Guidelines for the design of semi-rigid long-life pavements

Pavement distress leads to frequent rehabilitation that increases the global cost of pavement sections. A clear understanding of distress mechanisms is the cornerstone for extending pavement service life. The overall objective of this study was to provide guidance for the design of semi-rigid long-life pavements. The potential distress mechanisms in semi-rigid pavements were revisited in order to synthesize the primary factors affecting performance. One key observation from the literature was that, while thickness primarily controls fatigue cracking, material requirements are the primary factor governing other distress mechanisms. Semi-rigid sections proposed for the heaviest traffic conditions in Spain were analytically evaluated from the long-life perspective. Results showed that only some sections met the structural requirements to be considered long-life pavements; however, two of them were clearly overdesigned. In addition, thick asphalt lifts are used to delay the onset of reflective cracking, which is not a cost-effective approach. Findings from linear elastic analysis of alternative sections and observations on potential distress mechanisms led to establishment of guidelines for a more efficient design of semi-rigid long-life pavements. The established design concept integrated both layer thickness and material requirements.