The Use of Thin Asphalt Overlays for Pavement Preservation [techbrief]

Federal Highway Administration2019PDFBriefUnited States. Federal Highway Administration. Office of Asset Management, Pavements and ConstructionAhlstrom, GinaPetros, KatherineUnited States. Federal Highway Administration. Office of Asset Management, Pavements, and ConstructionUnited StatesOverlays (Pavements)Pavement maintenancePreservationAsphalt pavementsPavement preservationAsphalt overlayFHWA-HIF-19-053This Technical Brief provides an overview of thin asphalt overlays placed as a pavement preservation treatment. This document defines thin asphalt overlays as dense graded mixtures placed less than 1\ubd inches in thickness. Gap-graded and open-graded mixtures may be specifically designed for thin placement but they are considered specialty mixtures and are not discussed in this document. Thin asphalt overlays placed for pavement preservation are functional overlays to extend the service life of the pavement and are not intended to add structural capacity. The key benefits of a thin asphalt overlay are improved ride, corrected rutting, impermeability, and reduced noise. Project selection, mix design criteria, construction considerations and expected performance are presented. Since some aspects of the technology are still evolving; best practices and areas of caution are included.95