Analytic analysis of a grid-reinforced asphalt concrete overlay

This paper presented an analytic investigation of pavement systems subjected to mill-and-overlay treatments - including grid reinforcement in-between the new asphalt concrete (AC) overlay and the underlying (existing) cracked and aged AC. The investigation was based on an updated version of the classic layered elastic theory capable of handling a fragmented layer.

Such a layer mechanically replicates a multi-cracked AC offering considerable vertical stiffness alongside low bending rigidity. A thin high-modulus layer represented the reinforcing grid, fully bonded to the abutting AC layers. Three mill-and-overlay cases and an additional reference case were investigated for a pavement system under the loading of a dual-tire configuration.

The cases differed by the milling depth (thin, medium, and thick), and by the inclusion or exclusion of a reinforcing grid. Key responses in the structure and subgrade, commonly associated with different pavement distress, were calculated and compared across the different cases. The analysis suggests that a reinforcing grid can potentially reduce bottom-up cracking and permanent deformation within the AC overlay for the medium and thick mill-and-overlay cases.

For the thin mill-and-overlay case, the analysis suggests that topdown cracking is the expected distress mechanism. In this context, the inclusion of a reinforcing grid seemed to be ineffective. Finally, it is found that adding reinforcement to any of the mill-and-overlay cases produces only a marginal effect on key responses linked to the development of permanent deformation deeper in the structure and subgrade.