Asphalt Concrete Overlays of Flexible Pavements. Volume 2. Design Procedures.

摘要

This report is a user's manual for thickness design of flexible overlays for flexible pavements. The design procedure is limited primarily to fatigue cracking and rutting criteria. Three cases of existing pavement condition are recognized by the procedure. These subsystems are: (1) existing pavement with remaining life, (2) existing pavement mildly cracked,and (3) existing pavement severely cracked. Each requires input from the following areas: (1) deflection testing, (2) condition surveys, (3) traffic data,and (4) materials characterization. The deflection testing serves as an aid in establishing 'design sections'and in characterizing the subgrade. The condition surveys are used to select the proper design subsystem. Traffic data must be in the form of 18-kip equivalent axle loads. The materials characterization consists of laboratory testing to determine modulus values for each material. The overlay thickness design involves the use of inputs from the above four areas along with an elastic layered theory computer program, a fatigue equation and a rutting equation to detemine a thickness that satisfies both the fatigue and rutting criteria. A complete example problem solution for the remaining life subsystem is presented. This volume is the second in a series. The first is:Vol. 1. FHWA-RD-75-75Asphalt Concrete Overlays of Flexible Pavements -Development of New Design Criteria.