaviour and in particular the resistance to distress of a pavement under the action of loads and temperature variations is needed. With this aim, a significant study was performed by the Authors, in particular to evaluate the benefit offered by "inverted section" pavements versus the traditional. The Mechanistic-Empirical Pavement Design Guides Software (M-E PDG 2002 v.900) was used. At first both flexible and semi-rigid pavement sections from the Italian Catalogue for extra-urban roads were considered. For each study case performance deficits were estimated. Then, it was analyzed an inverted section characterized by the interposition of an unbounded layer between the asphalt layers on the top of the structure (wearing-course and binder) and the base. At last, the Authors show the advantages resulting from the use of the inverted section, especially in retarding the propagation of longitudinal cracks, which are a common distress of flexible and semi-rigid pavements. In particular, the service life increment due to the use of inverted instead of traditional sections and the pavement response to thermal and load stresses are evaluated, providing an important reference for experimentations in situ.