A partial depth patch is the process of removing existing HMA, typically to a depth of 3 in. to 6 in. then filling the area with HMA (HMA Patching, Type __). Longitudinal patching is usually required in a widened area, where the existing asphalt surface has an open longitudinal crack or joint at the mainline/widened interface.

Although HMA overlays can accommodate small differential subgrade movement without cracking, the large differential movement at slab and crack interfaces is great enough to crack a HMA overlay (called reflection cracking). There are several techniques to prevent (or at least delay the onset of) reflection cracking:

Thin HMA overlays are suitable for both flexible (asphalt) and rigid (concrete) pavements. Any cracks should be sealed before application of thin hot mix overlays. Why (advantages): Thin HMA overlay are the most effective preventive maintenance treatment …

Full scale accelerated aging and loading used to compare the fatigue cracking performance for four combinations of with and without 4.75 mm NMAS treatment plus with and without aging. The unaged 4.75 mm NMAS overlay performed much better in fatigue cracking resistance than the untreated existing pavement in Lane 8.

2002年7月2日 · An HMA overlay is a feasible rehabilitation alternative for an HMA pavement unless the condition of the existing pavement warrants substantial removal and replacement.

Thin hot mix asphalt (HMA) overlays are plant-mixed combinations of asphalt cement and aggregate placed in depths of ¾ to 1½ inches over aging pavements as a pavement preservation treatment. The liquid asphalt binds the rocks together in a strong but flexible pavement structure.

Structural overlays are used to increase pavement structural capacity. Therefore, they are considered rehabilitation, although they typically have some maintenance-type benefits as well. Asphalt concrete structural overlay design can be broadly categorized into the following (modified after Monismith and Finn, 1984 [1]):

A concrete inlay can be used to rehabilitate existing concrete or HMA pavements. Unlike an HMA overlay, a concrete inlay does not require an increase in the pavement elevation.

Guidelines on Design and Construction of High Performance Thin HMA Overlays Implementation Product 5-5598-05-P3 & P4 Cooperative Research Program TEXAS A&M …

Currently, the only department-approved rational method for design of structural HMA overlays on rigid pavements is by using the appropriate overlay option in DARWin® 3.1 (AASHTO 93).