Airport pavement design and evaluation

Original publisher: [Washington, D.C.] : U.S. Dept. of Transportation, Federal Aviation Administration, [2002] OCLC Number: (OCoLC)317495652 Subject: Pavements -- United States -- Design and construction. Excerpt: ... 7 / 7 / 95 AC 150 / 5320-6D 404. DESIGN OF STRUCTURAL HOT MIX ASPHALT OVERLAYS. Structural hot mix asphalt overlays can be applied to either flexible or rigid pavements. Certain criteria and design assumptions are different for hot mix asphalt overlays of flexible or rigid pavements. The design procedures are presented separately. 405. HOT MIX ASPHALT OVERLAYS ON EXISTING FLEXIBLE PAVEMENT. The design of structural hot mix asphalt overlays on existing flexible pavements is based on a thickness deficiency approach. That is, the existing pavement is compared to what is needed for a new pavement, and any deficiency is made up in the overlay. a. Calculate New Pavement Requirements. Using the appropriate flexible pavement design curves ( Figures 3-2 through 3-15 ), calculate the thickness requirements for a flexible pavement for the desired load and number of equivalent design departures. A CBR value is required for the subgrade material and subbase. Thicknesses of all pavement layers must be determined. b. Compare New Pavement Requirements With Existing Pavement. The thickness requirements for a new pavement are compared with the existing pavement to determine the overlay requirements. Adjustments to the various layers of the existing pavement may be necessary to complete the design. This is particularly difficult when overlaying old pavement. Hot mix asphalt surfacing may have to be converted to base, and / or base converted to subbase. Note that a high-quality material may be converted to a lower quality material, such as surfacing to base or base to subbase. A lesser-quality material may not be converted to a higher-quality material. For example, excess subbase cannot be converted to base. The equivalency factors shown in Tables 3-6 through 3-8 ma...