ASPHALT CONCRETE OVERLAY DESIGN CONSIDERATIONS
This report contains the results of a literature survey and small computer study using the ELSYM 5 computer program to investigate the state of stresses and strains in asphalt mixtures used as overlays as compared to those used in conventional pavement layers. Results from the literature survey indicate that very thin overlays on old flexible pavements should probably be avoided since the tensile stresses between dual tires are very high, in fact, several of the overlay design procedures avoid thicknesses of less than 3 inches because of the high tensile stress state in the overlays. As the overlay thickness increases beyond 3 inches the stresses decrease and fatigue cracking problems become less severe. However, overlays on rigid pavements appear to fail either by permanent deformation due to repeated loads or stripping or cracking caused by reflection of underlying cracks. The use of elastic layered theory to study the shear stresses in overlays on rigid pavements showed that shear stresses decreased with increase in stiffness of the underlying layer. However, as the modulus of the overlay decreased these shear stresses increased dramatically, such is probably the case when low density or moisture damage is sustained by the overlay. Results of this study indicate that there are mixture design questions that should be considered further including the effects of low density and moisture damage on the stability and permanent deformation characteristics of overlay mixtures. (FHWA)
- Study conducted in cooperation with the Federal Highway Administration Research Study title: Mixture Design for ACP Overlays.
University of Texas, AustinCenter for Transportation Research, 3208 Red River Street
Austin, TX United States 78705
Texas State Department of Highways & Public TransportationTransportation Planning Division, P.O. Box 5051
Austin, TX United States 78763
Washington, DC United States 20590
- Roberts, F L
- Kennedy, T W
- Publication Date: 1984-2
- Pagination: 32 p.
- TRT Terms: Accelerated tests; Asphalt concrete; Computer aided design; Computer programs; Density; Fatigue (Mechanics); Loss and damage; Modulus; Moisture content; Overlays (Pavements); Reflection cracking; Repeated loads; Rolling contact; Shear stress; Stiffness; Stripping (Pavements); Tension; Thickness
- Uncontrolled Terms: Tensile stress
- Old TRIS Terms: Layered theories
- Subject Areas: Design; Highways; Materials; Pavements; I22: Design of Pavements, Railways and Guideways; I31: Bituminous Binders and Materials;
- Accession Number: 00392219
- Record Type: Publication
- Report/Paper Numbers: FHWA-TA-84-13+318-1 Final Rpt.
- Contract Numbers: 3-9-82-318
- Files: TRIS, USDOT, STATEDOT
- Created Date: Feb 28 1985 12:00AM