Reformulation of the CBR Procedure, Report 2: Design, Construction, and Behavior Under Traffic of the Pavement Test Sections
ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS GEOTECHNICAL AND STRUCTURES LAB
Pagination or Media Count:
The California Bearing Ratio CBR procedure has been the principal method used for design of flexible pavements for both military roads and airfields since its development in the 1940s. In recent years, as the use of analytical models, such as the layered elastic and finite element models, became accepted for pavement design, the CBR design procedure was criticized as being empirical, overly simplistic, and outdated. A major criticism of the procedure was the use of a correction factor Alpha factor as a thickness adjustment for traffic volume. The objectives of this research were to reformulate the CBR-Alpha procedure so that design would be based on a more mechanistic methodology and to develop performance criteria for use with the reformulation. With these purposes in mind, this report details the developmental steps of the reformulation, starting with the original CBR-Alpha procedure and ending with a new procedure based on Fr hlich s theory for stress distribution. The reformulation was verified through review of historical test data and full-scale traffic tests and analyses of an actual airfield pavement failure. The reformulation of the procedure resulted in the elimination of both the equivalent single-wheel load concept and the Alpha factor.
- Terminal Flight Facilities