CATEGORIZATION OF ASPHALT OVERLAYS ON BROKEN AND SEATED PAVEMENTS

Breaking and seating (B/S) concrete pavements before the construction of an asphalt concrete overlay is a method adopted by several states to minimize the problem of reflection cracking in composite pavements. Breaking the slabs into smaller pieces decreases their effective length and reduces the thermal movements that are the root cause of the development of reflection cracking. The B/S treatment has a significant effect on the structural response and behavior of the concrete slab. After B/S, slab structural models such as the Westergaard model or finite element models are not applicable. The two most important factors that affect the performance of such pavements are (i) the extent of breaking and (ii) the sizes and patterns of the broken slabs. Traditionally, pavements with asphalt concrete overlays on broken and seated concrete slabs are categorized as flexible pavements, and an equivalent modulus characterizing the B/S layer is used for mechanistic modeling. To investigate the validity of this practice, a comparative analysis of a large quantity of Dynaflect deflection data on flexible, composite, and B/S pavements in Ohio is presented. The original pavement in all composite and B/S sections studied was jointed reinforced concrete. Based on maximum deflection, spreadability, and the (W sub 1)/(W sub 5) ratio, the observed performance of asphalt overlays on B/S pavements with 0.152- to 0.762-m fragments closely resembles that of composite pavements rather than that of flexible pavements.